Imports System
Imports System.Web
Imports System.Web.Security
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Imports System.Web.UI.HtmlControls
Imports System.Xml
Imports System.Data
Namespace RSSWebPartVB
    Public Class RSSWebPart
        Inherits WebPart
        ' Local variables to hold web-part
        ' property values
        Private _url As String
        Private _newPage As Boolean = True
        Private _showDescription As Boolean = True
        Private _showUrl As Boolean = True
        ' Property to determine whether article should
        ' be opened in same or new page
        <Personalizable()> _
        <WebBrowsable()> _
        Public Property NewPage() As Boolean
            Get
                Return _newPage
            End Get
            Set(ByVal value As Boolean)
                _newPage = value
            End Set
        End Property
        ' Should Description be displayed?
        <Personalizable()> _
        <WebBrowsable()> _
        Public Property ShowDescription() As Boolean
            Get
                Return _showDescription
            End Get
            Set(ByVal value As Boolean)
                _showDescription = value
            End Set
        End Property

' Should URL be displayed?
        <Personalizable()> _
        <WebBrowsable()> _
        Public Property ShowUrl() As Boolean
            Get
                Return _showUrl
            End Get
            Set(ByVal value As Boolean)
                _showUrl = value
            End Set
        End Property
        ' Property to set URL of RSS feed
        <Personalizable()> _
        <WebBrowsable()> _
        Public Property Url() As String
            Get
                Return _url
            End Get
            Set(ByVal value As String)
                _url = value
            End Set
        End Property
        ' This is where the HTML gets rendered to the
        ' web-part page.
        Protected Overloads Overrides Sub RenderContents( _
           ByVal writer As HtmlTextWriter)
            MyBase.RenderContents(writer)
            ' Step 1: Ensure Url property has been provided
            If Url <> "" Then
                ' Display heading with RSS location URL
                If ShowUrl Then
                    writer.WriteLine("<hr/>")
                    writer.WriteLine("<span style='font-size: larger;'>")
                    writer.WriteLine("Results for: ")
                    writer.WriteLine("<strong>")
                    writer.WriteLine(Url)
                    writer.WriteLine("</strong>")
                    writer.WriteLine("</span>")
                    writer.WriteLine("<hr/>")
                End If
                displayRSSFeed(writer)
            Else
                ' Tell user they need to fill in the Url property
                writer.WriteLine( _
                   "<font color='red'>RSS Url cannot be blank</font>")
            End If
        End Sub

Private Sub displayRSSFeed(ByVal writer As HtmlTextWriter)
            Try
                ' Step 2: Read the RSS feed into memory
                Dim wReq As System.Net.WebRequest
                wReq = System.Net.WebRequest.Create(Url)
                wReq.Credentials = _
                   System.Net.CredentialCache.DefaultCredentials
                ' Return the response.
                Dim wResp As System.Net.WebResponse = wReq.GetResponse()
                Dim respStream As System.IO.Stream = _
                   wResp.GetResponseStream()
                ' Load RSS stream into a DataSet for easier processing
                Dim dsXML As New DataSet()
                dsXML.ReadXml(respStream)
                ' Step 4: Loop through all items returned, displaying results
                Dim target As String = ""
                If NewPage Then
                    target = "target='_new'"
                End If
                For Each item As DataRow In dsXML.Tables("item").Rows
                    ' Step 5: Write the title, link, and description to page
                    writer.WriteLine( _
                       "<a href='" + item("link") + "' " + target + _
                       ">" + item("title") + "</a>" + "<br/>" + _
                       "<span style='color:silver'>" + _
                       item("pubDate") + "</span>" + "<br/>" _
                       )
                    If ShowDescription Then
                        writer.WriteLine("<br/>" + item("description"))
                    End If
                    writer.WriteLine("<hr/>")
                Next
            Catch ex As Exception
                ' Step 3: If error occurs, notify end user
                writer.WriteLine("<font color='red'><strong>" + _
                   "An error occurred while attempting to process " + _
                   "the selected RSS feed. " + _
                   "Please verify that the url provided references " + _
                   "a valid RSS page." _
                   )
            End Try
        End Sub
    End Class
End Namespace

using System;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml;
using System.Data;
namespace RSSWebPartCS
{
    public class RSSWebPart : WebPart
    {
        // Local variables to hold web-part
        // property values
        string _url;
        bool _newPage = true;
        bool _showDescription = true;
        bool _showUrl = true;
        // Property to determine whether article should
        // be opened in same or new page
        [Personalizable]
        [WebBrowsable]
        public bool NewPage
        {
            get
            {
                return _newPage;
            }
            set
            {
                _newPage = value;
            }
        }
        // Should description be displayed?
        [Personalizable]
        [WebBrowsable]
        public bool ShowDescription
        {
            get
            {
                return _showDescription;
            }

set
            {
                _showDescription = value;
            }
        }
        // Should URL be displayed?
        [Personalizable]
        [WebBrowsable]
        public bool ShowUrl
        {
            get
            {
                return _showUrl;
            }
            set
            {
                _showUrl = value;
            }
        }
        // Property to set URL of RSS feed
        [Personalizable]
        [WebBrowsable]
        public string Url
        {
            get
            {
                return _url;
            }
            set
            {
                _url = value;
            }
        }
        // This is where the HTML gets rendered to the
        // web-part page.
        protected override void RenderContents(HtmlTextWriter writer)
        {
            base.RenderContents(writer);
            // Step 1: Ensure Url property has been provided
            if (Url != "")
            {
                // Display heading with RSS location URL
                if (ShowUrl)
                {
                    writer.WriteLine("<hr/>");
                    writer.WriteLine("<span style='font-size: larger;'>");
                    writer.WriteLine("Results for: ");

writer.WriteLine("<strong>");
                    writer.WriteLine(Url);
                    writer.WriteLine("</strong>");
                    writer.WriteLine("</span>");
                    writer.WriteLine("<hr/>");
                }
                displayRSSFeed(writer);
            }
            else
            {
                // Tell user they need to fill in the Url property
                writer.WriteLine(
                   "<font color='red'>RSS Url cannot be blank</font>");
            }
        }

        private void displayRSSFeed(HtmlTextWriter writer)
        {
            try
            {
                // Step 2: Read the RSS feed into memory
                System.Net.WebRequest wReq;
                wReq = System.Net.WebRequest.Create(Url);
                wReq.Credentials =
                   System.Net.CredentialCache.DefaultCredentials;
                // Return the response.
                System.Net.WebResponse wResp = wReq.GetResponse();
                System.IO.Stream respStream = wResp.GetResponseStream();
                // Load RSS stream into a DataSet for easier processing
                DataSet dsXML = new DataSet();
                dsXML.ReadXml(respStream);
                // Step 4: Loop through all items returned,
                // displaying results
                string target = "";
                if (NewPage)
                    target = "target='_new'";
                foreach (DataRow item in dsXML.Tables["item"].Rows)
                {
                    // Step 5: Write the title, link, and description to page
                    writer.WriteLine(
                        "<a href='" + item["link"] +
                        "' " + target + ">" + item["title"] + "</a>" +
                        "<br/>" +
                        "<span style='color:silver'>" +
                        item["pubDate"] + "</span>" +
                        "<br/>");

if (ShowDescription)
                        writer.WriteLine("<br/>" + item["description"]);
                    writer.WriteLine("<hr/>");
                }
            }
            catch (Exception ex)
            {
                // Step 3: If error occurs, notify end user
                writer.WriteLine(
                    "<font color='red'><strong>" +
                    "An error occurred while attempting " +
                    "to process the selected RSS feed. " +
                    "Please verify that the url provided " +
                    "references a valid RSS page." +
                    "<BR/><BR/>" +
                    ex.Message;
                );
            }
        }
    }
}

First, you'll need to install the web part so SharePoint recognizes it. To do so, compile the web part with a strong name. Next, copy the web part .dll to the GAC, which is usually located at C:Windowsassembly. Last, create a <SafeControl> entry in the Web.config file of the target SharePoint web application that looks something like the following:

<SafeControl Assembly="RSSWebPartCS,
   Version=1.0.0.0,
   Culture=neutral,
   PublicKeyToken=5669ee1e85397acc"
   Namespace="RSSWebPartCS"
  TypeName="*"
  Safe="True" />

Of course, the Assembly, Version, PublicKeyToken, and Namespace attribute values will be those you assign rather than those shown in the preceding code.

Finally, navigate to the web-part gallery page for the site collection on which you want to place this web part (typically at http://<yourserver>/<sitecol>_catalogs/wp/Forms/AllItems.aspx, where <sitecol> is the root site of the collection). Click the New button and find your web part in the list of web-part type names. Select the checkbox to the left of the web-part type name, and click the Populate Gallery button.

Your web part should now be available to add to any web-part page in the current site collection. Select a web-part page and click the Site Actions

Figure 4.1. The custom RSS web-part property pane

Figure 4-2 shows the RSS web part in action.

Figure 4.2. The custom RSS web part in action

Imports System
Imports System.Web
Imports System.Web.Security
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Imports System.Web.UI.HtmlControls
Imports System.Xml
Imports System.Data
Public Class XMLWebPart
    Inherits WebPart
    ' Local variable to hold property values
    Private _url As String = ""
    Private _impersonate As Boolean = True
    Private _domain As String = ""
    Private _user As String = ""
    Private _password As String = ""
    Private _debug As Boolean = False
    Private _formatUsing As enumFormatUsing = enumFormatUsing.DataGrid

Private _xsltPath As String = ""
    'ENUM types will result in drop-down lists in
    'the web-part property sheet
    Public Enum enumFormatUsing
        DataGrid = 1
        XSLT = 2
    End Enum
    ' Property to set URL of source XML document
    <Personalizable()> _
    <WebBrowsable()> _
    <WebDisplayName("Url of XML document")> _
    Public Property Url() As String
        Get
            Return _url
        End Get
        Set(ByVal value As String)
            _url = value
        End Set
    End Property
    'Create property to determine whether DataGrid or
    'XSLT should be used to format output
    <Personalizable(PersonalizationScope.[Shared]), _
       WebBrowsable(), _
       WebDisplayName("Format Using:"), _
       WebDescription("What method do you want " + _
       "to use to format the results.")> _
    Public Property FormatUsing() As enumFormatUsing
        Get
            Return _formatUsing
        End Get
        Set(ByVal value As enumFormatUsing)
            _formatUsing = value
        End Set
    End Property
    'If XSLT will be used, this property specifies
    'its server-relative path
    <Personalizable(PersonalizationScope.[Shared]), _
      WebBrowsable(), _
      WebDisplayName("XSLT Path:"), _
      WebDescription("If formatting with XSLT, " + _
      "provide full path to XSLT document.")> _
    Public Property XSLTPath() As String
        Get
            Return _xsltPath
        End Get

Set(ByVal value As String)
            _xsltPath = value
        End Set
    End Property
    ' If explicit credentials have been requested,
    ' the following three properties, Domain, User, and
    ' Password, will be used to construct the credentials
    ' to pass to the page
    <Personalizable()> _
    <WebBrowsable()> _
    Public Property Domain() As String
        Get
            Return _domain
        End Get
        Set(ByVal value As String)
            _domain = value
        End Set
    End Property
    <Personalizable()> _
    <WebBrowsable()> _
    Public Property User() As String
        Get
            Return _user
        End Get
        Set(ByVal value As String)
            _user = value
        End Set
    End Property
    <Personalizable()> _
    <WebBrowsable()> _
    Public Property Password() As String
        Get
            Return _password
        End Get
        Set(ByVal value As String)
            _password = value
        End Set
    End Property
    ' If this option is checked, the web part will use
    ' the default credentials of the user viewing
    ' the web-part page.
    <Personalizable()> _
    <WebBrowsable()> _
    Public Property Impersonate() As Boolean
        Get
            Return _impersonate
        End Get

Set(ByVal value As Boolean)
            _impersonate = value
        End Set
    End Property
    ' Display debug info?
    <Personalizable()> _
    <WebBrowsable()> _
    Public Property Debug() As Boolean
        Get
            Return _debug
        End Get
        Set(ByVal value As Boolean)
            _debug = value
        End Set
    End Property
    ' This is where the HTML gets rendered to the
    ' web-part page.
    Protected Overloads Overrides Sub RenderContents( _
       ByVal writer As HtmlTextWriter)
        MyBase.RenderContents(writer)
        ' Step 1: Ensure Url property has been provided
        If Url <> "" Then
            ' Step 2: If debug info requested, display it
            If Debug Then
                writer.WriteLine("Url: " + Url + "<br/>")
                writer.WriteLine("Impersonate: " + _
                   Impersonate.ToString() + "<br/>")
                writer.WriteLine("Domain: " + Domain + "<br/>")
                writer.WriteLine("User: " + User + "<br/>")
                writer.WriteLine("Password: " + Password + "<br/>")
                writer.WriteLine("Format using: " + _
                   FormatUsing.ToString() + "<br/>")
                writer.WriteLine("<hr/>")
            End If
            ' Call helper function to render data as HTML to page
            displayXML(writer)
        Else
            ' Step 3: Tell user they need to fill in the Url property
            writer.WriteLine( _
               "<font color='red'>Source XML url cannot be blank</font>")
        End If
    End Sub
    Private Sub displayXML(ByVal writer As HtmlTextWriter)
        Try
            ' Step 4: Read the XML document into memory
            Dim wReq As System.Net.WebRequest
            wReq = System.Net.WebRequest.Create(Url)

' Step 5: Set the security as appropriate
            If Impersonate Then
                wReq.Credentials = _
                   System.Net.CredentialCache.DefaultCredentials
            Else
                wReq.Credentials = _
                   New System.Net.NetworkCredential(User, Password, Domain)
            End If
            wReq.Credentials = System.Net.CredentialCache.DefaultCredentials
            ' Step 6: Return the response.
            Dim wResp As System.Net.WebResponse = wReq.GetResponse()
            Dim respStream As System.IO.Stream = wResp.GetResponseStream()
            ' Step 7: Load XML stream into a DataSet for easier processing
            Dim dsXML As New DataSet()
            dsXML.ReadXml(respStream)
            ' Step 8: Determine display mechanism to use
            If FormatUsing = enumFormatUsing.DataGrid Then
                ' Step 9: Loop through each table in the DataSet,
                ' displaying each in a DataGrid
                Dim dgXML As DataGrid
                Dim lbl As Label
                For Each dtXML As DataTable In dsXML.Tables
                    ' Display table name
                    lbl = New Label()
                    lbl.Text = "<br/><strong>" + _
                       dtXML.TableName.ToUpper() + "</strong><br/><br/>"
                    lbl.RenderControl(writer)
                    ' Now display the data
                    dgXML = New DataGrid()
                    dgXML.DataSource = dtXML
                    dgXML.DataBind()
                    dgXML.RenderControl(writer)
                Next
            Else
                ' Step 10: Format using provided XSLT
                Dim xml As New System.Web.UI.WebControls.Xml()
                xml.DocumentContent = dsXML.GetXml()
                xml.TransformSource = XSLTPath
                xml.RenderControl(writer)
            End If
        Catch ex As Exception
            ' If error occurs, notify end user
            writer.WriteLine("<font color='red'><strong>" + _
               ex.Message + "</font>")
        End Try
    End Sub
End Class

using System;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml;
using System.Data;
namespace XMLWebPartCS
{
    public class XMLWebPart : WebPart
    {
        // Local variable to hold property values
        string _url = "";
        bool _impersonate = true;
        string _domain = "";
        string _user = "";
        string _password = "";
        bool _debug = false;
        enumFormatUsing _formatUsing = enumFormatUsing.DataGrid;
        string _xsltPath = "";
        //ENUM types will result in drop-down lists in
        //the web-part property sheet
        public enum enumFormatUsing
        {
            DataGrid = 1,
            XSLT = 2
        }
        // Property to set URL of source XML document
        [Personalizable]
        [WebBrowsable]
        [WebDisplayName("Url of XML document")]
        public string Url
        {
            get
            {
                return _url;
            }
            set
            {
                _url = value;
            }
        }

//Create property to determine whether DataGrid or
        //XSLT should be used to format output
        [Personalizable(PersonalizationScope.Shared), WebBrowsable(),
            WebDisplayName("Format Using:"),
            WebDescription("What method do you want " +
               "to use to format the results.")]
        public enumFormatUsing FormatUsing
        {
            get { return _formatUsing; }
            set { _formatUsing = value; }
        }
        //If XSLT will be used, this property specifies
        //its server-relative path
        [Personalizable(PersonalizationScope.Shared),
            WebBrowsable(), WebDisplayName("XSLT Path:"),
            WebDescription("If formatting with XSLT, " +
               "provide full path to XSLT document.")]
        public string XSLTPath
        {
            get { return _xsltPath; }
            set { _xsltPath = value; }
        }
        // If explicit credentials have been requested,
        // the following three properties, Domain, User, and
        // Password, will be used to construct the credentials
        // to pass to the page
        [Personalizable]
        [WebBrowsable]
        public string Domain
        {
            get
            {
                return _domain;
            }
            set
            {
                _domain = value;
            }
        }
        [Personalizable]
        [WebBrowsable]
        public string User
        {
            get
            {
                return _user;
            }

set
            {
                _user = value;
            }
        }
        [Personalizable]
        [WebBrowsable]
        public string Password
        {
            get
            {
                return _password;
            }
            set
            {
                _password = value;
            }
        }
        // If this option is checked, the web part will use
        // the default credentials of the user viewing
        // the web-part page.
        [Personalizable]
        [WebBrowsable]
        public bool Impersonate
        {
            get
            {
                return _impersonate;
            }
            set
            {
                _impersonate = value;
            }
        }
        // Display debug info?
        [Personalizable]
        [WebBrowsable]
        public bool Debug
        {
            get
            {
                return _debug;
            }
            set
            {
                _debug = value;
            }
        }

// This is where the HTML gets rendered to the
        // web-part page.
        protected override void RenderContents(HtmlTextWriter writer)
        {
            base.RenderContents(writer);
            // Step 1: Ensure Url property has been provided
            if (Url != "")
            {
                // Step 2: If debug info requested, display it
                if (Debug)
                {
                    writer.WriteLine("Url: " + Url + "<br/>");
                    writer.WriteLine("Impersonate: " +
                       Impersonate.ToString() + "<br/>");
                    writer.WriteLine("Domain: " + Domain + "<br/>");
                    writer.WriteLine("User: " + User + "<br/>");
                    writer.WriteLine("Password: " + Password + "<br/>");
                    writer.WriteLine("Format using: " + FormatUsing +
                       "<br/>");
                    writer.WriteLine("<hr/>");
                }
                // Call helper function to render data as HTML to page
                displayXML(writer);
            }
            else
            {
                // Step 3: Tell user they need to fill in the Url property
                writer.WriteLine(
                   "<font color='red'>Source XML url cannot be blank</font>");
            }
        }
        private void displayXML(HtmlTextWriter writer)
        {
            try
            {
                // Step 4: Read the XML data into memory
                System.Net.WebRequest wReq;
                wReq = System.Net.WebRequest.Create(Url);
                // Step 5: Set the security as appropriate
                if (Impersonate)
                {
                    wReq.Credentials =
                       System.Net.CredentialCache.DefaultCredentials;
                }

else
                {
                    wReq.Credentials = new System.Net.NetworkCredential(
                       User, Password, Domain);
                }
                wReq.Credentials =
                   System.Net.CredentialCache.DefaultCredentials;
                // Step 6: Return the response.
                System.Net.WebResponse wResp = wReq.GetResponse();
                System.IO.Stream respStream = wResp.GetResponseStream();
                // Step 7: Load XML stream into a DataSet for easier
                // processing
                DataSet dsXML = new DataSet();
                dsXML.ReadXml(respStream);
                // Step 8: Determine display mechanism to use
                if (FormatUsing == enumFormatUsing.DataGrid)
                {
                    // Step 9: Loop through each table in the DataSet,
                    // displaying each in a DataGrid
                    DataGrid dgXML;
                    Label lbl;
                    foreach (DataTable dtXML in dsXML.Tables)
                    {
                        // Display table name
                        lbl = new Label();
                        lbl.Text = "<br/><strong>" +
                           dtXML.TableName.ToUpper() +
                           "</strong><br/><br/>";
                        lbl.RenderControl(writer);
                        // Now display the data
                        dgXML = new DataGrid();
                        dgXML.DataSource = dtXML;
                        dgXML.DataBind();
                        dgXML.RenderControl(writer);
                    }
                }
                else
                {
                    // Step 10: Format using provided XSLT
                    System.Web.UI.WebControls.Xml xml =
                       new System.Web.UI.WebControls.Xml();
                    xml.DocumentContent = dsXML.GetXml();
                    xml.TransformSource = XSLTPath;
                    xml.RenderControl(writer);
                }
            }

catch (Exception ex)
            {
                // If error occurs, notify end user
                writer.WriteLine("<font color='red'><strong>" +
                   ex.Message + "</font>");
            }
        }
    }
}

The following listing provides the sample XML document that was used in conjunction with the XSLT that appears in the next section. The XML web part is designed, however, to work with any valid XML document.

<?xml version="1.0" encoding="utf-8"?>
<CustomerData>
     <Customer>
          <Name>ABC Corp.</Name>
          <Address>100 Main Street</Address>
          <Phone>(415) 999-1234</Phone>
          <Order>
               <OrderNo>1000</OrderNo>
               <Product>Widgets</Product>
               <Qty>10</Qty>
               <UnitPrice>100</UnitPrice>
               <ExtPrice>1000</ExtPrice>
          </Order>
          <Order>
               <OrderNo>1001</OrderNo>
               <Product>Gadget</Product>
               <Qty>50</Qty>
               <UnitPrice>50</UnitPrice>
               <ExtPrice>2500</ExtPrice>
          </Order>
          <Order>
               <OrderNo>0113</OrderNo>
               <Product>WhatsIt</Product>
               <Qty>100</Qty>
               <UnitPrice>70</UnitPrice>
               <ExtPrice>7000</ExtPrice>
          </Order>
     </Customer>

<Customer>
          <Name>XYZ Inc.</Name>
          <Address>123 Center Avenue</Address>
          <Phone>(650) 789-1234</Phone>
          <Order>
               <OrderNo>2000</OrderNo>
               <Product>Laptop</Product>
               <Qty>10</Qty>
               <UnitPrice>1000</UnitPrice>
               <ExtPrice>10000</ExtPrice>
          </Order>
          <Order>
               <OrderNo>2001</OrderNo>
               <Product>Memory</Product>
               <Qty>50</Qty>
               <UnitPrice>100</UnitPrice>
               <ExtPrice>5000</ExtPrice>
          </Order>
          <Order>
               <OrderNo>2003</OrderNo>
               <Product>LCD</Product>
               <Qty>100</Qty>
               <UnitPrice>300</UnitPrice>
               <ExtPrice>30000</ExtPrice>
          </Order>
     </Customer>
</CustomerData>

You could, of course, create any number of XSLT transforms to format the sample data. That's exactly the point of XSLT: to allow you to separate the source data from the means to display it. The following XSLT was used to provide the sample output in the "To Run" section.

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
   <xsl:output method="html"/>
   <xsl:template match="/">
      <xsl:for-each select="CustomerData/Customer">
         <h1>Orders for <xsl:value-of select="Name"/></h1>
         Address: <xsl:value-of select="Address"/><br/>
         Phone: <xsl:value-of select="Phone"/><br/><br/>
         <table cellpadding="3" cellspacing="3" width="80%">
            <tr valign="bottom">
               <td>
                  <strong>
                     <u>Order #</u>
                  </strong>
               </td>

<td>
                  <strong>
                     <u>Product</u>
                  </strong>
               </td>
               <td align="center">
                  <strong>
                     <u>Quanty</u>
                  </strong>
               </td>
               <td align="right">
                  <strong>
                     Unit<br/><u>Price</u>
                  </strong>
               </td>
               <td align="right">
                  <strong>
                     Extended<br/><u>Price</u>
                  </strong>
               </td>
            </tr>
            <xsl:for-each select="Order">
               <tr>
                  <td>
                     <xsl:value-of select="OrderNo"/>
                  </td>
                  <td>
                     <xsl:value-of select="Product"/>
                  </td>
                  <td align="center">
                     <xsl:value-of select="Qty"/>
                  </td>
                  <td align="right">
                  <xsl:value-of select="format-number(UnitPrice,'$ #,###')"/>
                  </td>
                  <td align="right">
                  <xsl:value-of select="format-number(ExtPrice,'$ #,###')"/>
                  </td>
               </tr>
            </xsl:for-each>

<tr>
               <td colspan="4"/>
               <td align="right">
                  ==========
               </td>
            </tr>
            <tr>
               <td colspan="4"/>
               <td align="right">
        <xsl:value-of select="format-number(sum(Order/ExtPrice),'$ #,###')"/>
               </td>
            </tr>
         </table>
      </xsl:for-each>
   </xsl:template>
</xsl:stylesheet>

After the web part has been successfully deployed, you can add your custom XML web part to any page in the site collection, open the web-part property sheet, and provide a URL to an XML document.

After you have set the URL property of the web part and selected the Debug checkbox, save your changes to display a result similar to that shown in Figure 4-3.

Figure 4.3. The XML web part in debug mode

Note that ADO.NET has inserted a Customer_Id column that did not appear in the source XML. .NET does this to maintain the parent-child relationship that is implicit in the XML.

Now let's spruce things up a bit. Open the web-part property pane and select XSLT from the Format drop-down list. Next enter a server-relative path to an XSLT document.

The resulting web-part output will look something like that shown in Figure 4-4.

Figure 4.4. Fully formatted output using the XML web part

Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Imports System.Data
Imports System.Xml
Public Class SQLWebPart
    Inherits WebPart
    'Define local variables to contain property values
    Private _connectionString As String = ""
    Private _connectionKey As String = ""
    Private _query As String = ""
    Private _formatUsing As enumFormatUsing = enumFormatUsing.DataGrid
    Private _xsltPath As String = ""
    Private _includeDebugInfo As Boolean = False
    'ENUM types will result in drop-down lists in
    'the web-part property sheet
    Public Enum enumFormatUsing
        DataGrid = 1
        XSLT = 2
    End Enum
    'Create property to hold SQL connection string
    <Personalizable( _
        PersonalizationScope.Shared), _
        WebBrowsable(), _
        WebDisplayName("Connection String:"), _
        WebDescription("Connection string to use" & _
           " when connecting to SQL source.")> _
    Property ConnectionString() As String
        Get
            Return _connectionString
        End Get

Set(ByVal Value As String)
            _connectionString = Value
        End Set
    End Property
    'Create property to hold SQL query
    <Personalizable( _
        PersonalizationScope.Shared), _
        WebBrowsable(), _
        WebDisplayName("SQL Query:"), _
        WebDescription("A valid SQL query to execute.")> _
    Property Query() As String
        Get
            Return _query
        End Get
        Set(ByVal Value As String)
            _query = Value
        End Set
    End Property
    'Create property to determine whether DataGrid or
    'XSLT should be used to format output
    <Personalizable( _
        PersonalizationScope.Shared), _
        WebBrowsable(), WebDisplayName("Format Using:"), _
        WebDescription("What method do you want " & _
            "to use to format the results.")> _
    Property FormatUsing() As enumFormatUsing
        Get
            Return _formatUsing
        End Get
        Set(ByVal Value As enumFormatUsing)
            _formatUsing = Value
        End Set
    End Property
    'If XSLT will be used, this property specifies
    'its path
    <Personalizable( _
        PersonalizationScope.Shared), _
        WebBrowsable(), _
        WebDisplayName("XSLT Path:"), _
        WebDescription("If formatting with XSLT, " & _
            "provide full path to XSLT document.")> _
    Property XSLTPath() As String
        Get
            Return _xsltPath
        End Get

Set(ByVal Value As String)
            _xsltPath = Value
        End Set
    End Property
    'Even though our web parts never have bugs...
    <Personalizable( _
        PersonalizationScope.Shared), _
        WebBrowsable(), _
        WebDisplayName("Include Debug Info?:"), _
        WebDescription("If selected, will " & _
            "display values of web part properties.")> _
    Property IncludeDebugInfo() As Boolean
        Get
            Return _includeDebugInfo
        End Get
        Set(ByVal Value As Boolean)
            _includeDebugInfo = Value
        End Set
    End Property
    'This is where the real work happens!
    Protected Overrides Sub RenderContents( _
          ByVal writer As System.Web.UI.HtmlTextWriter)
        'Process any output from the base class first
        MyBase.RenderContents(writer)
        ' Step 1: Display debug info if requested
        If IncludeDebugInfo Then
            writer.Write("Connection String: " & ConnectionString)
            writer.WriteBreak()
            writer.Write("SQL Query: " & Query)
            writer.WriteBreak()
            writer.Write("Format Using: " & FormatUsing.ToString)
            writer.WriteBreak()
            writer.Write("XSLT Path: " & XSLTPath)
            writer.Write("<hr>")
        End If
        ' Step 2: Query SQL database and return the result set
        Dim con As New SqlClient.SqlConnection(ConnectionString)
        Try
            con.Open()
        Catch ex As Exception
            writer.Write("<font color='red'>" & ex.Message & "</font>")
            Exit Sub
        End Try
        Dim da As New SqlClient.SqlDataAdapter(Query, con)
        Dim ds As New DataSet
        ' Step 3: Copy result set to DataSet

Try
            da.Fill(ds)
        Catch ex As Exception
            writer.Write("<font color='red'>" & ex.Message & "</font>")
            Exit Sub
        End Try
        ' Step 4: Format the output using an XSLT or DataGrid
        If FormatUsing = enumFormatUsing.DataGrid Then
            ' Step 5: Format using simple DataGrid
            Dim dg As New DataGrid
            dg.DataSource = ds
            dg.DataBind()
            dg.RenderControl(writer)
        Else
            ' Step 6: Format using provided XSLT
            Dim xml As New System.Web.UI.WebControls.Xml
            xml.DocumentContent = ds.GetXml
            xml.TransformSource = XSLTPath
            xml.RenderControl(writer)
        End If
    End Sub
End Class

using System;
using System.Collections.Generic;
using System.Text;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Data;
using System.Xml;
namespace SQLWebPartCS
{
    public class SQLWebPartCS : WebPart
    {
        //Define local variables to contain property values
        string _connectionString = "";
        string _query = "";
        enumFormatUsing _formatUsing = enumFormatUsing.DataGrid;
        string _xsltPath = "";
        bool _includeDebugInfo = false;
        //ENUM types will result in drop-down lists in
        //the web-part property sheet

public enum enumFormatUsing
        {
            DataGrid = 1,
            XSLT = 2
        }
        //Create property to hold SQL connection string
        [Personalizable(PersonalizationScope.Shared),
           WebBrowsable(), WebDisplayName("Connection String:"),
           WebDescription("Connection string to use" +
           " when connecting to SQL source.")]
        public string ConnectionString
        {
            get { return _connectionString; }
            set { _connectionString = value; }
        }
        //Create property to hold SQL query
        [Personalizable(PersonalizationScope.Shared),
           WebBrowsable(), WebDisplayName("SQL Query:"),
          WebDescription("A valid SQL query to execute.")]
        public string Query
        {
            get { return _query; }
            set { _query = value; }
        }
        //Create property to determine whether DataGrid or
        //XSLT should be used to format output
        [Personalizable(PersonalizationScope.Shared),
           WebBrowsable(), WebDisplayName("Format Using:"),
           WebDescription("What method do you want " +
           "to use to format the results.")]
        public enumFormatUsing FormatUsing
        {
            get { return _formatUsing; }
            set { _formatUsing = value; }
        }
        //If XSLT will be used, this property specifies
        //its path
        [Personalizable(PersonalizationScope.Shared),
           WebBrowsable(), WebDisplayName("XSLT Path:"),
           WebDescription("If formatting with XSLT, " +
           "provide full path to XSLT document.")]
        public string XSLTPath
        {
            get { return _xsltPath; }
            set { _xsltPath = value; }
        }

//Even though our web parts never have bugs...
        [Personalizable(PersonalizationScope.Shared),
           WebBrowsable(), WebDisplayName("Include Debug Info?:"),
           WebDescription("If selected, will " +
           "display values of web part properties.")]
        public bool IncludeDebugInfo
        {
            get { return _includeDebugInfo; }
            set { _includeDebugInfo = value; }
        }
        //This is where the real work happens!
        protected override void RenderContents(
           System.Web.UI.HtmlTextWriter writer)
        {
            //Process any output from the base class first
            base.RenderContents(writer);
            // Step 1: Display debug info if requested
            if (IncludeDebugInfo)
            {
                writer.Write("Connection String: " + ConnectionString);
                writer.WriteBreak();
                writer.Write("SQL Query: " + Query);
                writer.WriteBreak();
                writer.Write("Format Using: " + FormatUsing.ToString());
                writer.WriteBreak();
                writer.Write("XSLT Path: " + XSLTPath);
                writer.Write("<hr>");
            }
            // Step 2: Query SQL database and return the result set
            System.Data.SqlClient.SqlConnection con =
               new System.Data.SqlClient.SqlConnection(ConnectionString);
            try
            {
                con.Open();
            }
            catch (Exception ex)
            {
                writer.Write("<font color='red'>" + ex.Message + "</font>");
                return;
            }
            System.Data.SqlClient.SqlDataAdapter da =
               new System.Data.SqlClient.SqlDataAdapter(Query, con);
            DataSet ds = new DataSet();

// Step 3: Copy result set to DataSet
            try
            {
                da.Fill(ds);
            }
            catch (Exception ex)
            {
                writer.Write("<font color='red'>" + ex.Message + "</font>");
                return;
            }
            // Step 4: Format the output using an XSLT or DataGrid
            if (FormatUsing == enumFormatUsing.DataGrid)
            {
                // Step 5: Format using simple DataGrid
                DataGrid dg = new DataGr    id();
                dg.DataSource = ds;
                dg.DataBind();
                dg.RenderControl(writer);
            }
            else
            {
                // Step 6: Format using provided XSLT
                System.Web.UI.WebControls.Xml xml =
                   new System.Web.UI.WebControls.Xml();
                xml.DocumentContent = ds.GetXml();
                xml.TransformSource = XSLTPath;
                xml.RenderControl(writer);
            }
        }
    }
}

As I've noted before, XML Transformations (XSLT) is an incredibly powerful technology for manipulating any XML source, including of course the contents of any .NET DataSet or DataTable object. XSLT can be used to render XML as HTML for display, or to write XML to a new XML document with a different structure. In this case, we want to use XSLT to render our sample data as HTML for display on a web-part page. The following XSLT will be used in our example.

<?xml version="1.0" encoding="UTF-8" ?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:template match="/">
     <table cellpadding="3" cellspacing="0">
          <tr>
               <td>
                    <u><strong>President</strong></u>
               </td>

<td align="center">
                    <u>
                         <strong>Years In Office</strong>
                    </u>
               </td>
               <td style="width: 10px"/>
               <td style="background-color: silver; width: 1px"/>
               <td style="width: 10px"/>
               <td>
                    <u><strong>President</strong></u>
               </td>
               <td>
                    <u><strong>Years In Office</strong></u>
               </td>
          </tr>
          <xsl:for-each select="NewDataSet/Table">
               <xsl:if test="position() mod 2 = 1">
                    <xsl:text disable-output-escaping="yes">
                       &lt;tr&gt;
                    </xsl:text>
               </xsl:if>
               <td>
                    <xsl:value-of select="Name"/>
               </td>
               <td align="center">
                    <xsl:value-of select="YearsInOffice"/>
               </td>
               <xsl:if test="position() mod 2 = 1">
                    <td style="width: 10px"/>
                    <td style="background-color: silver; width: 1px"/>
                    <td style="width: 10px"/>
               </xsl:if>
               <xsl:if test="position() mod 2 = 0">
                    <xsl:text disable-output-escaping="yes">
                         &lt;/tr&gt;
                    </xsl:text>
               </xsl:if>
          </xsl:for-each>
     </table>
</xsl:template>
</xsl:stylesheet>

After you have added the SQL web part to a web-part page, you're ready to try it out.

The following example assumes the SQL data source provided in Table 4-1.

Of course, you will likely use a different server, and there is no requirement that you even use the same query—although if you choose to change the query, you will also need to change the XSLT accordingly.

Figure 4-5 shows the SQL web part in action. Figure 4-6 shows the associated custom properties on the web-part property sheet.

Figure 4.5. The Presidents table displayed by using the SQL web part

Figure 4.6. The SQL web part's property pane

Imports System
Imports System.Web
Imports System.Web.Security
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Imports System.Web.UI.HtmlControls
Imports System.Xml
Imports System.Data
Public Class PageViewerWebPartVB
    Inherits WebPart
    ' Local variable to hold property values
    Private _url As String = ""
    Private _impersonate As Boolean = True
    Private _domain As String = ""
    Private _user As String = ""
    Private _password As String = ""
    Private _debug As Boolean = False
    ' Property to set URL of page to display
    <Personalizable(), _
     WebBrowsable()> _
    Public Property Url() As String
        Get
            Return _url
        End Get
        Set(ByVal value As String)
            _url = value
        End Set
    End Property

' If explicit credentials have been requested,
    ' the following three properties will
    ' be used to construct the credentials
    ' to pass to the page
    <Personalizable(), _
     WebBrowsable()> _
    Public Property Domain() As String
        Get
            Return _domain
        End Get
        Set(ByVal value As String)
            _domain = value
        End Set
    End Property
    <Personalizable(), _
     WebBrowsable()> _
    Public Property User() As String
        Get
            Return _user
        End Get
        Set(ByVal value As String)
            _user = value
        End Set
    End Property
    <Personalizable(), _
     WebBrowsable()> _
    Public Property Password() As String
        Get
            Return _password
        End Get
        Set(ByVal value As String)
            _password = value
        End Set
    End Property
    ' Should user be impersonated?
    <Personalizable(), _
     WebBrowsable()> _
    Public Property Impersonate() As Boolean
        Get
            Return _impersonate
        End Get
        Set(ByVal value As Boolean)
            _impersonate = value
        End Set
    End Property

' Display debug info?
    <Personalizable(), _
     WebBrowsable()> _
    Public Property Debug() As Boolean
        Get
            Return _debug
        End Get
        Set(ByVal value As Boolean)
            _debug = value
        End Set
    End Property
    ' This is where the HTML gets rendered to the
    ' web-part page.
    Protected Overrides Sub RenderContents(ByVal writer As HtmlTextWriter)
        MyBase.RenderContents(writer)
        ' Step 1: If debug info requested, display it
        If Debug Then
            writer.WriteLine("Url: " + Url + "<br/>")
            writer.WriteLine("Impersonate: " + Impersonate.ToString _
               + "<br/>")
            writer.WriteLine("Domain: " + Domain + "<br/>")
            writer.WriteLine("User: " + User + "<br/>")
            writer.WriteLine("Password: " + Password + "<br/>")
            writer.WriteLine("<hr/>")
        End If
        ' Step 2: Make sure URL is provided
        If (Url = "") Then
            writer.WriteLine( _
               "<font color='red'>Please enter a valid Url</font>")
            Return
        End If
        ' Step 3: Create a web request to read desired page
        Dim wReq As System.Net.WebRequest
        wReq = System.Net.WebRequest.Create(Url)
        ' Step 4: Set the security as appropriate
        If Impersonate Then
            wReq.Credentials = System.Net.CredentialCache.DefaultCredentials
        Else
            wReq.Credentials = _
               New System.Net.NetworkCredential(User, Password, Domain)
        End If
        ' Step 5: Get the page contents as a string variable

Try
            Dim wResp As System.Net.WebResponse = wReq.GetResponse
            Dim respStream As System.IO.Stream = wResp.GetResponseStream
            Dim respStreamReader As System.IO.StreamReader = _
               New System.IO.StreamReader(respStream, _
               System.Text.Encoding.ASCII)
            Dim strHTML As String = respStreamReader.ReadToEnd
            ' Step 6: Render the HTML to the web-part page
            writer.Write(strHTML)
        Catch e As Exception
            writer.Write(("<font color='red'>" + e.Message))
        End Try
    End Sub
End Class

using System;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml;
using System.Data;
namespace PageViewerWebPartCS
{
    public class PageViewerWebPartCS : WebPart
    {
        // Local variable to hold property values
        string _url = "";
        bool _impersonate = true;
        string _domain = "";
        string _user = "";
        string _password = "";
        bool _debug = false;
        // Property to set URL of page to display
        [Personalizable]
        [WebBrowsable]
        public string Url
        {
            get
            {
                return _url;
            }

set
            {
                _url = value;
            }
        }
        // If explicit credentials have been requested,
        // the following three properties will
        // be used to construct the credentials
        // to pass to the page
        [Personalizable]
        [WebBrowsable]
        public string Domain
        {
            get
            {
                return _domain;
            }
            set
            {
                _domain = value;
            }
        }
        [Personalizable]
        [WebBrowsable]
        public string User
        {
            get
            {
                return _user;
            }
            set
            {
                _user = value;
            }
        }
        [Personalizable]
        [WebBrowsable]
        public string Password
        {
            get
            {
                return _password;
            }
            set
            {
                _password = value;
            }
        }

// Should user be impersonated?
        [Personalizable]
        [WebBrowsable]
        public bool Impersonate
        {
            get
            {
                return _impersonate;
            }
            set
            {
                _impersonate = value;
            }
        }
        // Display debug info?
        [Personalizable]
        [WebBrowsable]
        public bool Debug
        {
            get
            {
                return _debug;
            }
            set
            {
                _debug = value;
            }
        }
        // This is where the HTML gets rendered to the
        // web-part page.
        protected override void RenderContents(HtmlTextWriter writer)
        {
            base.RenderContents(writer);
            // Step 1: If debug info requested, display it
            if (Debug)
            {
                writer.WriteLine("Url: " + Url + "<br/>");
                writer.WriteLine("Impersonate: " + Impersonate.ToString() +
                   "<br/>");
                writer.WriteLine("Domain: " + Domain + "<br/>");
                writer.WriteLine("User: " + User + "<br/>");
                writer.WriteLine("Password: " + Password + "<br/>");
                writer.WriteLine("<hr/>");
            }
            // Step 2: Make sure URL is provided

if (Url == "")
            {
                writer.WriteLine(
                   "<font color='red'>Please enter a valid Url</font>");
                return;
            }
            // Step 3: Create a web request to read desired page
            System.Net.WebRequest wReq;
            wReq = System.Net.WebRequest.Create(Url);
            // Step 4: Set the security as appropriate
            if (Impersonate)
            {
                wReq.Credentials =
                   System.Net.CredentialCache.DefaultCredentials;
            }
            else
            {
                wReq.Credentials =
                   new System.Net.NetworkCredential(User, Password, Domain);
            }
            // Step 5: Get the page contents as a string variable
            try
            {
                System.Net.WebResponse wResp = wReq.GetResponse();
                System.IO.Stream respStream = wResp.GetResponseStream();
                System.IO.StreamReader respStreamReader =
                   new System.IO.StreamReader(respStream,
                   System.Text.Encoding.ASCII);
                string strHTML = respStreamReader.ReadToEnd();
                // Step 6: Render the HTML to the web-part page
                writer.Write(strHTML);
            }
            catch (Exception e)
            {
                writer.Write("<font color='red'>" + e.Message);
            }
        }
    }
}

After you have deployed the web part to your site collection, place an instance of the web part on a web-part page. Initially an error message will be displayed stating that you must provide a URL to a web page. To do so, open the web-part property sheet, fill in the URL, and click the OK button. The result is shown in Figure 4-7.

Figure 4.7. A simple web page displayed by using the custom Page Viewer web part

Assuming that the account under which you are currently logged in has permissions to that URL (or the site allows anonymous access), the page should be displayed. If your current account doesn't have the necessary permissions, you can deselect the Impersonate property and provide a specific domain, user, and password. Figure 4-8 shows the property settings to force the custom Page Viewer web part to connect as the user WebPartUser.

Figure 4.8. The custom Page Viewer web part's property pane

Imports System
Imports System.Collections.Generic
Imports System.Text
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Namespace ConnectablePageViewerVB

' Step 1: Create the Interface
    ' ----------------------------
    ' The interface is the glue between the "provider" web part
    ' that sends data to the "consumer" web page. It provides
    ' a structure in which to pass the data. In this case
    ' we're just passing a single string value that represents
    ' the URL to display, but we could pass multiple data
    ' items by providing multiple properties
    Public Interface IUrl
        ReadOnly Property Url() As String
    End Interface
    ' Step 2: Create the provider web-part class
    ' ------------------------------------------
    ' The "provider" web part will display a drop-down list
    ' or site-name/URL pairs. When the user selects a value,
    ' the selected URL will be passed to the "consumer".
    Public Class UrlProvider
        Inherits WebPart
        Implements IUrl
        Private ddlUrl As DropDownList = Nothing
        Private _urls As String = _
           "Microsoft;http://www.microsoft.com;Yahoo!;" & _
           "http://www.yahoo.com;Apress;http://www.apress.com"
        ' The "Urls" property will store a semicolon-delimited
        ' list of site-name/URL pairs to populate the drop-down list
        <Personalizable()> _
        <WebBrowsable()> _
        Public Property Urls() As String
            Get
                Return _urls
            End Get
            Set(ByVal value As String)
                _urls = value
            End Set
        End Property
        ' Step 3: Override the "CreateChildControls()" method
        ' ---------------------------------------------------
        ' The CreateChildControls() base method is called
        ' to populate the drop-down list of sites and
        ' add to the web-part output
        Protected Overloads Overrides Sub CreateChildControls()
            MyBase.CreateChildControls()

Try
                ' Create the drop-down list of URLs from
                ' the parsed string in "Urls" property
                Dim arrUrls As String() = _urls.Split(";"c)
                Dim li As ListItem
                ddlUrl = New DropDownList()
                ddlUrl.Items.Add(New ListItem("[Please select a Url]", ""))
                Dim i As Integer = 0
                While i < arrUrls.Length
                    li = New ListItem(arrUrls(i), arrUrls(i + 1))
                    ddlUrl.Items.Add(li)
                    i = i + 2
                End While
                ddlUrl.Items(0).Selected = True
                ddlUrl.AutoPostBack = True
                Me.Controls.Add(ddlUrl)
            Catch ex As Exception
                Dim lbl As New Label()
                lbl.Text = ex.Message
                Me.Controls.Add(lbl)
            End Try
        End Sub
        ' Step 4: Define any methods required by the interface
        ' ----------------------------------------------------
        ' This is the single method that was
        ' specified in the Interface, and must be provided
        ' to pass the selected URL to the "consumer" web
        ' part
        Public ReadOnly Property Url() As String Implements IUrl.Url
            Get
                Return ddlUrl.SelectedValue.ToString()
            End Get
        End Property
        ' Step 5: Define and "decorate" the ConnectionProvider() method
        ' -----------------------------------------------------------
        ' This method is required to wire up the
        ' "provider" with one or more "consumers."
        ' Note the "ConnectionProvider" decoration
        ' that tells .NET to make this the provider's
        ' connection point
        <ConnectionProvider("Url Provider")> _
        Public Function GetUrl() As IUrl
            Return Me
        End Function
    End Class

' Step 6: Define the consumer web-part class
    ' ------------------------------------------
    ' This class defines the "consumer" web part that will
    ' obtain the URL from the "provider"
    Public Class ConnectablePageViewer
        Inherits WebPart
        Private _url As String = ""
        ' Step 7: Override either or both the CreateChildControls() and/or
        ' RenderContents() base methods
        ' ----------------------------------------------------------------
        ' In the RenderContents() method we get the URL value
        ' which has been written to the _url local variable by
        ' the "UrlConsumer()" method that automatically fires
        ' when this web part is wired up with a "provider"
        Protected Overloads Overrides Sub RenderContents( _
           ByVal writer As System.Web.UI.HtmlTextWriter)
            MyBase.RenderContents(writer)
            Try
                If _url <> "" Then
                    ' Create an <IFRAME> HTML tag and set the
                    ' source to the selected url
                    writer.Write("Opening page: " + _url)
                    writer.Write("<hr/>")
                    writer.Write("<div>")
                    writer.Write("<iframe src='" + _url + _
                       "' width='100%' height='800px'></iframe>")
                    writer.Write("</div>")
                Else
                    writer.Write("Please select a Url from the provider.")
                End If
            Catch ex As Exception
                writer.Write(ex.Message)
            End Try
        End Sub
        ' Step 8: Define a ConnectionConsumer() method to receive
        ' data from the provider
        ' -------------------------------------------------------
        ' The UrlConsumer() method is wired up using the
        ' "ConnectionConsumer()" decoration, that tells
        ' .NET to automatically fire this method when
        ' the consumer is connected to a provider
        <ConnectionConsumer("Url Consumer")> _
        Public Sub UrlConsumer(ByVal url As IUrl)
            Try
                _url = url.Url
                ' No op

Catch ex As Exception
            End Try
        End Sub
    End Class
End Namespace

using System;
using System.Collections.Generic;
using System.Text;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
namespace ConnectablePageViewerCS
{
    // Step 1: Create the Interface
    // ----------------------------
    // The interface is the glue between the "provider" web part
    // that sends data to the "consumer" web page.  It provides
    // a structure in which to pass the data.  In this case
    // we're just passing a single string value that represents
    // the URL to display, but we could pass multiple data
    // items by providing multiple properties
    public interface IUrl
    {
        string Url { get; }
    }
    // Step 2: Create the provider web-part class
    // ------------------------------------------
    // The "provider" web part will display a drop-down list
    // or site-name/URL pairs.  When the user selects a value,
    // the selected URL will be passed to the "consumer."
    public class UrlProvider : WebPart, IUrl
    {
        DropDownList ddlUrl = null;
        string _urls =
          "Microsoft;http://www.microsoft.com; " +
          "Yahoo!;http://www.yahoo.com;Apress;http://www.apress.com";
        // The "Urls" property will store a semicolon-delimited
        // list of site-name/URL pairs to populate the drop-down list
        [Personalizable]
        [WebBrowsable]
        public string Urls
        {
            get { return _urls; }

set { _urls = value;  }
        }
        // Step 3: Override the "CreateChildControls()" method
        // ---------------------------------------------------
        // The CreateChildControls() base method is called
        // to populate the drop-down list of sites and
        // add to the web-part output
        protected override void CreateChildControls()
        {
            base.CreateChildControls();
            try
            {
                // Create the drop-down list of URLs from
                // the parsed string in "Urls" property
                string[] arrUrls = _urls.Split(';'),
                ListItem li;
                ddlUrl = new DropDownList();
                ddlUrl.Items.Add(new ListItem("[Please select a Url]", ""));
                for (int i = 0; i < arrUrls.Length; i = i + 2)
                {
                    li = new ListItem(arrUrls[i], arrUrls[i + 1]);
                    ddlUrl.Items.Add(li);
                }
                ddlUrl.Items[0].Selected = true;
                ddlUrl.AutoPostBack = true;
                this.Controls.Add(ddlUrl);
            }
            catch (Exception ex)
            {
                Label lbl = new Label();
                lbl.Text = ex.Message;
                this.Controls.Add(lbl);
            }
        }
        // Step 4: Define any methods required by the interface
        // ----------------------------------------------------
        // This is the single method that was
        // specified in the Interface, and must be provided
        // to pass the selected URL to the "consumer" web
        // part
        public string Url
        {
            get { return ddlUrl.SelectedValue; }
        }

// Step 5: Define and "decorate" the ConnectionProvider method
  // -----------------------------------------------------------
  // This method is required to wire up the
        // "provider" with one or more "consumers."
        // Note the "ConnectionProvider" decoration
        // that tells .NET to make this the provider's
        // connection point
        [ConnectionProvider("Url Provider")]
        public IUrl GetUrl()
        {
            return this;
        }
    }
    // Step 6: Define the consumer web-part class
    // ------------------------------------------
    // This class defines the "consumer" web part that will
    // obtain the URL from the "provider"
    public class ConnectablePageViewer : WebPart
    {
        string _url = "";
        // Step 7: Override either or both the CreateChildControls() and/or
        //   RenderContents() base methods
        // ----------------------------------------------------------------
        // In the RenderContents() method, we get the URL value
        // that has been written to the _url local variable by
        // the "UrlConsumer()" method that automatically fires
        // when this web part is wired up with a "provider"
        protected override void RenderContents(
           System.Web.UI.HtmlTextWriter writer)
        {
            base.RenderContents(writer);
            try
            {
                if (_url != "")
                {
                    // Create an <IFRAME> HTML tag and set the
                    // source to the selected URLl
                    writer.Write("Opening page: " + _url);
                    writer.Write("<hr/>");
                    writer.Write("<div>");
                    writer.Write("<iframe src='" + _url +
                       "' width='100%' height=800px'></iframe>");
                    writer.Write("</div>");
                }

else
                {
                    writer.Write("Please select a Url from the provider.");
                }
            }
            catch (Exception ex)
            {
                writer.Write(ex.Message);
            }
        }
        // Step 8: Define a ConnectionConsumer() method to receive
        // data from the provider
        // -------------------------------------------------------
        // The UrlConsumer() method is wired up using the
        // "ConnectionConsumer()" decoration that tells
        // .NET to automatically fire this method when
        // the consumer is connected to a provider
        [ConnectionConsumer("Url Consumer")]
        public void UrlConsumer(IUrl url)
        {
            try
            {
                _url = url.Url;
            }
            catch (Exception ex)
            {
                // No op
            }
        }
    }
}

Open a web-part page in the site collection where you have just deployed your two web parts, and then add both web parts to the page as shown in Figure 4-9.

Figure 4.9. The connectable Page Viewer waiting for the user to select a URL

Note that because no URL has yet been selected, the Connectable Page Viewer web part displays the message "Please select a URL from the provider." Before the Page Viewer part will recognize that a URL has been selected, however, you must connect the web parts. To do so, choose the Site Actions

Figure 4.10. Connecting the connectable Page Viewer to the URL source

Finally, select a site name from the URL provider web part to display the corresponding site in the Connectable Page Viewer, as shown in Figure 4-11.

Figure 4.11. The Connectable Page Viewer in action

Imports System
Imports System.Collections.Generic
Imports System.Text
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Imports Microsoft.SharePoint
Imports Microsoft.SharePoint.WebControls
Imports System.Data
Public Class QueryStringWebPartVB
    Inherits WebPart
    ' Define local variables
    Private _debug As Boolean = False
    Private _formatUsing As enumFormatUsing = enumFormatUsing.DataGrid
    Private _xsltPath As String = ""
    'ENUM types will result in drop-down lists in
    'the web-part property sheet
    Public Enum enumFormatUsing
        DataGrid = 1
        XSLT = 2
    End Enum

' Display debug info?
    <Personalizable()> _
    <WebBrowsable()> _
    <WebDisplayName("Debug?")> _
    <WebDescription("Check to cause debug information to be displayed")> _
    Public Property Debug() As Boolean
        Get
            Return _debug
        End Get
        Set(ByVal value As Boolean)
            _debug = value
        End Set
    End Property
    'Create property to determine whether DataGrid or
    'XSLT should be used to format output
    <Personalizable(PersonalizationScope.[Shared]), _
        WebBrowsable(), WebDisplayName("Format Using:"), _
        WebDescription("What method do you want to use " & _
        "to format the results.")> _
    Public Property FormatUsing() As enumFormatUsing
        Get
            Return _formatUsing
        End Get
        Set(ByVal value As enumFormatUsing)
            _formatUsing = value
        End Set
    End Property
    'If XSLT will be used, this property specifies
    'its server-relative path
    <Personalizable(PersonalizationScope.[Shared]), _
        WebBrowsable(), WebDisplayName("XSLT Path:"), _
        WebDescription("If formatting with XSLT, " & _
        "provide full path to XSLT document.")> _
    Public Property XSLTPath() As String
        Get
            Return _xsltPath
        End Get
        Set(ByVal value As String)
            _xsltPath = value
        End Set
    End Property
    Protected Overloads Overrides Sub RenderContents(ByVal writer As _
       System.Web.UI.HtmlTextWriter)
        MyBase.RenderContents(writer)

Try
            Dim qs As System.Collections.Specialized.NameValueCollection = _
               Page.Request.QueryString
            If _debug Then
                ' Step 1: Parse the querystring and display
                If qs.Count > 0 Then
                    writer.Write("<strong>Querystring parameters: </strong>")
                    writer.Write("<blockquote>")
                    For i As Integer = 0 To qs.Count - 1
                        writer.Write(qs.Keys(i) + " = " + qs(i) + "<br/>")
                    Next
                    writer.Write("</blockquote>")
                Else
                    writer.Write("No querystring parameters exist<br/>")
                End If
                ' Step 2: Display web-part property values
                writer.Write("<strong>Format output using:</strong> " + _
                  _formatUsing.ToString() + "<br/>")
                writer.Write("<strong>XSLT path:</strong> " + _
                  _xsltPath.ToString() + "<br/>")
                writer.Write("<hr/>")
            End If
            ' Step 3: Display items from Client list based on provided ID
            Dim clientId As String = qs("clientId")
            If clientId IsNot Nothing Then
                displayClientData(clientId, writer)
            Else
                writer.Write("Client ID was not provided in querystring")
            End If
        Catch e As Exception
            writer.Write("<font color='red'>" + e.Message + "</font>")
        End Try
    End Sub
    Private Sub displayClientData(ByVal clientId As String, _
       ByVal writer As System.Web.UI.HtmlTextWriter)
        Try
            ' Step 4: Get handle to current web site and client list
            Dim web As SPWeb = SPControl.GetContextWeb(Context)
            Dim clients As SPList = web.Lists("Clients")
            ' Step 5: Copy clients' data into a DataTable object
            ' for easier manipulation
            Dim dsClients As New DataSet("Clients")
            Dim dtClients As DataTable = clients.Items.GetDataTable()
            dtClients.TableName = "Clients"

' Step 6: Filter for the specified client ID
            Dim dvClients As New DataView()
            dvClients.Table = dtClients
            dvClients.RowFilter = "ClientId = '" + clientId + "'"
            ' Step 7: Determine display mechanism to use
            If FormatUsing = enumFormatUsing.DataGrid Then
                ' Step 8: Display as DataGrid
                Dim dgClients As New DataGrid()
                dgClients.DataSource = dvClients
                dgClients.DataBind()
                dgClients.RenderControl(writer)
            Else
                ' Step 9: Format using provided XSLT
                Dim xml As New System.Web.UI.WebControls.Xml()
                dsClients.Tables.Add(dvClients.ToTable("Clients"))
                xml.DocumentContent = dsClients.GetXml()
                xml.TransformSource = XSLTPath
                xml.RenderControl(writer)
            End If
        Catch ex As Exception
            ' If error occurs, notify end-user
            writer.WriteLine("<font color='red'><strong>" + _
               ex.Message + "</font>")
        End Try
    End Sub
End Class

using System;
using System.Collections.Generic;
using System.Text;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using Microsoft.SharePoint;
using Microsoft.SharePoint.WebControls;
using System.Data;
namespace QuerystringWebPartCS
{
    public class QueryStringWebPartCS : WebPart
    {
        // Define local variables
        bool _debug = false;
        enumFormatUsing _formatUsing = enumFormatUsing.DataGrid;
        string _xsltPath = "";
        //ENUM types will result in drop-down lists in
        //the web-part property sheet

public enum enumFormatUsing
        {
            DataGrid = 1,
            XSLT = 2
        }
        // Display debug info?
        [Personalizable]
        [WebBrowsable]
        [WebDisplayName("Debug?")]
        [WebDescription("Check to cause debug information to be displayed")]
        public bool Debug
        {
            get { return _debug; }
            set { _debug = value; }
        }
        //Create property to determine whether DataGrid or
        //XSLT should be used to format output
        [Personalizable(PersonalizationScope.Shared), WebBrowsable(),
            WebDisplayName("Format Using:"),
            WebDescription("What method do you want " +
                "to use to format the results.")]
        public enumFormatUsing FormatUsing
        {
            get { return _formatUsing; }
            set { _formatUsing = value; }
        }
        //If XSLT will be used, this property specifies
        //its server-relative path
        [Personalizable(PersonalizationScope.Shared),
            WebBrowsable(), WebDisplayName("XSLT Path:"),
            WebDescription("If formatting with XSLT, " +
               "provide full path to XSLT document.")]
        public string XSLTPath
        {
            get { return _xsltPath; }
            set { _xsltPath = value; }
        }
        protected override void RenderContents(
           System.Web.UI.HtmlTextWriter writer)
        {
            base.RenderContents(writer);
            try
            {
                System.Collections.Specialized.NameValueCollection qs =
                   Page.Request.QueryString;

if (_debug)
                {
                    // Step 1: Parse the querystring and display
                    if (qs.Count > 0)
                    {
                        writer.Write(
                           "<strong>Querystring parameters: </strong>");
                        writer.Write("<blockquote>");
                        for (int i = 0; i < qs.Count; i++)
                        {
                            writer.Write(qs.Keys[i] + " = " + qs[i] +
                               "<br/>");
                        }
                        writer.Write("</blockquote>");
                    }
                    else
                    {
                        writer.Write("No querystring parameters exist<br/>");
                    }
                    // Step 2: Display web-part property values
                    writer.Write("<strong>Format output using:</strong> " +
                       _formatUsing + "<br/>");
                    writer.Write("<strong>XSLT path:</strong> " +
                      _xsltPath + "<br/>");
                    writer.Write("<hr/>");
                }
                // Step 3: Display items from Client list
                // based on provided ID
                string clientId = qs["clientId"];
                if (clientId != null)
                {
                    displayClientData(clientId, writer);
                }
                else
                {
                    writer.Write(
                       "Client ID was not provided in querystring");
                }
            }
            catch (Exception e)
            {
                writer.Write("<font color='red'>" + e.Message + "</font>");
            }
        }

private void displayClientData(
           string clientId, System.Web.UI.HtmlTextWriter writer)
        {
            try
            {
                // Step 4: Get handle to current web site and client list
                SPWeb web = SPControl.GetContextWeb(Context);
                SPList clients = web.Lists["Clients"];
                // Step 5: Copy clients' data into a DataTable object
                // for easier manipulation
                DataSet dsClients = new DataSet("Clients");
                DataTable dtClients = clients.Items.GetDataTable();
                dtClients.TableName = "Clients";
                // Step 6: Filter for the specified client ID
                DataView dvClients = new DataView();
                dvClients.Table = dtClients;
                dvClients.RowFilter = "ClientId = '" + clientId + "'";
                // Step 7: Determine display mechanism to use
                if (FormatUsing == enumFormatUsing.DataGrid)
                {
                    // Step 8: Display as DataGrid
                    DataGrid dgClients = new DataGrid();
                    dgClients.DataSource = dvClients;
                    dgClients.DataBind();
                    dgClients.RenderControl(writer);
                }
                else
                {
                    // Step 9: Format using provided XSLT
                    System.Web.UI.WebControls.Xml xml =
                       new System.Web.UI.WebControls.Xml();
                    dsClients.Tables.Add(dvClients.ToTable("Clients"));
                    xml.DocumentContent = dsClients.GetXml();
                    xml.TransformSource = XSLTPath;
                    xml.RenderControl(writer);
                }
            }
            catch (Exception ex)
            {
                // If error occurs, notify end user
                writer.WriteLine("<font color='red'><strong>" +
                   ex.Message + "</font>");
            }
        }
    }
}

This is the XML transform used to format the XML representation of the selected client data as HTML on the page. This XSLT simply builds a well-formed HTML <TABLE> from the XML provided by the DataSet.

<?xml version="1.0" encoding="UTF-8" ?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
     <xsl:template match="/">
          <!-- Display each matching client -->
          <table cellpadding="10" border="1">
          <xsl:for-each select="Clients/Clients">
               <tr>
                    <td>
                         Client Id:
                    </td>
                    <td>
                         <strong>
                              <xsl:value-of select="ClientId"/>
                         </strong>
                    </td>
               </tr>
               <tr>
                    <td>
                         Client Name:
                    </td>
                    <td>
                         <strong>
                              <xsl:value-of select="ClientName"/>
                         </strong>
                    </td>
               </tr>
               <tr>
                    <td>
                         Address:
                    </td>
                    <td>
                         <strong>
                              <xsl:value-of select="Address"/>
                         </strong>
                    </td>
               </tr>
          </xsl:for-each>
          </table>
     </xsl:template>
</xsl:stylesheet>

The next step is to create a new list called Clients that includes three fields: ClientId, ClientName, and Address (actually, the only field the web part requires is ClientId, but the sample XSLT shown in the preceding section assumes all three fields will be in the XML output of the DataSet).

After you have created the Clients list, add some rows as shown in Figure 4-12.

Figure 4.12. Client data to use with the Querystring web part

After the Clients list has been created and a few rows have been added, navigate to a web-part page in the same site and add the Querystring web part. Initially, you will receive an error message indicating that a client ID was not provided in the querystring. To remedy this, simply add some text such as ?clientid=1001 to the end of the URL in the browser's location field. Figure 4-13 shows the Querystring web part using custom XSLT to format the output.

Figure 4.13. The Querystring web part using XSLT to format the results

Unlike standard web parts, where all UI elements are defined in the source code, an ASP.NET user control includes design surface elements as well as code. The following screen shot displays the elements of the layout. The radio buttons are named radRed, radYellow, and radGreen, respectively. The images are imgRed, imgYellow, and imgGreen. Figure 4-14 shows the user control displayed in Visual Studio's design surface.

Figure 4.14. The .ascx page shown in design view

Imports Microsoft.SharePoint
Imports Microsoft.SharePoint.WebControls
Partial Class SmartPartStatusWebPart
    Inherits System.Web.UI.UserControl
    'Define local variables
    Private _showImage As Boolean = True
    Private _statusListSiteUrl As String = "http://localhost"
    Private _statusListWeb As String = "spwp"
    Private _statusList As String = "Status"
    Private Sub Page_PreRender(ByVal sender As Object, _
       ByVal e As System.EventArgs) Handles MyBase.PreRender
        'Only run this code if this is the first time the
        'user control has been displayed on the current
        'page since it was opened

If Not IsPostBack Then
            HideAllImages()
            Select Case GetProfileStatus()
                Case "Green"
                    Me.imgGreen.Visible = True
                    Me.radGreen.Checked = True
                Case "Yellow"
                    Me.imgYellow.Visible = True
                    Me.radYellow.Checked = True
                Case "Red"
                    Me.imgRed.Visible = True
                    Me.radRed.Checked = True
                Case Else
            End Select
        End If
    End Sub
    Private Function GetProfileStatus() As String
        Try
            'Step 1: Define necessary objects
            Dim site As SPSite = New SPSite(_statusListSiteUrl)
            Dim web As SPWeb = site.AllWebs(_statusListWeb)
            Dim list As SPList = web.Lists(_statusList)
            'Step 2: Find the list item for the current user, and update its status
            'web.AllowUnsafeUpdates = True
            For Each ListItem As SPListItem In list.Items
                Try
                    'Step 3: If user is found, return their status
                    If ListItem("UserAlias").ToString.ToLower = _
                            Context.User.Identity.Name.ToLower Then
                        Return ListItem("Status")
                        Exit For
                    End If
                Catch ex As Exception
                    'No op
                End Try
            Next
            web.Dispose()
            site.Dispose()
        Catch ex As Exception
            'No op
        End Try
        'Step 4: If we got this far, no entry was found for the current user
        Return ""
    End Function

Private Sub UpdateStatus()
        Try
            'Step 1: Get a handle to the list that we're using to store
            'user status information
            Dim site As SPSite = New SPSite(_statusListSiteUrl)
            Dim web As SPWeb = site.AllWebs(_statusListWeb)
            Dim list As SPList = web.Lists(_statusList)
            Dim listItem As SPListItem
            Dim boolFound As Boolean = False
            'Step 2: Find the list item for the current user, and update its status
            For Each listItem In list.Items
                Try
                    'Step 3: If found, update the user's status
                    If listItem("UserAlias").ToString.ToLower = _
                        Context.User.Identity.Name.ToLower Then
                        listItem("Status") = GetUserControlStatus()
                        listItem.Update()
                        boolFound = True
                        Exit For
                    End If
                Catch ex As Exception
                End Try
            Next
            'Step 4: If an entry for the current user wasn't found in the list,
            'add one now.
            If Not boolFound Then
                listItem = list.Items.Add()
                listItem("UserAlias") = Context.User.Identity.Name
                listItem("Status") = GetUserControlStatus()
                listItem.Update()
            End If
            web.Dispose()
            site.Dispose()
        Catch ex As Exception
            Dim lbl As New Label
            lbl.Text = "<font color='red'>" & ex.Message & "</font><br/>"
            Me.Controls.Add(lbl)
        End Try
    End Sub
    'Get the currently selected status from
    'the user control UI
    Private Function GetUserControlStatus() As String
        If radRed.Checked Then
            Return "Red"
        ElseIf radYellow.Checked Then
            Return "Yellow"

Else
            Return "Green"
        End If
    End Function
    'Helper function to make sure all images are
    'hidden prior to displaying the selected one
    Public Sub HideAllImages()
        Me.imgGreen.Visible = False
        Me.imgYellow.Visible = False
        Me.imgRed.Visible = False
    End Sub
    'The following event handlers process button clicks to
    'display the image corresponding to the selected status
    Public Sub radGreen_CheckedChanged(ByVal sender As System.Object, _
       ByVal e As System.EventArgs) Handles radGreen.CheckedChanged
        HideAllImages()
        If radGreen.Checked Then
            If _showImage Then
                imgGreen.Visible = True
            End If
        End If
        UpdateStatus()
    End Sub
    Public Sub radYellow_CheckedChanged(ByVal sender As System.Object, _
       ByVal e As System.EventArgs) Handles radYellow.CheckedChanged
        HideAllImages()
        If radYellow.Checked Then
            If _showImage Then
                imgYellow.Visible = True
            End If
        End If
        UpdateStatus()
    End Sub
    Public Sub radRed_CheckedChanged(ByVal sender As System.Object, _
       ByVal e As System.EventArgs) Handles radRed.CheckedChanged
        HideAllImages()
        If radRed.Checked Then
            If _showImage Then
                imgRed.Visible = True
            End If
        End If
        UpdateStatus()
    End Sub
End Class

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using Microsoft.SharePoint;
using Microsoft.SharePoint.WebControls;
partial class SmartPartStatusWebPartCS : System.Web.UI.UserControl
{
    //Define local variables
    private bool _showImage = true;
    private string _statusListSiteUrl = "http://localhost";
    private string _statusListWeb = "spwp";
    private string _statusList = "Status";
    private void Page_PreRender(object sender, System.EventArgs e)
    {
        //Only run this code if this is the first time the
        //user control has been displayed on the current
        //page since it was opened
        if (!IsPostBack)
        {
            HideAllImages();
            switch (GetProfileStatus())
            {
                case "Green":
                    this.imgGreen.Visible = true;
                    this.radGreen.Checked = true;
                    break;
                case "Yellow":
                    this.imgYellow.Visible = true;
                    this.radYellow.Checked = true;
                    break;

case "Red":
                    this.imgRed.Visible = true;
                    this.radRed.Checked = true;
                    break;
                default:
                    break;
            }
        }
    }
    private string GetProfileStatus()
    {
        try
        {
            //Step 1: Define necessary objects
            SPSite site = new SPSite(_statusListSiteUrl);
            SPWeb web = site.AllWebs[_statusListWeb];
            SPList list = web.Lists[_statusList];
            //Step 2: Find the list item for the current user, and update its status
            //web.AllowUnsafeUpdates = True
            foreach (SPListItem ListItem in list.Items)
            {
                try
                {
                    //Step 3: If found, return their status
                    if (ListItem["UserAlias"].ToString().ToLower() ==
                       Context.User.Identity.Name.ToLower())
                    {
                        return ListItem["Status"].ToString();
                    }
                }
                catch (Exception ex)
                {
                    //No op
                }
            }
            web.Dispose();
            site.Dispose();
        }
        catch (Exception ex)
        {
            //No op
        }
        //Step 4: If we got this far, no entry was found for the current user
        return "";
    }

private void UpdateStatus()
    {
        try {
            //Step 1: Get a handle to the list that we're using to store
            //user status information
            SPSite site = new SPSite(_statusListSiteUrl);
            SPWeb web = site.AllWebs[_statusListWeb];
            SPList list = web.Lists[_statusList];
            SPListItem listItem;
            bool boolFound = false;
            //Step 2: Find the list item for the current user, and update its status
            foreach (SPListItem li in list.Items) {
                try {
                    //Step 3: If found, set their status
                    if (li["UserAlias"].ToString().ToLower() ==
                       Context.User.Identity.Name.ToLower()) {
                        li["Status"] = GetUserControlStatus();
                        li.Update();
                        boolFound = true;
                        break;
                    }
                }
                catch (Exception ex) {
                }
            }
            //Step 4: If an entry for the current user wasn't found in the list,
            //add one now.
            if (!boolFound) {
                listItem = list.Items.Add();
                listItem["UserAlias"] = Context.User.Identity.Name;
                listItem["Status"] = GetUserControlStatus();
                listItem.Update();
            }
            web.Dispose();
            site.Dispose();
        }
        catch (Exception ex) {
            Label lbl = new Label();
            lbl.Text = "<font color='red'>" + ex.Message + "</font><br/>";
            this.Controls.Add(lbl);
        }
    }

//Get the currently selected status from
    //the user control UI
    private string GetUserControlStatus()
    {
        if (radRed.Checked)
        {
            return "Red";
        }
        else if (radYellow.Checked)
        {
            return "Yellow";
        }
        else
        {
            return "Green";
        }
    }
    //Helper function to make sure all images are
    //hidden prior to displaying the selected one
    public void HideAllImages()
    {
        this.imgGreen.Visible = false;
        this.imgYellow.Visible = false;
        this.imgRed.Visible = false;
    }
    //The following event handlers process button clicks to
    //display the image corresponding to the selected status
    public void radGreen_CheckedChanged(object sender, EventArgs e)
    {
        HideAllImages();
        if (radGreen.Checked)
        {
            if (_showImage)
            {
                imgGreen.Visible = true;
            }
        }
        UpdateStatus();
    }
    public void radYellow_CheckedChanged(object sender, EventArgs e)
    {
        HideAllImages();
        if (radYellow.Checked)
        {
            if (_showImage)
            {
                imgYellow.Visible = true;

}
        }
        UpdateStatus();
    }
    public void radRed_CheckedChanged(object sender, EventArgs e)
    {
        HideAllImages();
        if (radRed.Checked)
        {
            if (_showImage)
            {
                imgRed.Visible = true;
            }
        }
        UpdateStatus();
    }
}

After you have successfully compiled your ASP.NET application containing the status user control, copy the user control .ascx and code-behind files (either .ascx.cs or .ascx.vb depending on the language you're using) to the UserControls folder you created earlier.

Next, navigate to a web-part page and place a SmartPart web part on the page. Open the SmartPart's property sheet and select the user control from the drop-down list of user controls in the UserControl folder. That's all there is to it!

When the status control is displayed for a given user for the first time, no image will be displayed. Clicking on one of the radio buttons will cause a new entry for the current user to be inserted into the status list. From that point forward, the Status web part will "remember" the user's status by looking up the user's entry in the status list. Figure 4-15 shows the Status web part as it will display on a web-part page.

Figure 4.15. The Status web part in action

The first of the two most interesting processes in this recipe is the overridden CreateChildControls() method that is responsible for drawing the tab menu.

The second interesting method is ShowHideWebParts(). This is a custom method that loops through all web parts in the current zone that are below the ZoneTab web part, and hides those that are not associated with the currently selected tab.

Imports System
Imports System.Collections.Generic
Imports System.Text
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Imports System.Drawing
Namespace ZoneTabWebPartVB
    Public Class ZoneTabWebPart
        Inherits WebPart
        ' Local variables
        Private _tabData As String = ""
        Private _debug As Boolean = False
        Private _selectedTab As String
        Private _tabWidth As Integer = 100
        Private _tabBackgroundColorSelected As String = "white"
        Private _tabBackgroundColorDeselected As String = "whitesmoke"
        <Personalizable()> _
        <WebBrowsable()> _
        <WebDisplayName( _
        "Flag indicating whether debug info should be displayed")> _
        Public Property Debug() As Boolean
            Get
                Return _debug
            End Get
            Set(ByVal value As Boolean)
                _debug = value
            End Set
        End Property
        ' String containing semicolon-delimited list
        ' of tab names. Tab names are preceeded by "*".
        '
        ' Example: *Tab 1;webpart1;webpart2;*Tab 2;webpart3
        '

<Personalizable()> _
        <WebBrowsable()> _
        <WebDisplayName( _
        "A delimited list of tab names and associated web parts")> _
        Public Property TabData() As String
            Get
                Return _tabData
            End Get
            Set(ByVal value As String)
                _tabData = value
            End Set
        End Property
        <Personalizable()> _
        <WebBrowsable()> _
        <WebDescription("Color of selected tab")> _
        Public Property SelectedColor() As String
            Get
                Return _tabBackgroundColorSelected
            End Get
            Set(ByVal value As String)
                _tabBackgroundColorSelected = value
            End Set
        End Property
        <Personalizable()> _
        <WebBrowsable()> _
        <WebDescription("Color of un-selected tab")> _
        Public Property DeSelectedColor() As String
            Get
                Return _tabBackgroundColorDeselected
            End Get
            Set(ByVal value As String)
                _tabBackgroundColorDeselected = value
            End Set
        End Property
        <Personalizable()> _
        <WebBrowsable()> _
        <WebDisplayName("Width in pixels for each tab")> _
        Public Property TabWidth() As Integer
            Get
                Return _tabWidth
            End Get
            Set(ByVal value As Integer)
                _tabWidth = value
            End Set
        End Property

' Add tab-links to page
        Protected Overloads Overrides Sub CreateChildControls()
            MyBase.CreateChildControls()
            Try
                Dim arrTabs As String() = _tabData.Split(";"c)
                ' Build list of tabs in the form
                ' of an HTML <TABLE> with <A> tags
                ' for each tab
                ' Step 1: Define <TABLE> and <TR> HTML elements
                Dim tbl As New Table()
                tbl.CellPadding = 0
                tbl.CellSpacing = 0
                Dim tr As New TableRow()
                tr.HorizontalAlign = HorizontalAlign.Left
                ' Step 2: Loop through list of tabs, adding
                ' <TD> and <A> HTML elements for each
                Dim tc As TableCell
                Dim tab As LinkButton
                Dim tabCount As Integer = 0
                For i As Integer = 0 To arrTabs.Length - 1
                    If arrTabs(i).IndexOf("*") = 0 Then
                        ' Step 3: Add a blank separator cell
                        tc = New TableCell()
                        tc.Text = "&nbsp;"
                        tc.Width = _
                           System.Web.UI.WebControls.Unit.Percentage(1)
                        tc.Style("border-bottom") = "black 1px solid"
                        tr.Cells.Add(tc)
                        ' Step 4: Create a <TD> HTML element to hold the tab
                        tc = New TableCell()
                        tc.ID = "tc_" + _
                           arrTabs(i).Substring(1).Replace(" ", "_")
                        tc.Width = _
                           System.Web.UI.WebControls.Unit.Pixel(_tabWidth)
                        ' Step 5: Create an <A> HTML element to represent
                        ' the tab. Discard first character, which
                        ' was a "*"
                        tab = New LinkButton()
                        tab.ID = "tab_" + _
                           arrTabs(i).Substring(1).Replace(" ", "_")
                        tab.Text = arrTabs(i).Substring(1)
                        ' Step 6: Attach event handler that will execute when
                        ' user clicks on tab link
                        AddHandler tab.Click, AddressOf tab_Click
                        ' Step 7: Set any other properties as desired
                        tab.Width = _
                           System.Web.UI.WebControls.Unit.Pixel(_tabWidth-2)

tab.Style("text-align") = "center"
                        tab.Style("font-size") = "larger"
                        ' Step 8: Insert tab <A> element into <TD> element
                        tc.Controls.Add(tab)
                        ' Step 9: Insert <TD> element into <TR> element
                        tr.Cells.Add(tc)
                        tabCount += 1
                    End If
                Next
                ' Add final blank cell to cause horizontal line to
                ' run across entire zone width
                tc = New TableCell()
                tc.Text = "&nbsp;"
                tc.Width = _
                   System.Web.UI.WebControls.Unit.Pixel(_tabWidth * 10)
                tc.Style("border-bottom") = "black 1px solid"
                tr.Cells.Add(tc)
                ' Step 10: Insert the <TR> element into <TABLE> and
                ' add the HTML table to the page
                tbl.Rows.Add(tr)
                Me.Controls.Add(tbl)
            Catch ex As Exception
                Dim lbl As New Label()
                lbl.Text = "Error: " + ex.Message
                Me.Controls.Add(lbl)
            End Try
        End Sub
        Protected Overloads Overrides Sub RenderContents( _
           ByVal writer As System.Web.UI.HtmlTextWriter)
            If _debug Then
                writer.Write("Tab Data: " + _tabData + "<hr/>")
            End If
            ShowHideWebParts(writer)
            MyBase.RenderContents(writer)
        End Sub
        ' Show web parts for currently selected tab,
        ' hide all others
        Private Sub ShowHideWebParts( _
           ByVal writer As System.Web.UI.HtmlTextWriter)
            Try
                Dim lbl As New Label()
                Dim arrTabs As String() = _tabData.Split(";"c)
                ' Step 1: If a tab has not been selected, assume
                ' the first one
                If _selectedTab Is Nothing Then
                    _selectedTab = arrTabs(0).Substring(1)
                End If

' Step 2: Hide all web parts in zone that are
                ' below the ZoneTab part
                For Each wp As WebPart In Me.Zone.WebParts
                    If wp.ZoneIndex > Me.ZoneIndex Then
                        wp.Hidden = True
                    End If
                Next
                For i As Integer = 0 To arrTabs.Length - 1
                    ' Step 3: Get web-part names associated with this tab
                    ' Step 4: Find the selected tab
                    If arrTabs(i) = "*" + _selectedTab Then
                        For j As Integer = i + 1 To arrTabs.Length - 1
                            ' Step 5: Get associated web-part names
                            ' Step 6: Loop until next tab name found,
                            ' or end of list
                            If arrTabs(j).IndexOf("*") <> 0 Then
                                ' Step 7: Show named web parts
                                For Each wp As WebPart In Me.Zone.WebParts
                                    If wp.Title = arrTabs(j) Then
                                        wp.Hidden = False
                                    End If
                                Next
                            Else
                                Exit For
                            End If
                        Next
                        ' Step 8: Bring tab border to "front"
                        Dim tc As TableCell = _
                           DirectCast(Me.FindControl("tc_" + _
                           arrTabs(i).Substring(1).Replace(" ", "_")), _
                          TableCell)
                        tc.Style("border-bottom") = "white 1px solid"
                        tc.Style("border-top") = "black 1px solid"
                        tc.Style("border-left") = "black 1px solid"
                        tc.Style("border-right") = "black 1px solid"
                        tc.Style("background-color") = _
                           _tabBackgroundColorSelected
                        ' Step 9: Highlight selected tab
                        Dim tab As LinkButton = _
                           DirectCast(Me.FindControl("tab_" + _
                           arrTabs(i).Substring(1).Replace(" ", "_")), _
                           LinkButton)
                        tab.Style("background-color") = _
                           _tabBackgroundColorSelected

Else
                        If arrTabs(i).IndexOf("*") = 0 Then
                            ' Step 10: Send tab border to "back"
                            Dim tc As TableCell = _
                               DirectCast(Me.FindControl("tc_" + _
                               arrTabs(i).Substring(1).Replace(" ", "_")), _
                               TableCell)
                            tc.Style("border-bottom") = "black 1px solid"
                            tc.Style("border-top") = "gray 1px solid"
                            tc.Style("border-left") = "gray 1px solid"
                            tc.Style("border-right") = "gray 1px solid"
                            tc.Style("background-color") = _
                               _tabBackgroundColorDeselected
                            ' Step 11: Lowlight selected tab
                            Dim tab As LinkButton = _
                               DirectCast(Me.FindControl("tab_" + _
                               arrTabs(i).Substring(1).Replace(" ", "_")), _
                               LinkButton)
                            tab.Style("background-color") = _
                               _tabBackgroundColorDeselected
                        End If
                    End If
                Next
            Catch ex As Exception
                writer.Write("Error: " + ex.Message)
            End Try
        End Sub
        ' This is the click event handler that was assigned
        ' to all tab LinkButton objects in CreateChildControls()
        ' method.
        Private Sub tab_Click(ByVal sender As Object, ByVal e As EventArgs)
            Try
                ' Set flag indicated current tab, for
                ' use in RenderContents() method
                Dim tab As LinkButton = DirectCast(sender, LinkButton)
                _selectedTab = tab.Text
            Catch ex As Exception
                Dim lbl As New Label()
                lbl.Text = ex.Message
                Me.Controls.Add(lbl)
            End Try
        End Sub
    End Class
End Namespace

using System;
using System.Collections.Generic;
using System.Text;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Drawing;
namespace ZoneTabWebPartCS
{
    public class ZoneTabWebPart : WebPart
    {
        // Local variables
        string _tabData = "";
        bool _debug = false;
        string _selectedTab;
        int _tabWidth = 100;
        string _tabBackgroundColorSelected = "white";
        string _tabBackgroundColorDeselected = "whitesmoke";
        [Personalizable]
        [WebBrowsable]
        [WebDisplayName(
           "Flag indicating whether debug info should be displayed")]
        public bool Debug
        {
            get { return _debug; }
            set { _debug = value; }
        }
        // String containing semicolon-delimited list
        // of tab names.  Tab names are preceeded by "*".
        //
        // Example: *Tab 1;webpart1;webpart2;*Tab 2;webpart3
        //
        [Personalizable]
        [WebBrowsable]
        [WebDisplayName(
           "A delimited list of tab names and associated web parts")]
        public string TabData
        {
            get { return _tabData; }
            set { _tabData = value; }
        }

[Personalizable]
        [WebBrowsable]
        [WebDescription("Color of selected tab")]
        public string SelectedColor
        {
            get { return _tabBackgroundColorSelected; }
            set { _tabBackgroundColorSelected = value; }
        }
        [Personalizable]
        [WebBrowsable]
        [WebDescription("Color of un-selected tab")]
        public string DeSelectedColor
        {
            get { return _tabBackgroundColorDeselected; }
            set { _tabBackgroundColorDeselected = value; }
        }
        [Personalizable]
        [WebBrowsable]
        [WebDisplayName("Width in pixels for each tab")]
        public int TabWidth
        {
            get { return _tabWidth; }
            set { _tabWidth = value; }
        }
        // Add tab links to page
        protected override void CreateChildControls()
        {
            base.CreateChildControls();
            try
            {
                string[] arrTabs = _tabData.Split(';'),
                // Build list of tabs in the form
                // of an HTML <TABLE> with <A> tags
                // for each tab
                // Step 1: Define <TABLE> and <TR> HTML elements
                Table tbl = new Table();
                tbl.CellPadding = 0;
                tbl.CellSpacing = 0;
                TableRow tr = new TableRow();
                tr.HorizontalAlign = HorizontalAlign.Left;
                // Step 2: Loop through list of tabs, adding
                //  <TD> and <A> HTML elements for each
                TableCell tc;
                LinkButton tab;
                int tabCount = 0;

for (int i = 0; i < arrTabs.Length; i++)
                {
                    if (arrTabs[i].IndexOf("*") == 0)
                    {
                        // Step 3: Add a blank separator cell
                        tc = new TableCell();
                        tc.Text = "&nbsp;";
                        tc.Width =
                           System.Web.UI.WebControls.Unit.Percentage(1);
                        tc.Style["border-bottom"] = "black 1px solid";
                        tr.Cells.Add(tc);
                        // Step 4: Create a <TD> HTML element to hold the tab
                        tc = new TableCell();
                        tc.ID = "tc_" +
                           arrTabs[i].Substring(1).Replace(" ", "_");
                        tc.Width =
                           System.Web.UI.WebControls.Unit.Pixel(_tabWidth);
                        // Step 5: Create an <A> HTML element to represent
                        // the tab.  Discard first character, which
                        // was a "*"
                        tab = new LinkButton();
                        tab.ID = "tab_" +
                           arrTabs[i].Substring(1).Replace(" ", "_");
                        tab.Text = arrTabs[i].Substring(1);
                        // Step 6: Attach event handler that will execute
                        // when user clicks tab link
                        tab.Click += new EventHandler(tab_Click);
                        // Step 7: Set any other properties as desired
                        tab.Width =
                           System.Web.UI.WebControls.Unit.Pixel(_tabWidth-2);
                        tab.Style["text-align"] = "center";
                        tab.Style["font-size"] = "larger";
                        // Step 8: Insert tab <A> element into <TD> element
                        tc.Controls.Add(tab);
                        // Step 9: Insert <TD> element into <TR> element
                        tr.Cells.Add(tc);
                        tabCount++;
                    }
                }
                // Add final blank cell to cause horizontal line to
                // run across entire zone width
                tc = new TableCell();
                tc.Text = "&nbsp;";
                tc.Width =
                   System.Web.UI.WebControls.Unit.Pixel(_tabWidth * 10);
                tc.Style["border-bottom"] = "black 1px solid";
                tr.Cells.Add(tc);

// Step 10: Insert the <TR> element into <TABLE> and
                // add the HTML table to the page
                tbl.Rows.Add(tr);
                this.Controls.Add(tbl);
            }
            catch (Exception ex)
            {
                Label lbl = new Label();
                lbl.Text = "Error: " + ex.Message;
                this.Controls.Add(lbl);
            }
        }
        protected override void RenderContents(
           System.Web.UI.HtmlTextWriter writer)
        {
            if (_debug)
            {
                writer.Write("Tab Data: " + _tabData + "<hr/>");
            }
            ShowHideWebParts(writer);
            base.RenderContents(writer);
        }
        // Show web parts for currently selected tab,
        // hide all others
        void ShowHideWebParts(System.Web.UI.HtmlTextWriter writer)
        {
            try
            {
                Label lbl = new Label();
                string[] arrTabs = _tabData.Split(';'),
                // Step 1: If a tab has not been selected, assume
                // the first one
                if (_selectedTab == null)
                   _selectedTab = arrTabs[0].Substring(1);
                // Step 2: Hide all web parts in zone that are
                // below the ZoneTab part
                foreach (WebPart wp in this.Zone.WebParts)
                {
                    if (wp.ZoneIndex > this.ZoneIndex)
                    {
                        wp.Hidden = true;
                    }
                }
                // Step 3: Get web-part names associated with this tab

for (int i = 0; i < arrTabs.Length; i++)
                {
                    // Step 4: Find the selected tab
                    if (arrTabs[i] == "*" + _selectedTab)
                    {
                        // Step 5: Get associated web-part names
                        for (int j = i + 1; j < arrTabs.Length; j++)
                        {
                            // Step 6: Loop until next tab name found,
                            // or end of list
                            if (arrTabs[j].IndexOf("*") != 0)
                            {
                                // Step 7: Show named web parts
                                foreach (WebPart wp in this.Zone.WebParts)
                                {
                                    if (wp.Title == arrTabs[j])
                                       wp.Hidden = false;
                                }
                            }
                            else
                            {
                                break;
                            }
                        }
                        // Step 8: Bring tab border to "front"
                        TableCell tc =
                           (TableCell)this.FindControl("tc_" +
                           arrTabs[i].Substring(1).Replace(" ", "_"));
                        tc.Style["border-bottom"] = "white 1px solid";
                        tc.Style["border-top"] = "black 1px solid";
                        tc.Style["border-left"] = "black 1px solid";
                        tc.Style["border-right"] = "black 1px solid";
                        tc.Style["background-color"] =
                           _tabBackgroundColorSelected;
                        // Step 9: Highlight selected tab
                        LinkButton tab =
                           (LinkButton)this.FindControl("tab_" +
                           arrTabs[i].Substring(1).Replace(" ", "_"));
                        tab.Style["background-color"] =
                           _tabBackgroundColorSelected;
                    }
                    else
                    {
                        if (arrTabs[i].IndexOf("*") == 0)
                        {

// Step 10: Send tab border to "back"
                            TableCell tc =
                               (TableCell)this.FindControl("tc_" +
                               arrTabs[i].Substring(1).Replace(" ", "_"));
                            tc.Style["border-bottom"] = "black 1px solid";
                            tc.Style["border-top"] = "gray 1px solid";
                            tc.Style["border-left"] = "gray 1px solid";
                            tc.Style["border-right"] = "gray 1px solid";
                            tc.Style["background-color"] =
                               _tabBackgroundColorDeselected;
                            // Step 11: Lowlight selected tab
                            LinkButton tab =
                               (LinkButton)this.FindControl("tab_" +
                               arrTabs[i].Substring(1).Replace(" ", "_"));
                            tab.Style["background-color"] =
                               _tabBackgroundColorDeselected;
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                writer.Write("Error: " + ex.Message);
            }
        }
        // This is the click event handler that was assigned
        // to all tab LinkButton objects in CreateChildControls()
        // method.
        void tab_Click(object sender, EventArgs e)
        {
            try
            {
                // Set flag indicatingcurrent tab, for
                // use in RenderContents() method
                LinkButton tab = (LinkButton)sender;
                _selectedTab = tab.Text;
            }
            catch (Exception ex)
            {
                Label lbl = new Label();
                lbl.Text = ex.Message;
                this.Controls.Add(lbl);
            }
        }
    }
}

After you have deployed the ZoneTab web part, browse to a web-part page in the site collection to which the ZoneTab has been deployed. Add the ZoneTab to a page and set the properties as shown in Figures 4-16 and 4-17.

Figure 4.16. The ZoneTab web part's property sheet

Figure 4.17. Syntax for entering tab names and associated web parts for each tab

In the preceding screen shots, you can see the ZoneTab web-part property sheet, along with an expanded view of the text that defines the tabs and associated named web parts, which will be displayed when a particular tab is selected. Figure 4-18 shows the ZoneTab web part as it will display on a web-part page.

Figure 4.18. The ZoneTab web part in action

The CreateChildControls() method is fairly interesting in that in it we build a dynamic <TABLE> to contain the list of properties in the site matching our prefix, and for site administrators, Add, Delete, and Save buttons as well.

The btn_Click() event handler fires when the user clicks the Save Changes button, and is responsible for writing changed or new properties back to SharePoint.

The delbtn_Click() event handler fires when the user clicks a Delete button to the right of an editable property, and is responsible for removing the corresponding site property from the property collection.

Imports System
Imports System.Collections.Generic
Imports System.Text
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Imports Microsoft.SharePoint
Imports Microsoft.SharePoint.WebControls
Imports Microsoft.SharePoint.Utilities
Public Class WebPropertiesWebPart
    Inherits WebPart
    ' Define location variables
    Private _debug As Boolean = False
    Private _prefix As String = "mg_"
    <Personalizable()> _
    <WebBrowsable()> _
    <WebDescription("Check to display debug information")> _
    <WebDisplayName("Debug?")> _
    Public Property Debug() As Boolean
        Get
            Return _debug
        End Get
        Set(ByVal value As Boolean)
            _debug = value
        End Set
    End Property

<Personalizable()> _
    <WebBrowsable()> _
    <WebDescription("Prefix to use when storing & retrieving properties")> _
    <WebDisplayName("Property prefix: ")> _
    Public Property Prefix() As String
        Get
            Return _prefix
        End Get
        Set(ByVal value As String)
            _prefix = value
        End Set
    End Property
    Protected Overloads Overrides Sub CreateChildControls()
        MyBase.CreateChildControls()
        Try
            ' Step 1: Create table to hold existing, new properties
            Dim tbl As New Table()
            Dim tr As TableRow
            Dim tc As TableCell
            Dim delBtn As ImageButton
            Dim tb As TextBox
            Dim lbl As Label
            Dim i As Integer = 1
            ' Just a bit of formatting
            tbl.CellPadding = 3
            tbl.CellSpacing = 3
            tbl.BorderStyle = BorderStyle.Solid
            ' Add a heading
            tr = New TableRow()
            ' #
            tc = New TableCell()
            tr.Cells.Add(tc)
            ' Key
            tc = New TableCell()
            tc.Text = "Property Key"
            tc.Font.Bold = True
            tr.Cells.Add(tc)
            ' Value
            tc = New TableCell()
            tc.Text = "Value"
            tc.Font.Bold = True
            tr.Cells.Add(tc)
            tbl.Rows.Add(tr)
            ' Delete button
            tc = New TableCell()
            tr.Cells.Add(tc)
            tc.Font.Bold = True

tr.Cells.Add(tc)
            tbl.Rows.Add(tr)
            ' Step 2: Loop through existing properties that match prefix
            ' and are not null, add to table
            Dim web As SPWeb = SPControl.GetContextWeb(Context)
            Dim properties As SPPropertyBag = web.Properties
            Dim isAdmin As Boolean = web.CurrentUser.IsSiteAdmin
            For Each key As Object In properties.Keys
                If key.ToString().IndexOf(_prefix) = 0 _
                   AndAlso properties(key.ToString()) IsNot Nothing Then
                    ' Create a new row for current property
                    tr = New TableRow()
                    ' #
                    tc = New TableCell()
                    tc.Text = i.ToString() + ". "
                    tr.Cells.Add(tc)
                    ' Key
                    tc = New TableCell()
                    tc.Text = key.ToString().Substring(_prefix.Length)
                    tc.ID = "key_" + i.ToString()
                    tr.Cells.Add(tc)
                    ' Value
                    tc = New TableCell()
                    ' 3. For admin users, show value in
                    ' an editable text box + delete button
                    If isAdmin Then
                        tb = New TextBox()
                        tb.Text = properties(key.ToString())
                        tb.ID = "value_" + i.ToString()
                        tc.Controls.Add(tb)
                        tr.Cells.Add(tc)
                        tc = New TableCell()
                        delBtn = New ImageButton()
                        delBtn.ImageUrl = "/_layouts/images/delete.gif"
                        AddHandler delBtn.Click, AddressOf delBtn_Click
                        delBtn.ID = "delete_" + i.ToString()
                        tc.Controls.Add(delBtn)
                        tr.Cells.Add(tc)
                    Else
                        ' for non-admin users, just show read-only
                        lbl = New Label()
                        lbl.Text = properties(key.ToString())
                        tc.Controls.Add(lbl)
                        tr.Cells.Add(tc)
                    End If

' Add new row to table
                    tbl.Rows.Add(tr)
                    i += 1
                End If
            Next
            ' Step 4: Add a final row to allow user
            ' to add new properties if current user is site admin
            If isAdmin Then
                tr = New TableRow()
                ' #
                tc = New TableCell()
                tc.Text = "*. "
                tr.Cells.Add(tc)
                ' Key
                tc = New TableCell()
                tb = New TextBox()
                tb.Text = ""
                tb.ID = "key_new"
                tc.Controls.Add(tb)
                tr.Cells.Add(tc)
                ' Value
                tc = New TableCell()
                tb = New TextBox()
                tb.Text = ""
                tb.ID = "value_new"
                tc.Controls.Add(tb)
                tr.Cells.Add(tc)
                tbl.Rows.Add(tr)
            End If
            ' Step 5: Add the completed table to the page
            Me.Controls.Add(tbl)
            ' Step 6: Now add a button to save changes,
            ' if current user is site admin
            If isAdmin Then
                lbl = New Label()
                lbl.Text = "<br/>"
                Me.Controls.Add(lbl)
                Dim btn As New Button()
                btn.Text = "Save changes"
                AddHandler btn.Click, AddressOf btn_Click
                Me.Controls.Add(btn)
            End If
        Catch ex As Exception
            Dim lbl As New Label()
            lbl.Text = "Error: " + ex.Message
            Me.Controls.Add(lbl)
        End Try
    End Sub

' Handles "Save Changes" button click event
    Private Sub btn_Click(ByVal sender As Object, ByVal e As EventArgs)
        Try
            ' Step 1: Get handle to web site property
            ' collection
            Dim isChanged As Boolean = False
            Dim web As SPWeb = SPControl.GetContextWeb(Context)
            Dim properties As SPPropertyBag = web.Properties
            web.AllowUnsafeUpdates = True
            ' Step 2: Add new property
            Dim tbNewKey As TextBox = _
               DirectCast(Me.FindControl("key_new"), TextBox)
            Dim tbNewValue As TextBox = _
               DirectCast(Me.FindControl("value_new"), TextBox)
            If tbNewKey.Text <> "" Then
                properties(_prefix + tbNewKey.Text) = tbNewValue.Text
                web.Properties.Update()
                isChanged = True
            End If
            ' Step 3: Loop through text boxes in web part,
            ' updating corresponding site property if
            ' checkbox has been changed.
            Dim tc As TableCell
            Dim tb As TextBox
            For i As Integer = 1 To 998
                tc = DirectCast( _
                   Me.FindControl("key_" + i.ToString()), TableCell)
                ' Step 4: If a control with the name "key_<n>" exists, get
                ' it, otherwise assume no more custom properties to edit
                If tc IsNot Nothing Then
                    ' Step 5: Ok, we found the text box containing the
                    ' property value, now let's see if the value in the
                    ' text box has been changed to something other than that
                    ' in the corresponding web property.
                    tb = DirectCast( _
                       Me.FindControl("value_" + i.ToString()), TextBox)
                    If properties(_prefix + tc.Text).Trim() _
                       <> tb.Text.Trim() Then
                        ' Step 6: The value was changed, update the web
                        ' property and set the flag indicating that web part
                        ' needs to be redrawn
                        properties(_prefix + tc.Text) = tb.Text
                        web.Properties.Update()
                        isChanged = True
                    End If
                Else
                    Exit For
                End If

Next
            ' Step 7: If any changes made, redraw web part
            ' to reflect changed/added properties
            If isChanged Then
                Me.Controls.Clear()
                CreateChildControls()
            End If
        Catch ex As Exception
            Dim lbl As New Label()
            lbl.Text = "<br/><br/>Error: " + ex.Message
            Me.Controls.Add(lbl)
        End Try
    End Sub
    ' Handles individual property delete button click
    Private Sub delBtn_Click(ByVal sender As Object, _
       ByVal e As System.Web.UI.ImageClickEventArgs)
        Try
            ' Step 1. Get handle to name of property to be
            ' deleted
            Dim delBtn As ImageButton = DirectCast(sender, ImageButton)
            Dim _id As String = delBtn.ID.Replace("delete_", "")
            Dim tc As TableCell = _
               DirectCast(Me.FindControl("key_" + _id), TableCell)
            ' Step 2: Get handle to web site, property collection
            Dim web As SPWeb = SPControl.GetContextWeb(Context)
            Dim properties As SPPropertyBag = web.Properties
            web.AllowUnsafeUpdates = True
            ' Step 3: Delete the unwanted property by setting
            ' its value to null (note: for some reason using
            ' the Remove() method was not sufficient to cause
            ' SharePoint to delete the property).
            web.Properties(_prefix + tc.Text) = Nothing
            web.Properties.Update()
            web.Update()
            ' Step 4: Refresh list
            Me.Controls.Clear()
            CreateChildControls()
            ' Step 5: Display message to user informing them
            ' that property has been deleted
            Dim lbl As New Label()
            lbl.Text = "<br/><br/>You deleted property '" + tc.Text + "'"
            Me.Controls.Add(lbl)
        Catch ex As Exception
            Dim lbl As New Label()
            lbl.Text = "<br/><br/>Error: " + ex.Message
            Me.Controls.Add(lbl)
        End Try

End Sub
    Protected Overloads Overrides Sub RenderContents( _
       ByVal writer As System.Web.UI.HtmlTextWriter)
        MyBase.RenderContents(writer)
        If _debug Then
            writer.Write("<hr/>")
            writer.Write("<strong>Prefix:</strong> " + _prefix)
            writer.Write("<hr/>")
        End If
    End Sub
End Class

using System;
using System.Collections.Generic;
using System.Text;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using Microsoft.SharePoint;
using Microsoft.SharePoint.WebControls;
using Microsoft.SharePoint.Utilities;
namespace WebPropertiesWebPartCS
{
    public class WebPropertiesWebPart : WebPart
    {
        // Define location variables
        bool _debug = false;
        string _prefix = "mg_";
        [Personalizable]
        [WebBrowsable]
        [WebDescription("Check to display debug information")]
        [WebDisplayName("Debug?")]
        public bool Debug
        {
            get { return _debug; }
            set { _debug = value; }
        }
        [Personalizable]
        [WebBrowsable]
        [WebDescription(
           "Prefix to use when storing and retrieving properties")]
        [WebDisplayName("Property prefix: ")]
        public string Prefix
        {
            get { return _prefix; }
            set { _prefix = value; }
        }

protected override void CreateChildControls()
        {
            base.CreateChildControls();
            try
            {
                // Step 1: Create table to hold existing, new properties
                Table tbl = new Table();
                TableRow tr;
                TableCell tc;
                ImageButton delBtn;
                TextBox tb;
                Label lbl;
                int i = 1;
                // Just a bit of formatting
                tbl.CellPadding = 3;
                tbl.CellSpacing = 3;
                tbl.BorderStyle = BorderStyle.Solid;
                // Add a heading
                tr = new TableRow();
                // #
                tc = new TableCell();
                tr.Cells.Add(tc);
                // Key
                tc = new TableCell();
                tc.Text = "Property Key";
                tc.Font.Bold = true;
                tr.Cells.Add(tc);
                // Value
                tc = new TableCell();
                tc.Text = "Value";
                tc.Font.Bold = true;
                tr.Cells.Add(tc);
                tbl.Rows.Add(tr);
                // Delete button
                tc = new TableCell();
                tr.Cells.Add(tc);
                tc.Font.Bold = true;
                tr.Cells.Add(tc);
                tbl.Rows.Add(tr);
                // Step 2: Loop through existing properties that match prefix
                // and are not null, add to table
                SPWeb web = SPControl.GetContextWeb(Context);
                SPPropertyBag properties = web.Properties;
                bool isAdmin = web.CurrentUser.IsSiteAdmin;

foreach (object key in properties.Keys)
                {
                    if (key.ToString().IndexOf(_prefix) == 0
                       && properties[key.ToString()] != null)
                    {
                        // Create a new row for current property
                        tr = new TableRow();
                        // #
                        tc = new TableCell();
                        tc.Text = i.ToString() + ". ";
                        tr.Cells.Add(tc);
                        // Key
                        tc = new TableCell();
                        tc.Text = key.ToString().Substring(_prefix.Length);
                        tc.ID = "key_" + i.ToString();
                        tr.Cells.Add(tc);
                        // Value
                        tc = new TableCell();
                        // 3. For admin users, show value in
                        // an editable text box + delete button
                        if (isAdmin)
                        {
                            tb = new TextBox();
                            tb.Text = properties[key.ToString()];
                            tb.ID = "value_" + i.ToString();
                            tc.Controls.Add(tb);
                            tr.Cells.Add(tc);
                            tc = new TableCell();
                            delBtn = new ImageButton();
                            delBtn.ImageUrl = "/_layouts/images/delete.gif";
                            delBtn.Click += new
                               System.Web.UI.ImageClickEventHandler(delBtn_Click);
                            delBtn.ID = "delete_" + i.ToString();
                            tc.Controls.Add(delBtn);
                            tr.Cells.Add(tc);
                        }
                        else // for non-admin users, just show read-only
                        {
                            lbl = new Label();
                            lbl.Text = properties[key.ToString()];
                            tc.Controls.Add(lbl);
                            tr.Cells.Add(tc);
                        }
                        // Add new row to table
                        tbl.Rows.Add(tr);
                        i++;
                    }
                }

// Step 4: Add a final row to allow user
                // to add new properties if current user is site admin
                if (isAdmin)
                {
                    tr = new TableRow();
                    // #
                    tc = new TableCell();
                    tc.Text = "*. ";
                    tr.Cells.Add(tc);
                    // Key
                    tc = new TableCell();
                    tb = new TextBox();
                    tb.Text = "";
                    tb.ID = "key_new";
                    tc.Controls.Add(tb);
                    tr.Cells.Add(tc);
                    // Value
                    tc = new TableCell();
                    tb = new TextBox();
                    tb.Text = "";
                    tb.ID = "value_new";
                    tc.Controls.Add(tb);
                    tr.Cells.Add(tc);
                    tbl.Rows.Add(tr);
                }
                // Step 5: Add the completed table to the page
                this.Controls.Add(tbl);
                // Step 6: Now add a button to save changes,
                // if current user is site admin
                if (isAdmin)
                {
                    lbl = new Label();
                    lbl.Text = "<br/>";
                    this.Controls.Add(lbl);
                    Button btn = new Button();
                    btn.Text = "Save changes";
                    btn.Click += new EventHandler(btn_Click);
                    this.Controls.Add(btn);
                }
            }
            catch (Exception ex)
            {
                Label lbl = new Label();
                lbl.Text = "Error: " + ex.Message;
                this.Controls.Add(lbl);
            }
        }

// Handles "Save Changes" button click event
        void btn_Click(object sender, EventArgs e)
        {
            try
            {
                // Step 1: Get handle to web site property
                // collection
                bool isChanged = false;
                SPWeb web = SPControl.GetContextWeb(Context);
                SPPropertyBag properties = web.Properties;
                web.AllowUnsafeUpdates = true;
                // Step 2: Add new property
                TextBox tbNewKey = (TextBox)this.FindControl("key_new");
                TextBox tbNewValue = (TextBox)this.FindControl("value_new");
                if (tbNewKey.Text != "")
                {
                    properties[_prefix+tbNewKey.Text] = tbNewValue.Text;
                    web.Properties.Update();
                    isChanged = true;
                }
                // Step 3: Loop through text boxes in web part
                // updating corresponding site property if
                // checkbox has been changed.
                TableCell tc;
                TextBox tb;
                for (int i = 1; i < 999; i++)
                {
                    tc = (TableCell)this.FindControl("key_"+i.ToString());
                    // Step 4: If a control with the name "key_<n>"
                    // exists, get it, otherwise assume no more custom
                    // properties to edit
                    if (tc != null)
                    {
                        // Step 5: Ok, we found the text box containing the
                        // property value, now let's see if the value in the
                        // text box has been changed to something other than
                        // that in the corresponding web property.
                        tb = (TextBox)this.FindControl("value_" +
                           i.ToString());
                        if (properties[_prefix+tc.Text].Trim() !=
                           tb.Text.Trim())
                        {
                            // Step 6: The value was changed, update the web
                            // property and set the flag indicating that web
                            // part needs to be redrawn
                            properties[_prefix+tc.Text] = tb.Text;

web.Properties.Update();
                            isChanged = true;
                        }
                    }
                    else
                    {
                        break;
                    }
                }
                // Step 7: If any changes made, redraw web part
                // to reflect changed/added properties
                if (isChanged)
                {
                    this.Controls.Clear();
                    CreateChildControls();
                }
            }
            catch (Exception ex)
            {
                Label lbl = new Label();
                lbl.Text = "<br/><br/>Error: " + ex.Message;
                this.Controls.Add(lbl);
            }
        }
        // Handles individual property delete button click
        void delBtn_Click(object sender, System.Web.UI.ImageClickEventArgs e)
        {
            try
            {
                // Step 1. Get handle to name of property to be
                // deleted
                ImageButton delBtn = (ImageButton)sender;
                string _id = delBtn.ID.Replace("delete_", "");
                TableCell tc = (TableCell)this.FindControl("key_" + _id);
                // Step 2: Get handle to web site, property collection
                SPWeb web = SPControl.GetContextWeb(Context);
                SPPropertyBag properties = web.Properties;
                web.AllowUnsafeUpdates = true;
                // Step 3: Delete the unwanted property by setting
                // its value to null (note: for some reason using
                // the Remove() method was not sufficient to cause
                // SharePoint to delete the property).
                web.Properties[_prefix + tc.Text] = null;
                web.Properties.Update();
                web.Update();

// Step 4: Refresh list
                this.Controls.Clear();
                CreateChildControls();
                // Step 5: Display message to user informing them
                // that property has been deleted
                Label lbl = new Label();
                lbl.Text = "<br/><br/>You deleted property '" +
                   tc.Text + "'";
                this.Controls.Add(lbl);
            }
            catch (Exception ex)
            {
                Label lbl = new Label();
                lbl.Text = "<br/><br/>Error: " + ex.Message;
                this.Controls.Add(lbl);
            }
        }
        protected override void RenderContents(
           System.Web.UI.HtmlTextWriter writer)
        {
            base.RenderContents(writer);
            if (_debug)
            {
                writer.Write("<hr/>");
                writer.Write("<strong>Prefix:</strong> " + _prefix);
                writer.Write("<hr/>");
            }
        }
    }
}

Open a web-part page in the site collection to which you have deployed the Web Properties web part, edit the page, and add an instance of the web part. Edit the web part properties to set the prefix you wish to use for properties that will be added or edited through this web part.

Figure 4-19 shows a Web Properties web part as it will be displayed for a user who is a site collection administrator, on a site where five properties have already been added: client#, client name, status, matter name, and #. A new property with a key of new key and value of new value will be added to the property collection when the Save Changes button is clicked. Figure 4-19 shows the Web Properties web part with several custom web site properties already added.

Figure 4.19. The Web Properties web part shown with custom web properties