Configure IFilters and File Types
In order for SharePoint to index a particular type of content, it must be able to load and process the file format of the page or document. SharePoint comes with the ability to index most standard file types, including all Office formats, text, XML, and—new to SharePoint 2010—both TIF and Zip files. At times, it is necessary to expand or adjust the list of formats that SharePoint can index by installing new IFilters and registering the new file types.
Understanding IFilters and File Formats
When SharePoint processes an address in a content source, it performs two tests on each file that it finds to determine whether it is able to index it:
1. SharePoint checks the extension of the content file against the list of permitted file types.
2. If the file extension is in the allowed list, SharePoint ensures that the appropriate IFilter has been installed on the crawler.
An IFilter is essentially a file-reading utility that the crawler uses to open a file of a particular type and extract the text contents while stripping away any formatting characters that are irrelevant to search. SharePoint comes with several IFilters, but others, such as the IFilter for the PDF file format, must be installed separately.
NOTE Adobe provides a free 64-bit PDF IFilter. However, IFilter version 9, the version available as of this writing, is known to have performance issues and is not recommended for production SharePoint installations. Commercial vendors including Foxit and PDFlib offer PDF IFilters for SharePoint 2010 that have better performance and support.
Installing IFilters
Commercial IFilters designed for SharePoint 2010 are available for most of the commonly used file types in the industry today.
Typically, the installation of an IFilter is simple and straightforward. The process may differ slightly depending on the vendor, but it will look something like this:
1. On each SharePoint server that will perform the crawl role in the farm, run the IFilter setup file provided by the vendor.
2. Restart the World Wide Web Publishing Service under the Services applet located under Administrative Tools on the SharePoint crawler.
Editing File Types
Once you have installed the correct IFilter, you must configure SharePoint to recognize the file extensions that are associated with the file type. To register a new file extension, do the following:
1. From the Search Administration page, click File Types.
2. Click New File Type.
3. Enter the extension of the file type that will be indexed (without the period at the front).
4. Click OK.
Once both the IFilter is installed and the file type is registered, perform a full crawl to index the files of that type.
Configuring File Icons
While it is sufficient to configure only the IFilter and the file type in order for content to be indexed, it is useful to users to see the appropriate icon next to the item in search results. The icons should be in GIF format and no more than 16 × 16 pixels in dimension at 96 DPI. To register a new file type icon, do the following:
1. Copy the icon to the C:Program FilesCommon FilesMicrosoft SharedWeb Server Extensions14TEMPLATEIMAGES folder.
2. Open the C:Program FilesCommon FilesMicrosoft SharedWeb Server Extensions14TEMPLATEXMLDOCICON.XML file in Notepad or another text editor.
3. Add a row to the <ByExtension> section of the file using the format <Mapping Key="three_letter_extension" Value="image_name.gif" /> and changing the extension and image name as appropriate. For example, you might add the following to register an icon for PDF files:
<Mapping Key="pdf" Value="icpdf.gif" />
4. Save and close the file.