The Application Tier

Various applications dynamically create end-user pages, most typically in HTML. These applications are processed on an application server. In the past few years, the Enterprise application server market has consolidated dramatically, with two main camps now extant: the Microsoft .Net technologies and the Java technologies.

Crystal Enterprise provides a Software Development Kit in three formats for each of the three most popular development environments: COM, Java, and .Net. These allow an organization maximum flexibility in integrating Crystal Enterprise into its applications.

The COM CE-SDK includes a set of COM objects that interact with Crystal Enterprise via the Crystal Enterprise Framework. Typical installations that use the COM CE-SDK include a Crystal Enterprise Web Connector on each of the Web-server machines, and a Crystal Enterprise Web Component Server within the Crystal Enterprise Framework. A typical example of a COM technology is Microsoft's Active Server Pages (ASP) technology. When Crystal Enterprise is installed in a Windows environment, the basic applications such as the Web Desktop are written in Crystal Server Pages (CSP), a technology analogous with ASP, except that processing takes place within the Crystal Enterprise Framework on the Web Component Server.

The Java CE-SDK includes a set of Java classes that communicate with the Crystal Enterprise Framework. In a Java application server environment, no Web Connector (WC) or Web Component Service (WCS) is required. Instead the Java CE-SDK is processed on the Web application server, which communicates via the Java SDK directly with the Crystal Enterprise Framework. In addition, the Crystal Enterprise Web Component Adapter (WCA) installs on the Web application server and provides the capabilities that you expect from the WCS: CSP processing and specific application support.

Microsoft produces the .Net Framework. Applications written within the .Net Framework are supported by Crystal Enterprise via the .Net format of the CE-SDK. This SDK includes primary interop assemblies and visual development controls for visual application development in Microsoft Visual Studio .Net. In a .Net application, there is no WCS, WCA, or WC required, as the native .Net assemblies are loaded into the .Net framework and communicate with Crystal Enterprise via the COM SDK.

The current state of support for the CE-SDK is both a reflection of the marketplace and a reflection of the historical progression of Crystal Enterprise in response to the maturation of the Web server market. Because Crystal Enterprise was introduced before the Web application market had matured, Crystal Enterprise included its own application server: the WCS. Now that the Web server and Web application server markets have consolidated and matured, the WCS is gradually being replaced by the capabilities of those application servers. Generally, all custom applications should be developed using the technology that is most appropriate: the Java or .Net SDKs. Although COM technology is supported in Crystal Enterprise 10, with Microsoft's migration to .Net from COM, it is recommended that development take place in .Net over COM where possible.