At the highest level, Crystal Enterprise has four main tiers: the client tier, application tier, Crystal Enterprise Server tier, and database tier (see Figure 24.1):
- The client tier consists of Web-based and installed applications. You can alternatively categorize these applications into end-user applications such as the Web-based Web Desktop, which enables end users to access data, management applications such as the Web-based Crystal Management Console, and content creation applications such as Crystal Reports or Crystal Analysis. In the majority of cases, the client tier for a Crystal Enterprise user is his Web browser.
- The application tier consists of application processingtypically on an application server, using the Crystal Enterprise Software Development Kit (CE-SDK). The CE-SDK provides a programmatic interface to the Crystal Enterprise server tier. These server-based programs are processed on an application server, such as BEA WebLogic, IBM's WebSphere, a Servlet container like Apache Tomcat or Microsoft .Net server. This application tier could provide an application centered on Crystal Enterprise functionality, like the Web Desktop, or an application that uses Crystal Enterprise functionality as part of a greater application (for example, an online banking application that provides full-service banking for customers, and provides detailed statements via Crystal Enterprise).
- The server tier consists of services (in Windows) or daemons (in Unix) registered with the Crystal Enterprise Framework. (They are generically referred to as either services or daemons as these terms are interchangeable.) Although this chapter uses the term "service" or "daemon" for technical accuracy, you might see references to these services as "servers" as well, for instance the Crystal Management Server. The server tier is usually subdivided into the intelligence and processing tiers.
- The data tier is composed of all data sources from which an organization can pull data. This data can be in a database, an application, a programmatic data source, XML, a Web service, or a variety of other sources.
Figure 24.1. The client, application, server, and data tiers compose an enterprise business intelligence infrastructure.
With a high-level understanding of the role of the client, application, server, and database tiers, you now consider each one in depth.