Server support

PowerBuilder developers can build clients that invoke the services of Sybase EAServer and COM+ servers, and build components (or objects) that execute business logic inside each of these servers.

PowerBuilder also provides support for building clients for Enterprise JavaBeans components (EJBs) running on any J2EE-compliant server.

EAServer

PowerBuilder and EAServer are fully integrated. A PowerBuilder application can act as a client to any EAServer component. In addition, EAServer can contain PowerBuilder custom class user (nonvisual) objects that execute as middle-tier components.

EAServer hosts the PowerBuilder virtual machine natively. This means that EAServer can communicate directly with PowerBuilder nonvisual user objects, and vice versa. EAServer components developed in PowerBuilder can take full advantage of the ease of use and flexibility of PowerScript and the richness of PowerBuilder’s system objects.

Components developed in PowerBuilder can exploit features such as transactions, interoperability, and instance pooling. As shown in Figure 23-1, any type of client can access any type of component running in EAServer, regardless of the language used to develop the component.

Figure 23-1: Clients and components in EAServer

The example shows E A Server running four components: a Power Builder, Java, C or C + +, and COM / Active X component. Three clients are shown : PowerBuilder, Java, C, or C + +, and COM / Active X. All three have access to the four components running in E A Server. E A Server is shown connected to a database server with access to corporate data.

For more information, see Chapter 24, “Building an EAServer Component” and Chapter 25, “Building an EAServer Client.”

COM+

A PowerBuilder application can act as a client to a COM server. The server can be built using PowerBuilder or any other COM-compliant application development tool and it can run locally, on a remote computer as an in-process server, or in COM+, as shown in Figure 23-2.

Figure 23-2: PowerBuilder clients for COM components

The example shows a client application, built with either Power Builder or another tool, running on a Local P B COM server containing P B user objects, on a Remote P B COM server that also contains P B user objects, and on M T S, which can contain P B COM servers that contain P B user objects. All three are connected to a database server with access to corporate data.

You can develop a custom class user object containing business logic in PowerBuilder and then package the object as a COM object. A PowerBuilder COM server can include one or more PowerBuilder custom class user objects. You code the user objects in the User Object painter and then build the server in the Project painter. You can also deploy the COM server directly to a local COM+ server or create a COM+ package from the Project painter.

For more information, see Chapter 27, “Building a COM or COM+ Component” and Chapter 28, “Building a COM or COM+ Client.”

J2EE servers

J2EE, the Java 2 Platform, Enterprise Edition, is the official Java framework for enterprise application development. A J2EE application is composed of separate components that are installed on different computers in a multitiered system. Figure 23-3 shows three tiers in this system: the client tier, middle tier, and Enterprise Information Systems (EIS) tier. The middle tier is sometimes considered to be made up of two separate tiers: the Web tier and the business tier.

Figure 23-3: J2EE client, middle, and EIS tiers

This example shows three tiers: the client tier, middle tier, and Enterprise Information Systems (EIS) tier. The client tier is separated from the others by a fire wall. The Middle tier includes an EJB Container that has Session, Entity, and Message-driven beans (all business components). The middle tier also has a Web container with Servlets, J S Ps, H T M L, and X M L. On a third server in the middle tier are J N D I, J M S, and JavaMail. The EIS tier includes legacy applications, corporate data, and enterprise resource planning.

Client components, such as application clients and applets, run on computers in the client tier. Web components, such as Java servlets and JavaServer Pages (JSP) components, run on J2EE servers in the Web tier. Enterprise JavaBeans (EJB) components are business components and run on J2EE servers in the business tier. The EIS tier is made up of servers running relational database management systems, enterprise resource planning applications, mainframe transaction processing, and other legacy information systems.

In PowerBuilder, you can build client applications that use the services of EJB components running on any J2EE-compliant server. For more information, see Chapter 29, “Building an EJB client.”