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Application Client architecture
Packaging and deployment
Deploying the application client components into a VisiClient container requires the
specification of deployment descriptors using XML. (Refer to J2EE 1.3 Specification for
more information about application clients, and their deployment into a J2EE 1.3
compliant container.)
Application clients are packaged in JAR files and include a deployment descriptor
(similar to other J2EE application components). The deployment descriptor defines the
EJB and the external resources referenced by the application. You can use the Borland
Enterprise Server Deployment Descriptor Editor for packaging and editing application
client components. For more information, go to the User’s Guide.
The deployment descriptor is necessary because there are a number of functions that
must be configured at deployment time, such as assigning names to EJBs and their
resources. The minimum requirements for deployment of an application client into a
VisiClient container are:
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All the client-side classes are packaged into a JAR. See below section on required
client JARs and files. A well-formed JAR should have the following:
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Application specific classes including the class containing the application entry
point (main class)
The JAR file must have a META-INF subdirectory with the following:
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A manifest file
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A standard XML file (application-client.xml), as required by J2EE 1.3
specifications
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A vendor-specific XML file (application-client-borland.xml)
RMI-IIOP stubs which can also be packaged separately. In this case, the file needs
the classpath attribute of the manifest file set to the appropriate value. The JAR
formed in this manner is deployable to a standalone container or to an EAR file. The
following sections in this chapter describe this process in detail.
Benefits of the VisiClient Container
VisiClient offers users a range of benefits from the use of J2EE applications. These
include:
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Client code portability: Applications can use logical names (as recommended in
the J2EE specifications) to access resources such as database connections, remote
EJBs and environment variables. The container, per the J2EE specification,
exposes the resources as administered objects in the local JNDI namespace
(java:comp/env).
JDBC Connection Pooling: Client applications in Borland Enterprise Server can
use JDBC 2-based datasources (factories). VisiClient Container provides
connection pooling to client applications in the Server that employ a JDBC 2-based
datasource. For example, the VisiClient container's application uses java.net.URL,
JMS, and Mail factories.
Datasource and URL factories are deployed in the in-process local JNDI subcontext
that resides in the client container virtual machine on startup. Other res-ref-types (such
as JMS and Mail) are configured and deployed using the relevant tools from the vendor
of these products. Refer to the Deployment, Datasources and Transaction chapters of
the Borland Enterprise Server Developer's Guide for more information about
configuration and deployment.
98 BES Developer’s Guide