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4.7.2.1: Resources referenced by a J2EE application client

4.7.2.1: Resources referenced by a J2EE application client

J2EE application clients access resources by performing lookup operations in the JNDI name space. The application client runtime then provides a mapping of the resource names, used and configured by client application programs, to the actual resource objects. This allows client application programs to access different resources, such as test or production databases, without the need for updates or recompiles.

To provide this service, the application client runtime requires information about the names and types of resources used by the client application program.
The three types of resources a J2EE application client can reference are:

  1. EJB references - are references to Enterprise Java Beans (EJBs) running on WebSphere Application Server.
  2. Resource references - are references to other types of resources, such as:
    • JDBC databases
    • URLs
    • Java Message Service message queues
    • Java Mail

  3. Environment entries - are references to simple data types that you would not want to code in your application program, such as timeout values or SQL query strings. The following Java basic data types are supported:
         java.lang.Boolean
    java.lang.String
    java.lang.Integer
    java.lang.Double
    java.lang.Byte
    java.lang.Short
    java.lang.Long
    java.lang.Float

The resource information is defined and configured using these two WebSphere Application Server tools:

  • Application Assembly Tool (AAT) (used for the definition)
  • Application Client Resource Configuration Tool (used for the configuration)
  • The Application Assembly Tool manages:

    • EJB references
    • non-client specific Resource references
    • all Environment entries

    The Application Client Resource Configuration Tool manages:

    • client specific Resource references such as a JDBC Datasource name
      This information is stored with the client application program in an Enterprise Archive File (.ear file).

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