20.1. Principles

The Client component programmer is responsible for providing the deployment descriptor associated with the developed client components.

The client component provider's responsibilities and the Application Assembler's responsibilities are to provide an XML deployment descriptor that conforms to the deployment descriptor's XML DTD as defined in the Java Application Client Specification Version 1.4. (Refer to $JONAS_ROOT/xml/application-client_1_4.xsd or http://java.sun.com/xml/ns/j2ee/application-client_1_4.xsd.)

To customize the Client components, information not defined in the standard XML deployment descriptor may be needed. Such information might include, for example, the mapping of the name of referenced resources to its JNDI name. This information can be specified during the deployment phase within another XML deployment descriptor that is specific to JOnAS. The JOnAS-specific deployment descriptor's XML schema is located in $JONAS_ROOT/xml/jonas-client_X_Y.xsd. The file name of the JOnAS-specific XML deployment descriptor must be jonas-client.xml.

JOnAS interprets the <!DOCTYPE> tag at the parsing of the deployment descriptor XML files. The parser first tries to get the specified DTD via the classpath, then it uses the specified URL (or path).

The parser gets the specified schema via the classpath (schemas are packaged in the $JONAS_ROOT/lib/common/ow_jonas.jar file).

The standard deployment descriptor (application-client.xml) should contain structural information that includes the following:

• A Client description

• Environment entries

• EJB references

• Resource references

• Resource env references

• The callback handler to use.

The JOnAS-specific deployment descriptor (jonas-client.xml) may contain information that includes the following:

• The JNDI name of the external resources referenced by a Client component

• The JNDI name of the external resources environment referenced by a Client component

• The JNDI name of the beans referenced by a Client component

• The security aspects including the JAAS file, the JAAS entry, and a login/password to use for a specific callback handler.