ejb-client-jar example from the core specification

Question

Hello all,
the ejb3.0 specification says (chapter 60 page 241):
the jar file that contains the client should contain one of the following: 
• a reference to the ejb-client JAR file 
• a reference to the ejb-jar file that contains the client view classes 
• a copy of the client view classes  There is also an example on page 242:
In this example, the Bean Provider has chosen to package the enterprise bean client view classes in a
separate jar file and to reference that jar file from the other jar files that need those classes. Those classes
are needed both by ejb2.jar, packaged in the same application as ejb1.jar, and by ejb3.jar,
packaged in a different application. Those classes are also needed by ejb1.jar itself because they
define the remote interface of the enterprise beans in ejb1.jar, and the Bean Provider has chosen the
by reference approach to making these classes available.
The deployment descriptor for ejb1.jar names the client view jar file in the ejb-client-jar
element. Because ejb2.jar requires these client view classes, it includes a Class-Path reference to
ejb1_client.jar.
The Class-Path mechanism must be used by components in app2.ear to reference the client view jar
file that corresponds to the enterprise beans packaged in ejb1.jar of app1.ear. Those enterprise
beans are referenced by enterprise beans in ejb3.jar. Note that the client view jar file must be
included directly in the app2.ear file.
    app1.ear:
        META-INF/application.xml
        ejb1.jar Class-Path: ejb1_client.jar
            deployment descriptor contains:
                <ejb-client-jar>ejb1_client.jar</ejb-client-jar>
        ejb1_client.jar
        ejb2.jar Class-Path: ejb1_client.jar
    app2.ear:
        META-INF/application.xml
        ejb1_client.jar
        ejb3.jar Class-Path: ejb1_client.jarNow finally my questions are:
1. Why did we need to include the ejb1_client.jar in app2.ear (or even in app1.ear), wasn't it enough to deploy the ejb1_client.jar separately then refer to it (using class-path in Manifest, or may be just by using <ejb-client-jar>) as the bullets quoted first suggest?
2. How come we didn't need to use <ejb-client-jar> for ejb2.jar
3. Since both of ejb1.jar and ejb2.jar are packaged in app1.ear couldn't we simply refer to the ejb1_client.jar in the Manifest file of app1.ear?
Please, I appreciate your input on this

Answer 1

I am guessing here and please correct me if I am wrong:
ejb1.jar uses interfaces in ejb1_client.jar as the interface for some of the beans so we needed to use ejb-client-jar and we needed a reference in the manifest file.
ejb2.jar uses some of the claess/interfaces as may be a return type but not as an interface for one of its beans so we didn't need to use ejb-client-jar but we needed an entry in the manifest file.
regarding app1.ear, we can put the ejb1_client.jar in the META-INF/lib app1.ear without the need for any entries in the manifest files.
Edited by: malrawi on Jun 14, 2009 11:59 PM