This topic provides debugging tips for resolving common Java 2 Platform Enterprise Edition (J2EE) application client problems. To use this troubleshooting guide, review the trace entries for one of the J2EE application client exceptions, and then locate the exception in the guide.
Some of the errors in the guide are samples, and the actual error you receive can be different than what is shown here. You might find it useful to rerun the launchClient command specifying the -CCverbose=true option. This option provides additional information when the J2EE application client run time is initializing.
| Explanation | This exception is thrown when Java code cannot load the specified class. |
| Possible causes |
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| Recommended response | Check to determine if the specified class exists in a Java Archive
(JAR) file within your Enterprise Archive (EAR) file. If it does, make sure
the path for the class is correct. For example, if you get the exception:
java.lang.NoClassDefFoundError: WebSphereSamples.HelloEJB.HelloHomeverify that the HelloHome class exists in one of the JAR files in your EAR file. If it exists, verify that the path for the class is WebSphereSamples.HelloEJB. If both the class and path are correct, then it is a class path issue. Most likely, you do not have the failing class JAR file specified in the client JAR file manifest. To verify this situation, perform the following steps:
This exception is generally caused by a missing Enterprise Java Beans (EJB) module name from the Classpath field. If you have multiple JAR files to enter in the Classpath field, be sure to separate the JAR names with spaces. If you still have the problem, you have a situation where a class is loaded from the file system instead of the EAR file. This error is difficult to debug because the offending class is not the one specified in the exception. Instead, another class is loaded from the file system before the one specified in the exception. To correct this error, review the class paths specified with the -CCclasspath option and the class paths configured with the Application Client Resource Configuration Tool. Look for classes that also exist in the EAR file. You must resolve the situation where one of the classes is found on the file system instead of in the .ear file. Remove entries from the classpaths, or include the .jar files and classes in the .ear file instead of referencing them from the file system. If you use the -CCclasspath parameter or resource classpaths in the tool, and you have configured multiple JAR files or classes, verify they are separated with the correct character for your operating system. Unlike the Classpath field, these class path fields use platform-specific separator characters. The system class path is not used by the Application Client run time if you use the launchClient batch or shell files. In this case, the system class path would not cause this problem. However, if you load the launchClient class directly, you do have to search through the system class path as well. |
| Explanation | This exception occurs when you perform a lookup on an object that is not installed on the host server. Your program can look up the name in the local client Java Naming and Directory Interface (JNDI) name space, but received a NameNotFoundException exception because it is not located on the host server. One typical example is looking up an EJB component that is not installed on the host server that you access. This exception might also occur if the JNDI name you configured in your Application Client module does not match the actual JNDI name of the resource on the host server. |
| Possible causes |
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| Recommended response | If you are accessing the wrong host server, run the launchClient command again with the -CCBootstrapHost parameter specifying the correct host server name. If you are accessing the correct host server, use the product dumpnamespace command line tool to see a listing of the host server JNDI name space. If you do not see the failing object name, the resource is either not installed on the host server or the appropriate application server is not started. If you determine the resource is already installed and started, your JNDI name in your client application does not match the global JNDI name on the host server. Use the Application Server Toolkit to compare the JNDI bindings value of the failing object name in the client application to the JNDI bindings value of the object in the host server application. The values must match. |
| Explanation | This exception occurs when you specify an invalid host server name. |
| Possible causes |
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| Recommended response | Run the launchClient command again and specify the correct name of your host server with the -CCBootstrapHost parameter. |
| Explanation | This exception occurs when you run the launchClient command to a host server that does not have the Application Server started. You also receive this exception when you specify an invalid host server name. This situation might occur if you do not specify a host server name when you run the launchClient tool. The default behavior is for the launchClient tool to run to the local host, because WebSphere Application Server does not know the name of your host server. This default behavior only works when you are running the client on the same machine with WebSphere Application Server is installed. |
| Possible causes |
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| Recommended response | If you are not running to the correct host server, run the launchClient command again and specify the name of your host server with the -CCBootstrapHost parameter. Otherwise, start the Application Server on the host server and run the launchClient command again. |
| Explanation | This exception is thrown when the Java code cannot locate the specified name in the local JNDI name space. |
| Possible causes |
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| Recommended response |
Open the EAR file with the Application Server Toolkit, and check the bindings for the failing name. Ensure this information is correct. If you are using Resource References, open the EAR file with the Application Client Resource Configuration Tool, and verify that the Resource Reference has client configuration information and the name of the Resource Reference exactly matches the JNDI name of the client configuration. If the values are correct, you might have a class loader error. |
| Explanation | This exception occurs when the application program attempts to narrow to the EJB home class and the class loaders cannot find the EJB client side bindings. |
| Possible causes |
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| Recommended response | Look at the EJB .jar file located in the .ear file and verify the class contains the Enterprise Java Beans (EJB) client side bindings. These are class files with file names that end in _Stub and _Tie. If the binding classes are in the EJB .jar file, then you might have a class loader error. |
| Explanation | This error occurs when the application client run time cannot read the Enterprise Archive (EAR) file. |
| Possible causes | The most likely cause of this error is that the system cannot find the EAR file cannot be found in the path specified on the launchClient command. |
| Recommended response | Verify that the path and file name specified on the launchclient command are correct. |
| Explanation | When running your application client using the launchClient command the WebSphere Application Server run time might need to display the security login dialog. To display this dialog, WebSphere Application Server run time creates an Abstract Window Toolkit (AWT) thread. When your application returns from its main method to the application client run time, the application client run time attempts to return to the operating system and end the Java virtual machine (JVM) code. However, since there is an AWT thread, the JVM code will not end until System.exit is called. |
| Possible causes | The JVM code does not end because there is an AWT thread. Java code requires that System.exit() be called to end AWT threads. |
| Recommended response |
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| Explanation | If you select the Developer Kit feature on the Application Client V6.0.0 installer, all the files are installed under the <client_install_root>/java directory, instead of leaving the Java Runtime Environment (JRE) files intact. The JRE files are unexpectedly downgraded to the V6.0.0 level. |
| Possible causes | Selecting the Developer Kit feature on the Application Client 6.0.0 installer will actually install all files under the <client_install_root>/java directory rather than leave the JRE files intact. Therefore, the JRE files are unexpected downgraded to the 6.0.0 level in the above installation scenario. |
| Recommended response | Complete the following installation steps to prevent unexpected downgrading of the JRE files. |
IBM Support has documents and tools that can save you time gathering information needed to resolve problems as described in Troubleshooting help from IBM. Before opening a problem report, see the Support page: