Developing custom services

Why and when to perform this task

To define a hook point to be run when a server starts and shuts down, you develop a custom service class and then use the administrative console to configure a custom service instance. When the application server starts, the custom service starts and initializes.

The following restrictions apply to the WebSphere custom services implementation:

Note that these restrictions apply to the shutdown and init methods equally. Some JNDI operations are available.

Steps for this task

  1. Develop a custom service class that implements the com.ibm.websphere.runtime.CustomService interface.
    The properties passed by the application server run-time to the initialize method can include one for an external file containing configuration information for the service (retrieved with externalConfigURLKey). In addition, the properties can contain any name-value pairs that are stored for the service, along with the other system administration configuration data for the service. The properties are passed to the initialize method of the service as a Properties object.

    There is a shutdown method for the interface as well. Both methods of the interface declare that they may throw an exception, although no specific exception subclass is defined. If an exception is thrown, the run-time logs it, disables the custom service, and proceeds with starting the server.

  2. On the Custom Service page of the administrative console, click New. Then, on the settings page for a custom service instance, create a custom service configuration for an existing application server, supplying the name of the class implemented.
    If your custom service class requires a configuration file, specify the fully-qualified path name to that configuration file in the externalConfigURL field. This file name is passed into your custom service class.

    To invoke a native library from the custom service, provide the path name in the Classpath field in addition to the path names that are used to locate the classes and JAR files for the custom service. Doing this adds the path name to the WAS extension classloader, which allows the custom service to locate and correctly load the native library.

  3. Stop the application server and then restart the server.
  4. Check the application server to ensure that the initialize method of the custom service ran as intended. Also ensure that the shutdown method performs as intended when the server or nodeagent stops.

Example

ServerInit
public class ServerInit implements CustomService
{
/**
* The initialize method is called by the application server run-time when the
* server starts. The Properties object passed to this method must contain all
* configuration information necessary for this service to initialize properly.
*
* @param configProperties java.util.Properties
*/
    static final java.lang.String externalConfigURLKey =
       "com.ibm.websphere.runtime.CustomService.externalConfigURLKey";
          
    static String ConfigFileName="";

    public void initialize(java.util.Properties configProperties) throws Exception
    {
        if (configProperties.getProperty(externalConfigURLKey) != null)
        {
           ConfigFileName = configProperties.getProperty(externalConfigURLKey);
        }

       // Implement rest of initialize method
    }
/**
* The shutdown method is called by the application server run-time when the
* server begins its shutdown processing.
*
* @param configProperties java.util.Properties
*/
    public void shutdown() throws Exception
    {
        // Implement shutdown method
    }

Related concepts
Custom services
Related reference
Custom service collection



Searchable topic ID:   trun_customservice
Last updated: Jun 21, 2007 9:56:50 PM CDT    WebSphere Application Server for z/OS, Version 5.0.2
http://publib.boulder.ibm.com/infocenter/wasinfo/index.jsp?topic=/com.ibm.websphere.zseries.doc/info/zseries/ae/trun_customservice.html

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