Why and when to perform this task
The following restrictions
apply to the WebSphere Application Server custom services implementation:
- The init and shutdown methods must return control to the runtime.
- No work is dispatched into the server instance until all custom service
initialize methods return.
- The init and shutdown methods are called only once on each service, and
once for each operating system process that makes up the server instance.
File I/O is supported.
- Initialization of process level static data, without leaving the process,
is supported.
- Only JDBC RMLT (resource manager local transaction) operations are supported.
Every unit of work (UOW) must be completed before the methods return.
- Creation of threads is not supported.
- Creation of sockets and I/O, other than file I/O, is not supported. Running
standard J2EE code (client code, servlets, enterprise beans) is not supported.
- The JTA interface is not available. This feature is available in J2EE
server processes and distributed generic server processes only.
- While the runtime makes an effort to call shutdown, there is no guarantee
that shutdown will be called prior to process termination.
Note that these restrictions apply to the shutdown and init methods equally.
Some JNDI operations are available.
Develop a custom service class that implements the com.ibm.websphere.runtime.CustomService
interface. The properties passed by the application server runtime
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
create an exception, although no specific exception subclass is defined.
If an exception is created, the runtime logs it, disables the custom service,
and proceeds with starting the server.
Example
ServerInitpublic 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
}