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oracle.as.scheduler
Interface Executable

All Known Subinterfaces:

AsyncExecutable

All Known Implementing Classes:

BatchDelete, ExecutableWrapper, SystemPurge

public interface Executable

Contract for implementing the executable for a Java job. The client application must supply a class that implements this interface for a request executable of job type JAVA_TYPE.

A client application specifies the Java executable class by setting the the CLASS_NAME system property, via either metadata or at request submission. The executable class may also implement the Cancellable interface. The executable class must provide an empty constructor.

When a request is ready to execute, Enterprise Scheduler will first invoke the pre-process callback if one was specified when the request was submitted. If the callback indicates that request execution should proceed, the Scheduler subsystem will then instantiate the Executable implementation class and call the execute method. Upon successful return from execute, the post-process callback will be invoked if one was specified for the request.

The execute method is called each time the request is executed and is passed an execution context and request parameters for the running request. The execution context specifes the request identifer and additional details needed if the job implementation submits sub-requests. The manner in which execute returns to the caller, either by succssful return or exception, determines how the Scheduler subsystem handles subsequent request processing.

For a given submitted request, the job executable may be called multiple times, but usually the execution context specifies a different (child) request identifier for each invocation. For example, if a job is submitted with a recurring schedule, the same request executable (class not instance) is invoked each time but with a different request identifer. However, if a failed request is retried or a paused request is resumed, the request identifier remains the same. A failed request that transitions to ERROR state may be retried depending on the value of the RETRIES system property. A resumed request is one that is being re-run after previously submitted sub-requests have completed execution.

A Java executable can submit sub-requests using RuntimeService.submitRequest. It must then throw ExecutionPausedException which causes the request to transition to PAUSED state. Once the sub-requests have completed, the parent request is re-run as a resumed request. The execution context can be used to determine if the executable is being run as a resumed request.

Enterprise Scheduler creates a new instance of the executable class each time a submitted job request is executed. As such, the job implementation should not rely on class static or instance member variables for maintaining state.

See Also:

RequestExecutionContext, State

Method Summary

void	execute(RequestExecutionContext context, RequestParameters parameters) Invoked every time the Java job request is executed.

Method Detail

execute

void execute(RequestExecutionContext context,
             RequestParameters parameters)
             throws ExecutionErrorException,
                    ExecutionWarningException,
                    ExecutionCancelledException,
                    ExecutionPausedException

Invoked every time the Java job request is executed. This method should eventually return control to the caller.

Parameters:

context - the execution context for associated with this request

parameters - the request parameters associated with this request

Throws:

ExecutionErrorException - Should be thrown when the job implementation detects a failure condition that it needs to communicate to the scheduling subsystem. The request will transition to ERROR state.

ExecutionWarningException - Should be thrown when the job implementation detects a failure condition that it needs to communicate to the scheduling subsystem. The request will transition to WARNING state.

ExecutionCancelledException - Should be thrown when the job implementation detects a condition for request cancellation that it needs to communicate to the scheduling subsystem. The request will transition to CANCELLED state.

ExecutionPausedException - Should be thrown when the job implementation submits a sub-request and is ready to pause to allow the sub-request to execute. The request will transition to PAUSED state.

See Also:

State

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