com.prosyst.mprm.backend.onetimetask

Interface OneTimeTask

public interface OneTimeTask

Service implementing this interface can be registered as OSGi service in order to execute one time task. The One Time Task service track such services and if tasks with such id and version bigger or equal is not executed on the mPRM then the executeTask method is called. The One Time Task service will execute the task at least once on the mPRM and will make all possible to do not execute it more then once. In 99.9999% the task will be executed exactly once. The task may be executed more then once only if there is lost of database connections and there are commnincation between mRPM hosts is broken. The executeTask call is made in its own thread (got from the thread pool) in dependence of registration property ASYNC_EXECUTION.

Author:

Avgustin Marinov, e-mail: a_marinov@prosyst.bg

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	ASYNC_EXECUTION The value of the registration property specifies if the executeTask should be called into separate thread.

Method Summary

Modifier and Type	Method and Description
void	executeTask(java.lang.String lastSuccesfulTaskVersion) Calls the task in order to executes its activities.
java.lang.String	getId() Returns the id of the Task.
java.lang.String	getVersion() The version of the task.
void	taskExecuted(java.lang.String lastSuccesfulTaskVersion) This method is called by the One Time Task service in order to notify one time task that that the task with this id is already excecuted with version equal or bigger then the version of this one time task.

Field Detail

ASYNC_EXECUTION

static final java.lang.String ASYNC_EXECUTION

The value of the registration property specifies if the executeTask should be called into separate thread. The allowed values are strings "true" and "false" as well as Boolean.TRUE, Boolean.FALSE. If the registration property miss the value is assumed to be false.

See Also:

Constant Field Values

Method Detail

getId

java.lang.String getId()

Returns the id of the Task.

Returns:

the task id.

getVersion

java.lang.String getVersion()

The version of the task. The version should be a string that consist from comma separated numbers. For instance a legal versions are "1", "1.2", "1.2.3", "1.2.3.2.3.4.4".

Returns:

the version of the task.

executeTask

void executeTask(java.lang.String lastSuccesfulTaskVersion)
          throws java.lang.Exception

Calls the task in order to executes its activities. The call is made in its own thread (got from the thread pool) in dependene of reagistration property ASYNC_EXECUTION.

Parameters:

lastSuccesfulTaskVersion - the version of the last successfully executed on mPRM instance task with this id. If task with such id has never executed then the lastSuccesfulTaskVersion will be null.

Throws:

java.lang.Exception - when exception occures. If the exception is thrown then the task will remain in unexecuted state and should be executed in future by this or another host.

taskExecuted

void taskExecuted(java.lang.String lastSuccesfulTaskVersion)

This method is called by the One Time Task service in order to notify one time task that that the task with this id is already excecuted with version equal or bigger then the version of this one time task. This method provides the One Time Task with hook to dispose any resurces it wants. For instance it can unregister itself as OneTimeTask OSGi service.

Parameters:

lastSuccesfulTaskVersion - the version of the last successfully executed on mPRM instance task with this id.