Package com.sapportals.wcm.service.taskqueue

Provides interfaces to write or read tasks in a platform-wide queue and to monitor their status.

See:
Description

Interface Summary

ITask	Entry of a task queue.
ITaskQueue	Priority queue for tasks.
ITaskQueueIterator	An iterator for task queues. This iterator is similar to the ListIterator interface.
ITaskQueueReader	A reader provides read-acces to a task queue belonging to a specific namespace.
ITaskQueueService	The task queue is a base service for clustered systems.
ITaskQueueWriter	A writer provides write-acces to a task queue belonging to a specific namespace.

Class Summary

TaskQueueServiceFactory	The task queue service factory.
TaskState	This class defines the identifiers for the different lifecycle states of a task in the task queue service.

Exception Summary

TaskQueueException	An exception wrapper for the task queue service.
TaskStateTransitionException	An excpetion that is raised on illegal task state tranistions.

Package com.sapportals.wcm.service.taskqueue Description

Provides interfaces to write or read tasks in a platform-wide queue and to monitor their status.

Package Specification

Purpose

The task queue is a base service for clustered systems. It provides interfaces to write and to read tasks in a platform-spreading queue and to monitor the tasks and (above all) their processing state.

Concepts

Access to the task queue is provided by a reader and a writer interface. This thin interfaces support the implementation of highly spezialised and customizable distributed services. (For example a service could implement a customized service writer as a wrapper of the task queue writer and a customized service daemon reader as a wrapper of the reader).

Reader and writer are assigned to a special namespace and a service user. A writer can only write tasks belonging to its namespace. A reader can only read task of its namespace. A namespace is a unique application identifier. This services provides support of different persistence layers. It is recommended to use the database persistence layer in production systems. File system and memory persistence layers are only recommended for testing to offer a high-performance test plattform with some restrictions.

Monitor

The monitor methods will return only a snapshot of the current task queue. For maintenance a remove method is provided to remove completly progressed or incorrectly aborted tasks from the queue.