Java Platform, Enterprise Edition (Java EE) 8 The Java EE Tutorial

## Main Components of the Concurrency Utilities

Concurrent resources are managed objects that provide concurrency capabilities to Java EE applications. In GlassFish Server, you configure concurrent resources and then make them available for use by application components such as servlets and enterprise beans. Concurrent resources are accessed through JNDI lookup or resource injection.

The primary components of the concurrency utilities are as follows.

- `ManagedExecutorService`: A managed executor service is used by applications to execute submitted tasks asynchronously. Tasks are executed on threads that are started and managed by the container. The context of the container is propagated to the thread executing the task.

  For example, by using an `ManagedExecutorService.submit()` call, a task, such as the GenerateReportTask, could be submitted to execute at a later time and then, by using the `Future` object callback, retrieve the result when it becomes available.

- `ManagedScheduledExecutorService`: A managed scheduled executor service is used by applications to execute submitted tasks asynchronously at specific times. Tasks are executed on threads that are started and managed by the container. The context of the container is propagated to the thread executing the task. The API provides the scheduling functionality that allows users to set a specific date/time for the Task execution programmatically in the application.

- `ContextService`: A context service is used to create dynamic proxy objects that capture the context of a container and enable applications to run within that context at a later time or be submitted to a Managed Executor Service. The context of the container is propagated to the thread executing the task.

- `ManagedThreadFactory`: A managed thread factory is used by applications to create managed threads. The threads are started and managed by the container. The context of the container is propagated to the thread executing the task. This object can also be used to provide custom factories for specific use cases (with custom Threads) and, for example, set specific/proprietary properties to these objects.

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