Name

GTask — supports asynchronous message processing on GAE by using the task queueing service as message queue

Overview

GTask endpoints support asynchronous message processing on GAE by using the task queueing service as message queue. For adding messages to a queue it uses the task queue API. For receiving messages from a queue, it installs an HTTP callback handler. The handler is called by an HTTP POST callback (a web hook) initiated by the task queueing service. Whenever a new task is added to a queue a callback will be sent. The GTask component abstracts from these details and supports endpoint URIs that make message queueing on GAE as easy as message queueing with JMS or SEDA.

URI format

The URI format for a GTask endpoint is:

gtask://queue-name

Dependencies

Maven users will need to add a dependency on camel-gae to their poms as shown in Example 9, “GTask dependency”.

Example 9. GTask dependency

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-gae</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

Options

Table 20, “GTask options” lists the options for a GTask endpoint.

Table 20. GTask options

NameDefault ValueContextDescription
workerRoot worker Producer The servlet mapping for callback handlers. By default, this component requires a callback servlet mapping of /worker/*. If another servlet mapping is used e.g. /myworker/* it must be set as option on the producer side: to("gtask:myqueue?workerRoot=myworker").
inboundBindingRef reference to GTaskBinding Consumer Reference to an InboundBinding<GTaskEndpoint, HttpServletRequest, HttpServletResponse> in the registry for customizing the binding of an Exchange to the Servlet API. The referenced binding is used as post-processor to org.apache.camel.component.http.HttpBinding.
outboundBindingRef reference to GTaskBinding Producer Reference to an OutboundBinding<GTaskEndpoint, TaskOptions, void> in the registry for customizing the binding of an Exchange to the task queueing service.

On the consumer-side, all options of the Servlet component are supported.

Message headers

On the consumer-side all headers of the Servlet component component are supported.

In addition the following GTaskBinding headers are used by on the consumer-side.

NameTypeDescription
GTASK_QUEUE_NAME String Name of the task queue.
GTASK_TASK_NAME String Name of the task.
GTASK_RETRY_COUNT int Number of callback retries.

Related topics

Servlet
task queueing service