5.5

Table Of Contents
Configuring and Using Blocking
Tasks and Notifications 10
vCloud Director allows a system administrator to configure many operations as blocking tasks, which are
suspended until a system administrator acts on them or a preconfigured timer expires. Blocking tasks also
generate AMQP messages that you can use to automate the handling of the underlying user request. A
system administrator can also enable nonblocking AMQP notifications of all system events.
When a user requests an operation that has been configured as a blocking task, the system sends a message
about the task to the configured AMQP broker. The system also creates a reference to the task in the cloud's
BlockingTaskReferences container. A system administrator can retrieve the list of BlockingTask elements by
making a GET request to the system's blockingTasks link, or to a URL included in the AMQP message.
About AMQP
AMQP, the Advanced Message Queuing Protocol, is an open standard for message queuing that supports
flexible messaging for enterprise systems. vCloud Director includes an AMQP service and defines a set of
events that, when notifications are enabled, trigger publication of messages by this service. A cloud operator
can configure the service to work with RabbitMQ and other AMQP brokers to provide a stream of
notifications about events in the cloud. By configuring specific tasks as blocking and writing AMQP clients
that process the messages generated when these tasks are launched, cloud operators can create a
programmatic facility for reviewing and acting on tenant requests.
By default, the vCloud Director AMQP service sends unencrypted messages. If you configure it to encrypt
these messages using SSL, it verifies the broker's certificate by using the default JCEKS trust store of the Java
runtime environment on the vCloud Director server. The Java runtime environment is typically located in
the $JRE_HOME/lib/security/cacerts directory.
To use SSL with the vCloud Director AMQP service, select Use SSL on the AMQP Broker Settings section of
the Extensibility page of the vCloud Director Web console, and provide either of the following:
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an SSL certificate pathname
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a JCEKS trust store pathname and password
If you do not need to validate the AMQP broker's certificate, you can select Accept all certificates.
For more information about AMQP, see http://www.amqp.org.
Subscribing to Notifications
Notifications of system events are sent to the AMQP message broker that was configured in the system
AMQP settings. Notifications are always generated in two formats:
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An XML document, which is sent to the AMQP exchange specified in the system AmqpSettings.
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A JSON object, which is sent to an AMQP exchange whose name has the form prefix.notifications20,
where prefix is the value of the AmqpPrefix element in the system AmqpSettings.
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