5.1

vCloud Director Extension Services 11
vCloud Director and the vCloud API include a framework for integration of extension services that a vCloud
API client can access as though they were native services. In addition to service-specific objects or operations
they provide, extension services can implement new operations for existing API objects.
A vCloud Director extension service is a program that presents a REST interface to vCloud API clients. When
you register an extension service with the vCloud API, you specify one or more URL patterns that the
vCloud Director REST service treats as extension requests. When it receives an extension request, the
vCloud Director REST service creates an AMQP notification with a service-specific exchange and routing key,
and sends it to the vCloud Director AMQP service. Each extension service subscribes to AMQP notifications
that have its service-specific routing key. A service processes its notifications, takes whatever actions they
require, and returns a response to the AMQP service, where the vCloud Director REST service retrieves it and
uses its contents to generate a response to the client that made the request.
Message Routing
Extension services use the vCloud Director AMQP service to communicate with vCloud Director. Every
extension service must register a unique AMQP routing key, which vCloud Director prepends to AMQP
messages destined for that service. To collect replies from services, vCloud Director creates a single reply
exchange for all services, creates a separate reply queue for each cell, and binds each of those queues to the
reply exchange.
vCloud Director extension services can also be vCloud API clients, authenticating to the vCloud API and
making their own REST requests to the vCloud API URL. This type of interaction is required when creating
tasks and events that track the progress of requests made to the service. It is also required by services that
operate on vCloud Director objects like vApps and virtual machines.
Creating Events and Tasks
The vCloud API extension framework implements operations that allow an extension service to create and
update an organization's lists of tasks and events, so the status of asynchronous events running in extension
services can be displayed with the same kinds of information posted by native services.
Authorization Framework
All requests to extension services are processed through the vCloud Director authentication framework. A
user making a request to an extension service must be authenticated by vCloud Director as a system
administrator or a member of a vCloud Director organization.
An extension service can add service-specific rights and associate those rights with operations on its own
objects or with operations it adds to vCloud API objects .
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