6. Consuming vCloud with the API : 6.3 What’s New in the vCloud Director 5.1 API
   
6.3 What’s New in the vCloud Director 5.1 API
vCloud Director 5.1 provides the following new features, and APIs have been updated accordingly:
*Query ServiceUseful when searching for resources. You do not have to traverse the resource tree to find specific children nodes.
*Metadata TaggingAnnotate vCloud resources with user-defined metadata.
*Block Tasks and NotificationsThis feature relates to the messages published and consumed by vCloud Director. In blocking tasks, the system waits for a user to take an action. For example, if a manager must provide approval when a developer requests vCloud resources, a blocking task might be created. When a developer deploys a vApp, the manager is notified and must approve before proceeding with deployment.
*In notifications, also called non-blocking events, a message is sent to the event’s Advanced Message Queuing Protocol (AMQP) broker.