As the end-user of NDS Labs, I should be able to send asynchronous notifications from the server to any connected clients in particular circumstances.

This task encompasses the work necessary to implement asynchronous event support in the workbench API server. Asynchronous events will likely be supported via Websockets.

Use case:
For project A, the administrator has a single instance open in the browser. For project B, the administrator has the project opened in two separate browsers (or two users are sharing the same login). When Project A adds a stack, the change is reflected in the Project A session. When Project B-1 adds a stack, the change is reflected in the Project B-2 session. When the cluster administrator adds a new service, the Project A, B-1, B-2 sessions are notified. The cluster administrator can send a broadcast message to all logged in sessions (i.e., outage notification)

Preconditions:

• User is logged into a project

Primary flow:

• When the user adds/updates/deletes a stack, stack service, or volume, a message is sent to all listeners associated with the project
• When the user starts or stops a stack, status messages are sent to all listeners associated with the project
• When the cluster admin adds/updates/removes a service spec, a message is sent to all listeners associated with any project

Alternative flows

• User is not logged in – access is denied to websocket
• Error conditions are sent to listeners only for stack/service status changes