tree c2497ef19498893a56e6e3833d633ac48b62be0c
parent 5cf1fe0566f04a8ba1fc338261052d919bbe8e63
author Pavlin Radoslavov <pavlin@onlab.us> 1404713999 -0700
committer Gerrit Code Review <gerrit2@gerrit.onos.onlab.us> 1404930731 -0700

Added Topology WebSocket server implementation.
It allows remote applications (e.g., the GUI) to subscribe
for Topology-related events.
The URL is:
ws://hostname:8081/ws/onos/topology

When a new client opens a socket, the server transmits the whole topology.
From that moment on, the server sends topology events (deltas) if there
are any changes in the topology. Currently, all objects are encoded in JSON.

The default WebSocket port number is set to 8081
(configurable in conf/onos.properties)

NOTE: In the current implementation, the initial fetching of the topology,
and adding topology events for transmission are done by two different threads.
Hence, when a new client opens a socket, there is a small window of time
when some of the added events are "moving back in time".
The final result of applying all events will be technically correct, but
those "moving back in time" events are semantically incorrect.
This issue will be addressed in later iterations / refactoring of the
implementation.

Change-Id: Id2cbf72d1384208201d916e0aa1e5926659878ee