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And closing the socket in Scenario 4 is again just a call to StreamSocket.close.
As with the DatagramSocket sample, setting breakpoints within openClient
(js/connectTo-Listener.js), onServerAccept (js/startListener.js), and sendHello (js/sendData.js) will let you
see what’s happening at each step of the process.
Web Sockets: MessageWebSocket and StreamWebSocket
Having now seen both Datagram and Stream sockets in action, we can look at their equivalents on the
WebSocket side. As you might already know, WebSockets is a standard created to use HTTP (and thus
TCP) to set up an initial connection after which the data exchange happens through sockets over TCP.
This provides the simplicity of using HTTP requests for the first stages of communication and the
efficiency of sockets afterwards.
As with regular sockets, the WebSocket side of WinRT supports both water balloons and water hoses:
the MessageWebSocket class provides for discrete packets as with datagram sockets (though it uses TCP
and not UDP), and StreamWebSocket clearly provides for stream sockets. Both classes are very similar to
their respective DatagramSocket and StreamSocket counterparts, so much so that their interfaces are
very much the same (with distinct secondary types like MessageWebSocket-Control):
• Like DatagramSocket, MessageWebSocket has control, information, and outputStream
properties, a messagereceived event, and methods of connectAsync and close. It adds a
closed event along with a setRequestHeader method.
• Like StreamSocket, StreamWebSocket has control, information, inputStream, and
outputStream properties, and methods of connectAsync and close. It adds a closed
event and a setRequestHeader method.
You’ll notice that there isn’t an equivalent to StreamSocketListener here. This is because the process
of establishing that connection is handled through HTTP requests, so such a distinct listener class isn’t
necessary. This is also why we have setRequestHeader methods on the classes above: so that you can
configure those HTTP requests. Along these same lines, you’ll find that the connectAsync methods take a
Windows.Foundation.Uri rather than hostnames and service names. But otherwise we see the same kind
of activity going on once the connection is established, with streams, Data-Reader, and DataWriter.
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