websockets.py

"""
AMP over WebSockets support.
"""
import json
import txws

from twisted.internet import defer, protocol
from twisted.python import log


class Bridge(protocol.Protocol):
    """
    Two-way AMP over WebSockets bridge.
    """
    def __init__(self, amp):
        self._amp = amp
        amp.boxSender = self


    def sendBox(self, box):
        """
        Sends a box over the WebSocket as JSON.
        """
        log.msg("Sending box: {}".format(box))
        self.transport.write(json.dumps(box))


    def jsonObjectReceived(self, obj):
        """
        Hands the JSON object (dict) over to ampBoxReceived.
        """
        log.msg("JSON object received: {}".format(obj))
        self._amp.ampBoxReceived(obj)


    def dataReceived(self, data):
        """
        Calls jsonObjectReceived.

        This assumes that JSON objects will always arrive as 1 chunk.
        """
        self.jsonObjectReceived(json.loads(data))



class BridgeFactory(protocol.Factory):
    """
    A factory for AMP over WebSockets bridges.
    """
    def __init__(self, ampFactory):
        self._ampFactory = ampFactory


    def buildProtocol(self, addr):
        """
        Builds a bridge and associates it with an AMP protocol instance.
        """
        return Bridge(self._ampFactory.buildProtocol(addr))



def makeFactory(ampFactory):
    """
    MAkes a WebSocket factory that bridges AMP messages.
    """
    return txws.WebSocketFactory(BridgeFactory(ampFactory))