Transcript
What is WebRTC?
WebRTC (Web Real-Time Communication) is an API definition drafted by the World Wide Web Consortium (W3C) that supports browser-to-browser applications for voice calling, video chat, and P2P file sharing without the need of either internal or external plugins.
rtcninja.js
https://github.com/eface2face/rtcninja.js
Nice name, right?!
Temasys WebRTC Plugin
Free (as in beer) plugin for IE and Safari
http://skylink.io/plugin/
getUserMediaif (!rtcninja.hasWebRTC()) { console.log('Are you from the past?!'); return;}!rtcninja.getUserMedia( // constraints {video: true, audio: true},! // successCallback function(localMediaStream) { var video = document.querySelector('video'); rtcninja.attachMediaStream(video, localMediaStream); },! // errorCallback function(err) { console.log("The following error occured: " + err); });
RTCPeerConnection (2)Get local media Send SDP offer
Get local media
Send SDP answer
ICE candidates
Audio / Video
ICEHelps find the best path for media
Solves NAT traversal and other hostile network problems
Communication Consent Verification
It can trickle!
RTCDataChannel
P2P, message boundary based channel for arbitrary data
Implemented using SCTP, different reliability choices possible
The ProtocolWebSocket based, JSON payload
Users enter the roulette when they connect over WebSocket
Session is negotiated / established
No end message, just disconnect the WebSocket
Shopping for a framework
Python >= 3.3, because future!
WebSocket support built-in
Async, because blocking is so 2001
New, because why not?
@asyncio.coroutinedef init(loop): app = web.Application(loop=loop) app.router.add_route('GET', '/', LazyFileHandler(INDEX_FILE, 'text/html')) app.router.add_route('GET', '/ws', WebSocketHandler()) app.router.add_route('GET', '/static/{path:.*}', StaticFilesHandler(STATIC_FILES))! handler = app.make_handler() server = yield from loop.create_server(handler, '0.0.0.0', 8080) print("Server started at http://0.0.0.0:8080") return server, handler
class StaticFilesHandler: def __init__(self, base_path): self.base_path = base_path self.cache = {}! @asyncio.coroutine def __call__(self, request): path = request.match_info['path'] try: data, content_type = self.cache[path] except KeyError: full_path = os.path.join(self.base_path, path) try: with open(full_path, 'rb') as f: content_type, encoding = mimetypes.guess_type(full_path, strict=False) data = f.read() except IOError: log.warning('Could not open %s file' % path) raise web.HTTPNotFound() self.cache[path] = data, content_type log.debug('Loaded file %s (%s)' % (path, content_type)) return web.Response(body=data, content_type=content_type)
class WebSocketHandler: def __init__(self): self.waiter = None! @asyncio.coroutine def __call__(self, request): ws = web.WebSocketResponse(protocols=('callroulette-v2',)) ws.start(request)! conn = Connection(ws) if self.waiter is None: self.waiter = asyncio.Future(loop=ws._loop) fs = [conn.read(), self.waiter] done, pending = yield from asyncio.wait(fs, return_when=asyncio.FIRST_COMPLETED) if self.waiter not in done: # the connection was most likely closed self.waiter = None return ws other = self.waiter.result() self.waiter = None reading_task = pending.pop() reading_task.cancel() asyncio.async(self.run_roulette(conn, other)) else: self.waiter.set_result(conn)! yield from conn.wait_closed()! return ws
from jsonmodels import models, fieldsfrom jsonmodels.errors import ValidationError!!class StringChoiceField(fields.StringField): def __init__(self, choices=None, *args, **kw): self.choices = choices or [] super(StringChoiceField, self).__init__(*args, **kw)! def validate(self, value): if value not in self.choices: raise ValidationError('invalid choice value') super(StringChoiceField, self).validate(value)!class Jsep(models.Base): type = StringChoiceField(choices=['offer', 'answer'], required=True) sdp = fields.StringField(required=True)!class Candidate(models.Base): candidate = fields.StringField(required=True) sdpMid = fields.StringField(required=True) sdpMLineIndex = fields.IntField(required=True)!class YoPayload(models.Base): yo = fields.StringField(required=True) jsep = fields.EmbeddedField(Jsep) candidate = fields.EmbeddedField(Candidate)
@asyncio.coroutine def run_roulette(self, peerA, peerB): log.info('Running roulette: %s, %s' % (peerA, peerB))! @asyncio.coroutine def close_connections(): yield from asyncio.wait([peerA.close(), peerB.close()], return_when=asyncio.ALL_COMPLETED)! def parse(data): try: data = json.loads(data) payload = YoPayload(**data) payload.validate() except Exception as e: log.warning('Error parsing payload: %s' % e) return None return payload
# request offer offer_request = YoPayload(yo='yo') peerA.write(json.dumps(offer_request.to_struct()))! # get offer data = yield from peerA.read(timeout=READ_TIMEOUT) if not data: yield from close_connections() return! offer = parse(data) if offer is None or offer.jsep is None or offer.jsep.type != 'offer': log.warning('Invalid offer received') yield from close_connections() return! # send offer peerB.write(json.dumps(offer.to_struct()))
# wait for answer data = yield from peerB.read(timeout=READ_TIMEOUT) if not data: yield from close_connections() return! answer = parse(data) if answer is None or answer.jsep is None or answer.jsep.type != 'answer': log.warning('Invalid answer received') yield from close_connections() return! # dispatch answer peerA.write(json.dumps(answer.to_struct()))
# wait for candidates / end while True: peer_a_read = asyncio.async(peerA.read()) peer_a_read.other_peer = peerB peer_b_read = asyncio.async(peerB.read()) peer_b_read.other_peer = peerA done, pending = yield from asyncio.wait([peer_a_read, peer_b_read], return_when=asyncio.FIRST_COMPLETED) for task in pending: task.cancel() for task in done: data = task.result() if not data: break # all we can get at this point is trickled ICE candidates candidate = parse(data) if candidate is None or candidate.candidate is None: log.warning('Invalid candidate received!') break task.other_peer.write(json.dumps(candidate.to_struct())) else: continue break # close connections yield from close_connections()
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