使用Python Twisted和Autobahn從Matlab通過WebSocket發送JSON數據

Question

我正在嘗試從Matlab創建一個連接，以通過WebSocket流式傳輸JSON幀。 我已經測試了我的高速公路安裝的高速公路並使用以下方法進行了扭曲。

工作實例

Matlab代碼

使用JSONlab工具箱將Matlab數據轉換為JSON格式然后壓縮和Base64編碼數據的示例驅動程序代碼。 由於我還沒有使用RPC工作，我正在使用命令行，我需要壓縮和Base64編碼，以避免行長和shell轉義問題。

clear all
close all

python = '/usr/local/bin/python'
bc = '/Users/palmerc/broadcast_client.py'
i = uint32(1)

encoder = org.apache.commons.codec.binary.Base64
while true
    tic;
    packet = rand(100, 100);
    json_packet = uint8(savejson('', packet));
    compressed = CompressLib.compress(json_packet);
    b64 = char(encoder.encode(compressed));
    message = sprintf('%s %s %s', python, bc, b64);
    status = system(message);

    i = i + 1;
    toc;
end

廣播客戶端代碼

客戶端代碼有兩種被調用方式。 您可以通過命令行傳遞消息，也可以創建BroadcastClient實例並調用sendMessage。

#!/usr/bin/env python

import sys
from twisted.internet import reactor
from txjsonrpc.web.jsonrpc import Proxy


class BroadcastClient():

    def __init__(self, server=None):
        self.proxy = Proxy(server)

    def errorMessage(self, value):
        print 'Error ', value

    def sendMessage(self, message):
        rc = self.proxy.callRemote('broadcastMessage', message).addCallback(lambda _: reactor.stop())
        rc.addErrback(self.errorMessage)


def main(cli_arguments):
    if len(cli_arguments) > 1:
        message = cli_arguments[1]
        broadcastClient = BroadcastClient('http://127.0.0.1:7080/')
        broadcastClient.sendMessage(message)
        reactor.run()

if __name__ == '__main__':
    main(sys.argv)

廣播服務器代碼

服務器在7080上提供RPC客戶端，在8080上提供Web客戶端，在9080上使用TXJSONRPC，Twisted和Autobahn提供WebSocket。 Autobahn Web Client對於調試很有用，應該與服務器代碼放在同一目錄中。

#!/usr/bin/env python

import sys

from twisted.internet import reactor
from twisted.python import log
from twisted.web.server import Site
from twisted.web.static import File
from txjsonrpc.web import jsonrpc

from autobahn.twisted.websocket import WebSocketServerFactory, \
    WebSocketServerProtocol, \
    listenWS


class BroadcastServerProtocol(WebSocketServerProtocol):

    def onOpen(self):
        self.factory.registerClient(self)

    def onMessage(self, payload, isBinary):
        if not isBinary:
            message = "{} from {}".format(payload.decode('utf8'), self.peer)
            self.factory.broadcastMessage(message)

    def connectionLost(self, reason):
        WebSocketServerProtocol.connectionLost(self, reason)
        self.factory.unregisterClient(self)


class BroadcastServerFactory(WebSocketServerFactory):

    """
    Simple broadcast server broadcasting any message it receives to all
    currently connected clients.
    """

    def __init__(self, url, debug=False, debugCodePaths=False):
        WebSocketServerFactory.__init__(self, url, debug=debug, debugCodePaths=debugCodePaths)
        self.clients = []

    def registerClient(self, client):
        if client not in self.clients:
            print("registered client {}".format(client.peer))
            self.clients.append(client)

    def unregisterClient(self, client):
        if client in self.clients:
            print("unregistered client {}".format(client.peer))
            self.clients.remove(client)

    def broadcastMessage(self, message):
        print("broadcasting message '{}' ..".format(message))
        for client in self.clients:
            client.sendMessage(message.encode('utf8'))
            print("message sent to {}".format(client.peer))


class BroadcastPreparedServerFactory(BroadcastServerFactory):

    """
    Functionally same as above, but optimized broadcast using
    prepareMessage and sendPreparedMessage.
    """

    def broadcastMessage(self, message):
        print("broadcasting prepared message '{}' ..".format(message))
        preparedMessage = self.prepareMessage(message.encode('utf8'), isBinary=False)
        for client in self.clients:
            client.sendPreparedMessage(preparedMessage)
            print("prepared message sent to {}".format(client.peer))


class MatlabClient(jsonrpc.JSONRPC):

    factory = None

    def jsonrpc_broadcastMessage(self, message):
        if self.factory is not None:
            print self.factory.broadcastMessage(message)


if __name__ == '__main__':

    if len(sys.argv) > 1 and sys.argv[1] == 'debug':
        log.startLogging(sys.stdout)
        debug = True
    else:
        debug = False
    factory = BroadcastPreparedServerFactory(u"ws://127.0.0.1:9000",
                                             debug=debug,
                                             debugCodePaths=debug)

    factory.protocol = BroadcastServerProtocol
    listenWS(factory)

    matlab = MatlabClient()
    matlab.factory = factory
    reactor.listenTCP(7080, Site(matlab))

    webdir = File(".")
    web = Site(webdir)
    reactor.listenTCP(8080, web)

    reactor.run()

問題 - 嘗試失敗

首先注意，如果你在使用matlab從python上運行時遇到麻煩，你需要確保使用pyversion命令在系統上指向正確版本的Python，你可以使用pyversion('/path/to/python')來修正它pyversion('/path/to/python')

Matlab無法運行reactor

clear all
close all

i = uint32(1)

while true
    tic;
    packet = rand(100, 100);
    json_packet = uint8(savejson('', packet));
    compressed = CompressLib.compress(json_packet);
    b64 = char(encoder.encode(compressed));
    bc.sendMessage(py.str(b64.'));
    py.twisted.internet.reactor.run % This won't work.

    i = i + 1;
    toc;
end

Matlab POST

另一個嘗試涉及使用Matlab的webwrite POST到服務器。 原來， webwrite只需傳遞正確的weboptions即可將數據轉換為JSON。

options = weboptions('MediaType', 'application/json');
data = struct('Matrix', rand(100, 100));
webwrite(server, data, options);

這有效，但每封郵件的速度很慢（~0.1秒）。 我應該提到矩陣不是我發送的真實數據，真實數據序列化為每個消息約280000字節，但這提供了合理的近似值。

如何調用bc.sendMessage以便正確設法讓reactor運行或以另一種更快的方式解決此問題？

Answer 1

使用Python和Matlab設置WebSocket

檢查Matlab指向正確版本的python

首先，您需要確保使用正確的python二進制文件。 在Mac上，您可能正在使用系統標准版本而不是Homebrew安裝的版本。 使用以下命令檢查python安裝的位置：

pyversion

您可以使用以下方法將Matlab指向正確的版本：

pyversion('path/to/python')

這可能需要你重啟python。

如上所述，我使用Twisted將我的Matlab數據多路復用到WebSocket客戶端。 我找到解決這個問題的最好方法就是創建一個處理POSTS的服務器，然后將其傳遞給WebSocket客戶端。 壓縮只會減慢速度，所以每個請求發送280 kB的JSON，每條消息大約需要0.05秒。 我希望這會更快，.01秒，但這是一個好的開始。

Matlab代碼

server = 'http://127.0.0.1:7080/update.json';
headers = py.dict(pyargs('Charset','UTF-8','Content-Type','application/json'));
while true
    tic;
    packet = rand(100, 100);
    json_packet = savejson('', packet);
    r = py.requests.post(server, pyargs('data', json_packet, 'headers', headers));
    toc;
end

我可以使用Matlab webwrite函數，但通常我發現調用python更靈活。

Python WebSocket-WebClient服務器

import sys

from twisted.internet import reactor
from twisted.python import log
from twisted.web.resource import Resource
from twisted.web.server import Site
from twisted.web.static import File

from autobahn.twisted.websocket import WebSocketServerFactory, \
    WebSocketServerProtocol, \
    listenWS


class BroadcastServerProtocol(WebSocketServerProtocol):

    def onOpen(self):
        self.factory.registerClient(self)

    def onMessage(self, payload, isBinary):
        if not isBinary:
            message = "{} from {}".format(payload.decode('utf8'), self.peer)
            self.factory.broadcastMessage(message)

    def connectionLost(self, reason):
        WebSocketServerProtocol.connectionLost(self, reason)
        self.factory.unregisterClient(self)


class BroadcastServerFactory(WebSocketServerFactory):

    def __init__(self, url, debug=False, debugCodePaths=False):
        WebSocketServerFactory.__init__(self, url, debug=debug, debugCodePaths=debugCodePaths)
        self.clients = []

    def registerClient(self, client):
        if client not in self.clients:
            print("registered client {}".format(client.peer))
            self.clients.append(client)

    def unregisterClient(self, client):
        if client in self.clients:
            print("unregistered client {}".format(client.peer))
            self.clients.remove(client)

    def broadcastMessage(self, message):
        for client in self.clients:
            client.sendMessage(message.encode('utf8'))


class BroadcastPreparedServerFactory(BroadcastServerFactory):

    def broadcastMessage(self, message, isBinary=False):
        if isBinary is True:
            message = message.encode('utf8')
        preparedMessage = self.prepareMessage(message, isBinary=isBinary)
        for client in self.clients:
            client.sendPreparedMessage(preparedMessage)


class WebClient(Resource):

    webSocket = None

    def render_POST(self, request):
        self.webSocket.broadcastMessage(request.content.read())

        return 'OK'


if __name__ == '__main__':

    if len(sys.argv) > 1 and sys.argv[1] == 'debug':
        log.startLogging(sys.stdout)
        debug = True
    else:
        debug = False
    factory = BroadcastPreparedServerFactory(u"ws://127.0.0.1:9000",
                                             debug=debug,
                                             debugCodePaths=debug)

    factory.protocol = BroadcastServerProtocol
    listenWS(factory)

    root = Resource()
    webClient = WebClient()
    webClient.webSocket = factory
    root.putChild('update.json', webClient)
    webFactory = Site(root)
    reactor.listenTCP(7080, webFactory)

    webdir = File(".")
    web = Site(webdir)
    reactor.listenTCP(8080, web)

    reactor.run()

我擺脫了RPC嘗試，只是直接POST。 仍有很多提升績效的機會。