使用ZMQ时，阻止从Ubuntu 16.04到Windows 7的出站TCP流量

Question

我在服务器和用Python编写的客户端之间建立了ZeroMQ PUB/SUB 连接。服务器发送消息，客户端将其打印出来。

这些程序在同一台计算机上运行得非常好（Ubuntu 16.04或Windows 7;两者都有效）。

当服务器在Windows 7计算机上且客户端在Ubuntu 16.04计算机上时，它们也可以工作。

但是，如果服务器位于Ubuntu 16.04计算机上，则Windows 7计算机上的客户端无法连接到该计算机。

此外，当我在两台独立的Windows 7计算机之间移动客户端和服务器程序时，没有通信问题。

有谁知道问题可能是什么？

以下是客户端代码：

#Based on code found on this Stack Overflow post:
#https://stackoverflow.com/questions/43817161/how-to-send-opencv-video-footage-over-zeromq-sockets

import cv2
import zmq
import base64
import numpy as np

context = zmq.Context()
footage_socket = context.socket(zmq.SUB)
address = 'tcp://192.168.128.229:5555'
footage_socket.connect(address)
footage_socket.setsockopt_string(zmq.SUBSCRIBE, unicode(''))

print "start"
print "connecting to ", address

while True:
    try:
        frame = footage_socket.recv_string()
        img = base64.b64decode(frame)
        npimg = np.fromstring(img, dtype=np.uint8)
        source = cv2.imdecode(npimg, 1)
        cv2.imshow("image", source)
        cv2.waitKey(1)

    except KeyboardInterrupt:
        cv2.destroyAllWindows()
        print "\n\nBye bye\n"
        break

这是服务器代码：

#Based on code found on this Stack Overflow post:
#https://stackoverflow.com/questions/43817161/how-to-send-opencv-video-footage-over-zeromq-sockets

import cv2
import zmq
import base64

context = zmq.Context()
footage_socket = context.socket(zmq.PUB)
footage_socket.bind('tcp://*:5555')
footage_socket.setsockopt(zmq.CONFLATE, 1)

camera = cv2.VideoCapture(0)

while True:
    try:
        (grabbed, frame) = camera.read()
        frame = cv2.resize(frame, (640, 480))
        encoded, buffer = cv2.imencode('.png', frame)
        footage_socket.send_string(base64.b64encode(buffer))


    except KeyboardInterrupt:
        camera.release()
        cv2.destroyAllWindows()
        print "\n\nBye bye\n"
        break

Answer 1

最佳实践列表：

• 解读：不要依赖重新装入 string 包装的原创内容（string成为问题之后会出现很多问题发布Python-3.0 +中的 byte
• 版本控制：并非所有版本的ZeroMQ核心设施都具有相同的操作方式（PUB/SUB 一侧发生PUB主题过滤在最近的版本中，虽然在早期的ZeroMQ中在 SUB 方面进行了操作。版本很重要。

• 效果：避免过多的开销＆＃34;外部＆＃34;尽可能地核心数据流。使用base64.{b64encode()|b64decode()}就是这种不利的表现舒适度的一个例子，没有提供任何足够的好处。

• 对基于 cv2 的任何基于 struct.pack( aPayloadMASK, .data, OptionA, OptionB, OptionC ) 的帧处理进行配置，调整并检查实际成本〜色彩空间转换可能需要+170 [ms ] pi （在左下方的窗口中）

• 可以以非常便宜的方式将任何进一步的细节添加到aMessagePAYLOAD中（通过aSeqNumUINT8, aUsecTimeSTAMP - 无论是旋转的PUB，还是其他任何想要添加的内容）

Do-s import numpy as np import zmq import cv2 import struct print( "INF: this process uses {0: >10s} v.{1:}".format( "ZMQ", zmq.__version__ ) ) print( "INF: this process uses {0: >10s} v.{1:}".format( "NUMPY", np.__version__ ) ) ... .. aPubSOCKET.setsockopt( zmq.LINGER, 0 ) aPubSOCKET.setsockopt( zmq.IMMEDIATE, 1 ) aPubSOCKET.setsockopt( zmq.TOS, aTypeOfSERVICE_PREFERENCE_ID ) aPubSOCKET.setsockopt( zmq.SNDHWM, 4 ) aPubSOCKET.setsockopt( zmq.SNDBUF, 4*640*480*3 ) aPubSOCKET.setsockopt( zmq.CONFLATE, 1 ) ... .. . aPayloadMAP = ">"+ ( 640 * 480 * 3 )*"B" HiResCAM = cv2.VideoCapture( 0 ) while True: try: ( _ , cv2HiResFRAME ) = HiResCAM.read() # acquire FRAME aPubSOCKET.send( struct.pack( aPayloadMAP, # pack to aMsgPAYLOAD, once .resize()'d cv2.resize( cv2HiResFRAME, ( 640, 480 ) ).data ), # OpenCV 2.2+ natively uses numpy arrays W * H * D * unit8 in BGR-ordering ( BGRA, if alpha used ) zmq.NOBLOCK ) except KeyboardInterrupt: # ... finally: # gracefully terminate all OpenCV resources # gracefully terminate all ZeroMQ resources break -side：

SUB

Do-s import numpy as np import zmq import cv2 import struct print( "INF: this process uses {0: >10s} v.{1:}".format( "ZMQ", zmq.__version__ ) ) print( "INF: this process uses {0: >10s} v.{1:}".format( "NUMPY", np.__version__ ) ) ... .. aSubSOCKET.setsockopt( zmq.LINGER, 0 ) aSubSOCKET.setsockopt( zmq.CONFLATE, 1 ) aSubSOCKET.setsockopt( zmq.MAXMSGSIZE, 100+640*480*3 ) aSubSOCKET.setsockopt( zmq.RCVHWM, 4 ) aSubSOCKET.setsockopt( zmq.RCVBUF, 4*640*480*3 ) aSubSOCKET.connect( address ) aSubSOCKET.setsockopt( zmq.SUBSCRIBE, "" ) aPayloadMASK = ">" + ( 640 * 480 * 3 * "B" ) while True: try: cv2.imshow( "LAST IMAGERY AVAILABLE:", struct.decode( aPayloadMASK, aSubSOCKET.recv() ) cv2.waitKey( 1 ) except KeyboardInterrupt: # ... finally: # gracefully terminate all OpenCV resources # gracefully terminate all ZeroMQ resources break - 侧：

function releaseSecond() {
    // After you do your code, then go and focus the second element
    document.getElementById('second').focus();
}