ROS多个master消息互通

需求

有时候我们需要有几个不同的master, 他们之间要交换topic的内容，这时候就不能使用ros自带的设置同一个master的方法.

我们的处理方法是，构造一个client和一个server，他们运行在不同的master下面, client在master1下订阅topic1，然后通过tcp协议(自己定义一个消息协议格式)发到master2下面的server,进行消息解析，再发布出master2下面的topic1，这样我们不改变ros自带的topic框架，就实现topic1的消息从master1到master2的传播.

下面我们实现的是将一个amcl_pose的topic，消息类型是PoseWithCovarianceStamped从master1传到master2，其他的topic代码类似

client 的代码

#! /usr/bin/env python# -*- coding=utf-8 -*-import socketimport structimport rospyimport timefrom geometry_msgs.msg import PoseWithCovarianceStamped,PoseStamped#message proto# id |  length | datadef send_msg(sock, msg ,id):
    # Prefix each message with a 4-byte id and length (network byte order)
    msg = struct.pack('>I',int(id)) + struct.pack('>I', len(msg)) + msg
    sock.sendall(msg)def odomCallback(msg):
    global odom_socket

    data = ""

    id = msg.header.seq    print "send id: ",id
    x = msg.pose.pose.position.x
    y = msg.pose.pose.position.y    #orientation
    orien_z = msg.pose.pose.orientation.z
    orien_w = msg.pose.pose.orientation.w

    data += str(x) + "," + str(y)+ "," + str(orien_z)+ "," + str(orien_w)

    send_msg(odom_socket,data,id)


odom_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
odom_socket.connect(('127.0.0.1',8000))

rospy.init_node('server_node')

rospy.Subscriber('/amcl_pose',PoseWithCovarianceStamped,odomCallback)

rospy.spin()

server 的代码

#! /usr/bin/env python# -*- coding=utf-8 -*-import socketimport time,os,fcntlimport structimport rospyfrom geometry_msgs.msg import PoseWithCovarianceStamped,PoseStamped#message proto# id | length | datadef recv_msg(sock):
    try:        # Read message length and unpack it into an integer
        raw_id = recvall(sock, 4)        if not raw_id:            return None
        id = struct.unpack('>I', raw_id)[0]        print "receive id: ",id
        raw_msglen = recvall(sock, 4)        if not raw_msglen:            return None
        msglen = struct.unpack('>I', raw_msglen)[0]        # Read the message data
        return recvall(sock, msglen)    except Exception ,e:        return Nonedef recvall(sock, n):
    # Helper function to recv n bytes or return None if EOF is hit
    data = ''
    while len(data) 
结论
上面的代码在局域网内测试过，发送图像，激光的数据都可以保证不丢数据。