ROSBridge简介以及理解使用（下）

├── CHANGELOG.rst
├── CMakeLists.txt
├── msg
│   └── TypeDef.msg         #消息类型定义
├── package.xml
├── scripts                 #脚本
│   └── rosapi_node         #初始化服务和参数
├── setup.py
├── src
│   └── rosapi              #API具体实现
│       ├── __init__.py
│       ├── objectutils.py  
│       ├── params.py
│       └── proxy.py
└── srv                     #定义各种服务
    ├── DeleteParam.srv
    ├── GetActionServers.srv
    ├── GetParamNames.srv
    ├── GetParam.srv
    ├── GetTime.srv
    ├── HasParam.srv
    ├── MessageDetails.srv
    ├── NodeDetails.srv
    ├── Nodes.srv
    ├── Publishers.srv
    ├── SearchParam.srv
    ├── ServiceHost.srv
    ├── ServiceNode.srv
    ├── ServiceProviders.srv
    ├── ServiceRequestDetails.srv
    ├── ServiceResponseDetails.srv
    ├── ServicesForType.srv
    ├── Services.srv
    ├── ServiceType.srv
    ├── SetParam.srv
    ├── Subscribers.srv
    ├── TopicsForType.srv
    ├── Topics.srv
    └── TopicType.srv

rospy.Service('/rosapi/topics', Topics, get_topics)
rospy.Service('/rosapi/topics_for_type', TopicsForType, get_topics_for_type)
rospy.Service('/rosapi/services', Services, get_services)
rospy.Service('/rosapi/services_for_type', ServicesForType, get_services_for_type)
rospy.Service('/rosapi/nodes', Nodes, get_nodes)
rospy.Service('/rosapi/node_details', NodeDetails, get_node_details)
rospy.Service('/rosapi/action_servers', GetActionServers, get_action_servers)
rospy.Service('/rosapi/topic_type', TopicType, get_topic_type)
rospy.Service('/rosapi/service_type', ServiceType, get_service_type)
rospy.Service('/rosapi/publishers', Publishers, get_publishers)
rospy.Service('/rosapi/subscribers', Subscribers, get_subscribers)
rospy.Service('/rosapi/service_providers', ServiceProviders, get_service_providers)
rospy.Service('/rosapi/service_node', ServiceNode, get_service_node)
rospy.Service('/rosapi/service_host', ServiceHost, get_service_host)
rospy.Service('/rosapi/message_details', MessageDetails, get_message_details)
rospy.Service('/rosapi/service_request_details', ServiceRequestDetails, get_service_request_details)
rospy.Service('/rosapi/service_response_details', ServiceResponseDetails, get_service_response_details)
rospy.Service('/rosapi/set_param', SetParam, set_param)
rospy.Service('/rosapi/get_param', GetParam, get_param)
rospy.Service('/rosapi/has_param', HasParam, has_param)
rospy.Service('/rosapi/search_param', SearchParam, search_param)
rospy.Service('/rosapi/delete_param', DeleteParam, delete_param)
rospy.Service('/rosapi/get_param_names', GetParamNames, get_param_names)
rospy.Service('/rosapi/get_time', GetTime, get_time)

rosbridge_capabilities = [CallService, Advertise, Publish, Subscribe, Defragment, AdvertiseService, ServiceResponse, UnadvertiseService]

for capability_class in self.rosbridge_capabilities:
             self.add_capability(capability_class)

def add_capability(self, capability_class):
    self.capabilities.append(capability_class(self))

def __init__(self, protocol):
       Capability.__init__(self, protocol)    
       protocol.register_operation("call_service", self.call_service)

def register_operation(self, opcode, handler):
   self.operations[opcode] = handler

def incoming(self, message_string=""):
    msg = self.deserialize(self.buffer)
    op = msg["op"]
    self.operations[op](msg)

def call_service(self, message):
     ServiceCaller(trim_servicename(service), args, s_cb, e_cb).start()
ServiceCaller是rosbridge_library/inernal/services.py里定义的线程类(继承自threading.Thread类)，ServiceCaller的run()方法:

def run(self):
    self.success(call_service(self.service, self.args))    def call_service(service, args=None):
    service = resolve_name(service)
     ...
    proxy = ServiceProxy(service, service_class)
    response = proxy.call(inst)
      ...

roslaunch rosbridge_server rosbridge_websocket.launch

def open(self):
   self.protocol = RosbridgeProtocol(cls.client_id_seed, parameters=parameters)
...
def on_close(self):
...
def on_message(self, message):
...
     self.protocol.incoming(message)
...
def send_message(self, message):
...

{
       "op":"publish",
       "id":"1",
        "topic":"/cmd_vel_mux/input/teleop",
         "msg":{
               "linear": {"x":1.0,"y": 0.0,"z": 0.0},
               "angular": {"x": 0.0,"y": 0.0,"z": 0.0}
               }
 }