call_service.py

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import fnmatch
from functools import partial
from rosbridge_library.capability import Capability
from rosbridge_library.internal.services import ServiceCaller
from rosbridge_library.util import string_types
 
 
class CallService(Capability):
 
    call_service_msg_fields = [(True, "service", string_types),
                               (False, "fragment_size", (int, type(None))),
                               (False, "compression", string_types)]
 
    services_glob = None
 
    def __init__(self, protocol):
        # Call superclas constructor
        Capability.__init__(self, protocol)
 
        # Register the operations that this capability provides
        protocol.register_operation("call_service", self.call_service)
 
    def call_service(self, message):
        # Pull out the ID
        cid = message.get("id", None)
 
        # Typecheck the args
        self.basic_type_check(message, self.call_service_msg_fields)
 
        # Extract the args
        service = message["service"]
        fragment_size = message.get("fragment_size", None)
        compression = message.get("compression", "none")
        args = message.get("args", [])
 
        if CallService.services_glob is not None and CallService.services_glob:
            self.protocol.log("debug", "Service security glob enabled, checking service: " + service)
            match = False
            for glob in CallService.services_glob:
                if (fnmatch.fnmatch(service, glob)):
                    self.protocol.log("debug", "Found match with glob " + glob + ", continuing service call...")
                    match = True
                    break
            if not match:
                self.protocol.log("warn", "No match found for service, cancelling service call for: " + service)
                return
        else:
            self.protocol.log("debug", "No service security glob, not checking service call.")
 
        # Check for deprecated service ID, eg. /rosbridge/topics#33
        cid = extract_id(service, cid)
 
        # Create the callbacks
        s_cb = partial(self._success, cid, service, fragment_size, compression)
        e_cb = partial(self._failure, cid, service)
 
        # Kick off the service caller thread
        ServiceCaller(trim_servicename(service), args, s_cb, e_cb).start()
 
    def _success(self, cid, service, fragment_size, compression, message):
        outgoing_message = {
            "op": "service_response",
            "service": service,
            "values": message,
            "result": True
        }
        if cid is not None:
            outgoing_message["id"] = cid
        # TODO: fragmentation, compression
        self.protocol.send(outgoing_message)
 
    def _failure(self, cid, service, exc):
        self.protocol.log("error", "call_service %s: %s" %
                          (type(exc).__name__, str(exc)), cid)
        # send response with result: false
        outgoing_message = {
            "op": "service_response",
            "service": service,
            "values": str(exc),
            "result": False
        }
        if cid is not None:
            outgoing_message["id"] = cid
        self.protocol.send(outgoing_message)
 
 
def trim_servicename(service):
    if '#' in service:
        return service[:service.find('#')]
    return service
 
 
def extract_id(service, cid):
    if cid is not None:
        return cid
    elif '#' in service:
        return service[service.find('#') + 1:]