rospy.impl.tcpros

1 # Software License Agreement (BSD License) 2 # 3 # Copyright (c) 2008, Willow Garage, Inc. 4 # All rights reserved. 5 # 6 # Redistribution and use in source and binary forms, with or without 7 # modification, are permitted provided that the following conditions 8 # are met: 9 # 10 # * Redistributions of source code must retain the above copyright 11 # notice, this list of conditions and the following disclaimer. 12 # * Redistributions in binary form must reproduce the above 13 # copyright notice, this list of conditions and the following 14 # disclaimer in the documentation and/or other materials provided 15 # with the distribution. 16 # * Neither the name of Willow Garage, Inc. nor the names of its 17 # contributors may be used to endorse or promote products derived 18 # from this software without specific prior written permission. 19 # 20 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 21 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 22 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 23 # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 24 # COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 25 # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 26 # BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 27 # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 28 # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 30 # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 31 # POSSIBILITY OF SUCH DAMAGE. 32 33 """Internal use: Service-specific extensions for TCPROS support""" 34 35 import io 36 import socket 37 import struct 38 import sys 39 import logging 40 41 import time 42 import traceback 43 44 import genpy 45 46 import rosgraph 47 import rosgraph.names 48 import rosgraph.network 49 50 from rospy.exceptions import TransportInitError, TransportTerminated, ROSException, ROSInterruptException 51 from rospy.service import _Service, ServiceException 52 53 from rospy.impl.registration import get_service_manager 54 from rospy.impl.tcpros_base import TCPROSTransport, TCPROSTransportProtocol, \ 55 get_tcpros_server_address, start_tcpros_server, recv_buff, \ 56 DEFAULT_BUFF_SIZE 57 58 from rospy.core import logwarn, loginfo, logerr, logdebug 59 import rospy.core 60 import rospy.msg 61 import rospy.names 62 63 import rospy.impl.validators 64 65 import threading 66 67 if sys.hexversion > 0x03000000: #Python3

68 - def isstring(s):

69 return isinstance(s, str) #Python 3.x

70 else:

71 - def isstring(s):

72 return isinstance(s, basestring) #Python 2.x

73 74 logger = logging.getLogger('rospy.service') 75 76 ######################################################### 77 # Service helpers 78

79 -def wait_for_service(service, timeout=None):

80 """ 81 Blocks until service is available. Use this in 82 initialization code if your program depends on a 83 service already running. 84 @param service: name of service 85 @type service: str 86 @param timeout: timeout time in seconds, None for no 87 timeout. NOTE: timeout=0 is invalid as wait_for_service actually 88 contacts the service, so non-blocking behavior is not 89 possible. For timeout=0 uses cases, just call the service without 90 waiting. 91 @type timeout: double 92 @raise ROSException: if specified timeout is exceeded 93 @raise ROSInterruptException: if shutdown interrupts wait 94 """ 95 master = rosgraph.Master(rospy.names.get_caller_id()) 96 def contact_service(resolved_name, timeout=10.0): 97 try: 98 uri = master.lookupService(resolved_name) 99 except rosgraph.MasterException: 100 return False 101 102 addr = rospy.core.parse_rosrpc_uri(uri) 103 if rosgraph.network.use_ipv6(): 104 s = socket.socket(socket.AF_INET6, socket.SOCK_STREAM) 105 else: 106 s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) 107 try: 108 # we always want to timeout just in case we're connecting 109 # to a down service. 110 s.settimeout(timeout) 111 logdebug('connecting to ' + str(addr)) 112 s.connect(addr) 113 h = { 'probe' : '1', 'md5sum' : '*', 114 'callerid' : rospy.core.get_caller_id(), 115 'service': resolved_name } 116 rosgraph.network.write_ros_handshake_header(s, h) 117 return True 118 finally: 119 if s is not None: 120 s.close()

121 if timeout == 0.: 122 raise ValueError("timeout must be non-zero") 123 resolved_name = rospy.names.resolve_name(service) 124 first = False 125 if timeout: 126 timeout_t = time.time() + timeout 127 while not rospy.core.is_shutdown() and time.time() < timeout_t: 128 try: 129 if contact_service(resolved_name, timeout_t-time.time()): 130 return 131 time.sleep(0.3) 132 except KeyboardInterrupt: 133 # re-raise 134 rospy.core.logdebug("wait_for_service: received keyboard interrupt, assuming signals disabled and re-raising") 135 raise 136 except: # service not actually up 137 if first: 138 first = False 139 rospy.core.logerr("wait_for_service(%s): failed to contact [%s], will keep trying"%(resolved_name, uri)) 140 if rospy.core.is_shutdown(): 141 raise ROSInterruptException("rospy shutdown") 142 else: 143 raise ROSException("timeout exceeded while waiting for service %s"%resolved_name) 144 else: 145 while not rospy.core.is_shutdown(): 146 try: 147 if contact_service(resolved_name): 148 return 149 time.sleep(0.3) 150 except KeyboardInterrupt: 151 # re-raise 152 rospy.core.logdebug("wait_for_service: received keyboard interrupt, assuming signals disabled and re-raising") 153 raise 154 except: # service not actually up 155 if first: 156 first = False 157 rospy.core.logerr("wait_for_service(%s): failed to contact [%s], will keep trying"%(resolved_name, uri)) 158 if rospy.core.is_shutdown(): 159 raise ROSInterruptException("rospy shutdown") 160 161

162 -def convert_return_to_response(response, response_class):

163 """ 164 Convert return value of function to response instance. The 165 rules/precedence for this are: 166 167 1. If the return type is the same as the response type, no conversion 168 is done. 169 170 2. If the return type is a dictionary, it is used as a keyword-style 171 initialization for a new response instance. 172 173 3. If the return type is *not* a list type, it is passed in as a single arg 174 to a new response instance. 175 176 4. If the return type is a list/tuple type, it is used as a args-style 177 initialization for a new response instance. 178 """ 179 180 # use this declared ROS type check instead of a direct instance 181 # check, which allows us to play tricks with serialization and 182 # deserialization 183 if isinstance(response, genpy.Message) and response._type == response_class._type: 184 #if isinstance(response, response_class): 185 return response 186 elif type(response) == dict: 187 # kwds response 188 try: 189 return response_class(**response) 190 except AttributeError as e: 191 raise ServiceException("handler returned invalid value: %s"%str(e)) 192 elif response == None: 193 raise ServiceException("service handler returned None") 194 elif type(response) not in [list, tuple]: 195 # single, non-list arg 196 try: 197 return response_class(response) 198 except TypeError as e: 199 raise ServiceException("handler returned invalid value: %s"%str(e)) 200 else: 201 # user returned a list, which has some ambiguous cases. Our resolution is that 202 # all list/tuples are converted to *args 203 try: 204 return response_class(*response) 205 except TypeError as e: 206 raise ServiceException("handler returned wrong number of values: %s"%str(e))

207

208 -def service_connection_handler(sock, client_addr, header):

209 """ 210 Process incoming service connection. For use with 211 TCPROSServer. Reads in service name from handshake and creates the 212 appropriate service handler for the connection. 213 @param sock: socket connection 214 @type sock: socket 215 @param client_addr: client address 216 @type client_addr: (str, int) 217 @param header: key/value pairs from handshake header 218 @type header: dict 219 @return: error string or None 220 @rtype: str 221 """ 222 for required in ['service', 'md5sum', 'callerid']: 223 if not required in header: 224 return "Missing required '%s' field"%required 225 else: 226 logger.debug("connection from %s:%s", client_addr[0], client_addr[1]) 227 service_name = header['service'] 228 229 #TODO: make service manager configurable. I think the right 230 #thing to do is to make these singletons private members of a 231 #Node instance and enable rospy to have multiple node 232 #instances. 233 234 sm = get_service_manager() 235 md5sum = header['md5sum'] 236 service = sm.get_service(service_name) 237 if not service: 238 return "[%s] is not a provider of [%s]"%(rospy.names.get_caller_id(), service_name) 239 elif md5sum != rospy.names.SERVICE_ANYTYPE and md5sum != service.service_class._md5sum: 240 return "request from [%s]: md5sums do not match: [%s] vs. [%s]"%(header['callerid'], md5sum, service.service_class._md5sum) 241 else: 242 transport = TCPROSTransport(service.protocol, service_name, header=header) 243 transport.set_socket(sock, header['callerid']) 244 transport.write_header() 245 # using threadpool reduced performance by an order of 246 # magnitude, need to investigate better 247 t = threading.Thread(target=service.handle, args=(transport, header)) 248 t.setDaemon(True) 249 t.start()

250 251

252 -class TCPService(TCPROSTransportProtocol):

253 """ 254 Protocol implementation for Services over TCPROS 255 """ 256

257 - def __init__(self, resolved_name, service_class, buff_size=DEFAULT_BUFF_SIZE):

258 """ 259 ctor. 260 @param resolved_name: name of service 261 @type resolved_name: str 262 @param service_class: Service data type class 263 @type service_class: Service 264 @param buff_size int: size of buffer (bytes) to use for reading incoming requests. 265 @type buff_size: int 266 """ 267 super(TCPService, self).__init__(resolved_name, service_class._request_class, buff_size=buff_size) 268 self.service_class = service_class

269

270 - def get_header_fields(self):

271 """ 272 Protocol API 273 @return: header fields 274 @rtype: dict 275 """ 276 return {'service': self.resolved_name, 'type': self.service_class._type, 277 'md5sum': self.service_class._md5sum, 'callerid': rospy.names.get_caller_id() }

278

279 -class TCPROSServiceClient(TCPROSTransportProtocol):

280 """Protocol Implementation for Service clients over TCPROS""" 281

282 - def __init__(self, resolved_name, service_class, headers=None, buff_size=DEFAULT_BUFF_SIZE):

283 """ 284 ctor. 285 @param resolved_name: resolved service name 286 @type resolved_name: str 287 @param service_class: Service data type class 288 @type service_class: Service 289 @param headers: identifier for Service session 290 @type headers: dict 291 @param buff_size: size of buffer (bytes) for reading responses from Service. 292 @type buff_size: int 293 """ 294 super(TCPROSServiceClient, self).__init__(resolved_name, service_class._response_class) 295 self.service_class = service_class 296 self.headers = headers or {} 297 self.buff_size = buff_size

298

299 - def get_header_fields(self):

300 """ 301 TCPROSTransportProtocol API 302 """ 303 headers = {'service': self.resolved_name, 'md5sum': self.service_class._md5sum, 304 'callerid': rospy.names.get_caller_id()} 305 # The current implementation allows user-supplied headers to 306 # override protocol-specific headers. We may want to 307 # eliminate this in the future if it is abused too severely. 308 for k, v in self.headers.items(): 309 headers[k] = v 310 return headers

311

312 - def _read_ok_byte(self, b, sock):

313 """ 314 Utility for reading the OK-byte/error-message header preceding each message. 315 @param sock: socket connection. Will be read from if OK byte is 316 false and error message needs to be read 317 @type sock: socket.socket 318 @param b: buffer to read from 319 @type b: StringIO 320 """ 321 if b.tell() == 0: 322 return 323 pos = b.tell() 324 b.seek(0) 325 ok = struct.unpack('<B', b.read(1))[0] # read in ok byte 326 b.seek(pos) 327 if not ok: 328 str = self._read_service_error(sock, b) 329 330 #_read_ok_byte has to reset state of the buffer to 331 #consumed as this exception will bypass rest of 332 #deserialized_messages logic. we currently can't have 333 #multiple requests in flight, so we can keep this simple 334 b.seek(0) 335 b.truncate(0) 336 raise ServiceException("service [%s] responded with an error: %s"%(self.resolved_name, str)) 337 else: 338 # success, set seek point to start of message 339 b.seek(pos)

340

341 - def read_messages(self, b, msg_queue, sock):

342 """ 343 In service implementation, reads in OK byte that preceeds each 344 response. The OK byte allows for the passing of error messages 345 instead of a response message 346 @param b: buffer 347 @type b: StringIO 348 @param msg_queue: Message queue to append to 349 @type msg_queue: [Message] 350 @param sock: socket to read from 351 @type sock: socket.socket 352 """ 353 self._read_ok_byte(b, sock) 354 rospy.msg.deserialize_messages(b, msg_queue, self.recv_data_class, queue_size=self.queue_size, max_msgs=1, start=1) #rospy.msg 355 #deserialize_messages only resets the buffer to the start 356 #point if everything was consumed, so we have to further reset 357 #it. 358 if b.tell() == 1: 359 b.seek(0)

360

361 - def _read_service_error(self, sock, b):

362 """ 363 Read service error from sock 364 @param sock: socket to read from 365 @type sock: socket 366 @param b: currently read data from sock 367 @type b: StringIO 368 """ 369 buff_size = 256 #can be small given that we are just reading an error string 370 while b.tell() < 5: 371 recv_buff(sock, b, buff_size) 372 bval = b.getvalue() 373 (length,) = struct.unpack('<I', bval[1:5]) # ready in len byte 374 while b.tell() < (5 + length): 375 recv_buff(sock, b, buff_size) 376 bval = b.getvalue() 377 return struct.unpack('<%ss'%length, bval[5:5+length])[0] # ready in len byte

378 379

380 -class ServiceProxy(_Service):

381 """ 382 Create a handle to a ROS service for invoking calls. 383 384 Usage:: 385 add_two_ints = ServiceProxy('add_two_ints', AddTwoInts) 386 resp = add_two_ints(1, 2) 387 """ 388

389 - def __init__(self, name, service_class, persistent=False, headers=None):

390 """ 391 ctor. 392 @param name: name of service to call 393 @type name: str 394 @param service_class: auto-generated service class 395 @type service_class: Service class 396 @param persistent: (optional) if True, proxy maintains a persistent 397 connection to service. While this results in better call 398 performance, persistent connections are discouraged as they are 399 less resistent to network issues and service restarts. 400 @type persistent: bool 401 @param headers: (optional) arbitrary headers 402 @type headers: dict 403 """ 404 super(ServiceProxy, self).__init__(name, service_class) 405 self.uri = None 406 self.seq = 0 407 self.buff_size = DEFAULT_BUFF_SIZE 408 self.persistent = persistent 409 if persistent: 410 if not headers: 411 headers = {} 412 headers['persistent'] = '1' 413 self.protocol = TCPROSServiceClient(self.resolved_name, 414 self.service_class, headers=headers) 415 self.transport = None #for saving persistent connections

416

417 - def wait_for_service(self, timeout=None):

418 wait_for_service(self.resolved_name, timeout=timeout)

419 420 # #425

421 - def __call__(self, *args, **kwds):

422 """ 423 Callable-style version of the service API. This accepts either a request message instance, 424 or you can call directly with arguments to create a new request instance. e.g.:: 425 426 add_two_ints(AddTwoIntsRequest(1, 2)) 427 add_two_ints(1, 2) 428 add_two_ints(a=1, b=2) 429 430 @param args: arguments to remote service 431 @param kwds: message keyword arguments 432 @raise ROSSerializationException: If unable to serialize 433 message. This is usually a type error with one of the fields. 434 """ 435 return self.call(*args, **kwds)

436

437 - def _get_service_uri(self, request):

438 """ 439 private routine for getting URI of service to call 440 @param request: request message 441 @type request: L{rospy.Message} 442 """ 443 if not isinstance(request, genpy.Message): 444 raise TypeError("request object is not a valid request message instance") 445 # in order to support more interesting overrides, we only 446 # check that it declares the same ROS type instead of a 447 # stricter class check 448 #if not self.request_class == request.__class__: 449 if not self.request_class._type == request._type: 450 raise TypeError("request object type [%s] does not match service type [%s]"%(request.__class__, self.request_class)) 451 452 #TODO: subscribe to service changes 453 #if self.uri is None: 454 if 1: #always do lookup for now, in the future we need to optimize 455 try: 456 try: 457 master = rosgraph.Master(rospy.names.get_caller_id()) 458 self.uri = master.lookupService(self.resolved_name) 459 except socket.error: 460 raise ServiceException("unable to contact master") 461 except rosgraph.MasterError as e: 462 logger.error("[%s]: lookup service failed with message [%s]", self.resolved_name, str(e)) 463 raise ServiceException("service [%s] unavailable"%self.resolved_name) 464 465 # validate 466 try: 467 rospy.core.parse_rosrpc_uri(self.uri) 468 except rospy.impl.validators.ParameterInvalid: 469 raise ServiceException("master returned invalid ROSRPC URI: %s"%self.uri) 470 except socket.error as e: 471 logger.error("[%s]: socket error contacting service, master is probably unavailable",self.resolved_name) 472 return self.uri

473

474 - def call(self, *args, **kwds):

475 """ 476 Call the service. This accepts either a request message instance, 477 or you can call directly with arguments to create a new request instance. e.g.:: 478 479 add_two_ints(AddTwoIntsRequest(1, 2)) 480 add_two_ints(1, 2) 481 add_two_ints(a=1, b=2) 482 483 @raise TypeError: if request is not of the valid type (Message) 484 @raise ServiceException: if communication with remote service fails 485 @raise ROSInterruptException: if node shutdown (e.g. ctrl-C) interrupts service call 486 @raise ROSSerializationException: If unable to serialize 487 message. This is usually a type error with one of the fields. 488 """ 489 490 # convert args/kwds to request message class 491 request = rospy.msg.args_kwds_to_message(self.request_class, args, kwds) 492 493 # initialize transport 494 if self.transport is None: 495 service_uri = self._get_service_uri(request) 496 dest_addr, dest_port = rospy.core.parse_rosrpc_uri(service_uri) 497 498 # connect to service 499 transport = TCPROSTransport(self.protocol, self.resolved_name) 500 transport.buff_size = self.buff_size 501 try: 502 transport.connect(dest_addr, dest_port, service_uri) 503 except TransportInitError as e: 504 # can be a connection or md5sum mismatch 505 raise ServiceException("unable to connect to service: %s"%e) 506 self.transport = transport 507 else: 508 transport = self.transport 509 510 # send the actual request message 511 self.seq += 1 512 transport.send_message(request, self.seq) 513 514 try: 515 responses = transport.receive_once() 516 if len(responses) == 0: 517 raise ServiceException("service [%s] returned no response"%self.resolved_name) 518 elif len(responses) > 1: 519 raise ServiceException("service [%s] returned multiple responses: %s"%(self.resolved_name, len(responses))) 520 except rospy.exceptions.TransportException as e: 521 # convert lower-level exception to exposed type 522 if rospy.core.is_shutdown(): 523 raise rospy.exceptions.ROSInterruptException("node shutdown interrupted service call") 524 else: 525 raise ServiceException("transport error completing service call: %s"%(str(e))) 526 finally: 527 if not self.persistent: 528 transport.close() 529 self.transport = None 530 return responses[0]

531 532

533 - def close(self):

534 """Close this ServiceProxy. This only has an effect on persistent ServiceProxy instances.""" 535 if self.transport is not None: 536 self.transport.close()

537

538 -class ServiceImpl(_Service):

539 """ 540 Implementation of ROS Service. This intermediary class allows for more configuration of behavior than the Service class. 541 """ 542

543 - def __init__(self, name, service_class, handler, buff_size=DEFAULT_BUFF_SIZE, error_handler=None):

544 super(ServiceImpl, self).__init__(name, service_class) 545 546 if not name or not isstring(name): 547 raise ValueError("service name is not a non-empty string") 548 # #2202 549 if not rosgraph.names.is_legal_name(name): 550 import warnings 551 warnings.warn("'%s' is not a legal ROS graph resource name. This may cause problems with other ROS tools"%name, stacklevel=2) 552 553 554 self.handler = handler 555 if error_handler is not None: 556 self.error_handler = error_handler 557 self.registered = False 558 self.seq = 0 559 self.done = False 560 self.buff_size=buff_size 561 562 start_tcpros_server() #lazy-init the tcprosserver 563 host, port = get_tcpros_server_address() 564 self.uri = '%s%s:%s'%(rospy.core.ROSRPC, host, port) 565 logdebug("... service URL is %s"%self.uri) 566 567 self.protocol = TCPService(self.resolved_name, service_class, self.buff_size) 568 569 logdebug("[%s]: new Service instance"%self.resolved_name)

570 571 # TODO: should consider renaming to unregister 572

573 - def error_handler(self, e, exc_type, exc_value, tb):

574 logerr("Error processing request: %s\n%s" % (e, traceback.format_exception(exc_type, exc_value, tb)))

575

576 - def shutdown(self, reason=''):

577 """ 578 Stop this service 579 @param reason: human-readable shutdown reason 580 @type reason: str 581 """ 582 self.done = True 583 logdebug('[%s].shutdown: reason [%s]'%(self.resolved_name, reason)) 584 try: 585 #TODO: make service manager configurable 586 get_service_manager().unregister(self.resolved_name, self) 587 except Exception as e: 588 logerr("Unable to unregister with master: "+traceback.format_exc()) 589 raise ServiceException("Unable to connect to master: %s"%e)

590

591 - def spin(self):

592 """ 593 Let service run and take over thread until service or node 594 shutdown. Use this method to keep your scripts from exiting 595 execution. 596 """ 597 try: 598 while not rospy.core.is_shutdown() and not self.done: 599 time.sleep(0.5) 600 except KeyboardInterrupt: 601 logdebug("keyboard interrupt, shutting down")

602

603 - def _write_service_error(self, transport, err_msg):

604 """ 605 Send error message to client 606 @param transport: transport connection to client 607 @type transport: Transport 608 @param err_msg: error message to send to client 609 @type err_msg: str 610 """ 611 transport.write_data(struct.pack('<BI%ss'%len(err_msg), 0, len(err_msg), err_msg))

612

613 - def _handle_request(self, transport, request):

614 """ 615 Process a single incoming request. 616 @param transport: transport instance 617 @type transport: L{TCPROSTransport} 618 @param request: Message 619 @type request: genpy.Message 620 """ 621 try: 622 # convert return type to response Message instance 623 response = convert_return_to_response(self.handler(request), self.response_class) 624 self.seq += 1 625 # ok byte 626 transport.write_buff.write(struct.pack('<B', 1)) 627 transport.send_message(response, self.seq) 628 except ServiceException as e: 629 rospy.core.rospydebug("handler raised ServiceException: %s"%(e)) 630 self._write_service_error(transport, "service cannot process request: %s"%e) 631 except Exception as e: 632 (exc_type, exc_value, tb) = sys.exc_info() 633 self.error_handler(e, exc_type, exc_value, tb) 634 self._write_service_error(transport, "error processing request: %s"%e)

635

636 - def handle(self, transport, header):

637 """ 638 Process incoming request. This method should be run in its 639 own thread. If header['persistent'] is set to 1, method will 640 block until connection is broken. 641 @param transport: transport instance 642 @type transport: L{TCPROSTransport} 643 @param header: headers from client 644 @type header: dict 645 """ 646 if 'persistent' in header and \ 647 header['persistent'].lower() in ['1', 'true']: 648 persistent = True 649 else: 650 persistent = False 651 if header.get('probe', None) == '1': 652 #this will likely do more in the future 653 transport.close() 654 return 655 handle_done = False 656 while not handle_done: 657 try: 658 requests = transport.receive_once() 659 for request in requests: 660 self._handle_request(transport, request) 661 if not persistent: 662 handle_done = True 663 except rospy.exceptions.TransportTerminated as e: 664 if not persistent: 665 logerr("incoming connection failed: %s"%e) 666 logdebug("service[%s]: transport terminated"%self.resolved_name) 667 handle_done = True 668 transport.close()

669 670

671 -class Service(ServiceImpl):

672 """ 673 Declare a ROS service. Service requests are passed to the 674 specified handler. 675 676 Service Usage:: 677 s = Service('getmapservice', GetMap, get_map_handler) 678 """ 679

680 - def __init__(self, name, service_class, handler, 681 buff_size=DEFAULT_BUFF_SIZE, error_handler=None):

682 """ 683 ctor. 684 685 @param name: service name, ``str`` 686 @param service_class: Service definition class 687 688 @param handler: callback function for processing service 689 request. Function takes in a ServiceRequest and returns a 690 ServiceResponse of the appropriate type. Function may also 691 return a list, tuple, or dictionary with arguments to initialize 692 a ServiceResponse instance of the correct type. 693 694 If handler cannot process request, it may either return None, 695 to indicate failure, or it may raise a rospy.ServiceException 696 to send a specific error message to the client. Returning None 697 is always considered a failure. 698 699 @type handler: fn(req)->resp 700 701 @param buff_size: size of buffer for reading incoming requests. Should be at least size of request message 702 @type buff_size: int 703 704 @param error_handler: callback function for handling errors 705 raised in the service code. 706 @type error_handler: fn(exception, exception_type, exception_value, traceback)->None 707 """ 708 super(Service, self).__init__(name, service_class, handler, buff_size, 709 error_handler) 710 711 #TODO: make service manager configurable 712 get_service_manager().register(self.resolved_name, self)

713

Source Code for Module rospy.impl.tcpros_service