Result.msg for Service Responses

std_msgs/CMakeLists.txt

@@ -37,6 +37,7 @@ set(msg_files
   "msg/Int8MultiArray.msg"
   "msg/MultiArrayDimension.msg"
   "msg/MultiArrayLayout.msg"
+  "msg/Result.msg"
   "msg/String.msg"
   "msg/UInt16.msg"
   "msg/UInt16MultiArray.msg"

std_msgs/README.md

@@ -8,6 +8,7 @@ For more information about ROS 2 interfaces, see [docs.ros.org](https://docs.ros
 * [ColorRGBA](msg/ColorRGBA.msg): A single RGBA value for representing colors.
 * [Empty](msg/Empty.msg): Does not hold any information, useful when the sending of a message would provide sufficient information.
 * [Header](msg/Header.msg): Standard metadata for higher-level stamped data types used to communicate timestamped data in a particular coordinate frame.
+* [Result](msg/Result.msg): Basic structure for returning information in a Service Response.
 
 ### Primitive Types
 `std_msgs` provides the following wrappers for ROS primitive types, which are documented in the msg specification. It also contains the Empty type, which is useful for sending an empty signal. However, these types do not convey semantic meaning about their contents: every message simply has a field called "data". Therefore, while the messages in this package can be useful for quick prototyping, they are NOT intended for "long-term" usage. For ease of documentation and collaboration, we recommend that existing messages be used, or new messages created, that provide meaningful field name(s).

std_msgs/msg/Result.msg

@@ -0,0 +1,18 @@
+# Result code and message for service calls.
+# Note that additional results for specific services can defined within them using values above 100.
+
+uint8 RESULT_FEATURE_UNSUPPORTED   = 0    # Feature is not supported by the simulator, check GetSimulatorFeatures.
+                                          # While feature support can sometimes be deduced from presence of corresponding
+                                          # service / action interface, in other cases it is about supporting certain
+                                          # call parameters, formats and options within interface call.
+uint8 RESULT_OK                    = 1
+uint8 RESULT_NOT_FOUND             = 2    # No match for input (such as when entity name does not exist).
+uint8 RESULT_INCORRECT_STATE       = 3    # Simulator is in an incorrect state for this interface call, e.g. a service
+                                          # requires paused state but the simulator is not paused.
+uint8 RESULT_OPERATION_FAILED      = 4    # Request could not be completed successfully even though feature is supported
+                                          # and the input is correct; check error_message for details.
+                                          # Implementation rule: check extended codes for called service
+                                          #  (e.g. SpawnEntity) to provide a return code which is more specific.
+
+uint8 result                              # Result to be checked on return from service interface call
+string error_message                      # Additional error description when useful.