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 +1,41 @@
+# Result code and message for service calls.
+# Note that additional codes for specific services can defined within the service definition.
+# For example, you could define a service CalculateSquareRoot.srv as
+# float64 value
+# ---
+# int32 CODE_NEGATIVE_VALUE = -110
+# std_msgs/Result result
+# float64 root
+#
+# If a negative value is provided, the server could return the generic CODE_INVALID_ARGUMENT
+# as result.code, or it could provide more context with CODE_NEGATIVE_VALUE.
+#
+# As a general guideline,
+# Positive values are successes
+# Negative values are failures
+#       Values between -1 and -100 are for some generic high-level failures
+#       Values between -101 and -1000 are for client (caller) errors (a la HTTP 4XX errors)
+#       Values between -1001 and -2000 are for server errors (a la HTTP 5XX errors)
+
+int32 CODE_UNKNOWN                   =   0
+int32 CODE_OK                        =    1
+
+int32 CODE_GENERAL_FAILURE           =  -1
+
+# Client Errors
+int32 CODE_CANCELLED                 =  -101
+int32 CODE_INVALID_ARGUMENT          =  -102
+int32 CODE_NOT_FOUND                 =  -103
+int32 CODE_ALREADY_EXISTS            =  -104
+int32 CODE_PERMISSION_DENIED         =  -105
+int32 CODE_FAILED_PRECONDITION       =  -106
+int32 CODE_OUT_OF_RANGE              =  -107
+
+# Server Errors
+int32 CODE_INTERNAL                  = -1000
+int32 CODE_UNIMPLEMENTED             = -1001
+int32 CODE_UNAVAILABLE               = -1002
+int32 CODE_DEADLINE_EXCEEDED         = -1003
+
+int32 code                                # Code number to be checked on return from service interface call
+string error_message                      # Additional error description when useful.