ros2-service-pattern

A ROS 2 service server handles incoming requests and returns responses synchronously, while a client sends requests and waits for replies. Use the service server pattern to define a .srv interface, implement a callback handler, and spin the node; create an asynchronous client that sends requests with proper error handling and awaits responses.

Services enforce synchronous request-response semantics ideal for commands requiring confirmation, while topics enable asynchronous one-way messaging. Choose services for discrete tasks like AddTwoInts operations where the client must wait for completion; use topics for continuous sensor streams and event broadcasting.

Create an async client using create_client(), construct a request object matching your .srv definition, call the service with await, and handle exceptions for timeouts or failures. This pattern prevents blocking while waiting for the server response and follows ROS 2 Humble canonical templates.

Define request and response fields in a .srv file, create a server node with a callback that processes requests and returns responses, then build a client node that instantiates the service, sends requests, and processes replies. Follow official ROS 2 Humble patterns for both Python and C++ implementations.

Yes, this Skill validates generated service server and client code against live ROS 2 Humble documentation to ensure patterns match official standards. This guarantees your templates remain compatible with the current ROS 2 release and best practices.