ROS service and client examples in CPP, LISP and Python
In order to understand the ROS environment, salvaging it's parts and looking at it from more than one side can help a lot. This repository includes a simple "MP3 database server" which serves album names and included title names to other ROS nodes on the network.
The service server node
The service node is written in C++. It sends the filenames from within the "albums" folder when requested. When a client node requests a specific album, the server sends a list of all filenames included in this album's folder. A custom message type "MP3InventoryService" is used for this example.
The client nodes
Client node source code is given in three programming languages:
* C++ * Python * LISP
All three client nodes are looking for the service "mp3_inventory_interaction" on the ROS core and send their requests to the server node once found.
To start the example environment, do the following (assuming, you have a working ROS core running):
> roscd ros_service_examples > rosrun ros_service_examples mp3_inventory
The first line is important because the inventory server looks for the directory "albums" in its current working directory.
The C++ and Python client nodes can also be started using rosrun. There is no need to "roscd" to any specific directory first.
rosrun ros_service_examples mp3_controller_python.py
rosrun ros_service_examples mp3_controller
To launch the LISP client, be sure to completely set up your Emacs, LISP and roslisp environment first. After that, you can run the LISP client node through SLIME:
> (ros-load:load-system "ros_service_examples" :mp3-controller)
Purpose of this example
This example shows the use of custom messages, the exposition of a service from within a C++ node and the use of this service from various clients. The choice of different programming languages was intended explicitly to
a) show the differences between their usage and b) give a rough guide on how to execute these calls.
Furthermore, the directory structure as shown in this example fits the use of the ASDF build system for LISP.