Writing a service in C: How to pass and process arguments to running service?

Question

I want to write a service in C.

While this service is running in background and processing some information I need to grab the results from this service from other applications or from command line.

Background: I need a C application/service due to performance issues. The UI will be implemented in a higher language like Java or C#/Mono on Linux. The C application will basically process data, which will come in from another source. The UI layer should be able to grab the results in a loop every few milliseconds for example and display it to the user. Also it should be possible to pause/start/configure the service from the Java application. Thats where the question begins.

How do I implement the service in C, so that it can respond to commands in runtime?

Thanks, Eduard

Answer 1

If you want to separate a service and its UI, you need some kind of IPC mechanism to make them communicate. Several of these exist, but the standard on linux-based systems these days is D-Bus, which can be used to access a service written in C from a client written in any language that has D-Bus bindings (Java and Mono have them). Your service should provide a D-Bus service for the client to call. D-Bus also provides a way to autostart services. Stopping and configuring can easily be implemented.

I would not make your UI grab results every few milliseconds as humans can't process info that quickly. An update rate of 25-30 times per second should be more than enough.