Does the IPC protocol allow for double communication between two apps?

I’m building a project where, among other things, you have to send messages over MQTT. I clearly need to have multiple apps communicate with each other. I have a main app from which I have implemented the IPC protocol with another app. However, I would also like to do the other way around, that is to make an app be both client and server. From the secondary app I want to invoke the publish functions of the primary app and then call it again in the main app. When I do this I get the following error, which suggests that it cannot be done (I only put requires and bindings, if I remove them everything will work again):

Can you confirm that this thing cannot be done and that therefore I have to find another way? Because I can’t find anything about it in the Legato Reference Manual. Thank you all

You can see this, we can register a callback for a server to call client:

I understand…I think this post will be more helpful in other parts of my project, so thank you. But in this case I want only call a function from server app to client app.
In other way I have an helloWorld server app (I see how to build IPC on legato reference manual) and a client app that is mqtt. But I want to do another thing: in the server app I want to call the publish function of mqtt client app:
so in the requires and binding I gave mqtt.api. In mqttclient.c I do:
At the same time, mqttClientApp is the client app of helloWorld app component. I don’t know if I’ve made myself clear. Basically I wanted a way to build other functions and call the publish itself in them. I can compile the project, but I get the following error and everything stops:

Am I wrong? Is possible to implement this thing or am I simply doing something wrong?

Didn’t the sample code ipc_step4.rar already show you how to call a function in client by a server???

I am able to do it and without publish all works. The problem is that also in the server I call a function of the client and recall it in the server. I think I write well bindings, requires, provides, etc. Error UNKNOWN seems to be something not allowed… :frowning:
Anyway it’s not very important, I wanted to find a way to make the project more orderly. The worst case would be to have all functions in the same .c

hi need a sample to build a multiple app in a project

Do yoy running two applications with ipc?

s i need to inter communicate between the two application

You can see these samples

hi while communicating between the Applications it is possible to use the header file of an Application over the other Application

You can modify the c file to give full path of other header file in “#include

Or you can add the cflag with -I for header file search directory

Or you can define a common structure in .api file