Rails Application Integration Architecture

I have an application that has to integrate several other application (via different way rest api, etc.).

The problem is that I want to create an Application Integration Architecture (that is an abstract layer) in which I define the integration at an high level and then a way to implement each integration in a specific way.

I searched on the web on which are the best common practice for this challenge but did not find anything interesting.

For example let's say my application has to integrate with three other application called A,B and C.

My application call a method called createObject so depending on the object type I need to call A, B or C.

I would like to have an high level layer on which I can call just createObject and then a specific layer that automatically call the createObject method on A,B or C in different way. The output of the method should be the same.

I know that the question seems to generic but it is something related to the Software Engineering.

I'm working on ruby on rails.