The next approach of integration is application or process integration. In this approach, the data may or may not be shared among integrating systems. However, integrating systems can expose some functionality via a well-defined interface and other applications can invoke such functionality.

The result of calling the service can be an invocation of a function or a process in the invoked application or a return of processed data from it.

In applications with modern architecture, functionalities can be exposed using Simple Object Access Protocol (SOAP) or Representational State Transfer (REST) APIs. SOAP is a messaging protocol specification for exchanging structured data over web services. REST is an architectural design to define the constraints to be used for web services. However, in older architectures, you may see Remote Procedure Invocations called Remote Procedure Calls (RPCs). SOAP evolved as a successor of RPC.

SOAP provides extensibility, neutrality,...