You can interoperate with external systems in several different ways:
Web services. Communicate with external systems across a network using open standards.
File sharing. Writing data to a file that can then be transferred to an external system. This method of interoperability is common with mainframe services.
Component Object Model (COM). COM is a standard for communicating between processes on a single computer and for accessing external libraries.
Objective 1.2: Design Service Interaction covered designing web services, and exchanging files is a straightforward matter. Therefore, this objective focuses on interoperability with COM.