The demonstration application provided for this tutorial represents a legacy application, that is, one that has already been in production use for some time. Legacy applications are great candidates for improvement using the IMTK because the service you create based on the application enables you to access the application using a new, more modern interface.
The IMTK is designed to use COBOL programs that are subprograms in an application, that is, programs with a Linkage Section. The book.cbl program supplied with the demonstration COBOL legacy application is just such a program. It maintains an indexed file, which is a stock file such as might be in use at a book retailer.
To follow the tutorial you need to understand the outline logic of the book.cbl program and its parent program, booktest.cbl even though we do not directly use the parent program. Therefore, you might want to look at the COBOL source to get familiar with it. By default, it is in the %PUBLIC%\Documents\Micro Focus\Enterprise Developer\Samples\Interface Mapping Toolkit\ServiceInterfaces\BookDemo (Windows) or $COBDIR/demo/Interface Mapping Toolkit/ServiceInterfaces/BookDemo (UNIX) directory. You can display it in Eclipse or any text editor.