Mastering Layers in Software Architecture

Using Layers in Software Architecture

• Layers are useful in adding system environment information to evolve the analysis model into a design model of the software system.
• Each layer represents an element of the software architecture such as the problem domain, data management, user interface, and physical architecture.
• Layers can be portrayed using packages and package diagrams.
• The idea of separating the different elements of the architecture into separate layers can be traced back to the MVC architecture of Smalltalk.
• Smalltalk created the Model-View-Controller (MVC) architecture where Models implemented the application logic (problem domain) and Views and Controllers implemented the logic for the user interface.
• The foundation layer contains classes that are necessary for any object-oriented application to exist such as fundamental data types, fundamental data structures, and utility classes.
• The problem-domain layer requires further detailing of the classes to implement them effectively and efficiently.
• The data management layer addresses issues involving the persistence of objects contained in the system and contains Data Access and Manipulation (DAM) classes.
• DAM classes allow problem domain classes to be independent of the storage used, increasing the portability of the evolving system.
• The types of classes that appear in the data management layer deal with how objects can be stored and retrieved.
• There are different storage options such as sequential files, random access files, relational databases, object/relational databases, object-oriented databases, and NoSQL data stores, each optimized to provide solutions for different access and storage problems.
• A complete description of all the issues related to the data management layer is presented in Chapter 9 of the book.