Understanding Architectural Patterns in Software Engineering

1. SEA Side Software Engineering Annotations Architectural Patterns Professor Sara Stoecklin Director of Software Engineering- Panama City sstoecklin@mail.pc.fsu.edu stoeckli@cs.fsu.edu 850-522-2091 850-522-2023 Ex 182 Florida State University Computer Science

2. Patterns Pattern: A representation of a proven solution. Problem Applicable Forces Solution Consequences Benefits

3. Software Architecture • Architecture is OVERLOADED • System architecture • Application architecture • Architecture for this presentation is • The modules, processes, interconnections, and protocols which constitute the deployed software system. • Different from the behavioral architecture which describes how the business classes execute the business processes.

4. Architecture Specification • Document which defines in text and diagrams the design, flow and technologies of the design. • Shows how persistence, communication, and behavior are to be implemented in the system.

5. Types of Patterns • Lowest Level – Programming Patterns • Iterator, if, while • Design Level – Design Patterns • Factory, builder, --- gang of 4 • Before Design – Architectural Patterns • Martin Fowler- presentation, domain, data storage, environment • Analysis Patterns – • used in requirements analysis

6. Architectural Layers - Patterns • Presentation • interactions with the user – HTML, thick client, MVC, web services • Domain (Logic) • Business rules, validations, calculations, verifications • Data Storage • database • Environmental • Session management, messaging

7. Presentation Architectural Patterns • Presentation interactions with the user • No Client • Thick Client (rich client) • Thin Client

8. Presentation Architectural Patterns • Model View Controller • Application Controller • Input Controller • Page Controller • Front Controller • View Controller • Template View • Transform View • Two Step View

9. Model View Controller Separation of Presentation (View/Controller) from Domain (Model) Separation of View and Controller Model – Domain object View – Presentation object Controller – Controller object to handle user request/response

10. Application Controller A centralized point for handling screen navigation and flow of an application. Application Controller – determines which type of input is needed or which screen. Input Controller Application Controller Domain Layer View

11. Application Controller

12. Application Controller • A single point of control to change program flow and navigation • May be in mediating layer between the presentation and the domain • May be reusable across various presentations • Testable outside the UI framework.

13. Front Controller

14. Page Controller

15. Front vs Page Controller • Front Controller • Single point for adding behavior • Can add behavior dynamically (filter pattern) • Use with more complex applications • Page Controller • Simple - Input controller per page • Don’t put controller logic into scriplets – use separate classes • More prone to duplicate code with this controller

16. Template View

17. Transform View

18. Template vs Transform vs Two Step • Template View • Follows natural editing notions • Supports non=programmer editors of HTML • Needs discipline to avoid scriplets • Transform View • Can test without server • Works well with XML • Two Step View • Easy to make global appearance changes • Easy to support multiple appearances • Complex

19. Example

20. Data Storage • Need mechanisms to allow RDBMS to communicate in the OO world. • With OO databases none of these patterns necessary. • Useful even if non-OO language wants to communicate with RDBMS to make the DB flexible to change in type and to make the data representation protected.

21. Data Storage Patterns • Table Data Gateway • Row Data Gateway • Active Record • Data Mapper • Structural Patterns • Foreign Key Mapping, Identify Field Association, Table Mapping, Single Table Inheritance.

22. Table Data Gateway

23. Row Data Gateway

24. Row Data Gateway (2)

25. Active Record

26. Data Mapper

27. Distribution Patterns • Remote Façade • Data Transfer Object

28. Remote Facade

29. Data Transfer Object

30. Summary • No one patterns is an end all • Patterns are mechanisms to help decompose applications into reusable, maintainable, modules. • The layers of development help to define the needed patterns • No pattern is always correct -- fit the application.

31. Computing Degrees at FSU-Panama City Information System Degrees Scientific Degrees Computer Science (MS, Web-BS) Management Information Systems (BS) . Advisor Jeanne Dexter – jdexter@mail.pc.fsu.edu . Advisor Sara Stoecklin stoeckli@cs.fsu.edu • Systems Analysis • IT Management • Computer Consulting • Application Programming • Operating Systems • Systems Programming • Applications Programming • Database Administration • Systems Administration Math&Science Business General Math&EE Information Studies (Web – BS,MS) Computer Engineering (BS, Web-MS) . Advisor Alan Stromberg sdytomnrty@mail.pc.fsu.edu . Advisor Kamran Imen kimen@mail.pc.fsu.edu • Embedded Systems • Image Processing • Electronics and Electromagnetics • Signals and Systems • Communications • Microprocessors • Computer Architecture • Web Development • Network Management • Information Systems • Management of Information Services • Social Informatics • Information and Communication Technologies . Degree Programs http://www.pc.fsu.edu/degreeplansheets/default.asp