Computer Aided Systems Engineering (CASE)

1. Everyone has heard the old saying about the shoemaker's children: The shoemaker is so busy making shoes for others that his children don't have shoes of their own. Prior to the 1990s, many software developers were the "shoemaker's children." Although these technical professionals built complex systems and products that automated the work of others, they used very little automation themselves. Today, software engineers have their first new pair of shoes—computer-aided software engineering (CASE).

2. Computer Aided Systems Engineering (CASE) CASE is the application of computer technology to systems development activities, techniques, and methods. • COMPUTER-AIDED SOFTWARE ENGINEERING (CASE) • The automation of step-by -step methodologies for software and systems development CASE tools automate or support one or more phases of the SDLC to speed up development and improve quality.

3. What Is a CASE Tool?Since the early days of writing software, there has been an awareness of the need for automated tools to help the software developer. Initially the concentration was on program support tools such as translators, compilers, assemblers, macro processors, and linkers and loaders. However, as computers became more powerful and the software that ran on them grew larger and more complex, the range of support tools began to expand. In particular, the use of interactive time-sharing systems for software development encouraged the development of program editors, debuggers, code analyzers.

4. A CASE tool is a computer-based product aimed at supporting one or more software engineering activities within a software development process.

5. Computer-aided software engineering (CASE) is the use of software tools to assist in the development and maintenance of software. Tools used to assist in this way are known as CASE Tools. • Some typical CASE tools are: • Code generation tools • Data modeling tools • UML • Refactoring tools • QVT or Model transformation Tools • Configuration management tools including revision control

6. All aspects of the software development lifecycle can be supported by software tools, and so the use of tools from across the spectrum can, arguably, be described as CASE; from project management software through tools for business and functional analysis, system design, code storage, compilers, translation tools, test software, and so on.

7. Computer AidedSystems Engineering(CASE) • aims to improve quality of systems • focuses on automating structured techniques • upper CASE tools • lower CASE tools • relies on rigorous development methods

8. Planning Analysis Design Implementation Support CASE Framework

9. CASE Tools • upper-CASE • lower-CASE • cross life cycle CASE

10. Upper CASE Tools • systems planning • goals, objectives • business models • systems analysis • scope, boundaries • detailed modeling • prototyping

11. Lower CASE Tools • systems design • technology models • systems implementation • programmer workbench • code generation • systems support • reverse engineering • REVERSE ENGINEERING • The process of examining an existing application that has characteristics that are similar to a desired application. Using the existing application as a guide, the requirements for the new application are defined, analyzed, and extracted all the way back to specifications. From this point, the specifications are altered to comply with any new customer requirements and the new application is developed.

12. Planning Planned Project Existing System Support Analysis Production System Business Requirements Implementation Design Technical Design Cross Life Cycle CASE Tools • project management • process management • estimation • documentation

13. Automated process support (CASE) • Computer-aided software engineering (CASE) is software to support software development and evolution processes • Activity automation • Graphical editors for system model development • Data dictionary to manage design entities • Graphical UI builder for user interface construction • Debuggers to support program fault finding • Automated translators to generate new versions of a program

14. Case technology • Case technology has led to significant improvements in the software process though not the order of magnitude improvements that were once predicted • Software engineering requires creative thought - this is not readily automatable • Software engineering is a team activity and, for large projects, much time is spent in team interactions. CASE technology does not really support these

15. CASE classification • Classification helps us understand the different types of CASE tools and their support for process activities • Functional perspective • Tools are classified according to their specific function • Process perspective • Tools are classified according to process activities that are supported • Integration perspective • Tools are classified according to their organisation into integrated units

16. Functional tool classification

17. Activity-based classification

18. CASE integration • Tools • Support individual process tasks such as design consistency checking, text editing, etc. • Workbenches • Support a process phase such as specification or design, Normally include a number of integrated tools • Environments • Support all or a substantial part of an entire software process. Normally include several integrated workbenches

19. Tools, workbenches, environments

20. CASE Repository • a developers database • stores diagrams, specifications, code • ensures standardization, consistency • tracks people, data, process, network, technology • stored • locally • in work groups • centrally

21. Computer-Aided System Engineering (CASE) • CASE tools: Software tools designed to help system analyst complete development tasks • The CASE tool contains a database of information called a repository • Information about models • Descriptions • Data definitions • References that link models together • Case tools can check the models to make sure they are complete and follow diagramming rules • Also can check if the models are consistent • Adds a number of capabilities around the repository

22. CASE Approach (cont.) A CASE tool repository contains all information about the system.

23. Types of CASE tools • Upper CASE tools • Support analyst during the analysis and design phases • Lower CASE tools • Support for implementation – e.g. generating programs • Tools may be general, or designed for specific methodology (like for information engineering – TIs’ IEF, CoolTools) • Examples of CASE tools • Visual Analyst for creating traditional models • Called “integrated application development tool” • Rational Rose for object-oriented modeling • Based on UML standard for object orientation • Allows for reverse-engineering and code generation (can be integrated with other tools like Visual C++ etc.) • “Round trip engineering” – synchronized updating

24. Types of CASE tools (cont.) The CASE tool Visual Analyst showing a data flow diagram.

25. Types of CASE tools (cont.) The visual modeling tool Rational Rose showing diagrams from the object-oriented approach

26. Types of CASE tools (cont.) he round-trip engineering tool Together J showing a class diagram with synchronized Java source code.

27. What CASE can do to help • Help to make analysis and design process more rigorous and complete, to reduce bugs later • Examples of functions in tools: • Provide support for diagramming (for analysis and design) • Provide support for checking consistency of design • Provide graphing support to help users visualize an existing or proposed information system (e.g. Data flow diagrams) • Detail the processes of your system in a hierarchical structure • Produce executable applications based on your data flow diagrams (which can be made from point and click placements of icons) • Integrate specific methodologies into windowing environments

28. Evolution of Software Tools CASE- Code generators CASE- Analysis + Design sophistication Debuggers Compilers Assemblers

29. Current Status of CASE • A number of commercial products • Some aspects (e.g. diagramming support) are widely applicable and useful • Other features such as code generation are more specific • CASE tools not so successful for generic code generation • However, specific code generation is now being used for things such as user interface design (e.g. Visual C++ allows you to “draw” the interface and it generates the code) • As ideas become successful often no longer called CASE

30. Causes of failure (and symptoms) in software development • Requirements Analysis • No written requirements • Incompletely specified requirements • No user interface mock-up • No end –user involvement (can happen – may have talked to clients BUT not users!) • Design • Lack of, or insufficient, design documents • Poorly specified data structures and file formats • Infrequent or no design reviews

31. Causes of failure (and symptoms) in software development (cont.) • Implementation • Lack of, or insufficient coding standards • Infrequent or no code reviews • Poor in-line code documentation • Unit test and Integration • Insufficient module testing • Lack of proper or complete testing • Lack of an independent quality assurance group

32. Causes of failure (and symptoms) in software development (cont.) • Beta Test Release • Complete lack of a beta test • Insufficient duration for beta test • Insufficient number of beta testers • Wrong beta testers selected • Maintenance • Too many bug reports • Fixing one bug introduces new bugs

33. Stats on Software Errors (large systems) • Most software errors originate in the Analysis and Design phases (65%) • Unfortunately, less than one-third of these errors are caught before acceptance testing begins • About 35% of errors occur during coding • Cost of fixing an error goes up the later it is caught! • This is basis for emphasis in CASE on Analysis and Design

34. graphics facilities description facilities prototyping inquiry and reporting quality assurance decision support documentation transform generators data sharing security, version control housekeeping CASE Facilities and Functions

35. Planning Planned Project Existing System Support Analysis Production System Business Requirements Implementation Design Technical Design CASE Tool Integration • data integration • file transfer, linkage, or central interface • presentation integration • Windows, Motif, etc. • tool integration • interoperation

36. Planning Analysis Design Implementation Support CASE Workbench

37. Benefits of CASE • Increased Productivity • Improved Quality • Better Documentation • Reduced Lifetime Maintenance • Methods that really work

38. Costs of CASE • hardware and systems • software • training and consulting • justification for CASE

39. Implementation Recommendations • get your methods in order • select right people • develop reasonable expectations • choose appropriate pilot • create support mechanism • learn from others • continually improve

40. CASE tools 1980s… Upper CASE tools: support for the analysis and design Lower CASE tools: support for construction and maintenance Nowadays… Integrated CASE tools: Offer extensive life cycle coverage

41. CASE tools: Automated Diagram Support • Checks for syntactic correctness • Data dictionary support • Checks for consistency and completeness • Navigation to linked diagrams • Layering • Requirements traceability • Automatic report generation • System simulation • Performance analysis

42. CASE tools: Software construction and maintenance • Code generators • …Generate code from the design model… • Think of the advantages! • …may also generate database schemata… • Maintenance tools • Reverse Engineering • Analysis of program code

43. CASE tools: Advantages • Help standardization of notations and diagrams • Help communication between development team members • Automatically check the quality of the A&D models • Reduction of time and effort • Enhance reuse of models or models’ components

44. CASE tools: Disadvantages • Limitations in flexibility of documentation • May lead to restriction to the tool’s capabilities • Major danger: completeness and syntactic correctness does NOT mean compliance with requirements • Costs associated with the use of the tool: purchase + training

45. UML: History and Brief Summary Adoption of the OO paradigm … problematic Emergence of UML as a methods’ unification approach UML: An OMG standard since 1997… Under way to become an ISO standard! UML notation: a melding of graphical notations from various sources. + other concepts…

46. UML: History and Brief Summary UML: A method or a notation? • Modeling method: techniques + guidelines + notations è roadmap for the development of a model • Primarily a notation However, there are attempts todescribe OO methods or methodological frameworks that would be able to employ UML. • The Rational Unified Process • The Object-oriented Process, Environment and Notation (OPEN)