1. Systems Development Lifecycle Project Identification & Selection Project Initiation & Planning Analysis Logical Design Physical Design Implementation Maintenance

2. System Implementation Coding and Integration Testing Installation Documentation Training Support

3. Coding and Integration Start with the design products –data flow diagrams, structure charts, logic models, interface and database designs Get the components –write from scratch –buy packaged –generate Integrate the components –parameterize and tailor the components –write wrappers and glueware

4. System Integration Tailoring Glueware Wrapper

5. Testing Terms Coverage –ideally, testing will exercise the system in all possible ways –not possible, so we use different criteria to judge how well our testing strategy “covers” the system Test case –consists of data, procedure, and expected result –represents just one situation under which the system (or some part of it) might run

6. Test Planning A test plan includes: –test objectives –schedule and logistics –test strategies –test cases procedure data expected result –procedures for handling problems

7. Testing Phases Unit testing - does this piece work by itself? Integration testing - do these two pieces work together? System testing - do all the pieces work together? Alpha acceptance testing - try it out with in-house “users” Installation testing - can users install it and does it work in their environment? Beta acceptance testing - try it out with real users In development/ maintenance organization In user organization

8. Testing Techniques Structural testing techniques –“white box” testing –based on statements in the code –coverage criteria related to physical parts of the system –tests how a program/system does something Functional testing techniques –“black box” testing –based on input and output –coverage criteria based on behavior aspects –tests the behavior of a system or program

9. System Testing Techniques stress testing - test larger-than-normal capacity in terms of transactions, data, users, speed, etc. execution testing - test performance in terms of speed, precision, etc. recovery testing - test how the system recovers from a disaster, how it handles corrupted data, etc. operations testing - test how the system fits in with existing operations and procedures in the user organization compliance testing - test adherence to standards security testing - test security requirements

10. System Testing Techniques (cont.) requirements testing - fundamental form of testing - makes sure the system does what it’s required to do regression testing - make sure unchanged functionality remains unchanged error-handling testing - test required error-handling functions (usually user error) manual-support testing - test that the system can be used properly - includes user documentation historical test data - tests until the number of defects found approaches the average number of defects in the products produced under similar circumstances

11. Unit Testing Techniques input domain testing - pick test cases representative of the range of allowable input, including high, low, and average values equivalence partitioning - partition the range of allowable input so that the program is expected to behave similarly for all inputs in a given partition, then pick a test case from each partition boundary value - choose test cases with input values at the boundary (both inside and outside) of the allowable range

12. Unit Testing Techniques (cont.) statement testing - ensure the set of test cases exercises every statement at least once branch testing - each branch of an if/then statement is exercised path testing - every path is exercised (impossible in practice) fault seeding - put a certain number of known faults into the code, then test until they are all found

13. Manual Testing Techniques Attempt to evaluate a program without executing it Techniques: –inspections and reviews –walkthroughs and desk checking –mathematical correctness proofs –safety analysis –program measurements –data flow and control flow analysis

14. Installing the System Installation process –must be analyzed and designed, too –needs to be tested –needs to be scheduled and managed –need to have a conversion plan Consider business cycle Organizational change process

15. Conversion Refers to the process of switching from the previous system to the new one Conversion strategies –direct –parallel –single location –phased Have to consider conversion of data, hardware, documentation, work methods, physical spaces, business forms, etc.

16. Types of User Documentation User’s manuals Operator’s manuals Conversion manuals Tutorials Automated Demos Programmer’s Guide Failure Message Reference Guide On-line Help Quick Reference Guides

17. Documentation in the SDLC Often left to the most junior members of the team Or the most incompetent (can do less damage documenting rather than coding) Devote 5% effort at the last minute Result: inadequate documentation Exception when system success depends on satisfaction of general population users

18. How It Should Happen Should be managed properly, staffed appropriately, monitored according to schedule Get started early - before implementation Use professionals Thorough review of all documentation Provide mechanisms for feedback from users Revise regularly

19. Documentation Evaluation informal reviews by a variety of reviewers features checklists automated metrics information walkthroughs with users controlled experiments with users field trials with users

20. Documentation Audiences Users, operators, programmers, customers, maintainers Level of technical expertise and experience What they want to know –“I want to buy it” –“I want to learn it” –“I want to use it” –“I want to fix it” How much time they have to spend

21. Training and Support Often overlooked Can’t leave it entirely to documentation Training - upfront instruction, usually intensive Support - long-term assistance, often for occasional users On-line training and support more and more expected

22. Success Factors Management support of new system User involvement during development Commitment to the project from all parties Organizational commitment to change Quality of project definition and planning User expectations

23. Evolving the System In an ideal world: The system, once installed, is continuously monitored to determine areas for improvement, to immediately correct problems, and to quickly adapt to changing circumstances. In reality: The system, once installed, is largely ignored unless it has a catastrophic failure or someone complains loudly enough, in which case it is modified as quickly as possible with the minimum amount of effort.

24. Maintenance vs. Evolution Maintenance - individual changes that must be made to a system after installation Evolution - the long-term change in structure and quality that occurs in a system due to the overall effect of maintenance changes Evolution results in system deterioration unless it is managed Managing evolution requires managing maintenance

25. Systems must be changed because... A defect had to be corrected The user changed their mind The user thought of something new (that they’re willing to pay for) The environment changes Changes can be made to make future changes easier

26. Categories of Maintenance Changes Corrective - fixing bugs Adaptive - no change to functionality, but now works under new conditions Perfective - adds something new; makes the system “better” Preventive - enhances internal structure of system without affecting external behavior “Enhancements”

27. Maintenance Terms Configuration Control Board (CCB) - organizational unit that makes decisions about what proposed maintenance changes will actually be made Releases - planned collections of maintenance changes that are applied to a system before it is delivered to customers Patches - emergency fixes to a system that are delivered to customers between scheduled releases Configuration management - the process of keeping track of different versions of a system that have been supplied to different customers and that must be maintained separately

28. Maintenance Terms (cont.) Ripple effect - the (usually unintended) effects that a change in one part of a system has on other parts of the system Impact analysis - analysis of a planned modification to a system in an effort to determine all of the components of the system that will be affected by the modification, including ripple effects System decay - a degradation of system structure and quality over time due to poorly planned and executed changes Program comprehension - the human process of understanding a piece of software code Porting - a type of adaptive maintenance in which a system is translated from one operating system, language, or platform to another

29. Why is Maintenance Hard? System maintainers have limited sources of information about the system Systems are complex and interdependent Systems are not developed for maintainers Maintenance is not very glamorous Maintenance is not very well respected