Continuing Best Practices ► Slide information taken in large part from former Rational Corporation slides considerably modified and supplemented for classroom use.

Practice 5: Verify Software Quality Control Changes Develop Iteratively Use Component Architectures Manage Requirements VerifyQuality Quality, as used within Rational Unified Process, is defined as “The characteristic of having demonstrated the achievement of producing a product which meets or exceeds agreed upon requirements as measured by agreed upon measures and criteria And is produced by an agreed upon process. If done this way, the process can be repeated and managed In most organizations, testing accounts for 30-50% of development costs! Yet most people believe software is not adequately tested when delivered. Testing is difficult; complete testing is impossible; a good process and automated tools help!

Software problems are 100 to 1000 times more costly to find and repair after deployment Development Deployment Cost Practice 5: Verify Software Quality One of the ways to improve quality: Test early and continuously! Test functionality, reliability; performance; Test architectural decisions early.

Iterative Development Permits Continuous Testing – ensuring higher Quality T I M E Test T C D R Iteration 1Iteration 2Iteration 3 T C D R T C D R Test Life Cycle Assess Plan Design Implement Execute Assess! Plan Design Implement Execute Assess! Plan Design Implement Execute

Iterative Development – and Continuous Testing (cont.) ► ► Rather than test one time, spread testing out continuously.  Part of each iteration – BUT (see below) ► ► Each iteration produces an executable release (not a product release…)  Don’t think of an ‘executable’ as just an.exe or.dll. The executables may be part of an architecture……   Each iteration is tested and integrated into an evolving application. ► ► Note: Each ‘phase’ has iteration(s), and each phase has milestones! (A phase may have zero or more iterations prior to arriving at the phase milestone!) ► See your drawings of the RUP) ► Be careful: The ‘extent (how much)’ of R, D, C, T depends on which phase the iteration is in! (See your drawings of the RUP)

More…recall – talking about Verifying Quality ► ► Cannot ‘engineer in’ quality; Must be threaded throughout development! ► ► Notice: Continuous Testing and integration!  Distributes testing….ensures higher quality ► ► At end, entire system tested as a whole. ► ► Many errors can be found early and fixed while repair costs are inexpensive ► ► Architectural decisions (key decisions) tested early avoiding disastrous problems later. (What do we mean by architectural decisions? What might these be??) ► ► These features greatly reduce risks and liability of delivering poor quality systems.

Testing in an Iterative Environment Requirements Test Suite 1 Iteration 2 Iteration 3 Iteration 4 Test Suite 2 Test Suite 3 Test Suite 4 Iteration 1 Automated Tests Continuous integration!!! (one of the major problems of SDLC!) We will produce automated tests. As new requirements are added in iterations, new tests are generated and run. This means that some tests will be rerun – part of ‘Regression Testing.’

Quality – What is it? ► It is an elusive term ► Means different things to different people Next few slides from OOSE text slides; modified

Software Quality... ► Usability - Users can learn it fast and get their job done easily job done easily ► Efficiency - It doesn’t waste resources like CPU time and memory time and memory ► Reliability - It does what it is required to do without failing (MTBF, MTTR…) without failing (MTBF, MTTR…) ► Maintainability - It can be easily changed ► Reusability - Its parts can be used in other projects, so reprogramming is not needed projects, so reprogramming is not needed

Software Quality...again, means different things to different stakeholders QUALITY SOFTWARE Developer: easy to design; easy to maintain; easy to reuse its parts User: easy to learn; efficient to use; helps get work done Customer: solves problems at an acceptable cost in terms of money paid and resources used Development manager: sells more and pleases customers while costing less to develop and maintain

Software Quality ► The different qualities can conflict.  Increasing efficiency can reduce maintainability or reusability  Increasing usability can reduce efficiency ► Setting objectives for quality is a key engineering activity  Then design to meet these objectives  Avoids ‘over-engineering’ which wastes money  Obtain the highest possible reliability using a fixed budget

Short Term Vs. Long Term Quality ► Short term:  Does the software meet the customer’s immediate needs?  Is it sufficiently efficient for the volume of data we have today? ► Long term:  Maintainability  Customer’s future needs  Scalability

Dimensions of Software Quality Functionality Reliability Application Performance System Performance Does my app do what’s required? Does my app leak memory? Does my app respond acceptably? Does my system perform under production load? Test cases for each scenario implemented Analysis tools and code instrumentation Check performance for each use-case/scenario implemented Test performance of all use- cases under authentic and worst-case load TypeWhy?How? For each iteration, do the ‘above’ software quality checks. Remember: tests are ‘driven’ by Use Cases and Supplementary Specifications! Back to Rational…

Problems Addressed by Verifying Quality Testing provides objective project status assessment Objective assessment exposes inconsistencies early (continuous integration helps!) Testing and verification are focused on high risk areas Defects are found earlier and are less expensive to fix (because ‘testing’ is distributed… Automated testing tools provide testing for reliability, functionality, and performance Root Causes Solutions  Insufficient requirements  Ambiguous communications  Brittle architectures  Overwhelming complexity  Subjective assessment  Undetected inconsistencies  Poor testing  Waterfall development  Uncontrolled change  Insufficient automation

Practice 6: Control Changes to Software Control Changes Develop Iteratively Use Component Architectures Manage Requirements Verify Quality Must recognize that we CANNOT STOP CHANGE The only ‘constant’ is ‘change!’ But, we must be able to Manage Change! Must control How and When control is introduced and who introduces the changes. This DOES NOT MEAN that we absolutely accept ALL changes, But…(Discuss!) Want a process that can respond to change…(RUP) Must synchronize Change across development teams and locations too. (What impacts do proposed changes have on our architecture!)

Without explicit control, parallel development degrades to chaos!!!! Practice 6: Control Changes to Software ► Consider: we often have:  Multiple developers  Multiple teams  Multiple sites  Multiple iterations  Multiple releases  Multiple projects  Multiple platforms May have multiple developers organized into different teams at multiple sites all working together on multiple iterations, releases, products, and platforms (mostly based on the software architecture)

Three Major Aspects of a CM System Controlling Change involves a Change Management System and a Configuration Management System for version control releases, etc. (this is beyond where we will go in this course…) CR = change request (version control; evolving products…)

Concepts of Configuration & Change Management ►  Decompose the architecture into layers, packages, subsystems etc., and assign responsibility for these architectural elements to team/teams. ► Establish secure workspaces for each developer  Provide isolation from changes made in other workspaces  Control all software artifacts - models, code, docs, etc. ► Establish an integration workspace ► Establish an enforceable change control mechanism ► Know which changes appear in which releases ► Release a tested baseline at the completion of each iteration  Versioning; baselines; …

Problems Addressed by Controlling Changes Requirements change workflow is defined and repeatable Change requests facilitate clear communications Isolated workspaces reduce interference from parallel work Change rate statistics are good metrics for objectively assessing project status Workspaces contain all artifacts, facilitating consistency Change propagation is controlled Changes maintained in a robust, customizable system Root Causes Solutions  Insufficient requirements  Ambiguous communications  Brittle architectures  Overwhelming complexity  Subjective assessment  Undetected inconsistencies  Poor testing  Waterfall development  Uncontrolled change  Insufficient automation

Best Practices Reinforce Each Other ControlChanges DevelopIteratively Use Component Architectures ModelVisually VerifyQuality Ensures users involved as requirements evolve Validates architectural decisions early on. Drives development, planning, change control. …. Addresses complexity of design/implementation incrementally. Need tools/support environment! Measures quality early and often. Continuous testing and integration Evolves baselines incrementally Architecture  teams  localizing changes; Need CMS, Conf Control… ManageRequirements Remember: these best practices yield the best results WHEN USED COLLECTIVELY! What does iterative development do??

Summary: Best Practices of Software Engineering The result is software that is  On Time  On Budget  Meets Users Needs Project Manager Performance Engineer Release Engineer Analyst Developer Tester Control Changes Develop Iteratively Use Component Architectures ManageRequirements ModelVisually VerifyQuality