Planning and Monitoring the Process (c) 2007 Mauro Pezzè

Planning and Monitoring the Process (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 1

Learning objectives Understand the purposes of planning and monitoring Distinguish strategies from plans, and understand their relation Understand the role of risks in planning Understand the potential role of tools in monitoring a quality process Understand team organization as an integral part of planning (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 2

What are Planning and Monitoring? Planning: – Scheduling activities (what steps? in what order?) – Allocating resources (who will do it?) – Devising unambiguous milestones for monitoring Monitoring: Judging progress against the plan – How are we doing? A good plan must have visibility : – Ability to monitor each step, and to make objective judgments of progress – Counter wishful thinking and denial (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 3

Quality and Process Quality process: Set of activities and responsibilities – focused primarily on ensuring adequate dependability – concerned with project schedule or with product usability A framework for – selecting and arranging activities – considering interactions and trade-offs Follows the overall software process in which it is embedded – Example: waterfall software process –– “V model”: unit testing starts with implementation and finishes before integration – Example: XP and agile methods –– emphasis on unit testing and rapid iteration for acceptance testing by customers (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 4

Example Process: Cleanroom Customer Requirements Specification Function Usage Incremental Development Planning Functional specifications Formal Design Correctness Verification Source code Usage specifications Statistical test case generation Test cases Statistical testing Interfail times Improvement Feedback Quality Certification Model MTTF statistics (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 5

Example Process: Cleanroom Customer Requirements Activities and responsibilities focused on quality Specification Function Usage Incremental Development Planning Functional specifications Formal Design Correctness Verification Source code Integrated into an overall development process Usage specifications Statistical test case generation Test cases Statistical testing Interfail times Improvement Feedback Quality Certification Model MTTF statistics (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 6

Example Process: Software Reliability Engineering Testing (SRET) Define “Necessary” Reliability Development Operational Profiles Prepare for Testing Execute tests Requirements and Architecture Design and Implementation (c) 2007 Mauro Pezzè & Michal Young Interpret Failure Data System Test and Acceptance Test Ch 20, slide 7

Software Reliability Engineering Testing (SRET) Define “Necessary” Reliability Activities and responsibilities focused on quality Development Operational Profiles Integrated into an overall development process Requirements and Architecture Prepare for Testing Execute tests Design and Implementation (c) 2007 Mauro Pezzè & Michal Young Interpret Failure Data System Test and Acceptance Test Ch 20, slide 8

Example Process: Extreme Programming (XP) Incremental Release Next version Review, Refine, prioritiz e Passed all unit tests Generate User Stories Create Unit Tests pass Pair Programming unit testing Passed all unit tests Acceptance Testing Failed acceptance test Create Acceptance Tests (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 9

Extreme Programming (XP) Review, Refine, prioritiz e Activities and responsibilities focused on quality Incremental Release Next version Passed all unit tests Generate User Stories Create Unit Tests pass Pair Programming unit testing Passed all unit tests Acceptance Testing Failed acceptance test Create Acceptance Tests (c) 2007 Mauro Pezzè & Michal Young Integrated into an overall development process Ch 20, slide 10

Overall Organization of a Quality Process Key principle of quality planning – the cost of detecting and repairing a fault increases as a function of time between committing an error and detecting the resultant faults therefore . – an efficient quality plan includes matched sets of intermediate validation and verification activities that detect most faults within a short time of their introduction and . – V&V steps depend on the intermediate work products and on their anticipated defects (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 11

Verification Steps for Intermediate Artifacts Internal consistency checks – compliance with structuring rules that define “well-formed” artifacts of that type – a point of leverage: define syntactic and semantic rules thoroughly and precisely enough that many common errors result in detectable violations External consistency checks – consistency with related artifacts – Often: conformance to a “prior” or “higher-level” specification Generation of correctness conjectures – Correctness conjectures: lay the groundwork for external consistency checks of other work products – Often: motivate refinement of the current product (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 12

Strategies vs Plans Scope Strategy Plan Organization Project Structure Organization and content structure, based on experience and policy over several projects Standard structure prescribed in strategy Evolves Quickly, adapting to project needs Slowly, with organization and policy changes (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 13

Test and Analysis Strategy Lessons of past experience – an organizational asset built and refined over time Body of explicit knowledge – more valuable than islands of individual competence – amenable to improvement – reduces vulnerability to organizational change (e.g., loss of key individuals) Essential for – avoiding recurring errors – maintaining consistency of the process – increasing development efficiency (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 14

Considerations in Fitting a Strategy to an Organization Structure and size – example Distinct quality groups in large organizations, overlapping of roles in smaller organizations greater reliance on documents in large than small organizations Overall process – example Cleanroom requires statistical testing and forbids unit testing – fits with tight, formal specs and emphasis on reliability XP prescribes “test first” and pair programming – fits with fluid specifications and rapid evolution Application domain – example Safety critical domains may impose particular quality objectives and require documentation for certification (e.g,RTCA/DO-178B standard requires MC/DC coverage) (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 15

Elements of a Strategy Common quality requirements that apply to all or most products – unambiguous definition and measures Set of documents normally produced during the quality process – contents and relationships Activities prescribed by the overall process – standard tools and practices Guidelines for project staffing and assignment of roles and responsibilities (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 16

Test and Analysis Plan Answer the following questions: What quality activities will be carried out? What are the dependencies among the quality activities and between quality and other development activities? What resources are needed and how will they be allocated? How will both the process and the product be monitored? (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 17

Main Elements of a Plan Items and features to be verified – Scope and target of the plan Activities and resources – Constraints imposed by resources on activities Approaches to be followed – Methods and tools Criteria for evaluating results (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 18

Quality Goals Expressed as properties satisfied by the product – must include metrics to be monitored during the project – example: before entering acceptance testing, the product must pass comprehensive system testing with no critical or severe failures – not all details are available in the early stages of development Initial plan – based on incomplete information – incrementally refined (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 19

Task Schedule Initially based on – quality strategy – past experience Breaks large tasks into subtasks – refine as process advances Includes dependencies – among quality activities – between quality and development activities Guidelines and objectives: – schedule activities for steady effort and continuous progress and evaluation without delaying development activities – schedule activities as early as possible – increase process visibility (how do we know we’re on track?) (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 20

Sample Schedule ID 1 R equirements specifications 3 Architectural design 4 D etailed design of shopping facility subsys . 5 D etailed design of administrative biz logic 6 Shopping fac code and integration (incl unit test ) 7 Sync and stabilize shopping fac . 8 Admin biz logic code and integration (including unit test 9 Sync and stabilize administrative biz logic Inspection of requirements specs . 12 Inspection of architectural design 13 Inspection of det shop . facilities 14 Inspection of detailed design of admin logic . D esign of C ode inspection Inspection of shop . Fun . C ore code and unit tests 17 Inspection of admin . Biz . Log . C ode code and unit tests D esign tests 19 D esign acceptance tests 20 D esign system tests 21 D esign shop fun subsystem integration test 22 D esign admin bix log subsystem integration tests 23 3 rd quarter ) 16 18 2nd quarter 2 /4 D esign inspection 11 15 1/7 D evelopm ent fram ework 2 10 1 st quarter Task N ame Test execution 24 Exec integration tests 25 Exec system tests 26 Exec acceptance tests (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 21

Schedule Risk critical path chain of activities that must be completed in sequence and that have maximum overall duration – Schedule critical tasks and tasks that depend on critical tasks as early as possible to provide schedule slack prevent delay in starting critical tasks critical dependence task on a critical path scheduled immediately after some other task on the critical path – May occur with tasks outside the quality plan (part of the project plan) – Reduce critical dependences by decomposing tasks on critical path, factoring out subtasks that can be performed earlier (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 22

Reducing the Impact of Critical Paths Task name January Febrary March April May CRITICAL SCHEDULE Project start Analysis and design Code and integration Design and execute subsystem tests Design and execute system tests Produce user documentation Product delivery (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 23

Reducing the Impact of Critical Paths Task name January Febrary March April May UNLIMITED RESOURCES Project start Analysis and design Code and integration Design subsystem tests Design system tests Produce user documentation Execute subsystem tests Execute system tests Product delivery (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 24

Reducing the Impact of Critical Paths Task name January Febrary March April May LIMITED RESOURCES Project start Analysis and design Code and integration Design subsystem tests Design system tests Produce user documentation Execute subsystem tests Execute system tests Product delivery (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 25

Risk Planning Risks cannot be eliminated, but they can be assessed, controlled, and monitored Generic management risk – personnel – technology – schedule Quality risk – development – execution – requirements (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 27

Personnel Example Risks Loss of a staff member Staff member under-qualified for task (c) 2007 Mauro Pezzè & Michal Young Control Strategies cross training to avoid over-dependence on individuals continuous education identification of skills gaps early in project competitive compensation and promotion policies and rewarding work including training time in project schedule Ch 20, slide 28

Technology Example Risks High fault rate due to unfamiliar COTS component interface Test and analysis automation tools do not meet expectations (c) 2007 Mauro Pezzè & Michal Young Control Strategies Anticipate and schedule extra time for testing unfamiliar interfaces. Invest training time for COTS components and for training with new tools Monitor, document, and publicize common errors and correct idioms. Introduce new tools in lower-risk pilot projects or prototyping exercises Ch 20, slide 29

Schedule Example Risks Control Strategies Track and reward quality unit Inadequate unit testing as evidenced by low testing leads to fault densities in integration unanticipated Set aside times in a weekly expense and schedule in which delays in inspections take precedence integration testing over other meetings and Difficulty of work scheduling Try distributed and meetings makes asynchronous inspection inspection a techniques, with a lower bottleneck in frequency of face-to-face development inspection meetings (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 30

Development Example Risks Poor quality software delivered to testing group Inadequate unit test and analysis before committing to the code base Control Strategies Provide early warning and feedback Schedule inspection of design, code and test suites Connect development and inspection to the reward system Increase training through inspection Require coverage or other criteria at unit test level (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 31

Test Execution Example Risks Control Strategies Execution costs higher than planned Scarce resources available for testing Minimize parts that require full system to be executed Inspect architecture to assess and improve testability Increase intermediate feedback Invest in scaffolding (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 32

Requirements Example Risk High assurance critical requirements increase expense and uncertainty (c) 2007 Mauro Pezzè & Michal Young Control Strategies Compare planned testing effort with former projects with similar criticality level to avoid underestimating testing effort Balance test and analysis Isolate critical parts, concerns and properties Ch 20, slide 33

Contingency Plan Part of the initial plan – What could go wrong? How will we know, and how will we recover? Evolves with the plan Derives from risk analysis – Essential to consider risks explicitly and in detail Defines actions in response to bad news – Plan B at the ready (the sooner, the better) (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 34

Evolution of the Plan Preliminary Preliminary plan plan First First release release Second Second release release Final Final plan plan Emergency Emergency plan plan (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 35

Process Monitoring Identify deviations from the quality plan as early as possible and take corrective action Depends on a plan that is – realistic – well organized – sufficiently detailed with clear, unambiguous milestones and criteria A process is visible to the extent that it can be effectively monitored (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 36

Evaluate Aggregated Data by Analogy 160 140 faults 120 Total Critical Severe Moderate 100 80 60 40 20 0 1 3 5 Builds (c) 2007 Mauro Pezzè & Michal Young 7 9 Ch 20, slide 37

Process Improvement Monitoring and improvement within a project or across multiple projects: Orthogonal Defect Classification (ODC) &Root Cause Analysis (RCA) Ch 20, slide 38 (c) 2007 Mauro Pezzè & Michal Young

Orthogonal Defect Classification (ODC) Accurate classification schema – for very large projects – to distill an unmanageable amount of detailed information Two main steps – Fault classification when faults are detected when faults are fixed – Fault analysis (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 39

ODC Fault Classification When faults are detected activity executed when the fault is revealed trigger that exposed the fault impact of the fault on the customer When faults are fixed Target: entity fixed to remove the fault Type: type of the fault Source: origin of the faulty modules (in-house, library, imported, outsourced) Age of the faulty element (new, old, rewritten, refixed code) (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 40

ODC activities and triggers Review and Code Inspection – – – – – – – – – Design Conformance: Logic/Flow Backward Compatibility Internal Document Lateral Compatibility Concurrency Language Dependency Side Effects Rare Situation Structural (White Box) Test – Simple Path – Complex Path (c) 2007 Mauro Pezzè & Michal Young Functional (Black box) Test – – – – Coverage Variation Sequencing Interaction System Test – – – – – – Workload/Stress Recovery/Exception Startup/Restart Hardware Configuration Software Configuration Blocked Test Ch 20, slide 41

ODC impact Installability Integrity/Security Performance Maintenance Serviceability Migration Documentation (c) 2007 Mauro Pezzè & Michal Young Usability Standards Reliability Accessibility Capability Requirements Ch 20, slide 42

ODC Fault Analysis (example 1/4) Distribution of fault types versus activities – Different quality activities target different classes of faults – example: algorithmic faults are targeted primarily by unit testing. – a high proportion of faults detected by unit testing should belong to this class proportion of algorithmic faults found during unit testing – unusually small – larger than normal unit tests may not have been well designed proportion of algorithmic faults found during unit testing unusually large integration testing may not focused strongly enough on interface faults (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 43

ODC Fault Analysis (example 2/4) Distribution of triggers over time during field test – Faults corresponding to simple usage should arise early during field test, while faults corresponding to complex usage should arise late. – The rate of disclosure of new faults should asymptotically decrease – Unexpected distributions of triggers over time may indicate poor system or acceptance test Triggers that correspond to simple usage reveal many faults late in acceptance testing The sample may not be representative of the user population Continuously growing faults during acceptance test System testing may have failed (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 44

ODC Fault Analysis (example 3/4) Age distribution over target code – Most faults should be located in new and rewritten code – The proportion of faults in new and rewritten code with respect to base and re-fixed code should gradually increase – Different patterns may indicate holes in the fault tracking and removal process may indicate inadequate test and analysis that failed in revealing faults early – Example increase of faults located in base code after porting may indicate inadequate tests for portability (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 45

ODC Fault Analysis (example 4/4) Distribution of fault classes over time – The proportion of missing code faults should gradually decrease – The percentage of extraneous faults may slowly increase, because missing functionality should be revealed with use increasing number of missing faults may be a symptom of instability of the product sudden sharp increase in extraneous faults may indicate maintenance problems (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 46

Improving the Process Many classes of faults that occur frequently are rooted in process and development flaws – examples Shallow architectural design that does not take into account resource allocation can lead to resource allocation faults Lack of experience with the development environment, which leads to misunderstandings between analysts and programmers on rare and exceptional cases, can result in faults in exception handling. The occurrence of many such faults can be reduced by modifying the process and environment – examples Resource allocation faults resulting from shallow architectural design can be reduced by introducing specific inspection tasks Faults attributable to inexperience with the development environment can be reduced with focused training (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 47

Improving Current and Next Processes Identifying weak aspects of a process can be difficult Analysis of the fault history can help software engineers build a feedback mechanism to track relevant faults to their root causes – Sometimes information can be fed back directly into the current product development – More often it helps software engineers improve the development of future products (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 48

Root cause analysis (RCA) Technique for identifying and eliminating process faults – First developed in the nuclear power industry; used in many fields. Four main steps – What are the faults? – When did faults occur? When, and when were they found? – Why did faults occur? – How could faults be prevented? (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 49

What are the faults? Identify a class of important faults Faults are categorized by – severity impact of the fault on the product – Kind No fixed set of categories; Categories evolve and adapt Goal: – Identify the few most important classes of faults and remove their causes – Differs from ODC: Not trying to compare trends for different classes of faults, but rather focusing on a few important classes (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 50

Fault Severity Level Description Example Critical The product is unusable The fault causes the program to crash Severe Some product features cannot be used, and there is no workaround The fault inhibits importing files saved with a previous version of the program, and there is no workaround Moderat e Some product features require workarounds to use, and reduce efficiency, reliability, or convenience and usability The fault inhibits exporting in Postscript format. Postscript can be produced using the printing facility, but with loss of usability and efficiency Cosmeti c Minor inconvenience The fault limits the choice of colors for customizing the graphical interface, violating the specification but causing only Ch 20, slide 51 minor inconvenience (c) 2007 Mauro Pezzè & Michal Young

Pareto Distribution (80/20) Pareto rule (80/20) – in many populations, a few (20%) are vital and many (80%) are trivial Fault analysis – 20% of the code is responsible for 80% of the faults Faults tend to accumulate in a few modules – identifying potentially faulty modules can improve the cost effectiveness of fault detection Some classes of faults predominate – removing the causes of a predominant class of faults can have a major impact on the quality of the process and of the resulting product (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 52

Why did faults occur? Core RCA step – trace representative faults back to causes – objective of identifying a “root” cause Iterative analysis – – – – explain the error that led to the fault explain the cause of that error explain the cause of that cause . Rule of thumb – “ask why six times” (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 53

Example of fault tracing Tracing the causes of faults requires experience, judgment, and knowledge of the development process example – most significant class of faults memory leaks – cause forgetting to release memory in exception handlers – cause lack of information: “Programmers can't easily determine what needs to be cleaned up in exception handlers” – cause design error: “The resource management scheme assumes normal flow of control” – root problem early design problem: “Exceptional conditions were an afterthought dealt with late in design” (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 54

How could faults be prevented? Many approaches depending on fault and process: From lightweight process changes – example adding consideration of exceptional conditions to a design inspection checklist To heavyweight changes: – example making explicit consideration of exceptional conditions a part of all requirements analysis and design steps Goal is not perfection, but cost-effective improvement (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 55

The Quality Team The quality plan must assign roles and responsibilities to people assignment of responsibility occurs at – strategic level test and analysis strategy structure of the organization external requirements (e.g., certification agency) – tactical level test and analysis plan (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 56

Roles and Responsibilities at Tactical Level balance level of effort across time manage personal interactions ensure sufficient accountability that quality tasks are not easily overlooked encourage objective judgment of quality prevent it from being subverted by schedule pressure foster shared commitment to quality among all team members develop and communicate shared knowledge and values regarding quality (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 57

Alternatives in Team Structure Conflicting pressures on choice of structure – example autonomy to ensure objective assessment cooperation to meet overall project objectives Different structures of roles and responsibilities – same individuals play roles of developer and tester – most testing responsibility assigned to a distinct group – some responsibility assigned to a distinct organization Distinguish – oversight and accountability for approving a task – responsibility for actually performing a task (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 58

Roles and responsibilities pros and cons Same individuals play roles of developer and tester – potential conflict between roles example – a developer responsible for delivering a unit on schedule – responsible for integration testing that could reveal faults that delay delivery – requires countermeasures to control risks from conflict Roles assigned to different individuals – Potential conflict between individuals example – developer and a tester who do not share motivation to deliver a quality product on schedule – requires countermeasures to control risks from conflict (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 59

Independent Testing Team Minimize risks of conflict between roles played by the same individual – Example project manager with schedule pressures cannot – bypass quality activities or standards – reallocate people from testing to development – postpone quality activities until too late in the project Increases risk of conflict between goals of the independent quality team and the developers Plan – should include checks to ensure completion of quality activities – Example developers perform module testing independent quality team performs integration and system testing quality team should check completeness of module tests (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 60

Managing Communication Testing and development teams must share the goal of shipping a high-quality product on schedule – testing team must not be perceived as relieving developers from responsibility for quality should not be completely oblivious to schedule pressure Independent quality teams require a mature development process – Test designers must work on sufficiently precise specifications execute tests in a controllable test environment Versions and configurations must be well defined Failures and faults must be suitably tracked and monitored across versions (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 61

Testing within XP Full integration of quality activities with development – Minimize communication and coordination overhead – Developers take full responsibility for the quality of their work – Technology and application expertise for quality tasks match expertise available for development tasks Plan – check that quality activities and objective assessment are not easily tossed aside as deadlines loom – example XP “test first” together with pair programming guard against some of the inherent risks of mixing roles (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 62

Outsourcing Test and Analysis (Wrong) motivation – testing is less technically demanding than development and can be carried out by lower-paid and lower-skilled individuals Why wrong – confuses test execution (straightforward) with analysis and test design (as demanding as design and programming) A better motivation – to maximize independence and possibly reduce cost as (only) a secondary effect The plan must define – milestones and delivery for outsourced activities – checks on the quality of delivery in both directions (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 63

Summary Planning is necessary to – order, provision, and coordinate quality activities coordinate quality process with overall development includes allocation of roles and responsibilities – provide unambiguous milestones for judging progress Process visibility is key – ability to monitor quality and schedule at each step intermediate verification steps: because cost grows with time between error and repair – monitor risks explicitly, with contingency plan ready Monitoring feeds process improvement – of a single project, and across projects (c) 2007 Mauro Pezzè & Michal Young Ch 20, slide 64