Introduction to Software Review
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    Introduction to Software Review Introduction to Software Review Presentation Transcript

    • Introduction to Software Review Philip Johnson Collaborative Software Development Laboratory Information and Computer Sciences University of Hawaii
    • Objectives
      • Understand the motivation for technical review.
      • Become acquainted with “best practices” for “industrial strength” formal technical review.
      • Begin the journey toward 'optimal' review in your own practice.
    • Optimal Review
      • For me, an 'optimal' review will:
        • find all important defects
        • give all reviewers deep insight into the code
        • enable the author to improve the code
        • all with least possible effort
      • In other words:
        • Optimal quality improvement
        • Optimal knowledge acquisition
        • With lowest possible cost
      • Normally, though, it ’s “pick any two”.
    • Families of Review Methods
      • Walkthroughs
      Minimal overhead Developer training Quick turnaround Defect discovery Ambiguity resolution Training Method Family Typical Goals Typical Attributes Little/no preparation No formal process No measurement
      • Technical Reviews
      Some formal process Multiple stages Wide range of discussion Inspections Detect and remove all defects efficiently and effectively. Very formal process Measurement Verification
    • Methods vs. Optimality
      • Walkthroughs:
        • Cost: very low
        • Knowledge transfer: undependable
        • Quality improvement: undependable
      • Technical reviews:
        • Cost: moderate
        • Knowledge transfer: better
        • Quality improvement: at least some
      • Inspection:
        • Cost: high (and not necessarily ‘least possible’)
        • Knowledge transfer: almost guaranteed.
        • Quality improvement: almost guaranteed
    • What reviews do that testing doesn't
      • 1. Reviews improve schedule predictability.
      • 2. Reviews reduce rework.
        • Rework can account for 44% of dev. cost!
          • Reqs (1%), Design (12%), Coding (12%), Testing (19%)
      • 3. Reviews are pro-active tests.
        • Find errors not possible through testing, such as Errors of Omission (i.e. unimplemented requirement)
      • 4. Reviews are training.
        • Domain, corporate standards, group.
      N o R e v s . R e v s Req Design Code Test R R R Req Design Code Test
    • Industry experience
      • Aetna Insurance Company:
        • Review found 82% of errors, 25% cost reduction.
      • Bell-Northern Research:
        • Inspection cost: 1 hour per defect.
        • Testing cost: 2-4 hours per defect.
        • Post-release cost: 33 hours per defect.
      • Hewlett-Packard
        • Est. 1 year savings (1993): $21,454,000
      • IBM (using Cleanroom)
        • C system software
        • No errors from time of first compile.
    • There are many different kinds of review TekInspect Development Method Non-Cleanroom Cleanroom FTR inFTR Code Inspection (Fagan76) Inspection (Gilb93) 2-Person Inspection (Bisant89) N-Fold Inspection (Martin90) Walkthrough (Yourdon89) Verification- based Inspection (Dyer92) Active Design Reviews (Parnas85) FTArm (Johnson94) ICICLE (Brothers90) Scrutiny (Gintell93) CAIS (Mashayekhi94) Manual Tool-Based Code Reading (McConnell93) Software Review (Humphrey90) Phased Insp. (Knight93)
    • Inspection: the most formal review Preparation Orientation Planning Review Meeting Rework Verify Ensure rework was done correctly Correct defects. Consolidate issues.
      • Check product, note issues.
      • Present product, process, goals.
      Choose team, materials, dates.
    • Planning
      • Objectives
        • Gather review package : work product, checklists, references, and data sheets.
        • Form inspection team.
        • Determine dates for meetings.
      Planning Orientation Preparation Review Mt. Rework Verify
    • Orientation
      • Objectives
        • Author provides overview.
        • Reviewers obtain review package.
        • Preparation goals established.
        • Reviewers commit to participate.
      Planning Orientation Preparation Review Mt. Rework Verify
    • Preparation
      • Objectives
        • Find maximum number of non-minor issues.
      Planning Orientation Preparation Review Mt. Rework Verify
    • Example Issue Classification
      • Critical
        • Defects that may cause the system to hang, crash, produce incorrect results or behavior, or corrupt user data. No known work-arounds.
      • Severe
        • Defects that cause incorrect results or behavior with known work-arounds. Large and/or important areas of the system is affected.
      • Moderate
        • Defects that affect limited areas of functionality that can either be worked around or ignored.
      • Minor
        • Defects that can be overlooked with no loss of functionality.
    • Review Meeting
      • Objectives
        • Create consolidated, comprehensive listing of non-minor issues.
        • Provide opportunity for group synergy.
        • Improve reviewing skill by observing others.
        • Create shared knowledge of work product.
      Planning Orientation Preparation Review Mt. Rework Verify
    • Rework
      • Objectives
        • Assess each issue, determine if it is a defect, and remove it if necessary.
        • Produce written disposition of non-minor issue.
        • Resolve minor issues as necessary.
      Planning Orientation Preparation Review Mt. Rework Verify
    • Verify
      • Objectives
        • Assess the (reworked) work product quality.
        • Assess the inspection process.
        • Pass or fail the work product.
      Planning Orientation Preparation Review Mt. Rework Verify
    • ICS Software Engineering Technical Reviews
    • Goals for our Tech. Reviews
      • 1. Learn how to obtain useful feedback from classmates about your software system.
      • 2. Learn how to critically read and evaluate code written by another developer.
      • 3. Learn the difference between low-impact, “waste of time” reviews and high-impact, “would have never noticed this myself” reviews.
      • 4. Learn that reviewing other code can be an effective way to improve your own coding skills.
    • Initial approach: Checklist-based technical review
      • Use a checklist to:
        • focus reviewer attention.
        • specify the concerns of the review
      • Write down reviewer comments to:
        • provide a clear record of reviewer feedback.
        • assess coverage of review.
      • Go over reviewer comments with author to:
        • Clarify meaning of comments.
        • Assess validity.
        • Provide opportunity for new issues to arise.
    • Goals for the semester
      • We will be doing reviews all semester.
      • When doing a review, ask yourself:
        • Is my review revealing problems?
        • Is my review increasing understanding?
        • Is my review doing (1) and (2) efficiently?
      • If not, think about ways to improve your review process.
    • Bonus: How to ask questions
      • Effective software review requires effective technical communication.
      • "How to ask questions the smart way" addresses effective communication in another context: online discussion forums.
      • Use this semester to improve your ability to "ask questions the smart way".
        • We will likely see examples of "smart" and "not so smart" questions to the class discussion group!