Standards

What is a standard? What are the benefits of using a standard? What are the costs? Do the costs exceed the benefits?

Definition of standard A technical specification or other document available to the public, drawn up with the cooperation and consensus or general approval of all interests affected by it, based on the consolidated results of science, technology and experience, aimed at the promotion of optimum community benefits »British Standards Institute, 1981

Standards are checklists (like a pilot’s checklist) Remind you of things you may forget Force you to acknowledge the consequences of not doing one of the tasks on the standard Don’t build the list from scratch: use one built by hundreds or thousands of professionals

Standards outside SE measures (gallons, liters, mm) sizing (electrical plugs)

Comparison of Standards safe pushchairs safe software Internal Product External Product Process Resource

Comparison of Standards Other engineering: –guidelines for product evaluation –guidelines for acceptable outcomes Software engineering –guidelines for process –guidelines for techniques –few guidelines for product evaluation

Software Engineering Standards Technical specifications available to public Consensus, but not necessarily of all affected parties (usually by committee) Not necessarily based on science, technology, or experience –Language standards w/o case studies –Techniques (clean room, OO design) w/o science

Example: IEEE Standard for Software Safety Plans Abstract: The minimum acceptable requirements for the content of a software safety plan are established. This standard applies to the software safety plan used for the development, procurement, maintenance, and retirement of safety-critical software. This standard requires that the plan be prepared within the context of the system safety program. Only the safety aspects of the software are included. This standard does not contain special provisions required for software used in distributed systems or in parallel processors

Example: (R1993) IEEE Standard for Software Unit Testing 1. Scope and References 2. Definitions 3. Unit Testing Activities 3.1 Plan the General Approach, Resources, and Schedule. 3.2 Determine Features To Be Tested 3.3 Refine the General Plan 3.4 Design the Set of Tests 3.5 Implement the Refined Plan and Design 3.6 Execute the Test Procedures 3.7 Check for Termination 3.8 Evaluate the Test Effort and Unit

Partial list of standards IEEE Standard Glossary of Software Engineering Terminology 1062, 1998 Edition IEEE Recommended Practice for Software Acquisition IEEE Standard for Software Safety Plans 1233, 1998 Edition IEEE Guide for Developing System Requirements Specifications IEEE Standard for Software Quality Assurance Plans IEEE Standard for Software Configuration Management Plans

Partial list of standards (R1993) IEEE Standard for Software Unit Testing IEEE Standard for Software Verification and Validation IEEE Standard for Software Reviews IEEE Standard for Software Productivity Metrics IEEE Standard for Software Project Management Plans IEEE Standard for Developing Software Life Cycle Processes IEEE Standard for Software Maintenance

Partial list of standards IEEE Standard for Software Life Cycle Processes--Risk Management IEEE Standard for a Software Quality Metrics Methodology IEEE Standard for Software Test Documentation IEEE Recommended Practice for Software Requirements Specifications IEEE Recommended Practice for Software Design Descriptions IEEE Standard Classification for Software Anomalies

Classification of standards Reference only: Subjective Partially Objective Objective

Classification of standards Reference only: –declares something will happen, but there is no way to determine compliance –“Unit testing shall be carried out.” Subjective Partially Objective Objective

Classification of standards Reference only: Subjective –Only a subjective measure of conformance is possible –“Unit testing shall be carried out effectively.” Partially Objective Objective

Classification of standards Reference only: Subjective Partially Objective –A measure of conformance, but still has subjectivity –“Unit testing shall be carried Objective

Classification of standards Reference only: Subjective Partially Objective Objective –Conformance can be determined –“Unit testing shall be carried

Four categories of SE Standards Process –The Design Team shall validate the Software Specification by... Internal Product –e.g. code: “each module should have a single entry and exit External Product –e.g. reliability Resources

Motivation for standards Provide encapsulation of best practice Avoid repetition of past mistakes Provide framework for quality assurance (assure that standard has been followed) Assist in continuity between workers

Standards organizations IEEE ANSI US DoD NATO Bureau of Standards

How to use standards Understand the motivation behind the development of the standard Involve developers Adapt standard to meet needs of organization Review standards regularly and update to reflect changing technology Provide software tools when possible. Clerical standards are a source of complaint

“In many modern standards, the only truly mandatory activity is tailoring the standard to your particular needs.” »Lewis Gray

Walkthrough of DO178B Software Development Standard for avionics Handbook for problem areas of software development Catalog of certification requirements

FAA Certification The FAA certifies systems, not software Software tools are either trusted or untrusted The product of a trusted tool is trusted.

Software Criticality Levels Criticality Level Failure Consequence Example ACatastrophicAuto pilot BHazardousnavigation system CMajornavigation assist system Dminor Eno effectin-flight entertainment

DO178B Process Planning Requirements Design Coding Integral Processes

DO178 Process: Planning Languages: syntax, naming conventions, coding conventions, bounds on term complexity, indentation standards... Tools: which tools, which subsets,... Hardware: may be very stringent Methods

DO178B Planning Describe tasks needed to meet task objectives, such as code reviews, walkthroughs, change control, audits, Describe when processes occur, when processes exit, and who is responsible

DO178B Design How will requirements be satisfied? Need –architecture –algorithms/data structures –I/O Description –Data and control flow descriptions –Resource strategies –Scheduling and communication

DO178B Coding Implement low-level requirements Integration: load software onto target Cannot patch software: need to recertify entire system (expensive)

DO178B Integral Process Requirements-based test generation Low-level tests Additional Verification Integration tests Hardware integration tests Requirements coverage analysis Requirements coverage analysis

DO178B Testing MCDC: Every atomic predicate is tested last 5% of test cases are difficult to generate Rockwell: 30% of development budget is in structural testing

DO178B Tools Must certify for each system: previous qualification efforts don’t transfer Qualify the tool or qualify the output? Qualifying a verification tool is easier than qualifying a synthesis tool

Evaluating Software Engineering Standards (Pfleeger, 1994) What is a good standard? What do the standards apply to? What was the case study? What did the authors find in the case study? Teams of 2

Assignment: Project teams Find 2 IEEE standards and give 1 page summary of the standard (include references) Find 2 “programming standards” –Summarize the standards –Compare and contrast the two standards Develop a coding standard for your team Due 3/24