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A Spiral Model of Software Development and Enhancement. Barry Boehm Computer, May 1988 text pp34-45. Software Process Model.

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A spiral model of software development and enhancement

A Spiral Model of Software Development and Enhancement

Barry Boehm

Computer, May 1988

text pp34-45

Software process model
Software Process Model

  • “The primary functions of a software process model are to determine the order of the stages involved in software development and evolution and to establish the transition criteria for progressing from one stage to the next.”

Who discovered the waterfall model
Who discovered the waterfall model?

  • A. Royce in 1970

  • B. Boehm in 1988

  • C. Fred Waterfall in 1950

  • D. It always existed, someone just named it in 1966

  • E. Every other discipline knew about it long ago


  • Use a life-cycle development model to manage software development

    • The stages become milestones to mark progress


  • How do you decide whether a stage is complete?

    • A. The manager says it is complete

    • B. The team is ready to go on to the next stage

    • C. The team votes on whether it is complete

Trw s ada process model for incremental development of large software systems

TRW’s Ada Process Model for Incremental Development of Large Software Systems

Walker Royce

12th ICSE 1990

text pp46-55

Interesting approach
Interesting Approach Large Software Systems

  • Incremental development

  • Used Ada as spec language as well as implementation

  • Using stubs and drivers to execute partially implemented systems

Software process

Software Process Large Software Systems

“Software Processes

are software, too”

Leon Osterweil (1987)

Software process1
software process Large Software Systems

Definition Large Software Systems

  • A process model is a description of the significant aspects of the tasks that are accomplished during the development of software, including the artifacts produced, the agents involved in the activities, and the relationships between these entities.

Rules for pm diagrams
Rules for PM diagrams Large Software Systems

  • Every process must use one or more artifacts and must produce one or more artifacts.

  • There must be an artifact between two consecutive processes.

Testing fragment
Testing Fragment Large Software Systems

  • The test designer builds test cases using the source code and the documents. The output is a set of tests

  • The test team does testing using the tests from the test designer and the source code producing a test report

Example fragment
Example Fragment Large Software Systems

Example testing
Example - testing Large Software Systems

  • shows who is responsible for what tasks

  • shows what information is necessary for a task

  • shows what is produced by a task

  • shows sequences and dependencies of tasks

Pm notations
PM Notations Large Software Systems

  • Many possible notations

    • functional diagrams

    • state diagrams

    • petri models

    • textual descriptions

    • “programming languages”

Pm petri net
PM - petri net Large Software Systems




build t c

test team



test report

Entities in process models
Entities in Process Models Large Software Systems

  • Activities/Tasks

  • Information

    • Artifacts (Products)

    • Knowledge

  • Agents

    • People, Positions, Roles

  • Constraints

Control decisions
Control Decisions Large Software Systems

  • Some PM show control in terms of decisions

Example fragment with decision
Example Fragment with Decision Large Software Systems

L3as20 group task
L3aS20 Group Task Large Software Systems

  • Create a process model for a cooking-dinner task.

  • Work in groups of 2-4 only.

  • Turn in at beginning of 2nd hour.