A spiral model of software development and enhancement
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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

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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


Advice

Advice

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

    • The stages become milestones to mark progress


Question

Question

  • 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

  • Incremental development

  • Used Ada as spec language as well as implementation

  • Using stubs and drivers to execute partially implemented systems


Software process

Software Process

“Software Processes

are software, too”

Leon Osterweil (1987)


Software process1

software process


Definition

Definition

  • 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

  • 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

  • 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


Example testing

Example - testing

  • 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

  • Many possible notations

    • functional diagrams

    • state diagrams

    • petri models

    • textual descriptions

    • “programming languages”


Pm petri net

PM - petri net

doc

designer

source

build t c

test team

tests

testing

test report


Entities in process models

Entities in Process Models

  • Activities/Tasks

  • Information

    • Artifacts (Products)

    • Knowledge

  • Agents

    • People, Positions, Roles

  • Constraints


Control decisions

Control Decisions

  • Some PM show control in terms of decisions


Example fragment with decision

Example Fragment with Decision


L3as20 group task

L3aS20 Group Task

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

  • Work in groups of 2-4 only.

  • Turn in at beginning of 2nd hour.


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