Ch7: Software Production Process

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Questions

What is the life cycle of a software product? Why do we need software process models? What are the goals of a software process and

what makes it different from other industrial processes?

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Software production process

What is a software process?

Goal:

Hard to automate the production process:

Production models attempt to capture the software life cycle.

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Software production process (contd..)

Engineering disciplines have well-define processes

For example, to build a house:

Can software have a similar, methodological approach?

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Life cycle of a software product

What is a software life cycle?

Activities in the software life cycle

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Software process model

Attempt to organize the software life cycle by

Goals of a software process

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Code and fix model

Earlier programmers used the code-and-fix approach:

Source of difficulties and deficiencies:

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Need for models

Need for sophisticated models:

Symptoms of inadequacy of the code & fix model: the software crisis

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Need for models (contd..)

Software development process needed to:

Boehm states that the goals of a process model are:

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Process as a black-box

Product

Process

Informal Requirements

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Process as a white-box

Product

Process

Informal Requirements

feedback

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Main activities in software production

Relationship between the main activities:

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Feasibility study

What is a feasibility study?

People:

Produces a Feasibility Study Document

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Feasibility study (contd..)

For a commercial product:

For a product to be used in-house

Customized software

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Requirements engineering

Purpose:

People:

Focus on

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Requirements engineering (contd..)

Understand:

Identify:

Requirements analysis and elicitation activities produces a:

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Requirements specification document

Provides:

Has its own qualities

Role of stakeholders

Relationship with testing:

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Requirements specification document (contd..)

As any large document, it must be modular Vertical modularity:

Horizontal modularity:

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Requirements specification document (contd..)

Functional requirements:

Non-functional requirements:

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Software architecture and detailed design

Purpose:

People:

Produces a:

Decomposition usually has two phases:

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Software architecture and detailed design (contd..)

Design alternatives are suggested and evaluated:

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Code and module testing

Purpose:

People:

Coding and algorithm alternatives are implemented and evaluated:

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Code and module testing

Coding may be subject to company-wide standards:

Module testing may also follow company standards:

Other activities:

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Integration and system testing

Purpose:

People:

Integration may be done incrementally through subsystems

The last step is system test

Alpha testing:

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Integration and system testing (contd..)

Company standards may apply to:

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Delivery and maintenance

Purpose:

People:

Delivery is done in two stages:

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Delivery and maintenance (contd..)

Maintenance might be better named evolution Lientz and Swanson’s study:

Changes to user requirements (42%) Changes in the data format (17%) Emergency fixes (12%) Routine debugging (9%) Hardware changes (6%) Improvements in documentation (5%) Improvements in efficiency (4%) Other (5%)

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Delivery and maintenance (contd..)

Role of requirements analysis on maintenance:

Many errors are not removed until the system is delivered.

Change is an intrinsic property of software, but hard to incorporate into a product.

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Other software activities

Some activities span all phases of life cycle Documentation Verification:

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Other software activities (contd..)

Management:

Three main aspects: