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* Property of STI of 12

Software Engineering

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Software Engineering Layers

Software Engineering Paradigms

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* Property of STIPage 3 of 12


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Software Engineering Layers

process — the glue that holds the technology layers together and enables rational and timely development of computer software

methods — provide the technical “how to’s” for building software

tools — provide automated or semi-automated support for the process and the methods

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According to Fritz Bauer, software engineering is the establishment and use of sound engineering principles in order to obtain economically software that is reliable and works efficiently on real machines.

According to IEEE, software engineering is the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software – that is, the application of engineering to software.

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Software Engineering Paradigms

Classic Life Cycle

Prototyping

Spiral Model

Fourth Generation Technique

Object-Oriented Model

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Classic Life Cycle Model

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Prototyping Model

Prototyping can be problematic for the following reasons:

The customer sees what appears to be a working version of the software, unaware that in the rush to get it working we haven’t considered overall software quality or long-term maintainability.

The developer often makes implementation compromises in order to get a prototype working quickly.

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Prototyping Model

listen tocustomer

build/revisemock-up

customertest-drivesmock-up

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Spiral Model

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Spiral Model

SIX TASK REGIONS

customer communication — tasks required to establish effective communication between developer and customer

planning — tasks required to define resources, timelines, and other project related information

risk analysis — tasks required to assess both technical and management risks

engineering — tasks required to build one or more representations of the application

construction & release — tasks required to construct, test, install and provide user support (e.g., documentation and training)

customer evaluation — tasks required to obtain customer feedback based on evaluation of the software representations created during the engineering stage and implemented during the installation stage

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Fourth Generation Techniques

automatically generates source code based on the developer’s specification

focus on the ability to specify software to a machine at a level that is close to natural language or using a notation that imparts significant function

include some or all of the following tools: nonprocedural languages for database query, report generation, data manipulation, screen interaction and definition, and code generation

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Spiral Model

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Fourth Generation Techniques

Summary of the current state of 4GT approaches:

The use of 4GT has broadened considerably over the past decade and is now a viable approach for many different application areas.

Data collected from companies who are using 4GT indicates that the time required to produce software is greatly reduced for small and intermediate applications and that the amount of design and analysis for small applications is also reduced.

The use of 4GT for large software development efforts demands as much or more analysis, design, and testing to obtain the substantial time saving that can be achieved through the elimination of coding.

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handout 2

Design