01 Introduction
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Introduction Software - Components & Characteristics Software is the program and all the associated documentation & configuration data which is needed to make these programs operate correctly. A software system consist of
➔ Number of separate programs. ➔ Configuration files that are used to set up these programs. ➔ System documentation that describe the structure of the system. ➔ User documentation that explains how to use the system.
The 3 characteristics of a good software are
1. Operational characteristics, which are functionality based factors and related to the ‘exterior quality’ of software.
2. Revision characteristics, which are engineering based factors and related to the ‘interior quality’ of a software.
3. Transition characteristics, Key operational characteristics are
➔ Correctness – should meet all stated specification of the customer. ➔ Usability / Learnability – Easy to learn and user friendly for even IT illiterate people. ➔ Integrity – Should not have any side effects, means never affect the working of another
application. ➔ Reliability – Shouldn’t have any defects or fail while execution. ➔ Efficiency – Should optimally use all resources like hardware, memory etc. ➔ Security – Shouldn’t have ill effects on data or hardware or users. ➔ Safety – Should not hazardous to env or people.
Key revision characteristics are
➔ Maintainability Maintenance of the software should be easy for any kind of user. ➔ Flexibility Changes in the software should be easy to make. ➔ Extensibility It should be easy to increase the functions performed by it. ➔ Scalability It should be very easy to upgrade it for more work (or for more number of users). ➔ Testability Testing the software should be easy. ➔ Modularity Any software is said to make of units and modules which are independent of each
other. These modules are then integrated to make the final software. If the software is divided into separate independent parts that can be modified, tested separately, it has high modularity.
Key Transition characteristics are
➔ Interoperability Interoperability is the ability of software to exchange information with other applications and make use of information transparently.
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➔ Reusability If we are able to use the software code with some modifications for different purpose then we call software to be reusable.
➔ Portability The ability of software to perform same functions across all environments and platforms, demonstrate its portability
Importance of any of these factors varies from application to application. In systems where human life is at stake, integrity and reliability factors must be given prime importance. In any business related application usability and maintainability are key factors to be considered. Always remember in Software Engineering, quality of software is everything, therefore try to deliver a product which has all these characteristics and qualities.
SDLC - 4GL ➔ Use of software tools that allow software engineer to specify software characteristics at high
level. ➔ The tools generate codes based on specification. ➔ Mote time in design & testing increase productivity. ➔ Tools may not be easy to use, codes generated may not be efficient.