IBPS SO IT Officer Computer Networking Notes

SOFTWARE ENGINEERING notes for IBPS SO IT officer

Jan 23 • IBPS PO, IBPS Specialist Officer • 1702 Views • No Comments on SOFTWARE ENGINEERING notes for IBPS SO IT officer

SOFTWARE ENGINEERING notes for IBPS SO IT officer

Software engineering is professional dedicated to designing,implementing and modifying software. It is of high quality, affordable maintainable and fast to build. It is systematic approach to the analysis, design, assessment,implementation, testing and re-engineering.

Software = Program+documentation+operating procedures

Software process:

The which we produce software. This differs from organisation to organisation.

Software characteristics:

  1. Software  does not wear out.
  2. Software is not manufactured.
  3. Re-usability of components.
  4. Software is flexible.

SOFTWARE ENGINEERING notes for IBPS SO IT officer

Software life cycle model

   A software life cycle model is a particular abstraction that represents a software cycle. Software life cycle is also called SDLC(software development life cycle).

Waterfall model

Waterfall model has five phases such as:

1) Requirement analysis and specification :- The goal of this  phase is to understand the exact requirement of user and to document them properly. Requirement describe the what of a system not  how. Document is called software requirement specification(SRS).

2 ) Design :-  The goal of this phase is to transform the requirement into structure that is suitable for implementation. All work is documented and known as software design description(SDD).

3) Implementation and unit testing.:-  IN this phase coding is done. After coding unit testing is did by developer. Unit testing is done on single module individually.

4) Integration and system testing :- after unit testing all the modules of software are integrated into single unit and then test the entire system.

5) Operation and maintenance :- the purpose of this phase is to preserve the value of software over time.

SOFTWARE ENGINEERING notes for IBPS SO IT officer

Increment process models

1) Iterative enhancement model.: This model has same phase as waterfall model but fewer restrictions. In this model after several cycle are executed. A usable product is released at the end of every cycle. SRS document is prepared after analysis of user requirements.

2) The Rapid application Development Model :In this model user expectations are evolved in every phase. When one phase is completed then user feedback is given to the developer.

 

Requirement planning     user description       construction       cut over

    3)  Evolutionary  process Model :- This model is useful for projects using new technology that is not well understood. This also used for complex projects where all functionality must be delivered at one time.

 

   4) Prototyping Model : The prototype may be useful program, but is not suitable for final software product.the code of prototype is thrown away.
    5) Spiral model  : This model is used in large projects. It has strong approval  and document control. Changes are done at the end of process.

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Metrics for Project size Estimation

Project size is a measure of the problem complexity in terms of efforts and time required to develop the product. LOC(line of code) and FP(function point) are used to estimate size.

Line of code: using this metric, the project size is estimated by counting the number of instructions in program. Commenting and spaces are ignored.

Function point :  function point include

Number of inputs, numbers of output, numbers of inquiries, numbers of files, numbers of interfaces

Finally FP= UFP*TCF where

UFP (Unadjusted function point)    TCF(Technical complexity factor)

COCOMO

Constructive cost estimation model was proposed by Boehm. Boehm said that any software categorized into 3 classes

Organic, semidetached, embedded.

Basic cocomo model gives an approximation estimate of the project.

          efforts=a1*(KLOC) PM

KLOC  is the estimated size of software product expressed in kilo lines of code.

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Risk management

A risk is any unfavorable event that can occur while a project is in process. If risk is identified it can hamper the success and time of completion of project.

Risk consists of three activities: risk identification, risk assessment and risk containment.

Risk identification: to identify the risk to be held in future.

Risk assessment: prioritize the risk in terms of their damage.

Risk containment: avoid and transfer the risk.

Software design

    Coupling: it is measure of the degree of independence between modules.

Low coupling is best for software.

    Cohesion: it is measure of functional dependency between modules.

High cohesion is best for software.

Strategy of design

Bottom up approach : In this approach we decide how to combine these modules to provide larger one and larger one and so on.

Top down approach : In this approach we decide how to combine modules into single unit and start the approach from highest level.

Object oriented design

 This type of design is not dependent on any specific type language. Problems are modeled by objects. Objects have 1) behaviour  2) state

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SOFTWARE ENGINEERING notes for IBPS SO IT officer

Object : it refer to any entity eg car, home etc

Class : user defined data type which hold its own data members and member functions.

Attributes : class value held by the objects of class.

Operations : an operation is a function that applied by object on a class.

Abstraction : avoid irrelevant data and amplify the essential.

Inheritance : inherit data from base class called derived class.

Encapsulation : wrapping up of data and interface outside world with only messages.

Polymorphism : poly means “many” and morph-ism means “forms”. This occurs when same operation applied on multiple methods.

Validation and Verification

Validations means “ is program meets the expectations of user”

Validation means “involves its specifications”

Testing = verification + validation

Software coding and testing

Testing is to test the software with the intends of finding errors.

Error : error may be syntax or misunderstanding of specifications.

Bug : when developer make mistake while coding.

Fault : representation of error.

Failure : failure occurs when a fault execute.

Test cases : describes its input and expected output.

Test suit : set of test cases called test suit.

Types of testing

Unit testing : To test the single unit of a module called unit testing.

Integration testing : To test the individual module of a software and combine them

System testing : To test the whole software.

Alpha testing : This type of testing is done in a controlled environment at the developer’s site.

Beta testing : This type of testing is done at in the real environment at the user site.

Acceptance testing : This testing done at the end user/acceptance when software is complete.

Black box testing or functional testing : to test the functions of a software without the knowledge of language or coding. Only input and output are examined.some black box testing are as follows:

  1. Boundary value analysis
  2. Equivalence testing
  3. Decision table based testing

White box/ structural testing : In this type of testing one has to aware about coding or language. In this we have to examine internal structure of software.

Performance testing : whether the system meets the non-functional requirements of SRS document. Different type of testing under this testing are :

  1. Stress testing : To test the system performance.
  2. Recovery testing : Test the software performance in presence of errors, faults or power failure.
  3. Maintenance testing : Test the address program and other program that are used in implementing the software.
  4. Regression testing : To test the software after modification and addition of more functions.

Debugging : First locate the error and then fix that error called debugging.

Software re-engineering:  means restructuring or rewriting the all parts of the software called software re-engineering.

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