Overview of systems Analysis and design for Computer Science and MCA students

Write a short note on Object Oriented Methodology.

What is Object Oriented Methodology?
  • Object Oriented Methodology is a popular design approach for analyzing and designing an application.
  • It is an Object modeling language.
  • It is a new system development approach, encouraging and facilitating re-use of software components.
  • It employs international standard Unified Modeling Language (UML) from the Object Management Group (OMG).
  • Using this methodology, a system can be developed on a component basis, which enables the effective re-use of existing components.
Objectives of Object Oriented Methodologies
  • To encourage greater re-use.
  • To produce a more detailed specification of system constraints.
  • To have fewer problems with validation (Are we building the right product?).
Benefits of Object Oriented Methodology
  • It represents the problem domain, because it is easier to produce and understand designs.
  • It allows changes to be done more easily.
  • It provides a good structure for abstracting the modular design.
  • It reduces the complexity of software object model.
  • It increases the quality of software model.
  • It becomes easy to reuse the code in a new system.
  • As the objects are maintained separately, it helps in locating and fixing the problems easily.
  • The object oriented applications are more scalable than structured approach.
  • It is easier to make minor changes in the data representation of an object oriented program.
  • It involves the transmission of messages back and forth over a network.
Process of Object Oriented Methodologies

process of oob
a. Requirement
  • This process is related to identifying business needs and opportunities.
  • It defines a detail information about the system design and user requirements, but the requirements should be testable, measurable and documented.
  • Requirement process may result in success or failure of a software product.
  • This process can be too long.
b. Analysis
  • The main goal of the analysis is to build the models.
  • The requirements of the users, developers and managers provide the information needed to develop the initial problem statement.
c. Design
  • It specifies all the details required to describe how the system will be implemented.
  • The details of the system analysis and system design are implemented during this phase.
  • The objects identified in the system design phase are designed.
d. Implementation
  • It uses the structure created during the design phase.
  • It is the process that uses the lowest-level system elements in the software system.
  • The main purpose of this process is to design and create a software system according to their requirements.

Write a short note on Spiral Model.

What is Spiral Model?
  • Spiral model is a risk driven process model.
  • It is used for generating the software projects.
  • In spiral model, an alternate solution is provided if the risk is found in the risk analysis, then these alternate solutions are suggested and implemented.
  • It is a combination of prototype and sequential model.
  • In one iteration all activities are done, for large project's the output is small.
Why spiral model is a risk driven model?
  • The risk driven model identifies and prioritizes the risk, and in the spiral model, there is a possibility of various risks occurring while building the software product.
  • The risk driven model selects and applies a set of architecture techniques and evaluates risk reduction.
  • The main purpose of risk driven model is to help the developers to decide how much architecture work is to be done.
When should you use Spiral Model?
  • When the requirements are complex at that time spiral model is used.
  • This model is used for large projects.
  • Significant changes are required for projects.
  • When cost and risk evaluation is important then spiral model is used.
There are four phases in spiral model
1. Planning
2. Risk Analysis
3. Engineering
4. Evaluation

1. Planning
  • Requirements are gathered during the planning phase.
  • During this phase the requirements are understood and finalized.
2. Risk Analysis
  • In risk analysis phase, a process is used to identify risk and alternate solutions.
  • At the end of the phase a prototype is produced.
  • If a risk is found then alternate solutions are suggested and implemented.
3. Engineering phase
  • In engineering phase, a software is developed and tested at the end of the phase.
4. Evaluation phase
  • In the evaluation phase, a customer evaluates the output of the project before it goes to the next step of the spiral model.
Advantages of Spiral Model
  • It reduces high amount of risk.
  • It is good for large and critical projects.
  • It gives strong approval and documentation control.
  • In spiral model, the software is produced early in the life cycle process.
Disadvantages of Spiral Model
  • Highly specified expertise is required for risk analysis.
  • It can be costly to develop a software model.
  • It is not used for small projects.
spiral model

Compare Spiral Model and RAD Model.

Spiral ModelRAD Model
Spiral model is a risk driven process model.RAD is a rapid application development.
In spiral model, planning is done in early stages.In RAD model, planning is not done in early stages.
It is an appropriate model for handling the large projects.It is not appropriate for handling the large projects.
It uses detailed documentationIt uses limited documentation.
It is expensive.It is inexpensive.
In the beginning requirement specification are given.Requirement specifications are given at the time of box release.
The maintenance of project is typical.The maintenance of the project is easy.
Duration of project is long.Duration of project is short.
This project has medium to high risk involvement.This project has low risk involvement.
Testing is done at the end of the engineering phase.Testing is done after the completion of coding.
In this model, time frame is long.In this model, time frame is short.
At the end of every iteration a working software is available.At the end of life cycle a working software is available.