Unit - 4
System Analysis and Design
Systems are created to solve problems. One can think of the systems approach as an organized way of dealing with a problem. In this dynamic world, the subject System Analysis and Design (SAD), mainly deals with the software development activities.
Systems analysis and design refers to two closely related disciplines system analysis and system design.
- System analysis is concerned with understanding the business objectives, goals and developing business processes. The end product of systems analysis is systems specifications.
- System design uses the output from system analysis as its input. The main objective of system design is to interpret the system requirements into architectural, logical and physical designs of how the information system to be implemented.
System Analysis and Design as performed by the system analysts,
- Seeks to understand what human need to analyze data input or data flow systematically, process information in the context of a particular business.
- System analysis and design are used to analyze, design and implements in the support of users and the functioning of business that can be accomplished through the use of a computerized information system.
- Installing a system without proper planning leads to great user dissatisfaction and frequently causes the system to fall into disuse.
- System analysis and design lend structure to the analysis and design of information systems, a costly endeavor that might otherwise have been done in a haphazard way.
- It can be thought of as a series of processes systematically undertaken to improve a business through the use of a computerized information system.
- SAD involves working with current and eventual users of an information system to support them in working with technologies in an organizational setting.
Improved Service :
Emphasis is placed on ‘what must be done to solve the problem’. The final product of system analysis is a set of system requirement of a proposed information system.
Better Performance
Requirement determination, which is an important activity of system analysis, is a means of translating the ideas given by the users into a formal document. System analysis ensures that the system analyst understands the user’s requirements in a clear way and thus reduces the communication gap between the user and the developer.
Reduced Cost
It reduces the development cost by overcoming errors and misunderstandings early in the development and becomes a basis for reference for validation of the final product.
More Information
The main objectives of the system design are to produce system specifications, which can then be converted into an information system for use in the organization. The system design is a creative activity and is considered to evolve through two different levels of design, i.e. conceptual and detailed design.
Stronger Controls
System analysis is carried out with the help of certain tools. The main tools, which are used for analyzing and documenting the system specification, are data flow diagram, data dictionary, structured English, decision trees and decisions tables.
System Planning
- Project Definition
- Feasibility study
- Project Scope, Deliverables
- Standards, techniques and methods
- Task assessment , skill assessment , preliminary time estimation.
System Analysis
- Analysis of existing hardware/software
- User Requirement Analysis
- Logical Systems Design
Conceptual data model
Conceptual process model
Functional application description.
System Design
- Relational database model and data dictionary
- Detailed description of application inputs and outputs
- Detailed conceptual design of forms, reports, application programs and other application components.
Systems Implementation
- Application Development
- Testing and Evaluation
- Yields functional Information System
Systems Operation and Support
- Maintenance
- Revisions
- Yields Operating Information System.
Structured systems analysis and design methodology (SSADM) is a set of standards for systems analysis and application design.
It uses a formal methodical approach to the analysis and design of information systems.
Learmonth Burchett Management Systems (LBMS) and the Central Computer Telecommunications Agency (CCTA) developed it in 1980-1981 as a standard for developing British database projects.
The SSADM is an open methodology based on the waterfall model.
Used by many commercial businesses, consultants, educational establishments and CASE tool developers.
Features:
- Intensive user involvement in the requirements analysis stage.
- The users are made to sign off each stage as they are completed assuring that requirements are met
- SSADM breaks up a development project into stages, modules, steps and tasks. The first and foremost model developed in SSADM is the data model.
- It is a part of requirements gathering and consists of well defined stages, steps and products.
The techniques used in SSADM are logical data modeling, data flow modeling and entity behavior modeling.
- Logical Data Modeling: This involves the process of identifying, modeling and documenting data as a part of system requirements gathering. The data are classified further into entities and relationships.
- Data Flow Modeling: This involves tracking the data flow in an information system. It clearly analyzes the processes, data stores, external entities and data movement.
- Entity Behavior Modeling: This involves identifying and documenting the events influencing each entity and the sequence in which these events happen.
Some of the important characteristics of SSADM are:
- Dividing a project into small modules with well defined objectives
- Useful during requirements specification and system design stage
- Diagrammatic representation and other useful modeling techniques
- Simple and easily understood by clients and developers
- Performing activities in a sequence
The stages of SSADM include:
- Determining feasibility
- Investigating the current environment
- Determining business systems options
- Defining requirements
- Determining technical system options
- Creating the logical design
- Creating the physical design
Each of these stages applies certain techniques and a sequence of analysis. They include conventions and procedures for recording and interpreting the information with the help of diagrams and text.
User Interface Design
It focuses on designing the interaction between end users and computer systems
Designers concentrate on
- Input Output Methods
- The conversion of data and information between human readable and machine readable form.
This is a prototyping process where working models or prototypes of user interface methods are designed and modified with feedback from end users.
Data Design
Focuses on
- Design of Structure of databases
- Files that can be used by a proposed information system.
- Data design frequently produces a data dictionary, which catalogs detailed descriptions of
The attributes of the entities about which the proposed information system needs to maintain information
The relationship the entities have with each other
The specific data elements that is required to maintain for each activity.
Process Design
Focuses on the development of software resources needed by the proposed information system.
Process design procedures detailed program specifications and procedures to meet the user interface and data design specifications that are developed.
Meet the functional control and performance requirements developed in the analysis stage.
- Systems analysis plays a central role in the development of the MIS. Since the MIS is a conglomerate of the various systems, a systematic approach in its development helps in achieving the objective of the MIS.
- The tools of the systems analysis and the methods of development enforce a discipline on the designer to follow the steps strictly as stipulated. The possibility of a mistake or an Inadvertence is almost ruled out.
- The success of MIS lies in meeting the information needs of the various personnel in the organization across all levels of the management. The systems analysis with its structural analysis and design approach ensures an appropriate coverage of the sub-systems.
- The data entities and attributes are considered completely keeping in view the needs of the system in question and their interface with other systems.
- The systems analysis begin with the output design which itself ensures that the information needs are considered and displayed in the appropriate report or screen format.
- The subsequent design steps (viz., input process, procedure designs are taken to fulfil these) needs.
- The MIS may call for an open system design. In such a case while making the systems analysis and design, the aspect of open system design is that users actively come out with their requirements automatically ensuring that the user's needs are met more precisely.
- The systems analysis and design, as a tool of the MIS development, helps in streamlining the procedures of the Company to the current needs of the business and information objectives. New transactions, new documents, new procedures are brought in to make the systems more efficient before it is designed.
- An emerging model of the MIS is with the data bases stored in the back-end servers and the front end users having access to it to manipulate the data to the current requirement.
- Since the data and information processing becoming more and more like the natural language processing, the role of the systems analyst is more toward data generation, storage and its management in terms of quality, status, access and usage.
- The development methodology may be the conventional design of data, databases and files approach or object oriented analysis and design approach, the MIS design is same.
- The difference is in the development cycle time, quality of information, efficiency of design and the ease of maintenance of the system.
