MCS 014 System Analysis And Design Important Questions and Notes
With Solved Question/Answers
MCS-014 Notes
Block 1 – INTRODUCTION TO SAD
Unit 1
➢Information System
Information System is an arrangement of compatible networks of hardware and software that people and organizations used to collect, process, store and distribute information to support decision making, control analysis and visualization.
Characteristics :
1. Organisation : It implies structure and Order.
2. Interaction : It is the procedure in which each component interacts with other components of the system.
3. Interdependence : It implies dependency of one component on other components of the system.
4. Integration : It implies how parts of system work together within the system.
➢ Classification of systems
1. Formal or Informal
A formal system is one that is planned and is used according to schedule. For example - scheduling a meeting with predefined agenda.
An informal system is the system that is not described in advance and is used on need basis. For example - Customer care support system.
2. Physical or Abstract
Physical Systems are tangible entities (we can touch and feel them). They may be static or dynamic in nature. For Example – Computer systems, buildings etc
Abstract systems are non-physical or conceptual entities. For Example - formulas, representation or model of a real system.
3. Open or Closed
An open system must interact with its environment. It receives inputs from and delivers outputs to the outside of the system. For Example – Information system, organisations etc.
A closed system does not interact with its environment. It is a system that includes a closed loop, a control element and performance standard. For Example – Problem solving models (or processes) Closed loop system.
4. Manual and Automated Systems
Performance Standard Control Element Process Output Input The system, which does not require human intervention is called Automated system. Example: Traffic control system.
The system, which requires human intervention, is called a Manual System. Example: Face to face information centre at places like Railway stations etc.
▪ Real Time Systems
A real time system depicts an processing system with time limitations. A real time system should have done processing in fixed time or the system will fail. We use it when there are time requirements on flow of data. There are two types of real time systems –
1.Hard real time systems : which guarantees that critical tasks are completed on time. Example – Flight controller system.
2.Soft real time systems : In these systems a critical task gets priority over other tasks and retains the priority till it executed. Example – Telephone switches.
▪ Distributed Systems
A distributed system is a system with multiple components located across multiple computers on the network that communicate with each other in order to appear as a single coherent system to the end-user. Example - electronic banking systems, massive multiplayer online games, and sensor networks.
Advantages : Resource sharing, Computation speedup, Reliability, Communication
Distributed System Architecture -
▪ Presentation layer – includes user interface
▪ Presentation Logic layer – includes processing to establish user interface
▪ Application logic layer – includes logic and processing to support business application
▪ Data Manipulation layer – includes command and logic to store and retrieve data
▪ Data layer – includes stored data
➢ Structured Analysis and Design Approach
The goal of structured system analysis and design is to reduce maintenance time and effort. The first model driven approach is Structured Analysis and Design approach.
Structured Analysis : Structured Analysis is a development method that allows the analyst to understand the system and its activities in a logical way. It uses graphical tools that analyze and refine the objectives of an existing system and develop a new system specification which can be easily understandable by user. The major tasks of structured system analysis approach are:
• Preliminary Investigation
• Problem Analysis
• Requirement Analysis
• Decision Analysis.
Question – Differentiate between DFD and ERD?
Structured analysis introduced a process-modeling tool called the Data flow diagram.
1.It is used to illustrate business process requirements.
2.With the help of DFD, the systems analyst can show the system overview.
ERD
1.Entity relationship diagrams are used to illustrate business data requirements.
2.With the help of ERD, the analyst, can show database overview.
Structured Design : Structured Design uses graphic description (Output of system analysis) and focuses on development of software specifications. In structured design a problem is broken into several small problems and each small problem is individually solved until the whole problem is solved. These small problems are further divided into modules(set of program instructions) and these modules are designed according to some design principles. These principles are :
1.Modularity and partitioning : Each system should consist of a hierarchy of modules.
2.Coupling : Modules should be loosely coupled. It means that modules should have little dependence on other modules.
3.Cohesion : Modules should be highly cohesive. It means that modules should carry out a single processing function.
4. Size of Module : The number of instructions contained in a module should be limited so that module size is generally small.
Question – What is Structure Chart?**
Structured Design introduced a modeling tool called Structure Charts. They are used to illustrate software structure to fulfil business requirements. Structure charts describe the interaction between independent module and the data passing between the modules. These module specifications can be passed to programmers prior to the writing of program code.
➢ Accelerated approach: The goal of accelerated approach is to identify a construction model of a system. The first accelerated approach is Prototype approach.
Prototype approach : A prototyping approach shows us the construction model of a system. Designing and building a scaled-down but functional version of a desired system is the process known as Prototyping. A prototype is a working system that is developed to test ideas and assumptions about the new system.
The steps of Prototyping process are :
• Identify the user’s known information requirements and features needed in the system.
• Develop a working prototype.
• Revise the prototype based on feedback received from customer
• Repeat these steps to achieve a satisfactory system.
➢ Joint Application Development
It is defined as a structured approach in which users, managers, and analysts work together for several days in a series of intensive meetings to specify or review system requirements. The typical participants in a JAD are :
JAD session leader: The JAD leader organizes and runs the JAD. This person is trained in group management and facilitation as well as system analysis. The JAD leader remains neutral and sets the agenda and sees that it is met.
(1) Users: The users of the system vital participants in a JAD. They are the ones who have a clear understanding of what it means to use the system on a daily basis.
(2) Managers: The role of managers during JAD is to approve project objectives, establish project priorities, approve schedules and costs and approve identified training needs and implementation plans.
(3) Sponsors: A JAD must be sponsored by someone at a relatively high level in the company i.e. the person from top management.
(4) Systems Analysts: Analysts are there to learn from customers and managers, but not to run or dominate the process.
(5) Scribe: The scribe takes down the notes during the JAD sessions. This is usually done on a personal computer or a laptop.
(6) IS staff like systems analysts, other IS staff such as programmers, database analysts, IS planners and data centre personnel may attend to learn from the discussions and possibly to contribute their ideas on technical limitations of current systems.
❖ Questions Related to Unit 1
1. What is an Information System ? Explain the classification of systems in brief.
2. Explain Real Time Systems and Distributed Systems.***
3. Explain Structured Analysis and Structured Design. What are its goals.
4. What is meant by "Joint Application Development" ?Who are the participants in it ? What are their roles ? Explain briefly.****
5. List the underlying principles for a prototype design. Under which conditions will this design be useful ? With the help of an example system, explain its approach?**
6.Describe Open systems and Closed systems. Give two examples for each.
7.Explain various approaches for development of information systems.
* means asked in Exam