MCS-014(Systems Analysis and Design)

Define the term “Documentation”.
Documentation may be defined as the process of communicating about the system. It is a
process to help users of software and other people to use and interact with system. Effective and
accurate documentation is very necessary for the success of any system. Documentation
becomes part of each step of system development through out the process of system
development even before the documentation starts officially. During the process of system
development, study reports and other necessary information are documented to help people
involved in system development to understand the process. There are many kinds of
documentation namely analysis documentation, design documentation, interface documentation,
internal program documentation and user-oriented documentation. Documentation should not be
seen as a overhead for system development. Rather, documentation has to be seen as an
investment for the development of high quality software.
System Requirements Specification
System requirement specification is a set of complete and precisely stated properties along with
the constraints of the system that the software must satisfy. A well designed software
requirements specification establishes boundaries and solutions of system to develop useful
software. All tasks, however minute, should not be underestimated and must form part of the
documentation.
Requirements of SRS: The SRS should specify only the external system behavior and not the
internal details. It also specifies any constraints imposed on implementation. A good SRS is
flexible to change and acts as a reference tool for system developer, administrator and
maintainer.
Characteristics of a System Requirements Specification (SRS)
1. All the requirements must be stated unambiguously. Every requirement stated has only one
interpretation. Every characteristic of the final product must be described using a single and
unique term.
2. It should be complete. The definition should include all functions and constraints intended by
the system user. In addition to requirements of the system as specified by the user, it must
conform to any standard that applies to it.
3. The requirements should be realistic and achievable with current technology. There is no point
in specifying requirements which are unrealisable using existing hardware and software
technology. It may be acceptable to anticipate some hardware developments, but
developments in software technology are much less predictable.
4. It must be verifiable and consistent. The requirements should be shown to be consistent and
verifiable. The requirements are verified by system tester during system testing. So, all the
requirements stated must be verifiable to know conformity to the requirements. No
requirement should conflict with any other requirement.
5. It should be modifiable. The structure and style of the SRS are such that any necessary
changes to the requirements can be made easily, completely and consistently.
6. It should be traceable to other requirements and related documents. The origin of each
requirement must be clear. The SRS should facilitate the referencing of each requirement for
future development or enhancement of documentation. Each requirement must refer to its
source in previous documents.
7. SRS should not only addresses the explicit requirement but also implicit requirements that may
come up during the maintenance phase of the software. It must be usable during operation
and maintenance phase. The SRS must address the needs of the operation and
maintenance phase, including the eventual replacement of the software.
System Design Specification
The system design specification or software design specification as referred to have a primary
audience, the system implementer or coder. It is also an important source of information for the
system verification and testing. The system design specification gives a complete understanding
of the details of each component of the system, and its associated algorithms, etc.
The system design specification documents all as to how the requirements of the system are to
be implemented. It consists of the final steps of describing the system in detail before the coding
starts.
The system design specification is developed in a two stage process: In the first step, design
specification generally describes the overall architecture of the system at a higher level. The
second step provides the technical details of low-level design, which will guide the implementer. It
describes exactly what the software must perform to meet the requirements of the system.
Tools for describing design
Various tools are used to describe the higher level and lower level aspects of system design. The
following are some of the tools that can be used in the System Design Specification to describe
various aspects of the design.
· Data dictionary
· Database schema
· E-R model
· Security model
· Trade-off matrix
· Decision table
· Timing diagram
· State machine diagram
· Object Interaction Diagram
· Inheritance Diagram
· Aggregation Diagram
· Structure Chart
· Pseudocode
Test Document
During system development, this document provides the information needed for adequate
testing. It also lists approaches, procedures and standards to ensure that a quality product that
meets the requirement of the user is produced. This document is generally supplemented by
documents like schedules, assignments and results. A record of the final result of the testing
should be kept externally. This document provides valuable input for the maintenance phase.
The following is the typical content of Test Design Document:
1. Introduction
Purpose: The purpose of this document and its intended audience are clearly stated.
Scope: Give an overview of testing process and major phases of the testing process.
Specify what is not covered in the scope of the testing such as, supporting or not third
party software.
Glossary: It gives definition of the technical terms used in this document.
References: Any references to other external documents stated in this document
including references to related project documents. They usually refer the System
Requirement Specification and the System Design Specification documents.
Overview of Document: Describe the contents and organization of the document.
2. Test Plan
A test plan is a document that describes the scope, approach, resources and schedule of
intended testing activities. It identifies test items, the features to be tested, the testing tasks, and
the person who will do each task, and any risks that require contingency planning.
2.1. Schedules and Resources: An overview of the testing schedule in phases along with
resources required for testing is specified.
2.2. Recording of Tests: Specify the format to be used to record test results. It should
very specifically name the item to be tested, the person who did the testing,
reference of the test process/data and the results expected by the test, the date
tested. If a test fails, the person with the responsibility to correct and retest is also
documented. The filled out format would be kept with the specific testing schedule. A
database could be used to keep track of testing.
2.3. Reporting test results: The summary of what has been tested successfully and the
errors that still exist which are to be rectified is specified.
3. Verification Testing
3.1. Unit Testing: For each unit/component, there must be a test which will enable tester
to know about the accurate functioning of that unit.
3.2. Integration testing: Integration test is done on modules or sub-systems.
4. Validation Testing
4.1. System Testing: This is the top level of integration testing. At this level, requirements
are validated as described in the SRS.
4.2. Acceptance and Beta Testing: List test plans for acceptance testing or beta testing.
During this test, real data is used for testing by the development team (acceptance
testing/alpha testing) or the customer (beta testing). It describes how the results of such
testing will be reported back and handled by the developers.
User Manual
This document is complete at the end of the software development process.
Different Types of User Documentation
Users of the system are not of the same category and their requirements vary widely. In order to
cater to the need of different class of user, different types of user documentation are required.
The following are various categories of manuals:
• Introductory manual: How to get strted with the system?
• Functional description: Describes functionality of the system.
• Reference manual: Details about the system facility.
• System administrator guide: How to operate and maintain the system?
• Installation document: How to install the system


Q4: Explain the following kinds of information systems: (20 Marks)
Transaction Processing Systems
Businesses offer service and products to the customers. In simple terms, transaction processing
system is an information system that supports business in the delivery of various business
transactions. A transaction processing system records and processes data resulting from
business transaction. Transactions are events that occur as a result of business operations like
transfer of money from one account to another account, purchase of items, etc. Transactions are
basically a series of related operations that must all succeed or fail as a group. A single
transaction of withdrawing money from a bank account actually involves two operations are a
debit to an account and credit to another account. Transactions processing system allows the two
operations to group into a single transaction. When both the operations are successfully
completed, then the transaction is said to be complete. TPS can be classified into the category of
Operation information system. Example can be Sales Transaction Processing System. These
systems are transaction intensive and results of such transaction processing are used to update
various databases like customer databases, inventory databases and accounts receivable
databases. Transaction Processing Systems are also used to make day to day decisions that
control operational processes.
Transaction processing systems (TPS) could be on-line or off-line. In case of On-line Transaction
Processing systems, data is processed by the system immediately after the transaction occurs.
Point of Sale (POS) is a common example of the On-line Transaction Processing System (OLTP).
The following are major characteristics of Transaction Processing Systems :
• Support business operations;
• Focus on data resulting from business transactions; and
• Captures and processes data of business transactions.
Management Information Systems
Management Information System (MIS) is a special kind of information system that helps
managers to take decisions. MIS is tailored to provide specific information to individual managers
for long term and strategic decision-making. MIS is used by the middle and top-management for
their information requirements for decision-making. The use of MIS helps to produce the
information that organizations need to improve decision-making, problem solving, controlling
operations, and creating new products or services. Keeping this in view, a number of
organizations invest in development of a computerized MIS . The focus of MIS is to provide
strategic information required by top-management. Major volume of information for top
management comes from events not directly related to day-to-day business operations.
Therefore, the information from normal reporting systems is found inadequate for managers.
Therefore, special information system is developed for top management to support their activity,
which is not met by other information systems.
The following are the characteristics of Management Information Systems (MIS):
• Provides reports to management usually in semi-structured format ( in detailed, summary, and
exception);
• Usually uses shared database from many sources;
• Often based on management or statistical models;
• Information presented in both textual and graphical forms, but more often in graphical format;
• Provides information on trend analysis, exception reporting and what-if-analysis. It allows the
user to ask questions such as , what if we increase price by 10%, the effect on sales of the
product? If inflation increases by 5 per cent what will be the effect on the sales forecast?
Decision Support Systems
In contrast to other information systems which provide general information about organization’s
performance in fixed format to managers, Decision Support Systems provide information to
managers which will be helpful for them to make decisions. A manager at a higher level needs
adhoc information for strategic planning and control.
Decision Support Systems (DSS) can be defined as a specific class of information systems that
support business and organizational decision-making activities, as needed to managers. A
properly designed DSS is an interactive software-based system intended to help decision makers
compile useful information from raw data, documents, personal knowledge, and/or business
models to identify and solve problems and make decisions.
The following are the major characteristics of Decision Support Systems (DSS):
• Help decision makers to take decisions rather than replace them;
• Use underlying data and models;
• Have little or no reasoning capability;
• Are tailored to directly support decision-making styles of individual managers;
• Support interactive inquires and responses;
• Are used to aid semi-structured or unstructured decisions;
• Produce information on ad-hoc, flexible and adaptable format;
• Information is produced by analysis of operational and external data; and
• Analyses and supports comparison of specific alternative decisions.
Expert Systems
An Expert System is a computer program that simulates the judgment and behaviour of a human
expert or an organization that has expert knowledge and experience in a particular field. Typically,
such a system contains a knowledge base containing accumulated experience and a set of rules
for applying the knowledge base to each particular situation that is described to the program.
Sophisticated expert systems can be enhanced with additions to the knowledge base or to the set
of rules. The expert system is a knowledge-based information system to act as a consultant to the
user. Expert systems are being used in many specialized field like medicine, engineering and
business. An Expert System in the field of medicine can help diagnose illness. Unlike Decision
Support System, an expert System interacts with the user to get input and provides expert advice
on a problem in a specific domain.
Among the best-known expert systems have been those that play chess and those which assist
in medical diagnosis such as Mycin.
The following are the major characteristics of expert systems (ES):
• Captures knowledge and expertise of a problem solver or decision maker and simulates thinking
for those with less knowledge;
• Replaces a human advisor/expert for specific domain of knowledge;
• Its domain of knowledge is narrow;
• Has reasoning and explanation capability;
• Types of problem treated is repetitive; and
• The direction of interaction is from machine to the user.