prince sultan university course code : is 225 course name : systems analysis & design- i course...

Prince Sultan University

Course Code : IS 225

Course Name : Systems Analysis & Design- I

Course Instructor : Hisham Alkhawar

Credit Hours : 4

Text Book : Systems Analysis & Design

Author(s) : Jeffery Hoffer, Joseph Valich 5th Edition

Reference Book :

1. Systems Analysis & Design By Jeffery Whitten

Chapter 1

The Systems Development Environment

1.11.1

Learning Objectives

Define information systems analysis and design

Describe three types of information systems: Transaction Processing Systems (TPS) Management Information Systems (MIS) Decision Support Systems (DSS)

1.21.2

Learning Objectives

Describe the information systems development life cycle (SDLC)

Water fall Model Discuss Rapid Application Development

(RAD) and its constituents parts Prototyping JAD CASE

1.31.3

Learning Objectives

Describe Object Oriented Analysis and Rational Unified Process (RUP)

Describe the Agile Methodologies and eXtreme Programming

1.41.4

Information System-Introduction

An Information system ( IS) is a collection of interrelated components (hardware, software, and telecommunications networks) that people build and use to collect, process, store and provide/distribute as output useful information needed to complete a business task in organizations.

Examples: Payroll System Sales Management System

Information System-Introduction

Why do we design Information Systems?Information systems are built and rebuiltTo provide access to information anywhere

and anytime.

for organizational benefits by adding values during the process of creating, producing and supporting the organization’s product and services.

to improve employee efficiency by applying software solutions to key business tasks

Understand what the business requires from the Information System. In other words thorough “Systems Analysis & Design”

What is Systems Analysis & Design?

Systems Analysis means understanding and specifying in detail what the information system should accomplish.

Systems Design means how to accomplish what is needed by the information system, by specifying in details how many components of the information system should be physically implemented.

What is Systems Analysis & Design?

Information Systems Analysis and DesignComplex, and challenging

organizational process used by a team of business and system professionals, to develop and maintain computer-based information systems that helps in performing business functions efficiently.

1.51.5

What is the outcome of SAD ?

The total Information System includes the hardware, systems software on which the application software runs, documentation and training materials, the specific job roles associated with the overall system and the end users.

An important result of Systems A&D is Application Software, i.e. software designed to support a specific organizational function or process, such as Inventory management, payroll etc.

Who is Systems Analyst?

Systems Analyst performs analysis and design based upon: Understanding of organization’s objectives,

structure and processes. Studies the problems and needs of an organization Knowledge of how to exploit information technology

for advantage Determine how people, methods and IT can be best

combined to bring about improvements in the organization.

1.81.8

Types of Information Systems

Transaction Processing Systems

Management Information Systems

Decision Support Systems

1.121.12


Transaction Processing Systems (TPS) Automate handling of data about business activities the routine day to day business processes Data about each transaction are captured, transaction

are verified and accepted or rejected, and validated transaction are stored for later aggregation.

A transaction occurs each time a sale is made, supplies are ordered or interest payment is made

1.131.13


Transaction Processing Systems (TPS) -contd.The A&D of a TPS means

Focusing on the firm’s current proceduresThe goal of TPS development is to

improve transaction processing by speeding it up using fewer people,

improve efficiency and accuracy, integrate it with other organizational information

systems, provide information not previously available.

1.141.14


Examples of TPSBusiness to consumer e commerce systems

Point of Sale SystemOnline Registration SystemOnline Airline Reservation SystemATM SystemCar Rental SystemLibrary Information System

Business to Business e commerce systems


Management Information Systems (MIS) Converts raw data available through a transaction

processing system (TPS) into meaningful aggregated form (report) that managers need for planning and controlling business.

Examples of MISMIS used by executives often include external data on the competitive environment –

news about competitors Stock market reports Economic forecast


Decision Support Systems (DSS) Designed to help organizational decision makers make

decisions. Allows a user to explore the impact of available options

or decisions, and this is known as “what if” analysis, because the user asks the system to answer.

Provides interactive surroundings for decision making in which data can be quickly manipulated.

DSS uses both historical data as well as judgment about alternative histories or possible futures.

A DSS can help in exploring data at a high level of aggregation and selectively drill down into specific areas where more detailed understanding of business is required.


The A&D for a DSS concentrates on Database (data Orientation) Model base ( mathematical rules defining

interrelationships among different data, used to predict future data or to find best solutions to decisions problems.

User dialogue – decision maker should feel easy to use the system.

Systems Development Life Cycle

System Development methodology-

Standard set of steps to develop and support IS.

Development of IS follows a life cycle. During the life of an IS, it is first conceived as an idea, then it is designed, built and deployed during a development project and finally it is put into production and used to support the business.

SDLC – common methodology for system development

SDLC is used to describe the life of an information system from conception to retirement.

Life Cycle – a circular process Life cycle appear to be sequentially ordered

set of phases, but it is not. Some activities in one phase can be

completed in parallel with some activities of another phase.

Sometimes life cycle is iterative- phases are repeated until accepted.



Consists of five phases: Planning Analysis Design Implementation Maintenance

Each phase has a specific outcome and deliverable

1.221.22

Planning

Analysis

DesignImplementation

Maintenance


Ch 4-5

Ch 6-9

Ch 10-14Ch 15

Ch 16


Planning- Ist PhaseProject Identification and SelectionProject Initiation and Planning


Project Identification and Selection Examine Information needs. Identify the project Prioritization and translation of needs Development of Schedule for different projects Selection of a project.

Project Initiation and PlanningTwo Activities

Formal preliminary investigation of the problem at hand Determining the scope of the proposed system known as Feasibility

Study Producing a specific plan (Baseline project plan) for the proposed system

if it has been approved, specifying the time and resources needed for its execution.

Outcome Final presentation of the business case

1.251.25


Analysis - 2nd Phase To understand and document the business needs and the

processing requirements of the new system. A discovery and understanding process.

Activities Gather information Define system requirements Prioritize requirements Generate and evaluate alternatives matching the requirements Review recommendations with management.

Outcome Once the recommendation is accepted, the analyst makes plans to

acquire hardware and software necessary to build or operate the system as proposed

1.261.26


Design- 3rd phaseUsed to design the solution system, based on the requirements defined and decisions made during analysis.

High level design consisting of developing an architectural structure for the software components, database design, user interfaces and operating environment.Low level design entails developing the detailed algorithms and data structures required for software development.

1.271.27


The description of recommended alternative solution is converted into

Logical design Physical design

Logical design focuses on “what” rather than the “how”.

Logical design process is independent of any specific hardware or software platform – logical design.

Logical design concentrates on the business aspects of the system.

Logical design is oriented towards high level of design

• Physical design concentrates on the design of the various parts of the system to perform the physical operations necessary to facilitate data capture, processing and information output. Physical design includes

-Hardware selection, determination of software ( custom/off-the shelf applications)

-Data capture devices-Data input and report formats-The media to be used for input and output-Construction of database structure-Network communication, data security etc

Outcome:Physical system specifications in a form ready to be turned over to the programmers or other system builders for construction e.g. programming language, database, hardware platform



Implementation-4th phase Implementation

Coding- programmer write the program for the systemTestingOperationHardware and software installationUser Training Documentation


CodingPrograms can be written in Java, Visual

Basic etc.Testing

Individual testing of the programsSystem or Integration testing


Operation (System conversion) :It is the process abandoning the current system (automated or manual) and installing the new automated information system.

System conversion can be done in at least three ways :1. Direct changeover : Old system is discontinued on one day and the new is used on the next.2. Parallel running : Old and new systems are used at same time.3. Phased changeover : Part of the new system are implemented in phases.


InstallationApplication software is installed on existing

or new hardware.The new system becomes a part of the daily

activities of the organization.Training

Users are trained.


Documentation :

Many types of documentation must be produced for a software system

System documentation : Software Engineers develop system documentation that details the inner working of the system to ease future maintenance.


User Documentation : It is user–related documentation which contains the following

User and reference guides,User training and tutorialsInstallation procedures and

troubleshooting suggestions.Initial user support

In addition to documentation, users may also need training program and on going support to use a new system.


Maintenance- 5th PhaseMaintenance means system is changed to reflect changing conditions

Corrective Maintenance : Making changes to an information system to repair flaws in the design, coding or implementation.

Adaptive Maintenance : Making changes to an information system to accommodate changing business needs .


Perfective Maintenance : Making enhancements to improve processing performance or interface usability.

Preventive Maintenance: Making changes to a system to reduce the chance of future system failure.

The Traditional Waterfall SDLC

This model is known as ‘water fall model’ because, the output of one phase is the input of the next phase.

It is a traditional methodology used to analyze, design, implement and maintain information system.

The flow of the project begins in the planning phase.

Planning

Analysis

Design

Implementation

Maintenance



Strengths:The water fall cycle is a very good approach

to follow when the requirements for the information system are highly structured and straightforward and at the same time they are known in the early phases only. e.g. payroll, or inventory system.

Tackles complexity in an orderly way, works well for well understood projects That is why, waterfall model is mostly used for large systems engineering projects.


Drawbacks This model requires that all the

requirements should be specified in advance. It is difficult for end-users to anticipate how they will use new information systems to support their everyday work. If these systems are large and complex, it is probably impossible to make this assessment before the system is built and put into use. In short, the requirements are not clear to the end-users in the beginning.


Drawbacks contd

It was not possible to implement changes in the requirement specifications all the time during system development. The analyst freeze requirements in the early phase, even though those requirements might get changed. With the result it is very expensive to make changes in a system once it was developed.

The role of users are narrowly defined. Limited User involvement throughout the system development.


Drawbacks contd.

Focus on milestone deadlines, instead of obtaining feedback from the development process leads to too little focus on good analysis and design.

Focus on deadlines results in systems that do not match users’ needs and that require extensive maintenance, unnecessarily increasing development cost (maintenance cost is 40% – 70% of software development costs). Finding and fixing a problem after implementation is 100 time more expensive than finding and fixing it during A&D.

Different Approaches to improving Development

PrototypingCase toolsJoint Application Design

The Prototype- Approaches to Improve Development

What is a Prototype ? An easily modifiable and extensible working model of

a proposed system, not necessarily representative of a complete system

What is a Prototyping ? Prototyping is the process of building a working

replica of a system.


The Prototype Software Development approach is used to counter the limitations of the waterfall model. The basic idea is that instead of freezing the requirements before any design or coding can process, a prototype is built to help understand the requirements by exposing it to the user comment and refining this through many versions until adequate system has been developed.

© 2008 by Prentice Hall 47Chapter 1

Prototyping (Cont.)


Strengths: By using this prototype , the client can get an actual

feel of the system, because the interactions with the prototype can enable the client to better understand the requirements of the desired system. The prototype can be refined through many versions until adequate system has been developed.

This results in more stable requirements that change less frequently.

CASE (Computer-Aided Software Engineering) - Approaches to Improve Development

Software systems which are intended to provide automated support for software process activities. Diagramming tools- graphical representation of

processes, data and control structures.

Computer display and report generators- help the SA to identify data requirements and relationships.

Analysis tools-check for incompleteness, inconsistency or incorrect specification in diagrams, forms, reports

CASE (Computer-Aided Software Engineering) - Approaches to Improve Development

Central Repository- integrated storage of specifications, diagrams, reports, project management information

Documentation Generators- technical and user documentation

Code generators- enable the automatic generation of program and database definition code directly from the design documents, diagrams, forms and reports

CASE Tools

Microsoft VisioVisible AnalystRational RoseOracle

© 2008 by Prentice Hall 52Chapter 1

Joint Application Design (JAD)

Structured process involving users, analysts, and managers.

Several-day intensive workgroup sessions.

Purpose: to specify or review system requirements.

Joint Application Design (JAD): A structured process in which users, managers, and analyst

work together for several days in series of in a series of intensive meetings to specify or review system requirement.

Rapid Application Development

Methodology to radically decrease design and implementation time.

Involves: extensive user involvement, prototyping, JAD sessions, integrated CASE tools, and code generators.

Provides a series of techniques for compressing the analysis, design, build and test phases into a series of short iterative development cycles.

Rapid Application Development

System developers and end-users work together jointly in real time to develop system

Use of small, well trained development teams Phases are shortened and combined with

each other. Tasks done in parallel rather than sequentially. Prototyping is used extensively.

Rapid Application Development (RAD) (Cont.)

RAD – Comparing RAD to the SDLC

Labor – intensive activities of the SDLC are condensed through parallel actions

Use of JAD requirement Extensive iterative process. Includes the development and refinement of process

models and prototype In waterfall model, activities are performed in a

sequential manner whereas in RAD approach they are performed in a iterative, parallel manner.

In RAD, user requirements are refined, a solution is designed, the solution is prototyped, the prototype is reviewed, user input is provided and the process begins again.

Agile Methodologies

For engineering disciplines such as civil, requirements tend to be well understood. Once designing is completed, constructions becomes very predictable.

For software engineering: requirements are rarely well understood; they

change continually during the lifetime of the project.

Agile Methodologies

What is needed in software engineering? Methodologies that embrace change Methodologies that are able to deal with a lack of

predictability. Agile methodologies is based on the above

principles, which focuses on Iterative development Focus on people Promotes self adaptive software development

process

Agile Methodologies

Iterative developmentFrequent production of the working versions

of a system that have a subset of the total number of required features.

Provides feedback to the customer and developers alike.

Agile Methodologies

Focus on peopleFocus on individuals rather than on the

roles those people perform. Roles are not as important as the

individuals who fill those rolesDoesn’t view people as interchangeable

units instead as talented individuals.

Agile Methodologies

Promotes self adaptive software development process The process used to develop software should be

refined and improved by reviewing it repetitively which is of course done by a number of iterations.

AS the processes are adapted (modified), one would not expect to find a single monolithic methodology within an organization, instead many variations of the methodology which reflects the particular talents and experience of the team using it.

Agile Methodologies

When should we recommend Agile methodologies?Unpredictable or dynamic requirementsResponsible and motivated developersCustomers who understand the process and

will get involved

Extreme Programming

Short, incremental development cycles. Focus on automated tests written by

programmers and customers. Two-person programming teams. Customer on site during the development

process. Building working system in a very little time,

without written or diagramming design specification.

Extreme Programming

Coding and testing operate together.Advantages:

Communication between developers.High level of productivity.High-quality code.

Extreme Programming

Drawbacks:Long term commitment and dedication is

required from both the user and customer.Lack of design documentation.Not effective on large projectsRequires experienced developersNeglected planning

Object Oriented Analysis and Design

Views information system as collection of interacting objects that work together to accomplish tasks

Objects – things in computer system that can respond to messages

Conceptually, no processes, programs, data entities, or files are defined – just objects

Data and process are combined in to single entity known as objects.

Objects correspond to the real things an information system deals with, such as customer, supplier, contracts, rental agreement etc.

Maintenance of the software becomes much easier

Systems Analysis and Design in a Changing World, 4th Edition 67

Object-Oriented Approach (continued)

Object-oriented analysis (OOA) Defines types of objects users deal with Shows use cases are required to complete tasks

Object-oriented design (OOD) Defines object types needed to communicate with

people and devices in system Shows how objects interact to complete tasks Refines each type of object for implementation with

specific language of environment Object-oriented programming (OOP)

Writing statements in programming language to define what each type of object does


Class Diagram Created During OO Analysis

Rational Unified Process ( RUP)

Based on an iterative, incremental approach to system development.

Phases Inception, elaboration, construction, transition


Figure 1-14 Phases of OOSAD-based development


Life Cycles with Different Names for Phases (Figure 2-20)


InceptionDefine the scopeDetermine the feasibility of the projectUnderstand the user requirementsPrepare software development planShort phase and the least resource

intensive.Single iteration


Elaboration Major activities –Detailed Analysis (Define the requirements),

design a baseline architecture. Long phase and has several iterations. Less resource

intensive. Most critical phase Create use case diagrams, class diagrams, sequence

diagrams etc. Final cost and benefits estimates are also completed. The architecture includes a vision of the product, an

executable demonstration of the critical pieces, a detailed glossary and a preliminary user manual, a detailed construction plan and a revised of planned expenditures.


Construction Longest phase. Several iterations. Most resource

intensive. The software is actually coded, tested and documented. Some components are purchased and used in the code. As each executable is completed, it is tested and

integrated. Continue to build the system with additional features using

number of iterations that also include requirements, design and implementation, possibly creating multiple releases of the system.

Revised user requirements could require analysis and design.

At the end beta version of the project is released that should have operational capabilities.


TransitionThe System is goes for beta testing, and then

deployed, and the users are trained and supported.

The project gets acceptance in this phaseOnce accepted, the product can then be

released for distribution.Resource intensive but short phase.

76

Methodologies and ModelsMethodologies

Comprehensive guidelines to follow for completing every SDLC activity

Collection of models, tools, and techniquesModels

Representation of an important aspect of real world, but not same as real thing

Abstraction used to separate out aspectDiagrams and chartsProject planning and budgeting aids

77

Some Models Used in System Development

78

Tools and Techniques

ToolsSoftware support that helps create models or

other required project components Range from simple drawing programs to

complex CASE tools to project management software

TechniquesCollection of guidelines that help analysts

complete a system development activity or taskCan be step-by-step instructions or just general

advice

79

Some Techniques Used in System Development

80

Some Techniques Used in System Development

81

Relationships Among Components of a Methodology

Our Approach to SDLC

The SDLC is an organizing and guiding principle in this book.

We may construct artificial boundaries or artificially separate activities and processes for learning purposes.

Our intent is to help you understand all the pieces and how to assemble them.

Summary

In this chapter you learned how to: Define information systems analysis and

design. Describe the different types of information

systems. Describe the information Systems

Development Life Cycle (SDLC).

Summary

Explain Rapid Application Development (RAD), prototyping, Joint Application Development (JAD), and Computer Aided Software Engineering (CASE).

Describe agile methodologies and eXtreme programming.

Explain Object Oriented Analysis and Design and the Rational Unified Process (RUP).

prince sultan university course code : is 225 course name : systems analysis & design- i course...

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