Chapter 1: Chapter 1: The Object-Oriented Systems The Object-Oriented Systems

Development EnvironmentDevelopment Environment

Object-Oriented Systems Analysis and Design

Joey F. George, Dinesh Batra,

Joseph S. Valacich, Jeffrey A. Hoffer

Chapter ObjectivesChapter Objectives

After studying this chapter you should be able to:

– Define information systems analysis and design.

– Explain the basics about systems.

– Describe the information systems development cycle (SDC).

– Describe TPS, MIS, and DSS.

– Describe the role of systems analyst.

– Recount the evolution of system development methodologies.

What Is Systems Analysis and What Is Systems Analysis and Design?Design?

Systems analysis and design is the process of analyzing user requirements, designing a solution to meet those needs, and ultimately building a software system that meets those needs and requirements.

Requires knowledge of:– The business objectives, structure, processes– Information technology opportunities and

constraints

What Is a System?What Is a System?

A group of interrelated processes and procedures used for a business function, with an identifiable boundary, working together for some purpose.

A system has clear identifiable functional boundaries. Example a payroll system should not accept payments from outside customers. An email system should not create a spreadsheet

Characteristics of SystemsCharacteristics of Systems

Input – data from environment to systemOutput – data from system to environmentComponents – objects or a subparts of systems

operating independentlyInterrelationships – associations between

components of a systemInterfaces – mechanism for interacting with

componentsBoundary – identify the functionality limit of

system

Important System ConceptsImportant System Concepts

Decomposition – breaking down a system into smaller constituents

Modularity – the result of decomposition; parts of a system

Coupling – dependencies between subsystems

Cohesion – extent to which a subsystem performs a single function

Type Of SystemsType Of Systems

TPS – Transaction Processing System.Increases efficiency and productivitya.k.a. OLTP (online transactional processing)

MIS – Management Information System.Converts data into information to help management optimize business decisions

DSS – Decision Support SystemInteractively assist with decision making.Allows for what-if scenarios & comparisons

Transaction Processing System Transaction Processing System (TPS)(TPS)

Automate the handling of data for business activities or transactions

Also known as OLTP Online Transactional Processing system

Goal: improve transaction processing by increasing speed, enhancing productivity, simplifying processes

Management Information System Management Information System (MIS)(MIS)

Use raw data from TPS systems, and converts them into meaningful aggregate form.

Converts Data to Information

Goal: provide information to management to help them manage the business

Decision Support System (DSS)Decision Support System (DSS)

Interactively assist with decision making by applying mathematical or logical models and a dialogue of interactions to solve unstructured problems (allow for what ifs)

Goal: provide comparisons of alternatives and recommendation of preferred option

The Four Steps of The Four Steps of Systems Development Life CycleSystems Development Life Cycle

Systems Planning, Selection & ManagementSystems AnalysisSystems DesignSystems Implementation, and

Operations & Maintenance

(Sometimes Operations & Maintenance is viewed as a separate 5th step.)

Systems Planning, Selection Systems Planning, Selection & Management& Management

Analyze and arrange organization’s information needs, identify and describe potential project, determine system scope, and provide a business case for continuing with the project

Feasibility analysis: determine economic and organizational impact of the system

Management across all phases of development

Systems AnalysisSystems Analysis

Thorough study of organization’s current system and processes, determination of system requirements, structuring requirements, generate alternative design strategies.

Use of UML for system modeling

Goal: describe what needs to be done

Systems DesignSystems Design

Translating alternative solution generated by analysis phase into detailed logical and physical system specifications.– Logical design: not tied to any hardware or

software platform. From the business view.– Physical design: specific programming

languages, databases, architectures

Goal: identify how the task will be accomplished

System Implementation and System Implementation and OperationOperation

Information system is coded, tested, and installed, and undergoes periodic corrections and enhancements

Goal: provide a fully operational system, and the continued success of the system

The Role of the Systems AnalystThe Role of the Systems Analyst

Skills required: analytical, technical, managerial, interpersonal

Liaison between users, programmers, and other systems professionals

Evolution of System Evolution of System Development MethodologiesDevelopment Methodologies

The output-Input based methodology - Examine the output will lead you to the requirements

Structured Analysis and Design- Use of Data Flow Diagrams to represent data movement

The System Development Life Cycle - System Planning, Analysis, Design & Implementation

Object Oriented Systems Analysis & Design - Iterative & incremental approach to systems development - Use of Unified Modeling Language (UML) Diagrams

The current trend is to use OOSAD, but many organizations are still using structured analysis and design

Object Oriented Systems Object Oriented Systems Analysis & DesignAnalysis & Design

The best OO systems analysis & design methodology is RUP (Rational Unified Process). The methodology calls for a 4 phase approach:

Inception Elaboration Construction Transition

- Each phase is applied iteratively & incrementally

- Each phase applies the same 4 SDLC steps

Inception PhaseInception Phase

Defining the scope, determining the feasibility, understanding user requirements, preparing a software development plan

Relatively short, low resource requirements

Focus on planning and initial analysis

Elaboration PhaseElaboration Phase

Detailed user requirements and baseline architecture is established

Fairly long, but not high in resource demand

Focus on detail analysis and design

Construction PhaseConstruction Phase

Coding, testing, and documenting code

Longest and most resource-intensive

Focus is on design and implementation

Transition PhaseTransition Phase

System is deployed and users are trained and supported

Short-term, but resource-intensive

Focus is on installation, training, and support

Construction is the longest part

Iterative & Incremental Iterative & Incremental

A key feature of RUP is the iterative and incremental nature of the development process.

Iterative – means developing in pieces, and growing and improving each piece through successive iterations.

Incremental – means developing in pieces, and progressively adding new pieces through successive iterations.

RUP Phases across SDLC stepsRUP Phases across SDLC steps

Inception - mostly planning and analysis, low on design and implementation & operation.

Elaboration - high on planning, additional analysis, mostly design, low on implementation & operation.

Construction - high on planning, low on analysis, more design, mostly implementation & operations.

Transition – high on planning, low on analysis and design, high on implementation & operations.

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RecapRecapAfter studying this chapter we learned to:

– Define information systems analysis and design.– Explain the basics about systems.– Describe the information systems development

cycle (SDC).– Describe TPS, MIS, and DSS.– Describe the role of systems analyst.– Recount the evolution of system development

methodologies.