1 Introduction Sp

8/13/2019 1 Introduction Sp

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What Is Information SystemsAnalysis and Design?

A method to create and maintain

information systems that perform basicbusiness functions

The main goal is to improve organizationalsystems, typically by applying softwarethat can help employees accomplish key

business tasks more easily and efficiently.

Dr. Hyunju Kim, Jackson State University 08/2012


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System Analyst

The primary role is to study the problems

and needs of an organization in order todetermine how people, methods, andinformation technology can best becombined to bring about improvements inthe organization.

Should have

An understanding of the organizationsobjectives, structure, and processes

Knowledge of how to exploit informationtechnology for advantage



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System - Definition

An interrelated set of business

procedures, objects, or components usedwithin one business unit, working togetherfor some purpose



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System - Components

Application software

Hardware and system software

Documentation and training materials

Specific job roles Controls and security mechanisms

Users



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System - Characteristics System components

An irreducible part or aggregation of parts that makesa system; also called a subsystem

Interrelationships Dependence of one part of the system on one or

more other system parts Boundary

The line that marks the inside and outside of a systemand that sets off one system from other systems in

the organization Purpose

The overall goal or function of a system



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System Characteristics (cont.) Environment

Everything external to a system that interacts with thesystem

System interfaces Point of contact where a system meets its

environment or where subsystems meet each other

Input

Output

Constraints A limit to what a system can accomplish



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Systems Concepts Decomposition is the process of breaking down

a system into smaller constitutions, which maybe subsystems or terminal units.

Modularity is a direct result of decomposition. Itrefers to dividing a system into smaller chunks ormodules.

Coupling means that subsystems are dependenton each other.

Cohesion is the extent to which a subsystemperforms a single function.



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Steps in Systems Development

Systems Planning

Systems Analysis

Systems Design

Systems Implementation andManagement

Systems Testing

Specification

Design andImplementation

Validation

Evolution



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Systems Planning Identifies the need for a new or enhanced

system Results: a written plan and a schedule for

developing new major systems

Feasibility tests Investigates the system and determines

the proposed systems scope

Results: a baseline project plan and a formaldefinition of the project



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Systems Analysis

Studies the organizations current

procedures and the information systems

Identifies each task

Employs a use case, which is adescription of a set of sequences ofactions that a system performs

Develops test plans



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Steps in Systems Analysis Determine requirements of the system

Study the requirements and structure themaccording to their interrelationships, eliminatingany redundancies

Generate alternative initial designs to match therequirements

The final output of the analysis is a description of

one of the alternative solutions.



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Systems Design

Specifies how the recommended alternativesolution is translated into detailed logical and

physical systems specification Logical design is not tied to any specific

hardware and software.

In physical design, the logical design istranslated into technical specifications.

The final output of the design is the physicalsystems specifications.



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Systems Testing and Management

Tests subsystems

Tests systems integration

Tests the whole system according to the

test plans Installs the system

Evaluates the system

Maintains the system



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Characteristics of SuccessfulTeams

Diversity in background, skills, and goals

Tolerance of diversity, uncertainty, andambiguity

Clear and complete communication Trust

Mutual respect and putting ones ownviews second to the team



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Software Process A structured set of activities required to develop a

software system Specification

Design and implementation

Validation

Evolution

Software process model

An abstract representation of a process

A description of a process from some particularperspective



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Plan-driven and AgileProcesses

Plan-driven processes

Process activities are planned in advance andprogress is measured against this plan.

Agile processes

Planning is incremental and it is easier tochange the process to reflect changingcustomer requirements.

In practice, most practical processesinclude elements of both plan-driven andagile approaches.



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Software Process Models Waterfall model (plan-driven)

Separate and distinct phases of specificationand development.

Incremental development (plan-driven or agile)

Specification, development and validation areinterleaved.

Reuse-oriented SE (plan-driven or agile)

The system is assembled from existing

components.



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The Rational Unified Process

(RUP)

A modern generic process derived from

the work on the UML and associatedprocess



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RUP Phases Inception

Establishes the business case for the system Elaboration

Develops an understanding of the problem domain and

the system architecture Construction

Includes system design, programming and testing

Transition Deploys the system in its operating environment



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RUP Good Practice Develop software iteratively

Plan increments based on customer priorities anddeliver highest priority increments first.

Manage requirements

Explicitly document customer requirements and keeptrack of changes to these requirements.

Use component-based architectures

Organize the system architecture as a set of reusablecomponents.



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RUP Good Practice (cont.) Visually model software

Use graphical UML models to present staticand dynamic views of the software.

Verify software quality

Ensure that the software meets organizationalquality standards.

Control changes to software

Manage software changes using a changemanagement system and configurationmanagement tools.


Documents

1 Introduction Sp