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System Analysis Overview System Analysis Overview

System Analysis Overview - PowerPoint Presentation

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System Analysis Overview - PPT Presentation

approaches phases and requirements discovery Karolina Muszyńska Based on httpwwwcsunedudn58412IS431IS431SP13html Systems Analysis vs Systems Design Systems Analysis Phases and Tasks ID: 494459

system requirements systems analysis requirements system analysis systems project task problem tasks models business phase discovery data process design

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Slide1

System Analysis Overviewapproaches, phases and requirements discovery

Karolina Muszyńska

Based on http://www.csun.edu/~dn58412/IS431/IS431_SP13.htmlSlide2

Systems Analysis vs. Systems DesignSystems Analysis Phases and Tasks

User Requirements DiscoverySystems Analysis Approaches

2

Systems Analysis OverviewSlide3

3

System AnalysisSlide4

4

Systems Analysis vs. Systems Design

Systems Analysis

: development phases in a project that primarily

focus on the business problems

, i.e.,

WHAT

the system must do in terms of Data, Processes, and Interfaces,

independent of any technology

that can or will be used to implement a solution to that

problem.

Systems Design

: development phases

focus on the technical construction and implementation of the system

-

HOW

technology will be used in the system.Slide5

5

Context of System AnalysisSlide6

Scope Definition Phase –

WHAT PROBLEMIs the project worth looking at to solve problem?Problem Analysis Phase –

WHAT ISSUES

Is a new system worth building?

Requirements Analysis Phase –

WHAT REQUIREMENTS

WHAT do the users need and want from the new system?

Logical Design Phase –

WHAT TO DO

WHAT must the new system do to satisfy users’ needs?

Decision Analysis Phase –

WHAT SOLUTION

WHAT is the best solution among others?

6

Classic Systems Analysis PhasesSlide7

7

Scope Definition Phase Slide8

8

Scope Definition TasksSlide9

Task 1.1: Identify Problems, Opportunities, and Directives

Deliverable: Preliminary Problem StatementTask 1.2: Negotiate Preliminary ScopeDeliverable: Statement of Project Scope (boundary of the project)

what types of DATA to be studied,

what business PROCESSES to be included,

how the system INTERFACE with users, locations, and other systems

9

1.

Scope Definition Tasks…Slide10

Task 1.3: Assess Project Worthiness

Cost/benefit analysis Decision: approve, cancel, renegotiate the scopeTask 1.4

:

Schedule and Budget Plan for Project

Deliverables: Project Charter – schedule and resource assignment

Task 1.

5

:

Present the Project and Plan

Deliverable: Project Charter (participants, problems, scope, methodology, statement of work to be completed, deliverables, quality standards, schedule, budget)

10

1.

Scope Definition Tasks…Slide11

11

Problem Analysis Phase Slide12

12

Problem Analysis TasksSlide13

Task 2

.1: Study the Problem DomainDATA: currently stored data, their business terms

PROCESSES: current business events

INTERFACES: current locations and users

Deliverable: definition of

system domain/models of

Current System

Task

2

.2:

Analyze Problems and Opportunities

Deliverables: updated problem statements and the cause-effect analyses for each problem and opportunities

Task 2.3:

Analyze Business Processes

Deliverable:

current business process models

13

2. Problem Analysis Tasks…Slide14

Task 2.

4: Establish System Improvement ObjectivesDeliverable: System Improvement Objectives and Recommendations Report

Task

2

.

5

: :

Update the Project Plan

Deliverable: updated project plan

Task 2.6:

Present Findings and Recommendations

Deliverable: system improvement objectives

Decision: continue/adjust/cancel current project

14

2. Problem Analysis Tasks…Slide15

15

Requirements Analysis PhaseSlide16

16

Requirements Analysis TasksSlide17

17

3.

Requirements Analysis Tasks

Task 3.1:

Identify System Requirements

Functional requirements

: activities and services provided by a system: business functions, inputs, outputs, stored data.

Nonfunctional requirements

: features, characteristics defining a satisfactory system: performance, documentation, budget, ease of use and learn, cost saving, time saving, security

Deliverable: draft functional and nonfunctional requirements: improvement objectives and related input, output, processes, stored data to fulfill the objectivesSlide18

18

3.

Requirements Analysis Tasks

Task 3.2:

Prioritize Requirements

Mandatory vs. desirable requirements

Time boxing

: deliver the system in a set of subsequent versions in a time frame. The first version satisfies essential and highest prioritized requirements.

Task 3.

3

:

Update the Project Plan

If requirements exceed original vision: reduce the scope or increase the budget

Deliverable: consolidated system requirements (completed requirements and priorities)Slide19

19

Logical Design Phase Slide20

20

Logical Design TasksSlide21

21

4. Logical Design Tasks

Task 4.1:

Analyze Functional Requirements

Logical systems models: WHAT the system must do (not HOW)

Build prototypes to establish user interface requirements

Deliverables: Data models (ERD), Process models (DFD), Interfaces models (Context diagram, Use case diagram), Object models (UML diagrams) of the

Proposed System

Task 4.2:

Validate Functional Requirements

Completeness check, revisit, make changes and additions to system models and prototypes to assure that requirements are adequately defined.

Associate nonfunctional requirements with functional requirementsSlide22

22

Decision Analysis PhaseSlide23

23

Decision Analysis TasksSlide24

24

5. Decision Analysis Tasks

Task 5.1:

Identify Candidate Solutions

Deliverable: candidate systems (solutions) matrix

Task 5.2

: Analyze Candidate Solutions

Feasibility analysis is performed on each individual candidate without regard to the feasibility of other candidates - technical, operational, economic, schedule feasibilities (TOES)Slide25

25

5. Decision Analysis Tasks

Task 5.3:

Compare Candidate Solutions

Deliverable: recommended solution

Task 5.4

: Update the Project Plan

Review and update the latest project schedule and resource assignments

Deliverable: updated project plan

Task 5.5:

Recommend a Solution

Deliverable: System ProposalSlide26

The system may cost more than projected.The system may be delivered later than promised.The system may not meet the users’ expectations and that dissatisfaction may cause them not to use it.

Once in operation, the costs of maintaining and enhancing the system may be excessively high.The system may be unreliable and prone to errors and downtime.The reputation of the IT staff of the team is tarnished because any failure, regardless of who is at fault, will be perceived as a mistake by the team.

26

Results of Incorrect RequirementsSlide27

Consistent – requirements are not conflicting or ambiguous.Complete

– requirements describe all possible system inputs and responses.Feasible – requirements can be satisfied based on the available resources and constraints.Required – requirements are truly needed and fulfill the purpose of the system.

Accurate

– requirements are stated correctly.

Traceable

– requirements directly map to the functions and features of the system.

Verifiable

– requirements are defined so they can be demonstrated during testing.

27

Criteria to Define System RequirementsSlide28

Problem discovery and analysis Requirements discovery Documenting and analyzing requirements

Requirements management to handle changes28

The Process of Requirements DiscoverySlide29

Analyzing requirements to resolve problems of:Missing requirementsConflicting requirements

Infeasible requirementsOverlapping requirementsAmbiguous requirementsFormalizing requirementsRequirements definition documentCommunicated to stakeholders or steering body

29

Analyzing RequirementsSlide30

A requirements definition document should consist of the following:The functions and services that the system should provide.

Nonfunctional requirements including the system’s features, characteristics, and attributes.The constraints that restrict the development of the system or under which the system must operate.Information about other systems that the system must interface with.

 

30

Documenting RequirementsSlide31

Sampling of existing documentation, forms, and databases. Research and site visits. Observation of the work environment.

Questionnaires. Interviews. Discovery Prototyping. Joint requirements planning (JRP) / Joint application development (JAD)

31

Fact-Finding MethodsSlide32

Joint requirements planning (JRP) – a process whereby highly structured group meetings

(having defined agenda, key representatives) are conducted for the purpose of analyzing problems and defining requirements. (JRP is a subset of a more comprehensive joint application development or JAD technique that encompasses the entire systems development process

).

32

Joint Requirements PlanningSlide33

Model-driven AnalysisStructured analysis

Information engineeringObject-oriented analysisAccelerated Systems AnalysisDiscovery prototyping

Rapid Architected Analysis

33

Systems Analysis ApproachesSlide34

Model-driven Analysis

emphasizes the drawing of graphical system models to document and validate both existing and/or proposed systems. Ultimately, the system model becomes the blueprint for designing and constructing an improved system.

34

Model-Driven AnalysisSlide35

35

Model-Driven Methods

Structured Analysis:

a PROCESS-centered technique to analyze an existing system and define business requirements for a new system

.

The models illustrate the system’s components:

processes

(functions, tasks) and their associated

inputs

,

outputs

, and

files

Information Engineering (IE)

:

a DATA-centered, but process-sensitive technique to plan, analyze, and design information systems. IE illustrate and synchronize the system’s

data

and

processes

.

Object-oriented Analysis (OOA)

: a technique that integrates data and process concerns into constructs called OBJECTS

.

OOA illustrate the system’s objects from various perspectives such as

structure

and

behavior

.

Slide36

36

Accelerated Systems Analysis

Accelerated Systems Analysis

approaches emphasize the construction of prototypes to more rapidly identify business and user requirements for a new system

Discovery Prototyping

Rapid Architected AnalysisSlide37

37

Discovery Prototyping

Discovery Prototyping

– a technique used to identify the users’ business requirements by building a small-scale, representative or working model of the users’ requirements in order to discover or verify them.

Advantages

Prototypes cater to the “I’ll know what I want when I see it” way of thinking that is characteristic of many users and managers

Disadvantages

Can become preoccupied with final “look and feel” prematurely

Can encourage a premature focus on, and commitment to, design

Users can be misled to believe that the completed system can be built rapidly using prototyping toolsSlide38

38

Rapid Architected Analysis

Rapid Architected Analysis

– derive system models from existing systems or discovery prototypes.

Reverse Engineering

– the use of technology that reads the program code for an existing database, application program, and/or user interface and automatically generates the equivalent system model.