approaches phases and requirements discovery Karolina Muszyńska Based on httpwwwcsunedudn58412IS431IS431SP13html Systems Analysis vs Systems Design Systems Analysis Phases and Tasks ID: 494459
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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
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Systems Analysis OverviewSlide3
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System AnalysisSlide4
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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
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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)
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1.
Scope Definition Tasks…Slide11
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Problem Analysis Phase Slide12
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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
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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
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2. Problem Analysis Tasks…Slide15
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Requirements Analysis PhaseSlide16
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Requirements Analysis TasksSlide17
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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
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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
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Logical Design Phase Slide20
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Logical Design TasksSlide21
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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
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Decision Analysis PhaseSlide23
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Decision Analysis TasksSlide24
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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
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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.
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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.
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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
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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.
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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)
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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
).
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Joint Requirements PlanningSlide33
Model-driven AnalysisStructured analysis
Information engineeringObject-oriented analysisAccelerated Systems AnalysisDiscovery prototyping
Rapid Architected Analysis
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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.
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Model-Driven AnalysisSlide35
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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
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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
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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
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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.