System Analysis Overview approaches, phases and requirements ...
System Analysis Overview approaches, phases and requirements discovery Karolina Muszyska Based on http://www.csun.edu/~dn58412/IS431/IS431_SP13.html Systems Analysis Overview Systems Analysis vs. Systems Design
Systems Analysis Phases and Tasks User Requirements Discovery Systems Analysis Approaches 2 System Analysis 3
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.
4 Context of System Analysis 5 Classic Systems Analysis Phases Scope Definition Phase WHAT PROBLEM Is 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 Scope Definition Phase 7 Scope Definition Tasks 8 1. Scope Definition Tasks
Task 1.1: Identify Problems, Opportunities, and Directives Deliverable: Preliminary Problem Statement Task 1.2: Negotiate Preliminary Scope Deliverable: 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 Task 1.3: Assess Project Worthiness Cost/benefit analysis Decision: approve, cancel, renegotiate the scope Task 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 Problem Analysis Phase 11 Problem Analysis Tasks
12 2. Problem Analysis Tasks Task 2.1: Study the Problem Domain DATA: 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 causeeffect analyses for each problem and opportunities Task 2.3: Analyze Business Processes Deliverable: current business process models 13 2. Problem Analysis Tasks Task 2.4: Establish System Improvement Objectives Deliverable: 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
Requirements Analysis Phase 15 Requirements Analysis Tasks 16 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 objectives 17 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) 18
Logical Design Phase 19 Logical Design Tasks 20 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.
Task 5.1: Identify Candidate Solutions o Deliverable: candidate systems (solutions) matrix Task 5.2: Analyze Candidate Solutions o Feasibility analysis is performed on each individual candidate without regard to the feasibility of other candidates - technical, operational, economic, schedule
Task 5.4: Update the Project Plan o Review and update the latest project schedule and resource assignments o Deliverable: updated project plan Task 5.5: Recommend a Solution Deliverable: System Proposal
25 Results of Incorrect Requirements 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 Criteria to Define System Requirements
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 The Process of Requirements Discovery Problem discovery and analysis Requirements discovery
Documenting and analyzing requirements Requirements management to handle changes 28 Analyzing Requirements Analyzing requirements to resolve problems of: Missing requirements Conflicting requirements Infeasible requirements
Overlapping requirements Ambiguous requirements Formalizing requirements Requirements definition document Communicated to stakeholders or steering body 29 Documenting Requirements A requirements definition document should consist of the following: The functions and services that the system
should provide. Nonfunctional requirements including the systems 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 Fact-Finding Methods 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 Joint Requirements Planning 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 Systems Analysis Approaches Model-driven Analysis Structured analysis Information engineering
Object-oriented analysis Accelerated Systems Analysis Discovery prototyping Rapid Architected Analysis 33 Model-Driven Analysis 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 Methods Structured Analysis: a PROCESS-centered technique to analyze an existing system and define business requirements for a new system. The models illustrate the systems 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 systems data and processes. Object-oriented Analysis (OOA): a technique that integrates data and process concerns into constructs called OBJECTS. OOA illustrate the systems objects from various perspectives such as structure and behavior. 35
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 Analysis 36 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 Ill 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 tools 37 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. 38
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