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System Analysis Overview approaches, phases and requirements discovery

System Analysis Overview approaches, phases and requirements discovery. Karolina Muszyńska. 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

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System Analysis Overview approaches, phases and requirements discovery

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  1. System Analysis Overviewapproaches, phases and requirements discovery Karolina Muszyńska Based on http://www.csun.edu/~dn58412/IS431/IS431_SP13.html

  2. Systems Analysis Overview Systems Analysis vs. Systems Design Systems Analysis Phases and Tasks User Requirements Discovery Systems Analysis Approaches

  3. System Analysis

  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.

  5. Context of System Analysis

  6. 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?

  7. Scope Definition Phase

  8. Scope Definition Tasks

  9. 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

  10. 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)

  11. Problem Analysis Phase

  12. Problem Analysis Tasks

  13. 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 cause-effect analyses for each problem and opportunities • Task 2.3: Analyze Business Processes • Deliverable: current business process models

  14. 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

  15. Requirements Analysis Phase

  16. Requirements Analysis Tasks

  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 objectives

  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)

  19. Logical Design Phase

  20. Logical Design Tasks

  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 requirements

  22. Decision Analysis Phase

  23. Decision Analysis Tasks

  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)

  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 Proposal

  26. 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.

  27. 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.

  28. The Process of Requirements Discovery Problem discovery and analysis Requirements discovery Documenting and analyzing requirements Requirements management to handle changes

  29. 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

  30. Documenting Requirements 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.

  31. 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)

  32. 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).

  33. Systems Analysis Approaches • Model-driven Analysis • Structured analysis • Information engineering • Object-oriented analysis • Accelerated Systems Analysis • Discovery prototyping • Rapid Architected Analysis

  34. 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.

  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.

  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 Analysis

  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 tools

  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.

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