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Systems Analysis & Design

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  1. CSUN Information Systems Systems Analysis & Design http://www.csun.edu/~dn58412/IS431/IS431_SP14.htm System Analysis Overview IS 431: Lecture 3

  2. Systems Analysis Overview • Systems Analysis vs. Systems Design • Systems Analysis Approaches • Systems Analysis Phases (purposes, participants, inputs, outputs, techniques, and steps) • Scope Definition • Problem Analysis • Requirements Analysis • Logical Design • Decision Analysis • User Requirements Discovery IS 431 : Lecture 3

  3. System Development IS 431 : Lecture 3

  4. System Analysis IS 431 : Lecture 3

  5. 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.) IS 431 : Lecture 3

  6. Context of System Analysis IS 431 : Lecture 3

  7. 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. IS 431 : Lecture 3

  8. Model-Driven Methods Structured Analysis: a model-driven, 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. IS 431 : Lecture 3

  9. A Simple Process Model IS 431 : Lecture 3

  10. Model-Driven Methods… Information Engineering (IE):a model-driven and DATA-centered, but process-sensitive (context specific) technique to plan, analyze, and design information systems. IE illustrate and synchronize the system’s data and processes. IS 431 : Lecture 3

  11. A Simple Data Model IS 431 : Lecture 3

  12. Model-Driven Methods… Object-oriented Analysis (OOA): a model-driven 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. IS 431 : Lecture 3

  13. STUDENT COURSE -ID Number -Name -Subject -Grade Point Average -Number 0..* has record for> -Title -Credit +Admit() 0..* +Regsiter for Classes() +Withdraw() +Create a Course() +Change Address() +Delete from Course Master() 1 +Calculate GPA() +Change in Course Master() 1 +Graduate() TRANSCRIPT COURSE -Semester -Division -Grade +Add() +Drop() +Complete() +Change Grade() A Simple Object Model IS 431 : Lecture 3

  14. 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 IS 431 : Lecture 3

  15. Discovery Prototyping Discovery Prototyping – a technique used to identify the users’ business requirements by having them react to a quick-and-dirty implementation of those requirements. • 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 IS 431 : Lecture 3

  16. 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. IS 431 : Lecture 3

  17. Agile Methods Agile Method – the integration of various approaches of systems analysis and design for applications as deemed appropriate to the problem being solved and the system being developed. • Most commercial methodologies do not impose a single approach (structured analysis, IE, OOA) on systems analysts. • Instead, they integrate all popular approaches into a collection of agile methods. • System developers are given the flexibility to select from a variety of tools and techniques to best accomplish the tasks at hand, IS 431 : Lecture 3

  18. Classic Systems Analysis Phases • Scope Definition Phase • Is the project worth looking at, for WHAT? • Problem Analysis Phase • Is a new system worth building, for WHAT? • Requirements Analysis Phase • WHAT do the users need and want from the new system? • Logical Design Phase • WHAT must the new system do? • Decision Analysis Phase • WHAT is the best solution among others? IS 431 : Lecture 3

  19. Systems Analysis Phases • Scope Definition Phase : WHAT PROBLEM • Is the project worth looking at to solve problem? • Problem Analysis Phase:WHAT ISSUES • Is the new system worthwhile to build? • Requirements Analysis Phase: WHAT REQUIREMENTS • What do users need and want from the new system? • Logical Design Phase: WHAT TO DO • What the new system must do to satisfy user’s needs? • Decision Analysis Phase: WHAT SOLUTION • What is the best available solution for the business? IS 431 : Lecture 3

  20. Scope Definition Phase IS 431 : Lecture 3

  21. Scope Definition Tasks IS 431 : Lecture 3

  22. 1. Scope Definition Phase • Task 1.1: Identify Problems, Opportunities, and Directives (POD) • Input: Request for System Service (Fig 5.7) • Deliverable: Preliminary Problem Statement (Fig 5.8) • Urgency, Visibility, Benefits, Priority, Possible Solutions IS 431 : Lecture 3

  23. System Improvement Objectives • Objective – a measure of success. It is something (measurable) that we expect to achieve, if given sufficient resources. • Reduce the number of uncollectible customer accounts by 50 percent within the next year. • Increase by 25 percent the number of loan applications that can be processed during an eight-hour shift. • Decrease by 50 percent the time required to reschedule a production lot when a workstation malfunctions. • Constraint – something that will limit our flexibility in defining a solution to our objectives. Essentially, constraints cannot be changed. • The new system must be operational by April 15. • The new system cannot cost more than $350,000. • The new system must be web-enabled. • The new system must bill customers every 15 days. IS 431 : Lecture 3

  24. Problem Statement IS 431 : Lecture 3

  25. 1. Scope Definition Phase ... • 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 • Note: if later the scope changes, the budget and schedule should be changed accordingly IS 431 : Lecture 3

  26. 1. Scope Definition Phase … • Task 1.3: Assess Project Worthiness • “Is this project worth looking at ?” • Cost/benefit analysis • Decision • Approve project • Cancel project • Renegotiate the scope of project (with adjusted budget and schedule) IS 431 : Lecture 3

  27. 1. Scope Definition Phase … • Task 1.4: Schedule and Budget Plan for Project • Deliverables: Project Charter • Master plan for the whole project: schedule and resource assignments • Detail plan and schedule for completing the next phase IS 431 : Lecture 3

  28. 1. Scope Definition Phase … • Task 1.5: Present the Project and Plan • Present and defend the project and plan before steering committee • Formally launch the project and announce the project, goals, and schedule • Deliverable: Project Charter (participants, problems, scope, methodology, statement of work to be completed, deliverables, quality standards, schedule, budget) IS 431 : Lecture 3

  29. Problem Analysis Phase IS 431 : Lecture 3

  30. Problem Analysis Tasks IS 431 : Lecture 3

  31. 2. Problem Analysis Phase • Task 2.1: Study the Problem Domain • Understanding of the problem domain and business vocabulary • DATA: currently stored data, their business terms • PROCESSES: current business events • INTERFACES: current locations and users • Deliverables: definition of system domain / models of Current System IS 431 : Lecture 3

  32. 2. Problem Analysis Phase … • Task 2.2: Analyze Problems and Opportunities • Study causes and effects of each problem (Note: an effect may be the cause of other problems) • Deliverables: updated problem statements and the cause-effect analyses for each problem and opportunities (Fig 5.11) IS 431 : Lecture 3

  33. 2. Problem Analysis Phase … • Task 2.3: Analyze Business Processes (for BPR) • Measure the value added or subtracted by each process as it relates to the total organization • Volume of throughput, response time, bottlenecks, cost, value added, consequences of eliminating or streamline of the process • Deliverable: current business process models IS 431 : Lecture 3

  34. 2. Problem Analysis Phase … • Task 2.4: Establish System Improvement Objectives • Define specific system improvement objectives and constraints for each problem • Objectives to be precise, measurable • Constraints in terms of schedule, cost, technology, policy • Deliverable: System Improvement Objectives and Recommendations Report IS 431 : Lecture 3

  35. PROBLEMS, OPPORTUNITIES, OBJECTIVES, AND CONSTRAINTS MATRIX IS 431 : Lecture 3

  36. 2. Problem Analysis Phase … • Task 2.5: Update the Project Plan • Update project: • Reduce the scope to keep only higher priority objectives to meet a deadline/budget • Expanse the scope and adjust schedule and budget accordingly • Deliverable: updated project plan IS 431 : Lecture 3

  37. 2. Problem Analysis Phase … • Task 2.6: Present Findings and Recommendations • Deliverable: system improvement objectives • Decision: continue/adjust/cancel current project IS 431 : Lecture 3

  38. Requirements Analysis Phase IS 431 : Lecture 3

  39. Requirements Analysis Tasks IS 431 : Lecture 3

  40. 3. Requirements Analysis Phase • Task 3.1: Identify System Requirements • Functional requirements: activities and services providing 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 IS 431 : Lecture 3

  41. 3. Requirements Analysis Phase … • 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. IS 431 : Lecture 3

  42. 3. Requirements Analysis Phase … • 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) IS 431 : Lecture 3

  43. Logical Design Phase IS 431 : Lecture 3

  44. Logical Design Tasks IS 431 : Lecture 3

  45. 4. Logical Modeling Phase • Task 4.1: Analyze Functional Requirements • Logical systems models: WHAT the system must do (not HOW) • Separation of business concerns from technical solutions will help considering many different ways for business processes improvement and alternative technical solutions • 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. IS 431 : Lecture 3

  46. 4. Logical Modeling Phase … • 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 IS 431 : Lecture 3

  47. Consolidated Requirements Statement IS 431 : Lecture 3

  48. Decision Analysis Phase IS 431 : Lecture 3

  49. Decision Analysis Tasks IS 431 : Lecture 3

  50. 5. Decision Analysis Phase • Task 5.1: Identify Candidate Solutions • Identify all possible candidate solutions • Deliverable: candidate systems (solutions) matrix (Fig 5.19) IS 431 : Lecture 3