Systems Analysis & Design CSUN Information Systems Systems Analysis & Design http://www.csun.edu/~dn58412/IS431/IS431_SP15.htm System Analysis Overview IS 431: Lecture 3

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 No additional notes IS 431 : Lecture 3

System Development IS 431 : Lecture 3

System Analysis IS 431 : Lecture 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.) IS 431 : Lecture 3

Context of System Analysis IS 431 : Lecture 3

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

Model-Driven Methods Structured Analysis (Waterfall) : 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

A Simple Process Model IS 431 : Lecture 3

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

A Simple Data Model IS 431 : Lecture 3

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

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

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 :derive system models from existing systems or discovery prototypes. IS 431 : Lecture 3

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

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

Agile Methods … Agile methodology aims for customer satisfaction through early and continuous delivery of useful application software components developed by an iterative process using the bare minimum requirements Iterative development – Consists of a series of tiny projects IS 431 : Lecture 3

Extreme Programming Extreme Programming (XP) – Breaks a project into tiny phases, and developers cannot continue on to the next phase until the first phase is complete IS 431 : Lecture 3

Rational Unified Process (RUP) Rational Unified Process (RUP) – Provides a framework for breaking down the development of software into four gates Gate One: Inception Gate Two: Elaboration Gate Three: Construction Gate Four: Transition IS 431 : Lecture 3

SCRUM SCRUM – Uses small teams to produce small pieces of deliverable software using sprints, or 30- day intervals, to achieve an appointed goal Under this methodology, each day ends or begins with a stand-up meeting to monitor and control the development effort IS 431 : Lecture 3

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

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

Scope Definition Phase IS 431 : Lecture 3

Scope Definition Tasks IS 431 : Lecture 3

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

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

Problem Statement IS 431 : Lecture 3

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

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

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

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

Problem Analysis Phase IS 431 : Lecture 3

Problem Analysis Tasks No additional notes IS 431 : Lecture 3

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 No additional notes IS 431 : Lecture 3

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) No additional notes IS 431 : Lecture 3

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 No additional notes IS 431 : Lecture 3

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 No additional notes IS 431 : Lecture 3

PROBLEMS, OPPORTUNITIES, OBJECTIVES, AND CONSTRAINTS MATRIX No additional notes IS 431 : Lecture 3

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 No additional notes IS 431 : Lecture 3

2. Problem Analysis Phase … Task 2.6: Present Findings and Recommendations Deliverable: system improvement objectives Decision: continue/adjust/cancel current project No additional notes IS 431 : Lecture 3

Requirements Analysis Phase IS 431 : Lecture 3

Requirements Analysis Tasks IS 431 : Lecture 3

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

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

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

Logical Design Phase IS 431 : Lecture 3

Logical Design Tasks No additional notes. IS 431 : Lecture 3

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

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

Consolidated Requirements Statement No additional notes IS 431 : Lecture 3

Decision Analysis Phase IS 431 : Lecture 3

Decision Analysis Tasks No additional notes. IS 431 : Lecture 3

5. Decision Analysis Phase Task 5.1: Identify Candidate Solutions Identify all possible candidate solutions Deliverable: candidate systems (solutions) matrix (Fig 5.19) No additional notes IS 431 : Lecture 3

Candidate Systems Matrix No additional notes IS 431 : Lecture 3

Candidate Systems Matrix.. No additional notes IS 431 : Lecture 3

5. Decision Analysis Phase … 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) No additional notes IS 431 : Lecture 3

Feasibility Analyses Technical feasibility. Is the solution technically practical? Does our staff have the technical expertise to design and build this solution? Operational feasibility. Will the solution fulfill the users’ requirements? To what degree? How will the solution change the users’ work environment? How do users feel about such a solution? Economic feasibility. Is the solution cost-effective? Schedule feasibility. Can the solution be designed and implemented within an acceptable time period? No additional notes IS 431 : Lecture 3

5. Decision Analysis Phase … Task 5.3: Compare Candidate Solutions Select the candidate solution having the “best overall” combination of technical, operational, economic, and schedule feasibilities Feasibility matrix (Fig 5.20) Deliverable: recommended solution No additional notes IS 431 : Lecture 3

Feasibility Matrix No additional notes IS 431 : Lecture 3

5. Decision Analysis Phase … Task 5.4: Update the Project Plan Input: recommended solution Review and update the latest project schedule and resource assignments Deliverable: updated project plan No additional notes IS 431 : Lecture 3

5. Decision Analysis Phase … Task 5.5: Recommend a Solution Deliverable: System Proposal No additional notes IS 431 : Lecture 3

The Importance of Requirements Discovery System requirement (business requirement) is a description of the needs and desires for an information system. A requirement may describe functions, features (attributes), and constraints. Functional requirements: functions or features that must be included in an information system in order to satisfy the business need and be acceptable to the users. Nonfunctional requirements: features, characteristics, and attributes of the system as well as any constraints that may limit the boundaries of the proposed solution. Use PIECES framework for classification. No additional notes. IS 431 : Lecture 3

PIECES Classification of System Requirements No additional notes. IS 431 : Lecture 3

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 production, 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 on the team is tarnished because any failure, regardless of who is at fault, will be perceived as a mistake by the team. No additional notes. IS 431 : Lecture 3

Relative Cost to Fix an Error IS 431 : Lecture 3

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. No additional notes IS 431 : Lecture 3

The Process of Requirements Discovery Problem discovery and analysis Requirements discovery Documenting and analyzing requirements Requirements management to handle changes IS 431 : Lecture 3

Ishikawa Diagram The Ishikawa diagram: graphical tool to identify, explore, and depict problems, causes and effects of those problems. (Also called a cause-and-effect diagram or a fishbone diagram.) IS 431 : Lecture 3

Ishikawa Diagram … Four M’s: Four P’s: Four S’s: Materials, Machines, Manpower, and Methods Four P’s: Places, Procedures, Policies, and People Four S’s: Surroundings, Suppliers, Systems, and Skills IS 431 : Lecture 3

Context of Requirements for an Information System USER ORGANIZATION SYSTEM TASK TOOL IS 431 : Lecture 3

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 No additional notes. IS 431 : Lecture 3

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.     No additional notes. IS 431 : Lecture 3

Requirements Management Requirements management - the process of managing change to the requirements. Over the lifetime of the project it is very common for new requirements to emerge and existing requirements to change. Studies have shown that over the life of a project as much as 50 percent or more of the requirements will change before the system is put into production. IS 431 : Lecture 3

Fact-Finding Methods Sampling of existing documentation, forms, and databases. Research and site visits. Observation of the work environment. Questionnaires. Interviews. Prototyping. Joint requirements planning (JRP). IS 431 : Lecture 3

Discovery Prototyping Discovery prototyping – the act of building a small-scale, representative or working model of the users’ requirements in order to discover or verify those requirements. Advantages Disadvantages IS 431 : Lecture 3

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. IS 431 : Lecture 3

Benefits of JRP JRP actively involves users and management in the development project (encouraging them to take “ownership” in the project). JRP reduces the amount of time required to develop systems. JRP incorporates the benefits of prototyping as a means for confirming requirements and obtaining design approvals. IS 431 : Lecture 3