Systems Analysis and Design: Elements, Characteristics, and Components
SYSTEMS ANALYSIS AND DESIGN :
Systems Analysis and Design is the complex, challenging, and stimulating organizational process that a team of business and systems professionals uses to develop and maintain computer-based information systems. System Analysis – Process of gathering and interpreting facts, diagnosing problems, and using the facts to improve the system. Systems Design. Process of planning a new system to replace or complement the old. Analysis specifies what the system should do and design states how to achieve the objective
Elements of the system
Outputs and Inputs: A major objective of a system is to produce an output that has value to its user. Inputs are the elements that enter the system for processing and output is the outcome of the processing. Processors: The processor is the element of the system that involves the actual transformation of input into output. It is the operational component of a system. Processors modify the input totally or partially. Control: The control element guides the system. It is the decision-making subsystem that controls the pattern of activities governing input, processing, and output. Feedback: Control in a dynamic system is achieved by feedback. Feedback may be positive or negative routine or informational. Environment: It is the source of external elements that impinge on the system. It determines how a system must function. Boundaries and Interfaces: A system should be defined by its boundaries- the limits that identify its components, process, and interrelationship when it interfaces with another system.
The Characteristics of a system are: Organisation: It implies structure and order. It is the arrangement of components that helps to achieve objectives. Interaction: It refers to the manner in which each component functions with other components of the system. Interdependence: It means that parts of the organization or computer system depend on one another. They are coordinated, and linked together according to a plan. Integration: It refers to the completeness of systems. It is concerned with how a system is tied together. It is more than sharing a physical part or location. Central Objective: Objectives may be real or stated. Although a stated objective may be the real objective, it is not uncommon for an organization to state one objective and operate to achieve another.
Typical Components of Information Systems
Hardware: Computer-based information systems use computer hardware, such as processors, monitors, keyboard, and printers. Software: These are the programs used to organize, process, and analyze data. Databases: Information systems work with data, organized into tables and files. Network: Different elements need to be connected to each other, especially if many different people in an organization use the same information system. Procedures: These describe how specific data are processed and analyzed in order to get the answers for which the information system is designed.
Roles of system analyst:
1. System analyst and consultant. 2. System analyst as supporting expert. 3. System analyst as Agent of Change.
SYSTEM DEVELOPMENT LIFE CYCLE :
Planning: Priorities for systems and projects, an architecture for data, networks, and selection hardware, and information systems management are the result of associated systems Detailed steps, or work plan, for project Specification of system scope and planning and high-level system requirements or features. Analysis Description of the current system and where problems or opportunities exist, with a general recommendation on how to fix enhance, or replace the current system. Explanation of alternative systems and justification for the chosen alternative. Design: Functional, detailed specifications of all system elements (data, processes, inputs, and outputs). Technical, detailed specifications of all system elements (programs, files network, system software, etc.). Acquisition plan for new technology. Implementation: Code documentation, training procedures, and support capabilities. Maintenance: New versions or releases of software with associated updates to documentation, training, and support.
WATERFALL MODEL:
Waterfall model (sometimes called classic life cycle or the linear sequential model) is the oldest and the most widely used paradigm for information systems development. Application: 1. Requirements are very well documented, clear and fixed 2. Product definition is stable 3. Technology is understood and is not. 4. The project is short.
advantages of waterfall model.
1. Simple and easy to understand and use. 2. Phases are processed and completed one at a time. 3. Clearly defined stages. 4. Well understood milestones. 5. Easy to arrange tasks. 6. Process and results are well documented.
Disadvantages of waterfall model:
1. High amounts of risk and uncertainty. 2. Not a good model for complex and object-oriented projects. 3. Poor model for long and ongoing projects. 4. It is difficult to measure progress within stages. 5. No working software is produced until late in the life cycle.
CASE TOOLS:
Computer-aided systems engineering (CASE), also called computer-aided software engineering, is a technique that uses powerful software, called CASE tool, to help systems analysts develop and maintain information systems. Types of case tools: 1. Diagram tools. 2. Computer display and report generate. 3. Analysis tools. 4. Central repository. 5. Code generate
Prototype Approach:
The Prototyping Model is a methodology that is treated as a model for software development where a prototype, which is a premature approximated sample of the final product, is constructed and then tested. Model has two types. 1. Rapid Throwaway Prototyping. In this method, developers can explore the ideas as get proper customer feedback. 2. Evolutionary Prototyping: Here your developed prototype will primarily be Advantages of incremented for refining on the foundation of customer opinion until the final one gets aspect. Phases of the prototyping model: 1. Requirement gathering, 2. Quick Decision, 3. Build prototype, 4. User evaluation, 5. Refining prototype. Engineer product.
SPIRAL APPROACH:
The spiral development model is a risk-driven process model generator that is used to guide multi-stakeholder concurrent engineering of software-intensive systems. It has two main distinguishing features. Phases of the spiral model: 1. Objectives determination and identify alternative solutions. 2. Identify and resolve Risks. 3. Develop the next version of the Product. 4. Review and plan for the next Phase. Advantages of Spiral Model: 1. High amount of risk analysis. 2. Large and mission-critical projects. 3. Strong approval and documentation control. 4. Additional Functionality can be added at a later date. 5. Software is produced early in the software life cycle.
Disadvantages of Spiral Model
1. Can be a costly model to use. 2. Risk analysis requires highly specific expertise. 3. Project’s success is highly dependent on the risk analysis phase. 4. Doesn’t work well for smaller projects.
Agile Development Approach:
The Agile software development model was mainly intended for helping developers build a project that can adapt to transforming requests quickly. So the most important endeavor for developing the Agile model is to make easy and rapid project achievement. Stage of Agile Development process: 1. Exploration, 2. Planning, 3. Iteration of the first Release, 4. Productioning, 5. Maintenance.
agile development model advantages
1. Flexibility. 2. Faster time to market. 3. Collaboration. 4. Customer satisfaction.
Identification and selecting SDP
Project identification and selections senior manager, a business group, an IS manager, or a steering committee-identifies and ascertains possible systems development projects that an organizational unit could undertake.
Value chain Analysis
An important project evaluation method that is widely used for assessing information systems complex development projects is called value chain analysis.
Possible Evaluation criteria when classifying and ranking project.
Evaluation Criteria | Description
Value Chain Analysis: Extent to which activities add value and costs when developing products and/or services
Strategic Alignment: Extent to which the project is viewed as helping the organization activities and long-term goals
Potential Benefits: Extent to which the project is viewed as improving profits, customer service, etc., and the duration of these benefits
Resource Availability: Amount and type of resources the project requires and their availability
Project Size/Duration: Number of individuals and the length of time needed to complete the project
Technical Difficulty/Risks: Level of technical difficulty to successfully complete the project within given time and resource constraints
General Competitive Strategies:
Strategy | Description
Low-Cost Producer: This strategy reflects competing in an industry on the basis of product or service cost to the consumer. For example, in the automobile industry, the South Korean-produced Hyundai is a product line that competes on the basis of low cost.
Product Differentiation: This competitive strategy reflects capitalizing on a key product criterion requested by the market (for example, high quality, style, performance roominess). In the automobile industry, many manufacturers are trying to differentiate their products on the basis of quality.
Product Focus or Niche: This strategy is similar to both the low-cost and differentiation strategies but with a much narrower market focus. For example, a niche market in the automobile industry is the convertible sports car market. Within the market, some manufacturers may employ a low-cost strategy and others may employ a differentiation strategy based on performance or style.
Advantages to the top-down planning approach over other planning approaches
Advantages | Description
Broader Perspective: If not viewed from the top, information systems may be implemented without first understanding the business from a general management viewpoint.
Improve Integration: If not viewed from the top, totally new management information systems may be implemented rather than planning how to evolve existing systems.
Improved Integration: If not viewed from the top, planners may lack sufficient management acceptance of the role of information systems in helping them achieve business objectives. Better Understanding: If not viewed from the top, planners may lack the understanding necessary to implement information systems across the entire business rather than simply to individual operating units.
Commonly used economical cost-benefit analysis techniques
Analysis Technique | Description
Net Present Value (NPV): NPV uses a discount rate determined from the company’s cost of capital to establish the present value of a project. The discount rate is used to determine the present value of both cash receipts and outlays. Return of Investment (ROI): ROI is the ratio of the net cash receipts of the project divided by the cash outlays of the project. Trade-off analysis can be made among projects competing for investment by comparing their representative ROI ratios. Break Even Analysis: BEA finds the amount of time required for the cumulative cash flow from a project to equal its initial and ongoing investment
Better Understanding