System Analysis and Design PDF

**AISPrE 2: REVIEWER** **MODULE 1:** **System Analysis and Design** **[SYSTEM DEVELOPMENT] -** is systematic process which includes phases such as planning, analysis, design, deployment, and maintenance. System Analysis and Design (SAD) mainly focuses on: **[System Analysis]** It is a proces...

**AISPrE 2: REVIEWER** **MODULE 1:** **System Analysis and Design** **[SYSTEM DEVELOPMENT] -** is systematic process which includes phases such as planning, analysis, design, deployment, and maintenance. System Analysis and Design (SAD) mainly focuses on: **[System Analysis]** It is a process of collecting and interpreting facts, identifying the problems, and decomposition of a system into its components. **[System Design]** It is a process of planning a new business system or replacing an existing system by defining its components or modules to satisfy the specific requirements. **What is a [System]?** The word System is derived from Greek word Systema,which means an **[organized relationship]** between any set of components to achieve some common cause or objective. A system is "an **orderly grouping** of interdependent components linked together according to a plan to achieve a specific goal." **[Properties of a System:]** **ORGANIZATION -** It implies structure and order. It is the arrangement of components that helps to achieve predetermined objectives. **INTERACTION -** It is defined by the manner in which the components operate with each other. **INTERDEPENDENCE** - It means how the components of a system depend on one another. **INTEGRATION** - It is concerned with how a system components are connected together. **CENTRAL OBJECTIVE** - The objective of system must be central. It may be real or stated. It is not uncommon for an organization to state an objective and operate to achieve another. **[Elements of a System:]** **Inputs** - are the information that enters into the system for processing. **Output** - is the outcome of processing. **Processor** - It involves the actual transformation of input into output. It is the operational component of a system. Processors may modify the input either totally or partially, depending on the output specification. **Control** - It guides the system. It is the decision--making subsystem for the pattern of activities governing input, processing, and output. **Feedback** - It provides the control in a dynamic system. **Positive feedback** encourages the performance of the system. **Negative feedback** provides the controller with information for action. **[TYPES OF SYSTEM:]** **PHYSICAL OR ABSTRACT SYSTEMS** - **[PHYSICAL SYSTEMS]** are tangible entities. We can touch and feel them. Physical System may be static or dynamic in nature.(ex: desks & chairs.) - **[ABSTRACT SYSTEMS]** are non physical entities or conceptual that may be formulas, representation or model of a real system. **OPEN OR CLOSED SYSTEMS** - **[OPEN SYSTEM]** must interact with its environment. It receives inputs from and delivers outputs to the outside of the system. - **[CLOSED SYSTEM]** does not interact with its environment. It is isolated from environmental influences. **ADAPTIVE AND NON ADAPTIVE SYSTEM** - **[ADAPTIVE SYSTEM]** responds to the change in the environment in a way to improve their performance and to survive.(ex: human beings, animals.) - **[NON ADAPTIVE SYSTEM]** is the system which does not respond to the environment.(ex: machines.) **PERMANENT OR TEMPORARY SYSTEM** - **[PERMANENT SYSTEM]** - persists for long time.(ex: business policies.) - **[TEMPORARY SYSTEM]** - is made for specified time and after that they are demolished.(ex: A DJ system is set up for a program and it is dissembled after the program.) **NATURAL & MANUFACTURED SYSTEM** - **[NATURAL SYSTEMS]** - are created by the nature.(ex: Solar system, seasonal system. - **[MANUFACTURED SYSTEM]** - is the man-made system.(ex: Rockets, dams, trains. **DETERMINISTIC OR PROBABILISTIC SYS.** - **[DETERMINISTIC SYSTEM]** - operates in a predictable manner and between system components is known with certainty. - **[PROBABILISTIC SYSTEM]** - shows uncertain behavior. The exact output is not known.(ex: Weather forecasting, mail delivery.) **SOCIAL, HUMAN-MACHINE, MACHINE SYSTEM** - **[SOCIAL SYSTEM]** - is made up of people.(ex: social clubs, societies.) - **[HUMAN-MACHINE SYSTEM]** - both human and machines are involved to perform a particular task.(ex: Computer programming.) - **[MACHINE SYSTEM]** - is where human interference is neglected. All the tasks are performed by the machine.(ex: an autonomous robot.) **MAN--MADE INFORMATION SYSTEMS** \- It is an interconnected set of information resources to manage data for particular organization, under Direct Management Control (DMC). \- This system includes hardware, software, communication, data, and application for producing information according to the need of an organization. **Man-made information systems are divided into [three types:]** - **FORMAL INFORMATION SYSTEM**− It is based on the flow of information in the form of memos, instructions, etc. - **INFORMAL INFORMATION SYSTEM** − This is employee based system which solves the day to day work related problems. - **COMPUTER BASED SYSTEM** − This system is directly dependent on the computer for managing business applications.(ex: automatic library system, and banking system.) **[SYSTEM MODELS]** - **SCHEMATIC MODELS -** A schematic model is a 2-D chart that shows system elements and their linkages. - **FLOW SYSTEM MODELS** - A flow system model shows the orderly flow of the material, energy, and information that hold the system together. - **STATIC SYSTEM MODELS** - They represent one pair of relationships such as activity-- time or cost--quantity. The Gantt chart (ex: gives a static picture of an activity time relationship.) - **DYNAMIC SYSTEM MODEL** -Business organizations are dynamic systems. A dynamic model approximates the type of organization or application that analysts deal with. **[Categories of Information]** - **STRATEGIC INFORMATION** - This information is required by topmost management for long range planning policies for next few years.(ex: trends in revenues, financial investment, and human resources, and population growth.) This type of information is achieved with the aid of Decision Support System (DSS). - **MANAGERIAL INFORMATION** - This type of Information is required by middle management for short and intermediate range planning which is in terms of months.(ex: sales analysis, cash flow projection, and annual financial statements.) It is achieved with the aid of Management Information Systems (MIS). - **OPERATIONAL INFORMATION** - This type of information is required by low management for daily and short term planning to enforce day-to-day operational activities.(ex: keeping employee attendance records, overdue purchase orders, and current stocks available. It is achieved with the aid of Data Processing Systems (DPS). **MODULE 2:** **System Development Life Cycle** **System Development Life Cycle (SDLC) -** is a conceptual model which includes policies and procedures for developing or altering systems throughout their life cycles. **[PHASES OF SDLC]** - is a systematic approach which explicitly breaks down the work into phases that are required to implement either new or modified Information System. - **PLANNING:** obtain approval for project, Initiate, Assess feasibility, plan, schedule. - **ANALYSIS:** Understand business needs and processing needs. - **DESIGN:** Define solution system based on requirement and analysis decision. - **IMPLEMENTATION:** Construct, test, train users, install new system. - **MAINTENANCE/SUPPORT:** Keep system healthy and improve. **[System Analysts]** - is a person who is thoroughly aware of the system and guides the system development project by giving proper directions. \- He is an expert having technical and interpersonal skills to carry out development tasks required at each phase. **What are the attributes of a system analyst?** **[Interpersonal Skills]** Interface with users and programmer. Facilitate groups and lead smaller teams. Managing expectations. Good understanding, communication, selling and teaching abilities. Motivator having the confidence to solve queries. **[Analytical Skills]** System study and organizational knowledge Problem identification, problem analysis, and problem solving Sound common sense Ability to access trade-off Curiosity to learn about new organization **[Management Skills]** Understand users jargon and practices. Resource & project management. Change & risk management. Understand the management functions thoroughly. **[Technical Skills]** Knowledge of computers and software. Keep abreast of modern development. Know of system design tools. Breadth knowledge about new technologies. **MODULE 3:** **System Development Methodologies** **Software Development Methodology** - is a framework that is used to structure, plan, and control the process development of an information system. **8 Different Software Development Methodologies** - **Agile Software Development --** it is one of the best software development methods used to design a disciplined software management process which also allows some frequent alteration in the development project. **[ITERATIONS]** - It is used to minimize risk by developing software in short time boxes that generally last for one week to one month. - **DevOps Methodology** - These two departments are functioning together as a single team for all processes in the entire life-cycle. - **Scrum Software Development Mode**l - this method that allows a series of iterations in a single go. It is one of the best software development methodologies because it easily brings slowest progressing projects on track. - **Waterfall Methodology** - clarifies the software development process in a linear sequential flow.This traditional software development method is a rigid linear model. - **Prototype Methodology -** is the software development process that allows developers to create only the prototype of the solution to demonstrate its functionality to the clients. - **Feature Driven Development (FDD) -** This type of model is good for organizations that are transitioning from a phase-based approach to an iterative approach. - **Rapid Application Development (RAD)** - is an effective methodology that provides much quicker development and higher-quality results. - **Spiral Model**- is a sophisticated model that focuses on the early identification and reduction of project risks. **MODULE 4:** **System Analysis & Design System Planning** **REQUIREMENT** - is a vital feature of a new system which may include processing or capturing of data, controlling the activities of business, producing information and supporting the management. **REQUIREMENTS DETERMINATION** -involves studying the existing system and gathering details to find out what are the requirements, how it works, and where improvements should be made. **Major Activities in Requirement Determination** **REQUIREMENTS ANTICIPATION** It predicts the characteristics of system based on previous experience which include certain problems or features and requirements for a new system. **REQUIREMENTS INVESTIGATION** It is studying the current system and documenting its features for further analysis. **REQUIREMENTS SPECIFICATIONS** It includes the analysis of data which determine the requirement specification, description of features for new system, and specifying what information requirements will be provided. **Information Gathering Techniques** **INTERVIEWING -** The analyst can be formal, legalistic, play politics, or be informal; as the success of an interview depends on the skill of analyst as interviewer. It can be done in **two ways:** - - **QUESTIONNAIRES -** This method is used to gather information about large number of persons. There are **two types of questionnaires:** **OPEN-ENDED QUESTIONNAIRES** - questions that can be interpreted and lead to a specific direction of answer. **CLOSED-ENDED QUESTIONNAIRES** - It consists of questions that are used when the systems analyst effectively lists all possible responses, which are mutually exclusive. **REVIEW OF RECORDS, PROCEDURES,** **AND FORMS** Review of existing records, procedures, and forms helps to seek insight into a system which describes the current system capabilities, its operations, or activities. **OBSERVATION** This is a method of gathering information by noticing and observing the people, events, and objects. **JOINT APPLICATION DEVELOPMENT (JAD)** It is a new technique developed by IBM which brings owners, users, analysts, designers, and builders to define and design the system using organized and intensive workshops. **SECONDARY RESEARCH OR BACKGROUND** **READING** This method is widely used for information gathering by accessing the gleaned information. **FEASIBILITY STUDY** Feasibility Study can be considered as preliminary investigation that helps the management to take decision about whether study of system should be feasible for development or not. **Types of Feasibilities** **ECONOMIC FEASIBILITY** It is evaluating the effectiveness of candidate system by using cost/benefit analysis method. **OPERATIONAL FEASIBILITY** It determines whether the system is operating effectively once it is developed and implemented. **BEHAVIORAL FEASIBILITY** It evaluates and estimates the user attitude or behavior towards the development of new system. **SCHEDULE FEASIBILITY** It ensures that the project should be completed within given time constraint or schedule. **MODULE 5:** **Structured Analysis** **STRUCTURED ANALYSIS** is a development method that allows the analyst to understand the system and its activities in a logical way. **Data Flow Diagrams (DFD) or Bubble Chart -** It is a technique developed by Larry Constantine to express the requirements of system in a graphical form. It shows the flow of data between various functions of system and specifies how the current system is implemented. **BASIC ELEMENTS OF DFD** - DFD is easy to understand and quite effective when the required design is not clear and the user wants a notational language for communication.   **DECISION TREES -** are a method for defining complex relationships by describing decisions and avoiding the problems in communication. A decision tree is a diagram that shows alternative actions and conditions within horizontal tree framework. **DECISION TABLES -** are a method of describing the complex logical relationship in a precise manner which is easily understandable. It is useful in situations where the resulting actions depend on the occurrence of one or several combinations of independent conditions. It is a matrix containing row or columns for defining a problem and the actions. **COMPONENTS OF A DECISION TABLE** **Condition Stub** - It is in the upper left quadrant which lists all the condition to be checked. **Action Stub** - It is in the lower left quadrant which outlines all the action to do to meet such condition. **Condition Entry** - It is in upper right quadrant which provides answers asked in condition stub quadrant. **Action Entry** - It is in lower right quadrant which indicates the appropriate action resulting from the answers to the conditions in the condition entry quadrant. **STRUCTURED ENGLISH -** is derived from structured programming language which gives more understandable and precise description of process. It is based on procedural logic that uses construction and imperative sentences designed to perform operation for action. It is best used when sequences and loops in a program must be considered and the problem needs sequences of actions with decisions. It does not have strict syntax rule. It expresses all logic in terms of sequential decision structures and iterations. **PSEUDOCODE** - does not conform to any programming language and expresses logic in plain English. It may specify the physical programming logic without actual coding during and after the physical design. It is used in conjunction with structured programming. It replaces the flowcharts of a program **AISPrE 2:(Finals)** **LESSON 1:** **System Design** **[SYSTEM DESIGN]** - is the [phase that bridges the gap] between problem domain and the existing system in a manageable way. **[TYPES OF SYSTEM DESIGN:]** - **Logical Design -** [pertains to an abstract] representation of the data flow, inputs, and outputs of the system. - **Physical Design - [ ]**[It relates to the actual input and output] processes of the system. It focuses on how data is entered into a system, verified, processed, and displayed as output. - **Architectural Design -** It is also known as high level design that focuses on the design of system architecture. It [describes the structure and behavior of the system]. It defines the structure and relationship between various modules of system development process. - **Detailed Design - [ ]**[It follows Architectural design] and focuses on development of each module. **[Conceptual Data Modeling]** \- It is representation of organizational data which includes all the major entities and relationship. **[Entity Relationship Model (E-R model)]** \- It is a technique used in database design that helps describe the relationship between various entities of an organization. **[Terms used in E-R model:]** **ENTITY** − It [specifies distinct real world] items in an application. For example: vendor, item, student, course, teachers, etc. **RELATIONSHIP** - They are the [meaningful dependencies] between entities. For example, vendor supplies items, teacher teaches courses, then supplies and course are relationship. **ATTRIBUTES** - It [specifies the properties] of relationships. ***Symbols used in E-R model and their respective meanings:***  **LESSON 2:** **System Design** **[File Organization]** -It describes how records are stored within a file. ***There are four file organization methods:*** 1. **SERIAL** - Records are stored in chronological order. 2. **SEQUENTIAL** - Records are stored in order based on a key field which contains a value that uniquely identifies a record. 3. **DIRECT (RELATIVE)** - Each record is stored based on a physical address or location on the device. ***[Address]*** is calculated from the value stored in the record's key field. 4. **INDEXED** - Records can be processed both sequentially and non-sequentially using indexes. **[File Access] -** methods allow computer programs read or write records in a file. **[Sequential Access] -** It is efficient when a large number of the records on the file need to be accessed at any given time. **[Direct (Random) Access] -**Records are located by knowing their physical locations or addresses on the device rather than their positions relative to other records. ***Types of Files used in an Organization System*** - **MASTER FILE** − It contains the current information for a system. - **TABLE FILE** - It is a type of master file that changes infrequently and stored in a tabular format. - **TRANSACTION FILE** - It contains the day-to-day information generated from business activities. - **TEMPORARY FILE** - It is created and used whenever needed by a system. - **MIRROR FILE** - They are the exact duplicates of other files. - **LOG FILES** - They contain copies of master and transaction records in order to chronicle any changes that are made to the master file. - **ARCHIVE FILES** - Backup files that contain historical versions of other files. **[DOCUMENTATION CONTROL]** **Documentation** - is a process of recording the information for any reference or operational purpose. **[Programmers or Systems Analysts]** \- usually are responsible for preparing documentation to help users learn the system. **LESSON 3:** **System Design** **[Four Main Types of Documentations:]** - - - - **[Program Documentation]** It describes inputs, outputs, and processing logic for all the program modules. The program documentation process starts in the system analysis phase and continues during implementation. This documentation guides programmers, who construct modules that are well supported by internal and external comments and descriptions that can be understood and maintained easily. **[Operations Documentation]** It contains all the information needed for processing and distributing online and printed output. Operations documentation should be clear, concise, and available online if possible. **[User Documentation]** is valuable in training users and for reference purpose. It must be clear, understandable, and readily accessible to users at all levels. **[System Documentation]** serves as the technical specifications for the IS and how the objectives of the IS are accomplished. provides the basis for understanding the technical aspects of the IS when modifications are made. **LESSON 4:** **Design Strategies** **[TOP-DOWN STRATEGY]** \- uses the modular approach to develop the design of a system. It starts from the top or the highest-level module and moves towards the lowest level modules. **[BOTTOM-UP STRATEGY]** \- It follows the modular approach to develop the design of the system. It starts from the bottom or the basic level modules and moves towards the highest level modules. **LESSON 5:** **Design Strategies** **[STRUCTURED DESIGN]** -It is a data-flow based methodology that helps in identifying the input and output of the developing system. \- The **main objective** of structured design is *[to minimize the complexity and increase the modularity of a program. ]* **[MODULARIZATION]** \- Structured design partitions the program into small and independent modules. \- Modularization or decomposition *[to minimize the complexity and to manage the problem by subdividing it into smaller segments.]* **[STRUCTURED CHARTS]** \- They are a [recommended tool] for designing a modular, top down systems which define the various modules of system development and the relationship between each module. \- It [consists of diagram] consisting of rectangular boxes that represent the modules, connecting arrows, or lines. **CONTROL MODULE** - It is a higher-level module that directs lower-level modules, called [subordinate modules.] **LIBRARY MODULE** - It is a [reusable module] and [can be invoked from more than one point in the chart.] ***two different approaches to design a*** ***structured chart:*** **[Transform-Centered Structured Charts]** \- They are used when all the transactions follow same path. **[Transaction-Centered Structured Charts]** - They are used when all the transactions do not follow the same path. **[COUPLING]** \- is the [measure of the independence] of components. It defines the degree of dependency of each module of system development on the other. **[COUPLING MEASURES:]** - **CONTENT COUPLING** - [When one component actually modifies another,] then the modified component is completely dependent on modifying one. - **COMMON COUPLING** - When amount of coupling is reduced somewhat by organizing system design so that data [are accessible from a common data store.] - **CONTROL COUPLING** - When one [component passes parameters] to control the activity of another component. - **STAMP COUPLING** - [When data structures is used to pass information] from one component to another. - **DATA COUPLING** - [When only data is passed] [then components] are [connected by this coupling.] **COHESION** \- is the measure of closeness of the relationship between its components. It defines the amount of dependency of the components of a module on one another. The **[best modules]** are those that are functionally **cohesive.** The **[worst modules]** are those that are **coincidentally cohesive**. ***[The Worst Degree of Cohesion:]*** - **Coincidental cohesion** - is found in a component whose parts are [unrelated to another.] - **LOGICAL COHESION** - It is [where several logically related functions] or data elements are placed in same component. - **TEMPORAL COHESION** - is used to [initialize a system or set variables] performs several functions in sequence, but the functions are [related by timing] involved. **PROCEDURALLY COHESION** - It [is when] [functions are grouped together] in a component just to ensure this order. **SEQUENTIAL COHESION** - It is when the output from one part of a component i[s the] [input to the next part of it.] **LESSON 6:** **Input/Output and** **Forms Design** **INPUT DESIGN** \- input is the raw data that is processed to produce output. ***[Well designed input forms and screens have following properties:]*** It should serve specific purpose effectively such as storing, recording, and retrieving the information. It ensures proper completion with accuracy. It should be easy to fill and straightforward. It should focus on user's attention, consistency, and simplicity. All these objectives are obtained using the knowledge of basic design principles regarding:  ***[The objectives of input design are:]*** To design data entry procedures and to reduce input volume To design source documents for data capture or devise other data capture methods To design input data records, data entry screens, user interface screens, etc. To use validation checks and develop effective input controls. **[DATA INPUT METHODS]** \- It is important to design appropriate data input methods to prevent errors while entering data. **[INPUT INTEGRITY CONTROLS]** \- It includes a number of methods to eliminate common input errors by end-users. **[OUTPUT DESIGN]** \- During output design, developers identify the type of outputs needed, and consider the necessary output controls and prototype report layouts. **[EXTERNAL OUTPUTS]** \- enable the system to leave the trigger actions on the part of their recipients or confirm actions to their recipients. **[INTERNAL OUTPUTS]** \- are present inside the system, and used by end-users and managers. They support the management in decision making and reporting. ***Three types of reports:*** **DETAILED REPORTS** - They [contain present information] which has almost no filtering or restriction generated to assist management planning and control. **SUMMARY REPORTS** - They [contain trends and potential problems] which are categorized and summarized that are generated for managers who do not want details. **EXCEPTION REPORTS** - They c[ontain exceptions, filtered data] to some condition or standard before presenting it to the manager, as information. **[OUTPUT INTEGRITY CONTROLS]** \- include routing codes to identify the receiving system, and verification messages to confirm successful receipt of messages handled by network protocol. **Printed or screen-format reports** - should include a date/time for report printing and the data. **Multipage reports** - contain report title or description, and pagination. **Pre-printed forms** - usually include a version number and effective date. **[FORMS DESIGN]** \- Both forms and reports are the product of input and output design and are business document consisting of specified data. **[Forms] -** provide fields for data input **[Reports] -** are purely used for reading. **[OBJECTIVES OF GOOD FORM DESIGN]** A good form design is necessary to ensure the following: To keep the screen simple by giving proper sequence, information, and clear captions. To meet the intended purpose by using appropriate forms. To ensure the completion of form with accuracy. To keep the forms attractive by using icons, inverse video, or blinking cursors etc. and to facilitate navigation. **TYPES OF FORMS:** - **Flat Forms** - It is [a single copy form] prepared manually or by a machine and printed on a paper.It is a [simplest and inexpensive form] to design,print, and reproduce, which uses less volume. - **Unit Set/Snap Out Forms -** These are papers with [one-time carbons] interleaved into unit sets for either [handwritten or machine use.] - **Continuous Strip/Fanfold Forms -**These [are multiple unit forms] joined in a continuous strip with perforations between each pair of forms. It is a [less expensive] method for large volume use. - **No Carbon Required (NCR) Paper -** They use [carbon less papers] which have two chemical coatings (capsules), one on the face and the other on the back of a sheet of paper.