Module-1 SIA.pdf

IT12 MODELING REQUIREMENTS Dave D. Lota | Cyril Faeldan Topics What is Data and Information? Types and Classification of Information Characteristics of useful information What is a System? Characteristics of useful System? Components of an Information System? Types and Levels of Infor...

IT12 MODELING REQUIREMENTS Dave D. Lota | Cyril Faeldan Topics What is Data and Information? Types and Classification of Information Characteristics of useful information What is a System? Characteristics of useful System? Components of an Information System? Types and Levels of Information System Phases of System Development Life Cycle (SDLC) Software Modeling Data ü A “given” or fact; a number, statement, or an image ü Represents something (quantities, actions and objects) in the real world ü The raw materials in the production of information Information ü Data that have a meaning within a context ü Data that has been processed into a form that is meaningful to the recipient and is of real or perceived value in the current or in the prospective actions or decisions of the recipients Information Classification ü Action v/s no-action ü Recurring v/s no recurring ü Internal v/s external ü Planning Information ü Control Information ü Knowledge Characteristics of Useful Information üRelevant -Information must pertain to the problem at hand üComplete -Partial information is often worse than no information üAccurate -Erroneous information may lead to disastrous decisions üCurrent -Decisions are often based upon the latest information available üEconomical - In a business setting, the cost obtaining information must be considered as one cost element involved in any decisions What is System? ü A set of components that work together to achieve common goal. Computer-based Information Systems take data as raw materials, process it and produce information as output. ü A system is a group of interrelated components working together toward a common goal by accepting inputs and producing output in an organized transformation process. ü System is a functional unit, which involves set of procedures/functions to produce certain outputs by processing data/information given as input Characteristics of a Useful System ü A system is a whole üComponents of a system interact üSystems are goal seeking üSystems have input/output üSystem must be controlled üSystem forms a hierarchy üSystems exhibit differentiation Components of an Information System Classification of Information Systems Types of Information System üOperational – level systems support operational managers by keeping track of the elementary activities and transactions of the organization such as sales, receipts, cash deposits, payroll, credit decisions, and the flow of materials in a factory. üManagement-level systems serve the monitoring, controlling, decision – making and administrative activities of middle managers. The principal question addressed by such systems is this: Are things working well? üStrategic – level systems help senior management tackle and address strategic issues and long-term trends, both in the firm and in the external environment.  Types of Information System üTransaction Processing Systems (TPS) § Basic business systems that serve the operational level § A computerized system that performs and records the daily routine transactions necessary to the conduct of the business üManagement Information Systems (MIS) § Serve middle management § Provide reports on firm’s current performance, based on data from TPS § Provide answers to routine questions with predefined procedure for answering them Types of Information System üDecision Support System (DSS) § Serve middle management § Often use external information as well as information form TPS and MIS § Processing is interactive in nature § Output in form of Decision Analysis üExecutive Support System (ESS) § Support senior management – strategic level § Address non-routine decisions requiring judgement, evaluation, and insight § Incorporate data about external events (e.g., new tax laws or competitors) as well as summarized information from internal MIS and DSS § Processing is interactive and output in form of projections Software Development Life Cycle (SDLC) üA methodology that also forms the framework for planning and controlling the creation, testing, and delivery of an information system. üActs as the foundation for multiple different development and delivery methodologies such as the Hardware development life cycle and Software development life cycle. üA framework that provides a sequence of activities for system designers and developers to follow. It consists of a set of steps or phases in which each phase the SDLC uses the results of the previous one. üIt aims to produce high-quality software that meets or exceeds customer expectations, reaches completion within times and cost estimates. Phases of SDLC Phases of SDLC 1. Planning üIn the Planning phase, project leaders evaluate the terms of the project. This includes calculating labor and material costs, creating a timetable with target goals and creating the project’s teams and leadership structure. üPlanning can also include feedback from stakeholders. Stakeholders are anyone who stands to benefit from the application. Try to get feedback from potential customers, developer, subject matter experts, and sales reps. üPlanning should clearly define the scope and purpose of the application. It plots the course and provisions the teams to effectively create the software. It also sets boundaries to help keep the project from expanding or shifting from its original purpose. Phases of SDLC 2. Define Requirements üDefining requirements is considered part of planning to determine what the application is supposed to do and its requirement/ For example, a social media application would require the ability to connect with a friend. An inventory program might require a search feature. üRequirements also include defining the resources needed to build the project. For example, a team might develop software to control a custom manufacturing machine. The machine is a requirement in the process. Phases of SDLC 3. Design and Prototyping üThe design phase models the way the software applications will work. Some aspects of the design include: oArchitecture – specifies programming language, industry practices, overall design, and use any template or boilerplate. oUser interface – defines the ways customers interact with the software , and how the software responds to the input oPlatforms – defines the platforms on which the software will run, such as Apple, Windows version, Linux or even gaming consoles. Phases of SDLC oProgramming – not just the programming language but including methods of solving problems and performing tasks in the application. oCommunications – defines the methods that the application can communicate with the other assets such as central server or other instances of the application. oSecurity –defines the measures taken to secure the application and may include SSL traffic encryption password protection and secure storage of user credentials üA prototype is like one of the software in the iterative software development model. It demonstrates a basic idea of how the application looks and works.e early versions of Phases of SDLC 4. Software Development üThis is the actual writing of the program. A small project might be written by a single developer, while a large project might be broken up and worked by several teams. Use an Access Control or Source Code Management application on this phase. These systems help developers track changes to the code. They also help ensure compatibility between different team projects and to make sure target goals are being met. üThe coding process includes many other tasks. Many developers need to brush up in skills or work as a team. Fining and fixing errors and glitches is critical. Task often hold up the development process, such as waiting for test results or compiling code so an application can run. SDLC can anticipate these delays so that development can be tasked with other duties. Phases of SDLC 5. Testing üIt’s critical to test an application before making it available to users. Much of the testing can be automated like security testing. Other testing can only be done in a specific environment – consider creating a simulated production environment for complex deployments. üTesting should ensure that each function works correctly. Different parts of the application should also be tested to work seamlessly together – performance test, to reduce any hangs or lags in processing. üThe testing phase helps reduce the number of bugs and glitches that users encounter. This leads to a higher user satisfaction and a better usage rate. Phases of SDLC 6. Deployment üIn the development phase, the application is made available to users. Many companies prefer to automate the deployment phase. This can be as simple as a payment portal and download Phases of SDLC 7. Operations and Maintenance üAt this point, the development cycle is almost finished. The application is done and being used in the field. The Operation and Maintenance phase is still important though. In this phase, users discover bugs that weren’t found during testing. Theses errors need to be resolved, which can spawn new development cycles. üIn addition to bug fixes, models like iterative development plan additional features in future releases. For each new release, a new Development Cycle can be launched. System Modeling üSystem modeling is the process of developing abstract models of a system, with each model presenting a different view or perspective of that system. üSystem modelling helps the analyst to understand the functionality of the system and models are used to communicate with customers. üModels of the existing system are used during requirements engineering. They help clarify what the existing system does and can be used a basis discussing its strengths and weaknesses. These then lead to requirements for the new system. üModels of the new system are used during requirements engineering to help explain the proposed requirements to other system stakeholders. Engineers use these models to discuss design proposals and to document the system for implementation. System Perspective üAn external perspective, where you model the context or environment of the system. üAn interaction perspectives, where you model the interactions between a system and its environment, or between the components of a system. üA structural perspective, where you model the organization of a system or the structure of the data that is processed by the system. üA behavioral perspective, where you model the dynamic behavior of the system and how it responds to events. System Design üPhase of detailing how a system will meet the information requirements determined by the system analysis. This phase is broken into two subs phases: 1. Logical design 1st phase, lays out the components of the information system and their relationship to each other as they would appear to users. 2. Physical design 2nd phase, the process of translating the abstract logical model into the specific technical design for the new system. UML Diagram Types üActivity Diagrams Ø It shows the activities involved in process or in data processing. Ø It is basically a flowchart to represent the flow one activity to another activity. The activity can be described as an operation of the system. The basic purpose of activity diagrams is to capture the dynamic behavior of the system. It is also called object-oriented flowchart. Ø This UML diagram focuses on the execution and flow of the behavior of a system instead of implementation. Activity diagrams consist of activities that are made up of actions that apply to behavioral modelling technology. Activity Diagram Notations ØInitial states: The starting stage before an activity takes place is depicted as the initial state ØFinal states: The state which the system reaches when a specific process end is known as a Final State ØState or an activity box: ØDecision box: It is a diamond shape box which represents a decision with alternate paths. It represents the flow of control. Example of an Activity Diagram Notations Use – Case Diagram Notations üUse –case – this is used to represent high – level functionalities and how the user will handle the system. A use case represents a distinct functionality of a system, a component, a package or a class. It is denoted by an oval shape with the name of a use case written inside the oval shape. Use – Case Diagram Notations üActor – it is used inside use case diagrams. The actor is an entity that interacts with the system. A user is the best example of an actor. An actor is an entity that initiates the user case from outside the scope of a use case. It can be any element that can trigger an interaction with the use case. Example of Use Case Diagram Sequence Diagram Notations üLifeline Notation A sequence diagram is made up of several of these lifeline notation that should be arranged horizontally across the top of the diagram. No two lifeline notations should overlap each other. They represent the different objects or parts that interact with each other in the system during the sequence. Sequence Diagram Notations üActivation Bars The activation bar is the box placed on the lifeline. It is used to indicate that an object is active (or instantiated) during an interaction between two objects. The length of the rectangle indicates the duration of the objects staying active. Sequence Diagram Notations üMessage Arrows It diagrams generally permit the annotation of comments in all UML diagram types. The comment object is a rectangle with a folded-over corner as shown below. The comment can be linked to the related object with a dashed line. Sequence Diagram Notations üComment An arrow from the Message Caller to the Message Receiver specifies a message in a sequence diagram. A message can flow in any direction from left to right, right to left or back to the Message Caller itself. While you can describe the message being sent from one object to the other on the arrow, with different arrowheads you can indicate the type of message being sent or received. Example of Sequence Diagram UML Diagram Types üClass Diagrams ØIt shows the object classes in the system and the associations between these class. ØA Class is a blueprint that is used to create Object. The Class defines what object can do. ØIt gives an overview of a software system by displaying classes, attributes, operations, and their relationships. This Diagram includes the class name, attributes and operation separate designated compartments. Class Diagram Notations üClass Operations (Methods) ØClass Name The name of the class appears in the first partition. ØClass Attributes Attributes are shown in the second partition. The attribute type is shown after the colon. Attributes map onto member variables (data members) in code Class Diagram Notations üClass Operations (Methods) Operations are shown in the third partition. They are services the class provides. The return type of a method is shown after the colon at the of the method signature. The return type of method parameters are shown after the colon following the parameter name. Operations map onto class, methods in code. Example of Class Diagram UML Diagram Types üState Diagrams ØIt shows how the system reacts to internal and external events. ØUML State machine diagram can be used to model the behavior of a class, a subsystem, a package , or even an entire system. It is also called State chart or State Transition diagram. ØState chart diagrams provide us an efficient way to model the interactions or communication that occur within the external entities and a system. These diagrams are used to model the event- based system. A state of an object is controlled with the help pf an event. State Diagram Notations üInitial state This is used to indicate the beginning of a state machine diagram. üFinal state This symbol is used to indicate the end of a state machine diagram. üDecision box It contains a condition. Depending upon the result of an evaluated guard condition, a new path is taken form for program execution. State Diagram Notations üTransition A transition is change in one state into another state which is occurred because of some event. A transition causes a change in the state of an object. üState box It is a specific moment in the lifespan of an object. It is defines using some condition or a statement within the classifier body. It is used to represent any static as well as dynamic situations. Example of State Diagram Activity No. 1: Describe the UML Use Case Diagram of an ATM System Activity No. 2: Describe the UML State Diagram of an Airport Passenger Activity No. 3: Describe the UML Sequence Diagram of Online Shopping THANK YOU!