Systems Analysis and Design PDF

Systems Analysis and Design Tenth Edition Global Edition Chapter 2 Understanding and Modeling Organizational Systems Copyright © 2020 Pearson Education Ltd. Lear...

Systems Analysis and Design Tenth Edition Global Edition Chapter 2 Understanding and Modeling Organizational Systems Copyright © 2020 Pearson Education Ltd. Learning Objectives 2.1 Understand that organizations and their members are systems and that analysts need to take a systems perspective. 2.2 Depict systems graphically using context-level data flow diagrams, and entity-relationship models, use cases, and use case scenarios. 2.3 Recognize that different levels of management require different systems. 2.4 Comprehend that organizational culture impacts the design of information systems. Copyright © 2020 Pearson Education Ltd. Three Main Forces Interacting to Shape Organizations Levels of management Design of organizations Organizational cultures Copyright © 2020 Pearson Education Ltd. Organizations are Composed of Interrelated Subsystems Influenced by levels of management decision makers that cut horizontally across the organizational system – Operations – Middle management – Strategic management Influenced by organizational cultures and subcultures Copyright © 2020 Pearson Education Ltd. Major Topics Organizations as systems Depicting systems graphically – Data flow diagram – Entity-relationship model – Use case modeling Levels of management Organizational culture Copyright © 2020 Pearson Education Ltd. Organizations as Systems Conceptualized as systems designed to accomplish predetermined goals and objectives Composed of smaller, interrelated systems serving specialized functions Specialized functions are reintegrated to form an effective organizational whole Copyright © 2020 Pearson Education Ltd. Interrelatedness and Independence of Systems All systems and subsystems are interrelated and interdependent All systems process inputs from their environments. Processes change or transform inputs into outputs Typical processes in systems include verifying, updating, and printing All systems are contained by boundaries separating them from their environments System feedback for planning and control An ideal system self-corrects or self-regulates itself Copyright © 2020 Pearson Education Ltd. Figure 2.1 System Outputs Serve as Feedback That Compares Performance with Goals Copyright © 2020 Pearson Education Ltd. Organizational Environments Community – Physical location – Demographic profile (education, income) Economic – Market factors – Competition Political – State and local government Legal – Federal, state, regional, local laws, and guidelines Copyright © 2020 Pearson Education Ltd. Virtual Organizations and Virtual Teams A virtual organization has parts of the organization in different physical locations Computer networks and communications technology are used to bring virtual teams together to work on projects Copyright © 2020 Pearson Education Ltd. Benefits of Virtual Organizations and Teams Possibility of reducing costs of physical facilities More rapid response to customer needs Helping virtual employees to fulfill their familial obligations to children or aging parents Copyright © 2020 Pearson Education Ltd. Taking a Systems Perspective Allows system analyst to understand businesses they will come into contact with It is important that members of subsystems realize that they are interrelated with other subsystems (Fig 2.2) Problems occur when each manager thinks that his/her department is the most important (Fig 2.3) Bigger problems may occur when that manager rises through the ranks Copyright © 2020 Pearson Education Ltd. Figure 2.2 Taking a Systems Perspective Copyright © 2020 Pearson Education Ltd. Figure 2.3 Perspective of Functional Managers Copyright © 2020 Pearson Education Ltd. Enterprise Resource Planning Enterprise Resource Planning (ERP) is an integrated organizational information system Software that helps the flow of information between the functional areas within the organization Recently ERP systems are moving to cloud computing Copyright © 2020 Pearson Education Ltd. Enterprise Resource Planning ERP systems include: – manufacturing components – sales and operations planning – distribution – managing the supply train Problems with implementation: – difficult to analyze a system currently in use and then fit the ERP model to that system – companies tend to design their business processes before ERP is implemented Copyright © 2020 Pearson Education Ltd. ERP and the Organization ERP can affect every aspect of the organization, including: – Design of employees’ work – Skills required for job competency – Strategic positioning of the company Copyright © 2020 Pearson Education Ltd. Issues to Be Overcome for ERP Success Many issues must be overcome for the ERP installation is to be declared a success: – User acceptance – Integration with legacy systems and the supply chain – Upgrading functionality (and complexity) of ERP modules – Reorganizing work life of users and decision makers – Expanded reach across several organizations – Strategic repositioning of the company Copyright © 2020 Pearson Education Ltd. Depicting Systems Graphically Context-level data flow diagrams Entity-relationship model Use case modeling Copyright © 2020 Pearson Education Ltd. Context-Level Data Flow Diagrams Focus is on the data flowing into and out of the system and the processing of the data Shows the scope of the system: – What is to be included in the system – The external entities are outside the scope of the system Copyright © 2020 Pearson Education Ltd. Figure 2.4 The Basic Symbols of a Data Flow Diagram Copyright © 2020 Pearson Education Ltd. Figure 2.5 Airline Reservation System Copyright © 2020 Pearson Education Ltd. Figure 2.5 Airline Reservation System Copyright © 2020 Pearson Education Ltd. Case: Amazon Customers login to the system via credentials and search for a product. Amazon checks the vendor for the availability of the product Amazon communicates with the Customer Financial Instituton for the payment. Customer recieves an order confirmation. Copyright © 2020 Pearson Education Ltd. Case: YouTube Users can login to the system by account details, upload and view videos, use it as a social media (comment, like/dislike videos, etc.). Partners are capable of doing all user activities and get paid for the views. YouTube puts advertisement videos into the videos and charges advertisers. All the payments are handled via bank. Copyright © 2020 Pearson Education Ltd. Entity-Relationship Model The elements that make up an organizational system can be referred to as entities. A relationship is the association that describes the interaction among the entities. Focus is on the entities and their relationships within the organizational system Another way to show the scope of a system There are many different conventions for drawing E-R diagrams (with names such as crow’s foot, arrow, or Bachman notation). Copyright © 2020 Pearson Education Ltd. Relationships Relationships show how the entities are connected Three types of relationships: – One-to-one – One-to-many – Many-to-many Copyright © 2020 Pearson Education Ltd. Figure 2.7 Entity-Relationship Example An entity-relationship diagram showing a many-to-one relationship Copyright © 2020 Pearson Education Ltd. Figure 2.8 Examples of Different Types of Relationships in E-R Diagrams Copyright © 2020 Pearson Education Ltd. Entities Fundamental entity Associative entity Attributive entity Copyright © 2020 Pearson Education Ltd. Figure 2.9 Three Different Types of Entities Used in E-R Diagrams Copyright © 2020 Pearson Education Ltd. Figure 2.12 A More Complete E-R Diagram Showing Data Attributes of the Entities Copyright © 2020 Pearson Education Ltd. Attributes Data attributes may be added to the diagram. Patron Name Patron Patron address Patron phone Patron credit card Copyright © 2020 Pearson Education Ltd. Creating Entity-Relationship Diagrams List the entities in the organization Choose key entities to narrow the scope of the problem Identify what the primary entity should be Confirm the results of the above through data gathering (interviews, questionnaires, etc.) Copyright © 2020 Pearson Education Ltd. Use Case Modeling Part of the unified modeling language (UML) Describes what a system does without describing how the system works A view of the system requirements Analyst works with business experts to develop requirements Copyright © 2020 Pearson Education Ltd. Use Case Diagram Actor – Refers to a particular role of a user of the system – Similar to external entities; they exist outside of the system Use case symbols – An oval indicating the task of the use case Connecting lines – Arrows and lines used to diagram behavioral relationships Copyright © 2020 Pearson Education Ltd. Actor Divided into two groups – Primary actors: ▪ Supply data or receive information from the system ▪ Provide details on what the use case should do – Supporting actors: ▪ Help to keep the system running or provide help ▪ The people who run the help desk, the analysts, programmers, and so on Copyright © 2020 Pearson Education Ltd. Use Case A use case provides developers with a view of what the users want Free of technical or implementation details Documents a single transaction or event The use case model is based on the interactions and relationships of individual use cases Copyright © 2020 Pearson Education Ltd. A Use Case Always Provides Three Things An actor that initiates an event The event that triggers a use case The use case that performs the actions triggered by the event Copyright © 2020 Pearson Education Ltd. Use Case Relations Behavioral relationships – Communicates ▪ Used to connect an actor to a use case – Includes ▪ Describes the situation in which a use case contains behavior that is common to more than one use case Copyright © 2020 Pearson Education Ltd. Use Case Relations Behavioral relationships [continued] – Extends ▪ Describes the situation in which one use case possesses the behavior that allows the new case to handle a variation or exception from the basic use case – Generalizes ▪ Implies that one thing is more typical than the other thing Copyright © 2020 Pearson Education Ltd. Figure 2.13 Four Types of Behavioral Relationships and the Lines Used to Diagram Each Copyright © 2020 Pearson Education Ltd. Figure 2.14 Actors, Use Cases, and Relationships for a Student Enrollment Example Copyright © 2020 Pearson Education Ltd. Scope System scope defines its boundaries: – What is in or outside the system – Project has a budget that helps to define scope – Project has a start and an end time Actors are always outside of scope Communication lines are the boundaries and define the scope Copyright © 2020 Pearson Education Ltd. Developing Use Case Diagrams Review the business specifications and identify the actors involved Identify the high-level events and develop the primary use cases that describe those events and how the actors initiate them Review each primary use case to determine the possible variations of flow through the use case The context-level data flow diagram could act as a starting point for creating a use case Copyright © 2020 Pearson Education Ltd. Figure 2.15 A Use Case Diagram Representing a System Used to Plan a Conference Copyright © 2020 Pearson Education Ltd. Developing the Use Case Scenarios The description of the use case Three main areas: – Use case identifiers and initiators – Steps performed – Conditions, assumptions, and questions Copyright © 2020 Pearson Education Ltd. Figure 2.16 A Use Case Scenario is Divided into Three Sections Copyright © 2020 Pearson Education Ltd. Use Case Header Area Has a name and a unique ID Include application area List actors Include stakeholders Include the level Has a brief description of the use case The triggering event Type of trigger (external or temporal) Copyright © 2020 Pearson Education Ltd. Figure 2.16 A Use Case Scenario is Divided into Three Sections - 1 Copyright © 2020 Pearson Education Ltd. Use Case Levels Use case levels describe how global or detailed the use case description is: – White (like clouds): enterprise level ▪ This is the enterprise level, and there may be only four to five use cases at this level for the entire organization. ▪ Summary use cases typically execute over hours, days, weeks, months, or years. ▪ Examples might be to advertise goods, sell goods to customers, manage inventory, manage the supply chain, and optimize shipping. – Kite: business unit or department level ▪ May be at the business unit or department level and is a summary of goals. ▪ Examples would be to register students, or, if working with a travel company, to make an airline, hotel, car, or cruise reservation. Copyright © 2020 Pearson Education Ltd. Use Case Levels – Blue (sea level): user goals ▪ Customarily used to depict user goals. ▪ This level often has the greatest interest for users and is easiest for a business to understand. ▪ It is usually written for a business activity, and each person should be able to do one blue level activity in anywhere from 2 to 20 minutes. ▪ Examples are register a continuing student, add a new customer, place an item in a shopping cart, and order checkout. – Indigo (or fish): functional or subfunctional ▪ Shows lots of detail, often at a functional or subfunctional level. ▪ Examples are Choose a class, pay academic fees, look up the airport code for a given city, and produce a list of customers after entering a name – Black (or clam): most detailed ▪ The most detailed use cases, at a subfunction level. ▪ Examples might be to validate secure logon, add a new field using dynamic HTML, or use Ajax to update a web page in a small way. Copyright © 2020 Pearson Education Ltd. Use Case Levels Copyright © 2020 Pearson Education Ltd. Second Area Includes the steps performed and the information required for each of the steps It is desirable to write up a use case for the main path and then to write up one for each of the alternative paths separately Some use case descriptions include extensions or alternative scenarios, with the exceptions as additional sections following the standard flow of events Copyright © 2020 Pearson Education Ltd. Figure 2.16 A Use Case Scenario is Divided into Three Sections - 2 Copyright © 2020 Pearson Education Ltd. Second Area Copyright © 2020 Pearson Education Ltd. Second Area Copyright © 2020 Pearson Education Ltd. Use Case Footer Area Preconditions—need to be met before use case can be performed Postconditions or the state of the system after the use case has finished Assumptions Minimal guarantee Success guarantee Outstanding issues Optional priority and risk Requirements Met Copyright © 2020 Pearson Education Ltd. Figure 2.16 A Use Case Scenario is Divided into Three Sections - 3 Copyright © 2020 Pearson Education Ltd. Four Steps Used to Create Use Cases Use agile stories, problem definition objectives, user requirements, or a features list Ask about the tasks that must be done Determine if there are any iterative or looping actions The use case ends when the customer goal is complete Copyright © 2020 Pearson Education Ltd. Why Use Case Diagrams Are Helpful Identify all the actors in the problem domain Actions that need to be completed are also clearly shown on the use case diagram The use case scenario is also worthwhile Simplicity and lack of technical detail Copyright © 2020 Pearson Education Ltd. Figure 2.18 The Main Reasons for Writing Use Cases are Their Effectiveness in Communicating with Users and Their Capturing of User Stories Copyright © 2020 Pearson Education Ltd. Figure 2.19 Management in Organizations Exists on Three Horizontal Levels Operational control, managerial planning and control, and strategic management. Copyright © 2020 Pearson Education Ltd. Operations Control Make decisions using predetermined rules that have predictable outcomes Oversee the operating details of the organization Copyright © 2020 Pearson Education Ltd. Managerial Planning and Control Make short-term planning and control decisions about resources and organizational objectives Decisions may be partly operational and partly strategic Copyright © 2020 Pearson Education Ltd. Strategic Management Look outward from the organization to the future Make decisions that will guide middle and operations managers in the months and years ahead Work in highly uncertain decision-making environment Faced with semistructured problems Define the organization as a whole Copyright © 2020 Pearson Education Ltd. Implications for Information Systems Development Operations managers: – need internal information that is of a repetitive, low-level nature – highly dependent on information that captures current performance – large users of online, real-time information resources – need for past performance information and periodic information is moderate – have little use for external information that allows future projections Copyright © 2020 Pearson Education Ltd. Implications for Information Systems Development Middle management: – in need of both short and longer-term information – need for information in real time – need current information on performance as measured against set standards – highly dependent on internal information – need for historical information, along with information that allows prediction of future events Copyright © 2020 Pearson Education Ltd. Implications for Information Systems Development Strategic management: – highly dependent on information from external sources that supply news of market trends and the strategies of competing corporations – high need for information of a predictive nature – need accurate assessments of risk – need for periodically reported information Copyright © 2020 Pearson Education Ltd. Collaborative Design External and internal stakeholders follow processes to share in designing a system to meet their goals Giving power to those who possess a technical or strategic expertise Copyright © 2020 Pearson Education Ltd. Organizational Culture Organizations have cultures and subcultures Learn from verbal and nonverbal symbolism May help to overcome the resistance to change Copyright © 2020 Pearson Education Ltd. Summary (1 of 2) Organizational fundamentals – Organizations as systems – Levels of management – Organizational culture Graphical representation of systems – DFD – ERD – Use case diagrams and scenarios Copyright © 2020 Pearson Education Ltd. Summary (2 of 2) Levels of managerial control – Operational – Middle management – Strategic Organizational culture Copyright © 2020 Pearson Education Ltd.