Chapter 5

Chapter 5

Questions/Prompts

  • How are logical and physical models of a system different?
    • Logical Model: shows what a system MUST do, regardless of whether it will be implemented physically.
    • Physical Model: built that describes HOW the system will be constructed.
      • Shows how system requirements are implemented.
    • Relationship between them: many analysis creates a physical model first before creating a logical model. Allows better understanding of the system.
  • What logical structures are utilized in modular design?
    • Combines 3 logical structures
    • Sequence: completion of steps in sequential order, one after another.
    • Selection: completion of 1+ process steps based on the result of a test or condition.
    • Iteration: completion of a step that is repeated until a specific condition changes.
  • How are entities, and which types of entities, are connected to a data flow diagram?
    • A person, place, or thing or event for which data is collected and maintained. provide data to system or receive output from system
    • Source: supplies data to system
    • Sink: receives data
  • Understand the correct and incorrect uses of data flow diagram symbols.
    • Actors(external entity): provide data to system or receive output from system
      • Source: supplies data to system
      • Sink: receives data
    • Process (business activity): receives input data and produces output that has a different content, form, or both.
    • Data Flow (data in motion): path for data to move from one part of the information systems to another.
    • Data store (data at rest): represent data that user stores bc 1+ more processes need to use the data at a later time.
    • INCORRECT USE OF DATA FLOW:
      • actor -> actor
      • Actor -> data store
      • Data store -> data store
      • Spontaneous generation: Produce output but no input data flow <- ->
      • Black hole Has input but no output -><
      • Gray hole: has input and output but does not make sense.
  • Understand how to level and how to balance data flow diagrams.
    • Context diagram: top level view of an information system that shows the system boundaries and scope
    • Diagram 0 DFD: provides overview of all components that interact to form the overall system. Zoom in on the system and show major internal processes, data flows, and data stores.
      • Has reference numbers
    • Lower-level DFD: leveling and balancing techniques must be used.
      • Leveling: drawing series of increasingly detailed diagrams, until all functional primitives are identified
      • Balancing maintains consistency among a set of DFD.

Concepts

  • Functional primitive: process that consists of a single function that is not exploded further. Can't be torn apart further.
  • Structured English: subset of standard English that describes logical processes clearly and accurately. Looks familiar to coding
  • Decision tables: logical structure that shows every combination of conditions and outcomes. Tables can have 1 condition, 2 conditions, 3…
  • Decision trees: graphical representations of the conditions, actions, and rules found in a decision table. Trees with roots Like a table tree but shown differently
  • Data dictionary: also known as data repository, is a central storehouse of information about the systems data.
  • Document data elements, flows, stores, processes, entities and more.

Chapter 6

Questions/Prompts

  • What is Object Oriented analysis: describes an information system by identifying things called objects. Popular approach as it sees a system from the viewpoint of the objects as they function and interact.
  • What are objects, and what do we find in them?
    • Represents a real person, place, event, or transaction.
      • Method:tasks or functions that the object performs where it receives a message or command.
      • Attribute: characteristics that describes the object
      • Classes: objects that belong to a group or category.
        • Subclass: more specific category within a class
  • Understand object relationship diagrams (including how we illustrate inheritance).
    • Relationship allows objects to communicate and interact as they perform business functions and transactions required by the system.
    • Inheritance: type of object relationship that allows object to derive 1+ of its attributes.
    • After objects, classes, and relationships have been identified, an object relationship diagram is created to provide an overview of the system.
  • What details do we capture for each use case?
    • Use case: represents steps in a specific business function or process
    • Use case diagram: visual summary of several related use cases within a system or subsystem.
    • Class diagram: shows object class and relationship involved in a sue case. Uses rectangles and UML notation of 1 and 0 and 0… .
    • Sequence diagram: dynamic model of a use case showing interaction among classes during a specific time period. Includes classes, lifelines, messages, and focuses.
    • State transition diagram: shows how objects change from one state to another.
    • Activity diagram: horizontal flow chart that shows the actions and events as they occur.
    • Business process modeling: a tool to represent people, events, and interactions in a system.

Concepts

  • Unified Modeling Language (UML) :documenting and modeling a system for o-o systems. widely used method of visualizing and documenting information systems.
  • Object message: command that tells an object to perform a certain method.
  • Encapsulation : idea that all data and methods are self contained. Black box example
  • Polymorphism: message that gives different meanings to different objects
  • Actors (in use cases): also known as an external entity, initiates a use case by requesting the system to perform a function or process.

Chapter 7

Questions

  • How does In-house development differ from purchasing a software package?
    • In house development: an information center or help desk within the IT department that is responsible for providing user support and offering services such as hotline assistance, training, and guidance to users who need technical help.
      • Satisfy unique business requirements
      • Minimize changes in business procedures and policies
      • Meet constraints of existing technology
      • Develop internal resources and capabilities
      • Satirist unique security requirements,
    • Software package: software that is purchased or leased from another firm. A commercially produced software product or family of product.
      • Lower cost
      • Less time to implement
      • Proven reliability and performance benchmark
      • Less technical development staff
      • Future upgrade provided by vendor
      • Obtain input from other companies.
  • What types of models are used for outsourcing fees, and when might each be used?
    • Outsourcing: transfer of information system development, operation or maintenance to an outside firm that proxies these services, for a fee on a temporary or long term basis.
    • Fix free model: uses a set fee based on specified level of service and user support.
    • Subscription model: variable fee based on number of users or workstation that have access to application.
    • Usage model/ transaction model: charges variable fee based on volume of transaction or operations performed by the application.
  • What types of software package options are typically available to purchase?

Concepts

  • Request for proposal : needed to evaluare the information system requirement. RFP is a document that describes the company, lists the IT services or products needed, and specific the features required.
  • Request for quotation : more specific than an RFP. When an RFQ is used, the specific product or service desired is already known; only price quotations or bids are neede
  • Web 2.0: Three examples of evolving trends are Web 2.0, cloud computing, and mobile devices. describe a second generation of the web that enables people to collaborate, interact, and share information much more effectively
  • Horizontal/Vertical application. A software package that can be used by many different types of organizations is called a horizontal application. software package developed to handle information requirements for a specific type of business is called a vertical application
  • Outsourcing/offshoring
    • Outsourcing is the transfer of information systems development, operation, or maintenance to an outside firm that provides these services, for a fee, on a temporary or long-term basis.
    • Offshoring, also known as offshore outsourcing or global outsourcing, refers to the practice of shifting IT development, support, and operations to other countries. In a trend similar to the outflow of manufacturing jobs over a several-decade period, many firms are sending IT work overseas.
  • Service provider: firm that offers outsourcing solutions
  • Software as a Service: A model of software delivery in which functionality is delivered on demand as a network-accessible service, rather than as a traditional software application that is downloaded and installed on the customer’s computer.
  • Software license: A legal agreement that gives users the right to use the software under certain terms and conditions.