SSADM Methodology in Information Systems

SSADM Methodology

• Developed for analyzing and designing information systems
• Widely used in UK government projects from the 1980s onwards
• Allows analysts to view actual information required to satisfy new system requirements
• Includes producing a requirements specification that describes the system to be developed

Data Modeling

• Data store: a set of data items stored for use by one or more processes over time
• Data flow: a single item of data or a logical group of data items that is transferred when a process takes place
• Logical model: a representation of the current implementation to gain an understanding of how the system functions

DFD (Data Flow Diagram)

• Level 0 diagram: the highest level of DFD, representing the area (system) and all external entities that interact with it
• Level 1 diagram: the next level DFD, showing the main processes and their data stores
• Functional decomposition diagram: used to show the top-down decomposition of a process
• Balancing: ensuring that data flows shown on the lower level DFD match those shown on the higher level DFD

Agile Development

• Agile: an incremental and iterative approach to development, with each incremental part developed over an iteration
• Spike: a development approach similar to a prototype
• Metaphors: a common vision of how the system would work
• Logical: describing the processes and information that are relevant to the business, rather than its form

XP (Extreme Programming)

• XP: an important process model under the agile umbrella, proposed by Kent Beck in 1999
• User story: a conversational description by the user about a feature of the required system
• Initial investigation: undertaken to see whether the requirements can be satisfied by an IT solution
• XP activities:
  • Coding: drawing diagrams that will be transformed to code
  • Designing: proper design to avoid complexity, dependencies, and difficulty solutions
  • Simplicity: making the solution to a problem as simple as possible
  • Testing: high-performance testing to develop a fault-free software
  • Feedback: recognizing the importance of user feedback in understanding the exact customer requirements
  • Listening: developers need to carefully listen to customers to develop a good quality software

UML (Unified Modeling Language)

• Use case: elements that describe what the system does
• Extension point: a detailed version of extend relationship
• Actor: someone or something that uses the system to achieve a goal
• System: a website, a software component, a business process, an app, or any other thing
• Association: used to connect an actor to a use case
• Generalization: also known as inheritance
• Rectangle: used to represent a system
• Oval: used to represent a use case
• Stick figure: used to represent an actor