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UML Sequence Diagrams for Requirements Engineering

Learn about the importance, rules, and examples of sequence diagrams in requirements modeling and dynamic analysis. Includes requirements management tools and elicitation process details.

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UML Sequence Diagrams for Requirements Engineering

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  1. UML Diagrams:Sequence DiagramsThe Requirements Model, andThe Dynamic Analysis Model Prof. Hany H. Ammar, CSEE, WVU, and Dept. of Computer Science, Faculty of Computers and Information, Cairo University

  2. Outline • The Requirements Model and the Analysis model • Introduction to Requirements Engineering • Importance of Sequence Diagrams • Rules of sequence diagrams • Use Cases and Sequence Diagrams • The System Sequence Diagrams • The Sound Recorder Example • The E-Commerce Example • Other Examples

  3. The Requirements Model and the Analysis Model The Requirements Elicitation Process Functional/ Nonfunctional Requirements Use Case Diagrams/ Sequence Diagrams (the system level) The Object-Oriented Analysis Process Static Analysis Dynamic Analysis - Class Diagrams - State Diagrams/ Refined Sequence Diagrams (The object level)

  4. What is Requirements Engineering ? • Requirements Engineering

  5. What is Requirements Engineering? • Requirements Management: Requirements management activities include evaluating the impact of proposed changes, tracing individual requirements to downstream work products, and tracking requirements status during development • Several Requirements management tools are available in industry

  6. What is Requirements Engineering? • Major Requirements Management Tools: 1. Caliber-RM by Technology Builders, Inc.; www.tbi.com 2. RequisitePro by Rational Software Corporation; www.rational.com 3. RTM Workshop by Integrated Chipware, Inc.; www.chipware.com

  7. What is Requirements Engineering? • Requirements Elicitation • is the process of gathering the different types of requirements from suitable stakeholders. • Business requirements describe why the product is being built and identify the benefits for both the customers and the business. • User requirements, describe the tasks or business processes a user will be able to perform with the product. (Developing use-cases) • Functional requirements describe the specific system behaviors that must be implemented (Developing usage scenarios) • Non-functional requirements, describe the non-functional features such as quality attributes of Reliability, Performance, availability, and maintainability.

  8. What is Requirements Engineering? • Requirements analysis: Requirements analysis includes decomposing high-level requirements into detailed functional requirements, constructing graphical requirements models or logical models (structured Analysis models, or Object-Oriented Analysis models) (for developers), and building prototypes. • Analysis models and prototypes provide alternative views of the requirements, which often reveal errors and conflicts that are hard to spot in a textual SRS.

  9. What is Requirements Engineering? Requirements Specification • Specification key practice is to write down the requirements in some accepted, structured format as you gather and analyze them. • The objective of requirements development is to communicate a shared understanding of the new product among all project stakeholders. • Historically, this understanding is captured in the form of a textual SRS document written in natural language, augmented by appropriate analysis models. (to be discussed in detail)

  10. What is Requirements Engineering? • Requirements Verification Verification involves evaluating the correctness and completeness of the requirements, to ensure that a system built to those requirements will satisfy the users’ needs and expectations. The goal of verification is to ensure that the requirements provide an adequate basis to proceed with design • Prototyping (or executable specifications) is a major technique used in verification. Examples include GUI development for user requirements verification, and Formal requirements specification environments

  11. Importance of Sequence Diagrams • Depict object interactions in a given scenario identified for a given Use Case • Specify the messages passed between objects using horizontal arrows including messages to/from external actors • Time increases from Top to bottom

  12. Rules of Sequence Diagrams • Sequence Initiation

  13. Rules of Sequence Diagrams • Identify objects needed to support use case, determine sequence of internal events following the external initiating event • Diagrams that are not initiated with an external actor represent only a partial sequence • Partial sequence diagrams should clearly identify the actor initiated sequence diagrams from which they are launched

  14. Rules of Sequence Diagrams • Messages specified on interactions can be synchronous or asynchronous Synchronous call

  15. Rules of Sequence Diagrams Asynchronous call

  16. Rules of Sequence Diagrams • Display operation names on call arrows

  17. Rules of Sequence Diagrams Compound and Simple Iteration

  18. ‘included’ sequence diagrams

  19. Showing alternate behavior in a sequence diagram

  20. Showing Extension Point

  21. Specifying Timing Requirements

  22. Requirements Elicitation ProcessStep 4. Refining Use Cases usingSystem Sequence Diagrams • System sequence diagrams establish the dynamic behavior in terms of key scenarios of the system for each use case • The system sequence diagram models a scenario of the system interactions with the environment for a given use case • Input/output events are clearly identified in each sequence diagram, • The State of the system before and after each event are also depicted • Different diagrams model scenarios with the normal flow of events and the abnormal flow of events

  23. Sequence Diagrams and Use CasesSystem Sequence Diagram The use case diagram Of system S The sequence diagram of use case UC1 for system S

  24. UML Use Case Diagrams: The Requirements Model Case Study

  25. UML Use Case Diagrams: The Requirements ModelDigital Sound Recorder Case Study • A sequence diagram displays object interactions arranged in a time sequence capturing a specific scenario of interactions in a use case supported by the system Time

  26. Example: Use Case Diagram of E-Commerce Example

  27. Place Requistion

  28. Other Examples of Sequence Diagrams

  29. A Simple Example of Using UML2 • EXAMPLE: SATELLITE CONTROL SYSTEM

  30. Example of Software Architecture Using UML2 • SATELLITE CONTROL SYSTEM Architecture

  31. A Simple Example Using UML2 • SATELLITE CONTROL SYSTEM Architectural behavior

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