Model-Driven User Requirements Specification using SysML Authors: Michel dos Santos Soares, Jos Vrancken Source: Journal of Software(JSW), Vol. 3, No. 6, 57-68, Jun 2008 ISSN X Presenter: Ming-Chih Li ESL, Dept. of CSIE, CCU 2011/03/11

Outline  Introduction  A Proposed User Requirements Classification  User Requirements Specification Using SysML Diagrams  SysML Requirements Diagram Extensions  Case Study  Discussion  Conclusion 2011/3/112

Introduction  Requirements engineering(RE) is an important phase in a system’s life cycle. When poorly performed failures, cost overrun and delays  RE can be divided into two main groups of activities Requirements development  Documenting and analyzing Requirements management 2011/3/113

Introduction (cont.)  Well-written user requirements documentation is fundamental as it facilitates later phases, not only during RE, but during the whole system life cycle. 2011/3/114

Introduction (cont.)  The increasing complexity of systems makes requirements engineering activities both more important and more difficult. large number of elements and reliability factors  must be decomposed into several smaller components increase the level of abstraction Model-driven approaches 2011/3/115

Introduction (cont.)  UML and its profiles(e.g. SysML, MARTE) are the current dominant graphical languages used in model- driven approaches  This paper is about applying a Model-Driven Requirements Engineering approach based on SysML  Requirements diagrams  Use Case diagrams 2011/3/116

Introduction (cont.)  First, a classification for each atomic requirement is proposed  the SysML Requirements diagram is used to represent graphically single user requirements and their relationships 2011/3/117

Introduction (cont.)  Then, User requirements are also represented in a tabular format, which may facilitate requirements tracing during the system life cycle.  Finally, SysML Use Case diagrams are applied to represent the actors involved and the use cases, giving a context diagram delimiting the system 2011/3/118

Introduction (cont.)  After being structured and graphically represented, user requirements may be detailed into systems requirements 2011/3/119

A Proposed User Requirements Classification  A common classification proposed for requirements is based on the level of abstraction functional  describes what the system should do non-functional  are related to emergent system properties, such as reliability and performance external  a detailed description of all inputs into and outputs from the software system 2011/3/1110

User Requirements Specification Using SysML Diagrams  The SysML Requirements Diagram is a stereotype of the UML Class diagram 2011/3/1111

User Requirements Specification Using SysML Diagrams (cont.)  Requirements relationships hierarchy derive satisfy  dependency relationship between a requirement and a model element verify  how a test case can verify a requirement refine trace 2011/3/1112

User Requirements Specification Using SysML Diagrams (cont.)  Requirements Table This allows an agile way to identify, prioritize and trace requirements 2011/3/1113

User Requirements Specification Using SysML Diagrams (cont.)  The SysML Use Case Diagram The SysML Use Case diagram is derived without important extensions from the UML 2.0 Use Case diagram The Use Case diagram shows system functionalities that are performed through the interaction of the system with its actors. 2011/3/1114

SysML Requirements Diagram Extensions 2011/3/1115 Type: tagged values e.g. Performance, Security and Efficiency for non-functional req. User, Hardware, Software and Communication for External Interface req.

SysML Requirements Diagram Extensions (cont.)  Grouping Requirements Requirements may be decomposed into atomic requirements, and may later even be related in the sense that together they are capable of delivering a whole feature 2011/3/1116

Case Study  The case study is based on a document with 79 atomic requirements for a road traffic management system.  We have selected in this paper to model the requirements of the Traffic Manager(TM, 10) and the Traffic Management Center(TMC, 8). 2011/3/1117

Case Study (cont.) 2011/3/1118

Case Study (cont.) 2011/3/1119

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Discussion  natural language is the only description of requirements ambiguity, lack of easy visualization and impossibility to analyze and simulate.  SysML is a language is highly customizable and can be extended into families of languages Profiles may specialize language semantics, provide new graphical icons and domain-specific model libraries 2011/3/1123

Conclusion (cont.)  It is essential to have properly- structured and controlled requirements specifications  requirements tables are useful to represent decomposition in a tabular form and improve traceability  Using a specific diagram for requirements is a SysML advantage over UML 2011/3/1124

Conclusion  An extension to the basic SysML Requirements diagram is proposed, based on a classification for user requirements  It is also shown that related requirements can be grouped, which can be seen as an initial system decomposition into subsystems 2011/3/1125

 Thanks for your listening 2011/3/1126