Model-Driven User RequirementsSpecification using SysML

Authors: Michel dos Santos Soares, Jos Vrancken

Source:Journal of Software(JSW), Vol. 3, No. 6, 57-68, Jun 2008ISSN 1796-217X

Presenter:Ming-Chih LiESL, Dept. of CSIE, CCU2011/03/11

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Outline

Introduction A Proposed User Requirements

Classification User Requirements Specification Using

SysML Diagrams SysML Requirements Diagram Extensions Case Study Discussion Conclusion

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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

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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.

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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

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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

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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

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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

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Introduction (cont.)

After being structured and graphically represented, user requirements may be detailed into systems requirements

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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

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User Requirements Specification Using SysML Diagrams

The SysML Requirements Diagram is a stereotype of the UML Class diagram

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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

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User Requirements Specification Using SysML Diagrams (cont.)

Requirements Table This allows an agile way to identify,

prioritize and trace requirements

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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.

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SysML Requirements Diagram Extensions

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Type: tagged valuese.g. Performance, Security and Efficiency for non-functional req. User, Hardware, Software and Communication for External Interface req.

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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

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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).

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Case Study (cont.)

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Case Study (cont.)

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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

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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

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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

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Thanks for your listening

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