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I-Logix Inc. y 3 Riverside Drive y Andover, MA 01810 y Tel 978.682.2100 y Fax 978.682.5995 y www.ilogix.com
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SysML and Rhapsody
Jack Low, Vice President Emerging Technologies & Markets
Unleashing the power of SysML
SysML is focused on providing system engineers with modeling language semantics to
facilitate their design activities. Although the final specification is yet to be approved
1
,
many stable concepts are emerging which demonstrate the power and utility of the
language. The specification’s stated goal is to provide the SE (systems engineer) with a
language that enables them to ensure their design has correctness, precision,
conciseness, consistency and understandability
2
.
For the reader who is not familiar with SysML, the modeling language is based on a
subset of the UML 2.0 specification with extensions. These extensions are focused on
providing the SE with specific elements and diagrams needed to concisely represent a
system in a modeling language. Elements such as requirements, blocks, and
constraints are examples of such extensions. These in turn required new diagrams to
represent these new elements, specifically the Block, Parametric, and Requirement
diagrams. Figure 1 shows the current diagrams for SysML.
S
y
sML Dia
g
rams
Requirement Diagram
Parametric Diagram
Structure Dia
g
rams
Block Dia
g
rams
Block Definition Diagram
Internal Block Diagram
A
ssembly Diagram
Behavior Dia
g
rams
A
ctivity Diagram
Sequence Dia
g
ram
State Machine Dia
g
ram Use Case Dia
g
ram
Timing Diagram
Figure 1 - SysML Diagram Taxonomy
1
The current version is 0.9 and is as of the date of this writing still being developed
2
Systems Modeling Language (SysML) Specification ver. 0.9, Chapter 8 Language Formalism
I-Logix Inc. y 3 Riverside Drive y Andover, MA 01810 y Tel 978.682.2100 y Fax 978.682.5995 y www.ilogix.com
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These new elements and diagrams (shaded in yellow) will greatly enhance and improve
an SE’s ability to model their system regardless of whether it is software, hardware,
electrical, or a combination of each. These elements and diagrams can now be used to
improve the understandability and conciseness of a design when using it as a means of
interchange between the various groups working on a project. While there will
undoubtedly be many drawing tools on the market that will provide SysML profiles, such
as the popular Visio™ tool from Microsoft, these basic drawing tools are not engineered
to meet large, complex project demands.
This paper will discuss the essential needs of Design Organization, Fine Grained
Version Control, Static and Dynamic Analysis and Requirements Management for
successful outcomes with SysML. Further, the paper will show how Rhapsody
addresses these key domains while simple drawing tools like Visio cannot.
Good Start but need more…
The definition of the language, while necessary, is not sufficient to meet the goals of the
SysML specification. It becomes clear that in the context of a complex or large model
using the language, it would become extremely difficult and onerous for the SE to
ensure correctness, precision or consistency with respect to their design if there was no
language aware automation to ensure the goals listed above are met. Tools that provide
the ability to organize the design, and provide for fine grain version control, static and
dynamic analysis, and requirements traceability are the only way to ensure that the
systems design has correctness, precision, consistency and improves the basic
capabilities of conciseness, and understandability for both small and large scale
projects.
Design/Model Organization
One of the key advantages to modeling, and by extension SysML, is the inherent
organization and navigability that is possible through the explicit structure of the model.
Elements within a model can be grouped and organized to allow for quick and easy
navigation, as well as provide a clear contextual framework. In addition, relationships
between elements can also be captured and organized to ease in understandability.
Tools providing design or model organization will allow the user to view all of the
information relevant to an element down to the finest grained detail. In addition, they will
permit the extraction or filtering of specific information to generate customized reports of
the model. For example, users could generate specific reports for the Interfaces used by
the elements (e.g. and Interface Control Document), or segregate the aspects of the
design that are software, electrical or mechanical to produce specifications for those
respective groups.
I-Logix Inc. y 3 Riverside Drive y Andover, MA 01810 y Tel 978.682.2100 y Fax 978.682.5995 y www.ilogix.com
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Many of the drawing tools in the market today do not provide the ability to organize and
extract information selectively. For example, MS Visio allows users to organize and
navigate in the form of the Model Explorer, but it does not show all of the information
related to element-like links. Furthermore, Visio lacks any ability to reference elements
or information outside of the model itself such as requirements. Finally, there is no easy
or straightforward way to filter a model for specific reporting purposes.
Only tools that provide a robust and comprehensive means of organizing and navigating
the complex data found in large System models will be able to exploit the true
capabilities and potential of SysML.
Design Version Control
An extended benefit of a fine-grained organizational structure of a model is the ability to
provide equally fine-grain version control of the elements. In any medium to large-scale
systems endeavor, there are a variety of people concurrently working on a design. For
this reason it is essential that they be able to partition a model into logical units that can
be managed and modified separately. This allows for the team to independently work on
those segments of the model assigned to them without disrupting the activities of the
other team members. It also allows larger teams to ensure they have the most current
versions of the elements in their model.
Once again tools like Visio fall short in meeting this demand. Models in Visio can be
version controlled, but only at the model level. There is no provision for finer grained
version control of elements like blocks or requirements within the model. Thus, the only
way to accomplish this is to separate the elements into separate models. This creates a
reference and navigation nightmare for all the members of the team.
Teams working on medium to large-scale projects can only effectively use tools that
provide a fine-grained version control capability natively.
Static Analysis
Another critical advantage of having a tool that can fully exploit SysML is to provide
checks of the model for semantic or syntactical errors. In large complex models, it can
be become a daunting task to try to review all the elements of a model to ensure there
are no errors or omissions. Because SysML establishes rules, tools that can scan a
model and identify mistakes or potential omissions will bring real value to the user.
Checking for unresolved references, circular references, and dangling transitions for
example can save hours of time and effort, as well as minimizing confusion among team
members.
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资源评论
- 天外飞仙之福2012-01-16这个是从ILogix公司拷贝过来的白皮书,有助于宏观了解Rhapsody的功能。
- 杨丰玉2014-03-31正好想了解rhapsody和sysml的基本知识,谢谢
- coolmacjing2013-05-23了解rhapsody的基本知识很有帮助。
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