International Telecommunication Union
Integrated Application of
URN
Daniel Amyot
University of Ottawa, Canada
damyot@site.uottawa.ca
ITU-T Workshop on the Integrated Application of Formal Languages
Geneva, September 13, 2003
© ITU-T Study Group 17
URN
o User Requirements Notation
• Allows engineers to specify or discover
requirements for a proposed system or an
evolving system, and review such requirements
for correctness and completeness
• Helps bridging the gap between informal and
formal concepts, and between requirements
models and design models
o URN = GRL + UCM
• Combines goals and scenarios
• Graphical notations
• Reusable patterns
o Applicable to various domains (e.g.
telecom services, distributed or reactive
systems), in industry and SDOs
© ITU-T Study Group 17 2003
GRL (URN)
Low
Cost
High
Performance
Less need for
new hardware
Minimum
Changes to
Infrastructure
Maximum
Hardware
Utilisation
High
Throughput
o Goal-oriented Requirement Language
• For incomplete, tentative, (non-functional)
requirements
• Capture goals, objectives, contributions,
alternatives, and rationales
• Supports goal analysis and qualitative
evaluations
© ITU-T Study Group 17 2003
UCM (URN)
o Use Case Maps
• Causal sequences of responsibilities,
allocated to components
• For operational requirements, as scenarios
• Support validation, performance analysis,
and evaluation of architectural alternatives
© ITU-T Study Group 17 2003
Integrating GRL and UCM
o Traceability between:
• Goals/tasks and UCMs (or UCM scenario definitions)
• Tasks and UCM responsibilities
• Different granularity
• Requirements management
• Others…
o Underspecification and overspecification
• Discovery of new goals and scenarios
• Removal of unnecessary goals and scenarios
• Examples:
• Why is a UCM scenario without any link to a GRL goal?
• Why is a GRL goal without any link to a UCM scenario?
o Refinements of alternative solutions
• From GRL (identification) to UCM (evaluation)
© ITU-T Study Group 17 2003
Example GRL Model (Wireless Service)
Low
Cost
High
Performance
High
Evolveability
Less need for
new hardware
Impact is
vendor-specific
Minimum
Changes to
Infrastructure
Maximum
Hardware
Utilisation
Determine
SDF Location
SDF in SCP
High
Throughput
Minimum
Message
Exchange
Minimum
MobSC Load
SDF in SN
Service
in MobSC
© ITU-T Study Group
17 2003
Service
in SCP
Three Alternative Solutions
(a) Service in MobSC
(b) Service in MobSC, SDF in SN
(c) Service and SDF in SCP
© ITU-T Study Group 17 2003
Integrating UCM and MSC
o Automated transformation from UCM
to MSC
• Traversal of UCMs based on Scenario
Definitions
• Enables scenario highlight on UCMs
• Paths visited can be transformed to
MSCs
• Enables the generation of more
detailed design scenarios
© ITU-T Study Group 17 2003
UCMNav and Scenario
Definitions
© ITU-T Study Group 17 2003
Two Resulting MSCs
© ITU-T Study Group 17 2003
Integrating UCM and SDL
o Generating MSC enables the synthesis
of SDL specifications
• Early prototyping and requirements
analysis
• Some results already available
• Presented at the 11th SDL Forum, 2003
UCM
UCM
Exporter
MSC
MSC2SDL
© ITU-T Study Group 17 2003
SDL
Integrating UCM and UML
o Similar transformations from UCM to:
• UML sequence diagrams
• UML activity diagrams
o These can be used to further
synthesize state diagrams
© ITU-T Study Group 17 2003
Integrating UCM and TTCN-3
o UCM scenarios can be used as test
goals
• Structured UCM scenarios converted
to test suite
• Coverage of operational
requirements
• Another transformation: TTCN-3
© ITU-T Study Group 17 2003
UCMNav and UCMExporter
o UCMNav 2 generates scenarios (in XML) from
traversals
• http://www.UseCaseMaps.org/tools/uvmnav
o UCMExporter takes these as input and
generates:
• MSC (Z.120, textual form)
• UML sequence diagrams (in XMI)
• TTCN-3
o http://ucmexporter.sourceforge.net/
© ITU-T Study Group 17 2003
Integrating UCM and LQN
o Quantitative performance analysis
with Layered Queuing Networks
o Transformation from complete UCM
model to an LQN model
• Supported by UCMNav
o Enables:
• Analytic evaluations (LQNS)
• Simulations (LQSim)
o http://www.LayeredQueuing.org
© ITU-T Study Group 17 2003
UCMs and Performance
Arrival
Characteristics
• Exponential, or
• Deterministic, or
• Uniform, or
• Erlang, or
• Other
Population size
Timestamp
TaxPayer
Device Characteristics
• Processors, disks, DSP,
external services…
• Speed factors
Security
T1
E_Accountant
T2
CheckBio Continue
Access
Ready
Rejected
Components
• Allocated responsibilities
• Processor assignment
Can generate Layered Queuing
Networks (LQN) automatically!
OR Forks
• Relative weights
(probability)
Response Time
Requirement
• From T1 to T2
• Name
• Response time
• Percentage
Responsibilities
•Data access modes
•Device demand parameters
•Mean CPU load (time)
•Mean operations on
other devices
© ITU-T Study Group 17 2003
From Goals to Design,
Performance, and Test Artifacts
o Initial traceability from GRL goals to
UCMs leads (transitively) to
traceability between goals and:
• Design scenarios (MSC, UML SD)
• Internal behaviour (SDL)
• Test (TTCN-3)
• Performance evalutions (LQN)
© ITU-T Study Group 17 2003
Still To Be Explored…
o Integrated use of URN and
• eODL
• object interfaces
• Deployments
• ASN.1
• Interface/message definitions
• Other requirements
• URN can’t express everything…
© ITU-T Study Group 17 2003
For More Information…
o User Requirements Notation
• URN Focus Group
• http://www.UseCaseMaps.org/urn/
o Papers
• UCM Virtual Library
• http://www.UseCaseMaps.org/pub/
© ITU-T Study Group 17 2003