international telecommunication union © itu-t study group 17 integrated application of urn daniel...
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© ITU-T Study Group 17
International Telecommunication Union
Integrated Integrated Application of URNApplication of URN
Daniel AmyotUniversity of Ottawa, Canada
ITU-T Workshop on the Integrated Application of Formal Languages
Geneva, September 13, 2003
© ITU-T Study Group 17 2003
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)
o Goal-oriented Requirement Language• For incomplete, tentative, (non-functional)
requirements• Capture goals, objectives, contributions,
alternatives, and rationales• Supports goal analysis and qualitative
evaluations
HighPerformance
HighThroughput
MaximumHardwareUtilisation
MinimumChanges to
Infrastructure
LowCost
Less need for new hardware
HighPerformance
HighPerformance
HighThroughput
HighThroughput
MaximumHardwareUtilisation
MaximumHardwareUtilisation
MinimumChanges to
Infrastructure
MinimumChanges to
Infrastructure
LowCostLowCost
Less need for new hardwareLess need for new hardware
© 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
MinimumMobSC Load
MinimumMessageExchange
Servicein SCP
Servicein MobSC
SDF in SCP SDF in SN
Determine SDF Location
Impact is vendor-specific
HighEvolveability
HighPerformance
HighThroughput
MaximumHardwareUtilisation
MinimumChanges to
Infrastructure
LowCost
Less need for new hardware
Example GRL Model (Wireless Service)
© ITU-T Study Group 17 2003
(a) Service in MobSC
(b) Service in MobSC, SDF in SN (c) Service and SDF in SCP
Three Alternative Solutions
© 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 UCMExporter MSC SDLMSC2SDL
© ITU-T Study Group 17 2003
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
Response TimeRequirement• From T1 to T2• Name• Response time• Percentage
Security E_Accountant
ReadyContinueCheckBio
TaxPayer
Access
T1
Timestamp
T2
Device Characteristics• Processors, disks, DSP, external services…• Speed factors
Rejected
ArrivalCharacteristics• Exponential, or• Deterministic, or• Uniform, or• Erlang, or• OtherPopulation size
Responsibilities•Data access modes•Device demand parameters
•Mean CPU load (time)•Mean operations on other devices
OR Forks• Relative weights (probability)
Components• Allocated responsibilities• Processor assignment
Can generate Layered Queuing Networks (LQN) automatically!
© 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/