User Requirements Notation - ITU

User Requirements Notation - ITU

ITU-T Workshop on the "Use of Description Techniques" Using the User Requirements Notation Daniel Amyot Q.18/17 Rapporteur SITE, University of Ottawa, Canada [email protected] SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA, CANADA About this presentation What is the User Requirements Notation (URN)? What can we model with URN? What answers can these models provide? What are the typical/potential usages? URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 2 URN Main objectives

Focus on early stages of development with goals and scenarios From user requirements to system functional and non-functional requirements No messages, components, or component states required Reusability of argumentations (goal patterns and analysis) of scenarios (patterns and architectural alternatives) Early performance analysis Traceability and transformations to other languages Particularly MSC, SDL, TTCN, and UML URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 3 Current Proposal for URN Draft documents for Z.150, Z.151, Z.152 Combined use of two complementary notations: Goal-oriented Requirement Language (GRL) for NFRs (http://www.cs.toronto.edu/km/GRL/) Use Case Maps (UCM) for Functional Requirements (http://www.UseCaseMaps.org/) Create ITU-T standard by end of 2003 http://www.UseCaseMaps.org/urn/

URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 4 URN Missing Piece of the Modelling Puzzle? Structural Diagrams SDL, eODL, or UML class, object, component, & deployment diagrams UCMs visually associate behavior and structure at the system level Informal Requirements, Textual Use Cases URN-NFR/GRL ? ? Goals, non-functional requirements, alternatives, rationales Data ASN.1 where appropriate UCMs link to operationalizations (tasks) in GRL

models URN-FR / UCMs MSC, UML Use Superimpose Case Diagram visually & system level behavior Activity Diagram onto structures of abstract components. Can replace UML use case & deployment diagams. UCMs represent visually use cases in terms of causal responsibilities Behavioral Diagrams MSC/SDL, or UML sequence, collabor., & statechart diagrams UCMs provide a framework for making high level and detailed design decisions Testing and Performance Languages TTCN, LQN, ...

URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 5 GRL in a Nutshell Goal-oriented Requirement Language graphical notation connects requirements of requirements to business objectives allows reasoning about (non-functional) requirements GRL models the why aspect objectives, alternatives, as well as decision rationale no operational details Supports goal analysis and evaluations URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 6 Basic GRL Notation Softgoal ? Break Hurt Some- Unknown Belief Make Help Some+ Equal

System Security Contribution Biometrics is no regular off-the-shelf technology Argumentation . Security of Terminal Access Authorization Cost of Terminal Security of Host . Make Encryption Task Correlation (side-effect) Decomposition (AND) Authentication Means-End Cardkey

Password Identification Goal Biometrics URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 7 Evaluations with GRL Satisficed System Security Weakly Satisficed Undecided Weakly Denied Biometrics is no regular off-the-shelf technology Denied . Security of Terminal Access Authorization Cost of Terminal

Authentication Cardkey Password Security of Host . Encryption Identification Biometrics URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 8 UCMs in a Nutshell Use Case Maps graphical scenario notation causal relationships between responsibilities scenario elements may (optionally) be allocated to components UCMs model the what aspects functional requirements as scenarios integration and reusability of scenarios guidance for architecture and detailed behaviour

Performance analysis, conflict detection URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 9 Pool Start Point Stub AND-Fork Slot End Point Responsibility Component a) Root UCM c) PassWord Plug-in b) Biometrics Plug-In Timer OR-Fork URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 10 GRL - UCM Relationship Goal-based approach Focuses on answering why questions

Scenario-based approach Focuses on answering what questions Goals are operationalized into tasks and tasks are elaborated in (mapped to) UCM scenarios Focuses on answering how questions GRL goals can guide the selection of a particular architecture for the UCM scenarios URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 11 Typical Usage of URN Modelling and documentation User and system requirements, rationales Analysis of business goals Evaluations of alternative requirements or solutions Discovery of tradeoffs that can optimize the stakeholders degree of satisfaction for conflicting goals Architecture analysis Based on NFRs and design constraints Performance analysis

Generation of individual scenarios Training, documentation Detection of conflicts Transformation to MSC and test cases Reverse-engineering URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 12 Experiences with GRL Used on industrial projects New family of Web-based telephone sets Documentation of discussions involving multiple stakeholders Visualization and analysis of conflicting goals Evaluation of architectural solutions, and rationales for the retained solution Proved to be very helpful for keeping discussions on track and for avoiding repeating the same discussions over and over again. Accelerated the reaching of an agreement and Improved (short-term and long-term) understanding. Used in academic projects Security applications Web-based systems (in combination with UCMs) Architectural/performance tradeoffs at a qualitative level URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 13

Performance Engineering with UCMs 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 Access E_Accountant T2 CheckBio Continue Rejected Components Allocated responsibilities Processor assignment OR Forks Relative weights (probability)

Automated translation to Layered Queuing Networks (LQNs), for analytical evaluations and simulations. Being applied to industrial case studies. URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 Ready 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 14 UCM Scenario Definitions and Path Traversal (Highlight) Extraction of individual scenarios Conditions attached to selection points Initialization of Boolean variables,

and selection of start points URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 15 Tool Support: UCMNav 2.1 URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 16 From UCM Requirements to More Detailed Design Models Requires: Path Data Model (global Booleans variables) Scenario Definitions Path Traversal Mechanism Mapping Rules (MSC, UML, TTCN, LQN, LOTOS...) URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 17 Experiences with TIAs Wireless Intelligent Network ICS invocation with Normal Termination and Distinctive Alerting Originating System MSC Serving System HLR SCP

VLR MSC call origination MS a LOCREQ [DGTSDIAL, TRANSCAP] b SERVREQ [SRVID, DGTSDIAL] SVRT c servreq [ACTCODE, ALRTCODE] ROUTREQ [MIN, ALRTCODE] LRT e ROUTREQ [MIN, ALRTCODE] RRT RRT routreq [TLDN] routreq [TLDN] locreq [TERMLIST] d

f g h TLDNAT i call setup j call setup [ALRTCODE] URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 k 18 Simplified UCM for Incoming Call Screening WIN Phase 1 covers three major services: Calling Name Presentation (CNAP) Incoming Call Screening (ICS) Voice Controlled Services (VCS) The following ICS Use Case Map is for illustration purpose. NormalAlerting (NA) IncomingCall (IC) Screening (S) PlayBlockAnnounce (PBA) URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 CallSetup (CS) CallBlocked (CB)

19 Incoming Call Screening Scenario on Functional Entities IC FE5 NA IC CS FE1 IC FE3 FE1 FE3 S FE1 S FE6 PBA CB FE2 FE4 NA

PBA S CB FE2 NA CS (a) First Structure (b) Second Structure FE4 PBA CB CS (c) Different Mapping of UCM URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 20 Binding Functional Entities to Network Entities NE1 NE2 FE1 NE3

FE2 NE4 FE3 FE4 (a) First Structure NE1 FE1 NE2 FE2 NE3 FE3 NE1 FE1 NE2 FE3 NE3 FE4 (b) Second Structure URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 FE2 FE4 (c) Different Mapping of FEs 21

Refinement with MSC IC NE1 NE1 NE2 NE3 NE1 NE2 NE3 NE2 IC FE1 FE3 m1 IC m2 m1 m2 S S m3 m4 m5

NA NE3 CS S FE2 FE4 NA PBA PBA CB CB CS (a) UCM to FEs to NEs (b) A MSC for URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 (c) A MSC for 22 Plug-in UCM for ICS + + SCP

HLR Legend LRFH Blk : Blocking Chk : Check SDF SF Chk CF : CheckFunction DA : DistinctiveAlerting Loc NA : NormalAlerting SCF VM SCF NA DA CF Nb Nb : Number PBA : PlayBlockAnnounce Req : Request

MSC MACF Routing SSF IP SF : ScreeningFunction VM : VoiceMail SRF Blk PBA Loc : Location CCF IncomingCall CallSetup Req SRF VoiceMail CallForwarded Announcement CallBlocked + + URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002

23 Coming soon 48 FILE ScenarioMessage 6 Logic LogicLayer ProcessMsg ProcessMsg MsgToTool MsgToTool 1 MsgSentToTool 18 Socket SocketLayer SendMsg SendMsg GetRequest 34 GetRequest 9

MsgSentToTool BufferLayer 8 32 32 1 URN-oriented Reverse-Engineering UCMs for reverse-engineering already popular. Can cope with very complex systems UCM to UML scenarios UCM to TTCN test cases URN and Requirements Management UCM and Requirements-based Design (synthesis) Already a tool-support mapping to LOTOS URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 24 Conclusions URN Allows engineers to specify or discover requirements for a proposed system or an evolving system, and review such requirements for correctness and completeness.

Is usable in industry and in standardization bodies Combines goals and scenarios Helps bridging the gap between informal and formal concepts, and between requirements models and design models Big benefits for little modelling investment, even when used informally GRL For incomplete, tentative, (non-functional) requirements Capture goals, objectives, alternatives and rationales UCM For operational and functional requirements Enables analysis and transformations Architectural alternatives and dynamic systems URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 25 7th Feature Interaction Workshop Ottawa, June 9-11, 2003 http://www.site.uottawa.ca/fiw03/ Submission deadline: December 9 URN, ITU-T Workshop on the "Use of Description Techniques", November 23, 2002 26

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