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User Requirements Notation (URN ). Daniel Amyot Q18/17 (URN) Rapporteur [email protected]. Objectives. Brief overview of URN Goal-oriented Requirement Language (GRL), Use Case Maps (UCMs), and their relationships Connections between URN and several languages from ITU and OMG - PowerPoint PPT Presentation
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SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING
UNIVERSITY OF OTTAWA, CANADA
Daniel AmyotQ18/17 (URN) Rapporteur
User Requirements Notation (URN )
Workshop on "Framework and scope of formal languages", Geneva, March 2, 2002 2
Objectives
Brief overview of URN Goal-oriented Requirement Language (GRL),
Use Case Maps (UCMs), and their relationships
Connections between URN and several languages from ITU and OMG
Several Challenges
Workshop on "Framework and scope of formal languages", Geneva, March 2, 2002 3
Need improvement to cope with new realities of complex, dynamic, and evolving systems
Common design and standardisation methodologies already use scenarios
Requirements and Service Description
Stage 1
Message Sequence
Information
Stage 2
Protocols,Procedures,Behaviour
Stage 3
SDL orUML Statechart
diagrams
MSC orUML interaction
diagrams
Informal requirements?Use Cases?
URN!
Motivation for URN
Workshop on "Framework and scope of formal languages", Geneva, March 2, 2002 4
URN - Initial Objectives
Focus on early stages of design, with scenarios Capture user requirements when little design detail is
available No messages, components, or component states
required Reusability of scenarios and allocation to components Dynamic refinement capabilities Modelling of agent systems, early performance
analysis, and early detection of undesirable interactions
Workshop on "Framework and scope of formal languages", Geneva, March 2, 2002 5
URN - Additional Objectives
Express, analyse and deal with non-functional requirements (NFRs)
Express the relationship between business objectives/goals and system requirements
Capture reusable analysis (argumentation) and design knowledge (patterns) for addressing non-functional requirements
Connect to other ITU-T languages (and to UML)
Workshop on "Framework and scope of formal languages", Geneva, March 2, 2002 6
Current Proposal for URN
Draft documents for Z.150, Z.151, Z.152– http://www.UseCaseMaps.org/urn/
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
(Z.150-153)
Workshop on "Framework and scope of formal languages", Geneva, March 2, 2002 7
GRL in a Nutshell
Goal-oriented Requirement Language — a graphical notation that allows reasoning about (non-functional) requirements
GRL is concerned with intentional elements, actors, and their relationships
Intentional elements model the “why” aspect — objectives, alternatives, as well as decision rationale and criteria — but not operational details
GRL satisfies most of URN’s additional objectives
Workshop on "Framework and scope of formal languages", Geneva, March 2, 2002 8
Basic GRL Notation
Means-End Goal
Decomposition(AND)Correlation
(side-effect)
Belief
Argumentation
Task
Make..
Contribution
Softgoal
PasswordCardkey Biometrics
Identification
Cost ofTerminal
Biometrics is noregular off-the-shelf
technology
AccessAuthorization Encryption
Authentication
Security ofHost
Security ofTerminal
SystemSecurity
Workshop on "Framework and scope of formal languages", Geneva, March 2, 2002 9
Evaluations with GRL
..
PasswordCardkey Biometrics
Identification
Cost ofTerminal
Biometrics is noregular off-the-shelf
technology
AccessAuthorization Encryption
Authentication
Satisficed
Weakly Satisficed
Undecided
Weakly Denied
Denied
Security ofHost
Security ofTerminal
SystemSecurity
Workshop on "Framework and scope of formal languages", Geneva, March 2, 2002 10
UCMs in a Nutshell
Use Case Maps – a graphical scenario notation for describing causal relationships between responsibilities
Scenario elements may (optionally) be linked to components
The intent of UCMs is to facilitate the integration and reusability of scenarios, and to guide the design of high level architectures and detailed scenarios from requirements
UCMs satisfy most initial URN requirements
Workshop on "Framework and scope of formal languages", Geneva, March 2, 2002 11
Component
StartPoint
End Point
Responsibility
Stub
AND-Fork
Pool
a) Root UCM
Slot
b) Biometrics Plug-In c) PassWord Plug-in
Timer
OR-Fork
Workshop on "Framework and scope of formal languages", Geneva, March 2, 2002 12
GRL - UCM Relationship
Goal-based approach– Focuses on answering “why” questions– Addresses functional and non-functional
requirements 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
Workshop on "Framework and scope of formal languages", Geneva, March 2, 2002 13
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...)
Workshop on "Framework and scope of formal languages", Geneva, March 2, 2002 14
Informal Requirements,
Textual Use Cases
URN — OMG/SG17 Puzzle
UCMs link to operationalizations
(tasks) in GRL models
Structural Diagrams
SDL, or UML Class, Object, Component, &
Deployment Diagrams
Testing and Performance Languages
TTCN, LQN, ...
Behavioral DiagramsMSC/SDL, or UML
Sequence, Collabor., & Statechart Diagrams
UCMs represent visually use cases in terms of causal
responsibilities
UCMs provide a framework for
making high level and detailed
design decisions
UCMs visually associate
behavior with structure at the
system level
?
?UML Use Case
Diagram & Activity Diagram
URN-NFR/GRLGoals, non-functional requirements, alterna-
tives, rationales
URN-FR / UCMsSuperimpose visually system level behavior
onto structures of abstract components
Workshop on "Framework and scope of formal languages", Geneva, March 2, 2002 17
Several Challenges (I)
Degree of formalisation– Qualitative/quantitative GRL evaluations?– UCM path traversal algorithms?– Reasoning in presence of looseness,
incompleteness, inconsistencies? Formalisation of languages
– BNF? Graphical grammar? XML & schemas?
– Layout information?
Workshop on "Framework and scope of formal languages", Geneva, March 2, 2002 18
Several Challenges (II) Extensibility and Adaptability
– UML Profiles? Connections to other languages
– Traceability, transformations, meta-model? Methodologies
– What subsets of languages make sense together?
– Do methodologies drive the evolution of standard languages?
– Who are the stakeholders?