Feature Description and Feature Interaction Analysis with Use

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Feature Description and Feature Interaction Analysis with Use Case Maps and LOTOS Daniel Amyot

Feature Description and Feature Interaction Analysis with Use Case Maps and LOTOS Daniel Amyot et al. SITE, University of Ottawa, Canada [email protected] uottawa. ca FIW’ 00, Glasgow, May 19, 2000 SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA

Collaborators n n n n Leïla Charfi, University of Ottawa Nicolas Gorse, University of

Collaborators n n n n Leïla Charfi, University of Ottawa Nicolas Gorse, University of Ottawa Tom Gray, Mitel Corporation Luigi Logrippo, University of Ottawa Jacques Sincennes, University of Ottawa Bernard Stépien, University of Ottawa Tom Ware, Mitel Corporation SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 2

Introduction n New methodology for feature design, specification and validation Jointly by U. of

Introduction n New methodology for feature design, specification and validation Jointly by U. of Ottawa and Mitel Corp. Application to new product – Enterprise private networks – Agent-based call model – Features: Outgoing Call Screening, Call Forward Always, Call Forward Busy, Call Hold, Recall, Call Pickup, Call Transfer SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 3

Approach n Use Case Maps – Causal scenario notation – Description and documentation of

Approach n Use Case Maps – Causal scenario notation – Description and documentation of requirements and high-level designs n LOTOS – Formal algebraic specification language – Powerful validation & verification tools and techniques, enabling FI detection n Both have an FI history, in isolation SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 4

Related Work n Formal Methods – Precise, mathematical, but low penetration n Scenario-Driven Approaches

Related Work n Formal Methods – Precise, mathematical, but low penetration n Scenario-Driven Approaches – Higher level of acceptance, accessible to a broad range of readers; but integration of scenarios and V&V remains difficult n Some Well-Known Approaches – SDL and Message Sequence Charts – Unified Modeling Language SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 5

Two Complementary Techniques n Use Case Maps – Visual and intuitive scenario notation –

Two Complementary Techniques n Use Case Maps – Visual and intuitive scenario notation – Capture, integrate, and help reasoning about functional requirements – FI avoidance n LOTOS – Formalization, abstract prototyping and validation – Automated FI detection SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 6

In This Presentation. . . n n n n Use Case Maps Notation System

In This Presentation. . . n n n n Use Case Maps Notation System Architecture with Call Model UCMs UCM-Based FI Avoidance From UCMs to LOTOS Validation and FI Detection with LOTOS Traces, MSCs and Animations Conclusions SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 7

Use Case Maps Notation n Visualization of causal relationships between responsibilities allocated to abstract

Use Case Maps Notation n Visualization of causal relationships between responsibilities allocated to abstract components Start Point Alice Responsibility Agent. A Condition Agent. B vrfy req [idle] End Point Bob upd ring [busy] msg mb Component SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 8

Refining UCMs with Message Exchanges Alice Agent. A Agent. B Bob req Alice Agent.

Refining UCMs with Message Exchanges Alice Agent. A Agent. B Bob req Alice Agent. A Agent. B vrfy upd req Bob msg 1 vrfy ring upd ring SN Alice upd Switch SN Bob req vrfy Alice Switch Bob vrfy req ring SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA msg 2 msg 3 msg 4 msg 5 ring upd 9

Plug-ins for Stub. O Integrating UCM Scenarios OCSlist in 1 out 1 Root Map

Plug-ins for Stub. O Integrating UCM Scenarios OCSlist in 1 out 1 Root Map [allowed] md out 1 [denied] out 2 Originating plug-in User. O Plug-in for Stub. T chk in 1 Agent. O Stub. O OCS plug-in Agent. T User. T Stub. T ring req msg upd in 2 vrfy out 3 [idle] [busy] mb out 4 mrb Terminating plug-in SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 10

System Architecture n Agents types: – Device Agents (DAGENT or DEB) – Personal Agents

System Architecture n Agents types: – Device Agents (DAGENT or DEB) – Personal Agents (PAGENT or CEB) – Functional Agents (FAGENT or LEB) n Agents roles: – Originating, Terminating, 3 rd party n Call objects instantiated dynamically SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 11

Design of the Call Model UCMs n Created by industrial partners – 1 senior

Design of the Call Model UCMs n Created by industrial partners – 1 senior designer and 2 junior designers n More than 100 UCMs – Basic call and 10 features – Structured with 60 stubs – 7 levels deep – Many plug-ins reused – Recently added 3 features, low impact – Use of the UCM Navigator SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 12

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FI Avoidance at UCM Level n n Many FI solved at integration time Before

FI Avoidance at UCM Level n n Many FI solved at integration time Before the generation of a prototype Remaining FI mostly in dynamic stubs Several problems detected by inspection – Non-determinism in selection policies – Erroneous UCMs – Ambiguous UCMs, lack of comments n New techniques (e. g. Namakura et al. ) SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 14

Towards LOTOS n n ISO standard, process algebra Powerful constructs – Composition: multiway rendezvous

Towards LOTOS n n ISO standard, process algebra Powerful constructs – Composition: multiway rendezvous – Hiding – Abstract Data Types (ADT) – Flexible inter-process synchronization n Constructs similar to those of UCMs SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 15

From UCMs to LOTOS Start/end points Responsibilities Agents/components Stubs Plug-ins Inter-path causality Databases, conditions

From UCMs to LOTOS Start/end points Responsibilities Agents/components Stubs Plug-ins Inter-path causality Databases, conditions Visible gates Hidden gates Processes (implement selection policies) Processes Hidden inter-process synchronization (msg) Abstract Data Types SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 16

Validation n Scenarios derived from UCMs paths for: – Basic System Properties – Individual

Validation n Scenarios derived from UCMs paths for: – Basic System Properties – Individual Features Properties – Feature Interaction n Scenarios simpler than specification – Few features considered at once – No component, close to requirements n Verdicts obtained with LOLA SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 17

FI Analysis Phase n n n FI team: 2 students No major fault, but

FI Analysis Phase n n n FI team: 2 students No major fault, but several problems detected LOTOS specification: 2450 lines 36 test scenarios: 1300 lines Currently being extended in new phase Other LOTOS-based techniques and tools to be used SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 18

Feature Interaction “Suspiscion” n n Derivation of properties of individual features Analysis in Prolog

Feature Interaction “Suspiscion” n n Derivation of properties of individual features Analysis in Prolog to determine: – direct and transitive FI – non-determinisim – loops n Generation of FI prone scenarios and configurations SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 19

Traces, MSCs and Animations n n n LOTOS traces are translated to MSCs by

Traces, MSCs and Animations n n n LOTOS traces are translated to MSCs by associating direction to gates and identifying sender and receiver entities Translation of MSCs to LOTOS permits validation against external scenarios A graphical animator displays a given trace as a structural diagram of the system, in a step-by-step fashion SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 20

Conclusions n n n UCM-LOTOS approach for specification and validation of telecommunications systems seems

Conclusions n n n UCM-LOTOS approach for specification and validation of telecommunications systems seems feasible and effective Encouraging results so far, more to come in the near future… Technology transfer in progress SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 21

Use Case Maps Web Page http: //www. Use. Case. Maps. org/ Bon appétit! SCHOOL

Use Case Maps Web Page http: //www. Use. Case. Maps. org/ Bon appétit! SCHOOL OF INFORMATION TECHNOLOGY AND ENGINEERING UNIVERSITY OF OTTAWA 22