Using UML Models for the Performance Analysis of Network

Systems

Nico de Wet and Pieter KritzingerDepartment of Computer Science

University of Cape Town

Context

1. M.Sc. Dissertation

2. SPECS (SDL Performance Evaluation of Concurrent Systems)

standard SDL/PR models annotated via GUI specify non-functional duration constraints

block: actions per time unit process: action quota signal tranfer via channels: randomly distributed delay

Protocol Validation, Verification and Performance

Protocol Validation and Verification using FDTs accepted Specification and Description Language (SDL) Estelle Process Meta Language (PROMELA) and SPIN

Performance fundamental quality attribute: performability UML 1.x

general purpose language, no formal semantics Map to formal method Specialize UML with a profile (ITU-T Z.109 “SDL Combined with

UML”)

Model-Driven Development and UML 2.0 “The model is the implementation”

Syntax needed for graphical programming SDL used as model-driven development language for decades

in teleco industry Specialized diagrams and abstractions useful in protocol

development High-level programming language but target language

independant UML 2.0

UML 1.x: formal semantics, excessive size, architectural modelling UML 2.0: architectural modelling based on SDL and ROOM

Telelogic Tau Generation 2 Draft UML 2.0 specifications and ITU-T Z.109 “SDL combined with

UML” Telelogic Tau UML 2.0 and non-standard UML Syntax

Performance Modelling with SDL

Core problem: means of specifying non-functional duration constraints

lacking in standard Solutions:

SPECS, ObjectGEODE, SPEET, QUEST, SDL/OPNET, SDL*, TSDL, perfSDL

Some approaches modify standard SDL syntax Better: use annotated approach

Specifying Non-functional Time Related Aspects

Communication delay

Processing times

Execution modes

Time constraints on external environment

Scheduling

proSPEX

UML 2.0 and ITU-T Z.109 Recommendation “SDL Combioned with SDL” SDL abstractions, tightened semantics & target-language

independent syntax available Previous work & UML Profile for schedulability, performance

and time specification Use annotated approach Create model processor (tool integration) using XMI as

interface Map to process-based discrete event simulation library

The proSPEX Methodology Overview

The proSPEX Tool Architecture

Telelogic Tau G2 model editor XML format In future: editor supporting XML Metadata Interchange (XMI)

2.0 format Filter Tau XML and place in data structures

XML extremely verbose, no supporting documentation, DTD Extend open-source Simmcast network simulation

framework Network simulation primitives How to map Telelogic UML 2.0 asbstractions to simulation

model Use Text Templating engine to generate simulation code

The proSPEX Tool Architecture

Concluding Remarks

The proSPEX methodology Identified the UML 2.0 diagram roles and performance

annotations Problem of detail in state machines remains

The proSPEX tool architecture Use pure UML 2.0 and XMI 2.0, not Telelogic UML 2.0

and XML in future Vendor lock-in Tau XML proprietary, no company support