Using UML Models for the Performance Analysis of Network Systems

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Using UML Models for the Performance
Analysis of Network Systems

• Nico de Wet and Pieter Kritzinger
• Department of Computer Science
• University of Cape Town

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Context

• M.Sc. Dissertation
• 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

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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)

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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

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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

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Specifying Non-functional Time Related Aspects

• Communication delay
• Processing times
• Execution modes
• Time constraints on external environment
• Scheduling

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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

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The proSPEX Methodology Overview
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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

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The proSPEX Tool Architecture
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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