Scenario-Driven Dynamic Analysis of Distributed Architectures

Presented by: Thabet Kacem

Spring 2010

OutlineContributionsIntroductionProposed ApproachRelated WorkReconception of ADLsXTEAM Tool ChainDiscussionConclusionFuture Work

ContributionsAddress the shortcoming of ADLsPropose a new conception of ADL within

MDE paradigm Approach combines extensible modeling

language within a framework enabling implementation of customized dynamic analysis at architectural level

Approach was implemented in XTEAM which helped to accommodate both new modeling features and new architectural styles

IntroductionEmergence of highly distributed, resource

constrained and mobile computing environments

Consequence: Complexity of software development increased difficulties to cope with network latency, security & unpredictable network topology

Efforts went toward raising the level of abstraction for describing large scale software systems beyond OO concept

ADL emerged to provide the architect with a higher level of architectural constructs

IntroductionADL has many problems:

Focus on structural elementsRely on rigid formalisms

Many crucial aspects of a system cannot be expressed

MDE emerged as an approach to distributed software systems combining DSMLs with model transformers, analyzers and generators

Proposed ApproachThe approach combines extensible modeling

languages with a model interpreter framework for rapid implementation of dynamic analysis at arch level

Analysis provides information about the behavior & cross-cutting properties that help an architect to compare architectural alternatives and weigh tradeoffs

XTEAM:Provides ADL extension for mobile systemsImplements a set of dynamic analysis on top of

the model interpreter framework

Proposed ApproachTwo requirements to success:

Extensibility of the language to accommodate new domain-specific concepts

Flexibility of tools to allow rapid implementation of new architectural analysis techniques

Related workGME: tool implementing MDE paradigm that

enables the creation of DSML and other related models

Related workMILAN: compromises DSML for embedded

systems based on a dataflow representation & a set of models to generate executable specs for simulation engines

Automates the synthesis of software implementation for system models

It provides highly accurate simulationsDrawback: suitable for signal processing

systems but not efficient for large scale distributed architectures

Related workWML &CUTS: it’s a DSML that enables

dynamic analysis of component-based architectures

WML creates models that are transformed into XML-based inputs for CUTS

Drawbacks: WML performs syntactic translation not

semanticThe analysis is implemented in the emulator

engine not the model interpreterIt does not capture component behavior

Related workxADL: can accommodate new domain specific

concepts. It is defined by XML schemas.Core Schema: standard constructs to all ADLsExtension Schema: new modeling elements

that are written by domain expertsDrawback: xADL toolset is semantically

agnostic then it cannot be extended to enforce semantic consistency

Related WorkFSP: a modeling notation for capturing the

behavior of software architectural constructsAllows construction of composite behaviorDrawback: It lacks research concerning the

execution in heterogeneous environment, deployment and extensibility

Reconception of ADLsKey shortcomings for arch. Based approaches

to software modeling:Inflexible notation with a narrow vocabularySupporting tools that enable only a limited set

of analysisAssumption: Shortcomings can be addressed

by representing ADL via domain specific language DSML and performing arch. Analysis via model interpreter

Reconception of ADLsAvoid the creation of ADL from scratch and

use ADL composition and enhancementThese concepts are present in XTEAMModel Interpreter framework allows the

architect to implement custom analysis techniques without knowing details of semantic mapping

Use the ‘hook’ methods implemented by architect where objects are arch. constructs defined in ADL extensions

Reconception of ADLsTwo types of analysis techniques:

Static: relies on the formalism underlying models to provide info about system properties or possible errors Problem: Difficulty that system implementation

must match the model so that the analysis can be relevant

Dynamic: explores the behavior of the model-based arch. representations at runtime by executing them

It is more useful in comparing high level design possibilities early in the development cycle and don’t rely on the experience of the architect

XTEAM Tool ChainXTEAM ADL: compose a structural ADL

(xADL) with a behavioral ADL (FSP)Creates execution architecture

representationAdds language extension to capture system

change in order to help Model Interpreter to implement architectural analysis

Semantic mapping is done by the Model Interpreter

XTEAM Tool Chain

XTEAM Tool ChainDomain Specific ADL extension:

Example: Energy consumption

XTEAM Tool ChainMobile Application testbed used to illustrate

the energy consumption:

XTEAM Tool ChainThe energy consumption simulation

generator allows to do some measurements that can be plotted in function of time

XTEAM Tool ChainMany factors affect energy consumption:

Assignment of components to host or deployment architecture

Determining a dynamic redeployment strategy when consumption values differ from expected values

Many other ADL extensions exist in XTEAM:End to end latencyMemory utilizationComponent reliability

DiscussionThree cases where the approach is relevant

Providing design rationaleWeighing tradeoffsUnderstanding compositions of Off-the-shelf

componentsAre these three cases enough to judge that

the approach is reliable ?Is implementing the approach in XTEAM

sufficient to say the approach is correct ?

ConclusionThe paper presented a software arch-based

approach to modeling & analysis of distributed architecture that leverage the domain specific extensibility provided by model-driven engineering

Approach addressed shortcomings of ADLDeployed & evaluated on XTEAMConsidered as an improvement over

traditional ADL and other MDE tools

Future WorkUse XTEAM in the context of real world

security application in embedded & mobile devices

Integrate XTEAM with Desi and Prism-MWDetermine the exact class of analysis

technologies