Architecture As Language

www.voelter.devoelter@acm.org

Markus Voelterwww.itemis.degraf@itemis.de

Andreas Graf

About

1

What is a language?

Set of well-defined terms

INFORMAL

Stakeholdersagree on meaning

INFORMAL

MetamodelFORMAL

MetamodelGrammar

FORMAL

MetamodelGrammarNotation

FORMAL

A DSL is a focussed, processable

language for describing a specific

concern when building a system in a

specific domain. The abstractions and

notations used are natural/suitable for

the stakeholders who specify that

particular concern.

2

Architecture DSLs

Architecture

As youunderstandand develop

yourArchitecture…

Develop a language toexpress it!

Language resemblesarchitectural concepts

We express theapplication(s) with

the language.

DEMO I

An architectural DSL for embedded systems

3

Benefits

Clear Understandingfrom building the

language

UnambigiousVocabulary

Concepts independentfrom Technology

Programming Model canbe defined based on

Conceptual Arcitecture

Architecture „executable“(i.e. more than rules and docs)

4

Why Textual?

4

… or: why not graphical?

Languages and Editorsare easier to build

Languages and Editorsare easier to build

Evolve Language and simple editoras you understand and discuss the

architecture, in real time!

Integrates easily withcurrent infrastructure:CVS/SVN diff/merge

Model evolutionis trivial, you canalways use grep.

adapting existingmodels as the DSL evolves

Many Developers prefer textual

notations

When a graphicalnotation

is better, you can

visualize.

5

Tooling

Several tools available.Example: oAW Xtext

Specify Grammar

Antlr Grammar andParser is generated

from this specification

Generated Metamodel

Specify Constraints

Generated Editor

DEMO II

The language-aware editor for our DSL

6

Generating Code

Since we alreadyhave a formal model….

Generate APIMaps Architectural Concepts to

Implementation language (non-trivial!)

Im plem entation

Code

Program m ing

M odel A PI

Runtim e Infrastructure

(Platform /M iddlew are)

G lue Code

ImplementationImplementation only depends on

the generated programming model API

Im plem entation

Code

Program m ing

M odel A PI

Runtim e Infrastructure

(Platform /M iddlew are)

G lue Code

Programming ModelGenerated API + Usage Idioms

Completely Technology-Independent

Im plem entation

Code

Program m ing

M odel A PI

Runtim e Infrastructure

(Platform /M iddlew are)

G lue Code

Runtime InfrastructureSelect based on fit wrt. to architectural

concepts and non-functional requirements

Im plem entation

Code

Program m ing

M odel A PI

Runtim e Infrastructure

(Platform /M iddlew are)

G lue Code

Glue CodeAka Technology Mapping CodeMaps API to selected platform

Im plem entation

Code

Program m ing

M odel A PI

Runtim e Infrastructure

(Platform /M iddlew are)

G lue Code

Glue CodeContains Configuration Files for Platform

Might require „mix in models“

Im plem entation

Code

Program m ing

M odel A PI

Runtim e Infrastructure

(Platform /M iddlew are)

G lue Code

Several PlatformsDifferent Platforms, not Languages

Support for Scaling (non-functional req)

Im plem entation

Code

Program m ing

M odel A PI

Runtim e Infrastructure

(Platform /M iddlew are)

G lue Code

Platform 2

G lue Code 2

Testing!

Benefits:More Efficient Impl.Technology IndependentConsistence/QualityArchitecture-Conformance

Code Gen Sequence

Im plem entation

Code

Program m ing

M odel A PI

P latform

G lue Code

1) Generate API

2) Write Impl Code

3) Select Platform

4) Generate Glue Code

Separate Modelsfor stuff relevant for the APIvs. system/deployment stuff

Program m ing

M odel A PI

M odel 1

(Types)

M odel 2

(System ,

D eploym ent)

G lue Code

DEMO III

Generating C for thetarget device

7

Expressing Variability

Different Variantsof the Systemfor different customers.

How do I express

this in themodels?

Negative Variability:Conditionally taking

something away

Negative Variability:Conditionally taking

something away

Feature Models

System

Failover Monitoring

Graceful

DegradationRedundancy

Data

Management

Centralized Distributed

component DelayCalculator {

provides default: IDelayCalculator

requires screens[0..n]: IInfoScreen

provides mon: IMonitoring feature monitoring

}

component DelayCalculator {

provides default: IDelayCalculator

requires screens[0..n]: IInfoScreen

provides mon: IMonitoring feature monitoring

}

System

Failover Monitoring

Graceful

DegradationRedundancy

Data

Management

Centralized Distributed

namespace monitoringStuff feature monitoring {

component MonitoringConsole {

requires devices:[*]: IMonitor

}

instance monitor: MonitoringConsole

dynamic connect monitor.devices query {

type = IMonitor

}

}

Positive Variability:Conditionally adding

something to a minimal core

Positive Variability:Conditionally adding

something to a minimal core

Aspects

namespace monitoring {

component MonitoringConsole …

instance monitor: …

dynamic connect monitor.devices …

aspect (*) component {

provides mon: IMonitoring

}

}

component DelayCalculator {

…

}

component AircraftModule {

…

}

component InfoScreen {

…

}

component DelayCalculator {

…

}

component AircraftModule {

…

}

component InfoScreen {

…

}component DelayCalculator {

…

provides mon: IMonitoring

}

component AircraftModule {

…

provides mon: IMonitoring

}

component InfoScreen {

…

provides mon: IMmonitoring

}

aspect (*) component {

provides mon: IMonitoring

}

Weaver is generic:

works with all (container)model elements

aspect (*) <type>all instances of type

aspect (tag=bla) <type>all instances with tag bla

aspect (name=S*) <type>all instances whose namestarts with S

namespace monitoring feature monitoring {

component MonitoringConsole …

instance monitor: …

dynamic connect monitor.devices …

aspect (*) component {

provides mon: IMonitoring

}

}

AO + Features

DEMO III

Adding Variability and connectivity to a feature model to the previous DSL

Based on actualpractical experience

Currently in use withfour of my customers

Benchmarked bysuitability for use in today‘s projects

THE END.Thank you.

Questions?