Extending GCM and Fscript for the Distributed Reconfiguration of Components

SAFA’ 08INRIA – Univ Nice Sophia Antipolis -

CNRS

Extending GCM and Fscript for the

Distributed Reconfiguration of

ComponentsBoutheina Bennour, Ludovic Henrio, Marcela Rivera

{bbennour,lhenrio,mrivera}@sophia.inria.fr

December 2008

SAFA’ 08INRIA – Univ Nice Sophia Antipolis

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Agenda

Context

Distributed Reconfiguration

Execution Context

Experimentation

Conclusion and Perspectives

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Agenda

Context


Execution Context

Experimentation


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Component Model

Primitive component= business code

Required interface

Provided interface

binding

Composite component

Fractal its distributed extension: GCM Component

Encapsulation Composition Hierarchical

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Primitive component= business code

SAFA’ 08

GCM/ProActive

Distributed components Deployed over several nodes Components abstract away distribution

Implementation: ProActive Active objects Asynchronous communication Futures


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GCM/ProActive: Distribution and Communication JVM 1 (Host A)

JVM 2 (Host B) JVM 3 (Host B)

Asynchronous remote method invocation

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Reconfiguration, adaptation

Dynamic reconfiguration Architectural modification during execution Change of functional/non-functional behaviour Adaptation to context and requirements

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Component Models and reconfigurationComponent Model

Composition

Distribution

Management of non functional code

CCM Hierarchical Specified Separation of concerns

CCA Flat Specified Separation of concerns

SCA Hierarchical Non specified Implementation

Fractal Hierarchical Non specified Membrane

GCM Hierarchical Specified Membrane

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GCM API for Reconfiguration

Life-cycle controller

Binding controller

Content Controller

string getFcState ();void startFc () throws IllegalLifeCycleException;void stopFc () throws IllegalLifeCycleException;

string[] listFc ();any lookupFc (string clientItfName) throws NoSuchInterfaceException;void bindFc (string clientItfName, any serverItf) throws . . .void unbindFc (string clientItfName) throws. . .

any[] getFcInternalInterfaces ();any getFcInternalInterface (string itfName) throws . . . Component[] getFcSubComponents ();void addFcSubComponent (Component c) throws . . .void removeFcSubComponent (Component c) throws . . .

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FScript

A Scripting reconfiguration language Dedicated to Fractal components Expressions, actions, control structures

(exceptions) FPath expressions: navigate and select

elements in the components architecture One primitive by method of the Fractal API

A language dedicated to reconfiguration of Fractal components

A language dedicated to reconfiguration of Fractal components

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Example

Add the component given_child to the composite given_parent

given_parent

given_child

given_parent

Add($given_parent, $given_parent/child::given_child)

try { ContentController cc = (ContentController) givenParent.getFcInterface("content-controller"); try {

cc.addFcSubComponent(givenChild); } catch (IllegalLifeCycleException ilce) { /* Handle error */ } catch (IllegalContentException ice) { /* Handle error */ }} catch (NoSuchInterfaceException nsie) { /* Handle error */ }

FScript:

Fractal API:

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Objective: A distributed reconfiguration language Distributed reconfiguration

Allow a component/node to interpret a reconfiguration script

Actions can be executed in parallel Extension of the FScript language to

Trigger distributed reconfiguration Handle the distributed execution

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Agenda

Context


Execution Context

Experimentation


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A Controller for Reconfigurations Manages and allows the invocation of the

script interpreter Is collocated with the component Exposes methods for reconfiguration

setInterpreter(interpreterClassName) loadScript(scriptFileName) executeAction(actionName, arguments...)

Reconfiguration interface

Interpreter

Membrane

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Triggering Distributed Reconfigurations in the Scripting LanguageA primitive for the distributed script interpretation

Triggers the action action_name by the interpreter located in target_component

Receives action arguments as parameter Precondition (Reconfigurability)

The target component must havea reconfiguration controller, i.e. it must expose the RC interface


action(arguments)

Inte

rpre

ter

target_component

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remote_call(target_component, action_name, parameters, ...);


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Example

Add the component given_child to the composite given_parent

given_parent

given_child

given_parent

remote_call($given_parent, ‘add’, ‘$given_parent’, ‘given_child’);

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definition action1

...

remote_call(C2,’action2’)



...

definition action12

...


... Interpreter Membrane

C2

RC 1

RC 12

RC 121

RC 2

RC 11

Reconfiguration scripts

C121

C11

C1

C12

ExampleReconfiguration interface

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definition action1

...




...

definition action12

...


... Interpreter

RC 1

RC 12

RC 121

RC 2

RC 11

C121

C11

C1

C12

Example

action1( )


Membrane

C2Reconfiguration scripts

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definition action1

...




...

definition action12

...


... Interpreter

RC 1

RC 12

RC 121

RC 2

RC 11

C121

C11

C1

C12

Example

action1( )

action11( )

action2( )

action12( )


Membrane


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definition action1

...




...

definition action12

...


... Interpreter

RC 1

RC 12

RC 121

RC 2

RC 11

C121

C11

C1

C12

Example

action1( )

action11( )

action2( )

action12( )

action121( )


Membrane


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definition action1

...




...

definition action12

...


... Interpreter

RC 1

RC 12

RC 121

RC 2

RC 11

C121

C11

C1

C12

Example

action1( )

action11( )

action2( )

action12( )

action121( )

Conclusion: The interpretation is parallel and distributed


Membrane


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Agenda

Context


Execution Context

Experimentation


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Adaptation of FScript to Distributed Interpretation

Provide an access point for the component architecture Add a global variable in the interpreter Holds a reference to the component that owns the

interpreter

Managing action’s parameters Arguments passed to the target interpreter are serialised Make usual arguments (mainly FPath) serializable


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void createGlobalVariable(String name, Object reference)

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Managing Execution Contexts Arguments are evaluated by the source interpreter by

default It might be more adequate to evaluate them in the target

evaluation context especially for Fpath expressions

Transmit the FPath expression as a string Add a primitive for the evaluation of Fpath expressions

This primitive can then be called by the action, and evaluated in the target interpreter


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argument2 = ’$$C11_name/parent::C1_name/interface::interface_name’ ; remote_call($$C1_name/child::C11_name,’action11’, argument2) ;

. . . . .evaluate(argument2) ;

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Agenda

Context


Execution Context

Experimentation


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Implementation

ProActive Add the reconfiguration controller interface in

GCM/ProActive components ProActive allows the configuration of provided control

interfaces when creating a component

FScript Definition of the distributed interpretation primitive

Experimentation Reconfiguration of GCM components

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Experience

Interpreter Membrane


Client

ClientServer

Server

ServerClient

Root

r r

r r s

s s

s

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Experience

Interpreter Membrane


Client

ClientServer

Server

ServerClient

Root

r r

r r s

s s

s

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Experience: Reconfiguration script action change_client(root) {

client = $root/child::Client; intf-root-r = $root/interface::r; unbind($client/interface::s); unbind($intf-root-r); client2 = new('ClientImpl'); set-name($client2,"Client2"); add($root,$client2); intf-client2-r = $client2/interface::r; intf-client2-s = $client2/interface::s; bind($intf-client2-s,$root/child::Server/interface::s); bind($intf-root-r,$intf-client2-r);}

action reconfigure_root(root){ change_client($root); remote_call($root/child::Server,'change_client',$root/child::ClientServer); remote_call($root/child::ClientServer/child::Server,'echo','Hello World'); start($root);}

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Result

Successfully reconfigured components New clients connected and working We check the new configuration thanks to FPath expressions

Evaluated to True

bound($root/child::Client2/interface::r) and bound($root/child::Client2/interface::s) and not(bound($root/child::Client/interface::r)) and not(bound($root/child::Client/interface::s))

Feasibility of our approach and distributed reconfigurability of GCM

components

Feasibility of our approach and distributed reconfigurability of GCM

components

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Agenda

Context


Execution Context

Experimentation


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Conclusion

Extend FScript reconfiguration language

Better reconfigurability of distributed components

Introduced a reconfiguration controller

New primitive for distributed script evaluation

New primitives for better managing the distributed nature of the execution context

Prototype and experimentation

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Perspectives (1)

Type reconfiguration scripts to validate script relatively to a component structure

Reconfiguration atomicity Provided by FScript Difficult to implement efficiently in a distributed

manner Could provide primitives to choose if a

reconfiguration is atomic or tools to know if a reconfiguration succeeded

and take adequate decisions

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Perspectives (2)Reconfiguration Primitives

Primitives for structural changes Duplicate a component Replace a component Migrate a component (of node, or to another

composite) Suppress a component Auto-connection

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Thanks!

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Extending GCM and Fscript for the Distributed Reconfiguration of Components

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