www.objectweb.org

DreamA Fractal-based communication framework

ObjectWeb Architecture Meeting

July, 8th 2004

M. Leclercq, V. Quéma, J.-B. Stefani

Sardes Project, INRIA-LSR-IMAG

www.objectweb.org Architecture Meeting - D2 - 07/08/2004

Outline

Motivations

Dream

Experiments

Future work

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Motivations

Existing communication middleware (CM)Provide a fixed communication model

RPC (CORBA, RMI, SOAP, …)JMS (JORAM, WebSphere MQ, iBus, …)Ad-Hoc (BEA MessageQ, Gryphon, SIENA, …)

But… share a lot of architectural components

Provide several non-functional properties

Are not extensively (re)configurableFixed monolithic architecture with few parameters to configure

The application developer is constrained to fixed abstractions

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What do we need?

(re)configurable CMsFunctionally

Build various communication paradigms–RPC, Message passing, event/reaction, publish/subscribe

Non functionallyProvide various non-functional properties

–Security, transactions, persistency, ordering, …

ArchitecturallyAdapt to various kind of execution environments

–PC, PDA, cell phones, …

www.objectweb.org Architecture Meeting - D5 - 07/08/2004

What is Dream?

A framework for building CMsCore

Abstractions and tools for resource management–Messages–Activities

ADL for the configuration and deployment of CMsA component library

Components commonly found in CMs

Used to build several personalitiesJMS, Probabilistic broadcast, Internet services, …

Integrated in LeWYS

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Outline

Motivations

DreamCoreADLComponent library

Experiments

Future work

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Dream core

Define abstractions and tools to manage resources

Messages Activities

105 classes (12054 lines)dream-core.jar = 113k

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Messages

Messages are fractal composites encapsulatingChunks

Unit of data allocationImplement a Fractal server interface

Sub messages

Two interfacesMessage

Methods to retrieve chunks and sub messages

ExtensibleMessage extends MessageMethods to add/remove chunks and sub messages

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Message managers

Shared components that manage messages and chunks

Implement the MessageManager interfaceMethods to create, delete, duplicate chunks and messages

Pool messages and chunks for efficiency

Generic versus specific implementations

Future work: dynamic generation of messages using ASM

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Inputs/outputs

Fractal interfaces that allow message exchanges between components

push(message, ctxt) ;

void push(Message m, Map ctxt){ // Processing of message m}

Push connection

Message m = pull(ctxt);// Processing of // message m

Message pull (Map ctxt){// Returns a message}

Pull connection

Component A

Component B

Input

Output

Principle

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Activities

Components can be active or passive

Active components define tasks to be executed

For a task to be executed, it must be registered to one activity manager component

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Activity managers

Shared components that encapsulates tasks and schedulers

Activity manager

Task(thread)

FIFO Scheduler

Task A1 Task A2 Task B

Component A

Third party

Component B

taskManager

schedulerManager

taskController

Task(thread)

schedule

executeregister(A1)

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Schedulers and tasks

Schedulers are responsible for mapping higher level tasks onto lower-level tasks

Schedule server interfaceExecute client interfaceImplement a scheduling policy

FIFO, round-robin, with priority, ...

TasksExecute server interfaceSchedule client interfaceThree kinds of tasks

Higher-level tasks = applicative tasksLowest-level tasks = threads (Execute = Runnable)Middle-level tasks = allow inter-schedulers scheduling

Note: shares a lot of similarities with P. Merle’s orchestration framework… should be merged soon !

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Outline

Motivations

DreamCoreADLComponent library

Experiments

Future work

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ADL

Use Fractal ADLAll this work is not Dream specific

Added modulesDescription of legacy componentsClass loading management (uses OSCAR’s module

loader)

Future workExtend (re)configuration capabilitiesSupport for distributed asynchronous deployment

www.objectweb.org Architecture Meeting - D16 - 07/08/2004

Outline

Motivations

DreamCoreADLComponent library

Experiments

Future work

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Component library (1)

Components commonly found in CMsFine grain components

Ease reuseImprove configurability

76 classes (9025 lines)dream-lib.jar = 116k

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Component library (2)

Message queueOrdering (FIFO, causal, …) Behavior in the different states (empty, full)

RouterRouting policy (round-robin, chunk name, …)

AggregatorAggregate messages received on the input(s)Deliver a message on its output

PumpPeriodically pull a message on its input and then push it

ChannelAllow message exchanges between different address spaces (TCP socket, …)

Protocol components, Transformers, Filters …

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Outline

Motivations

Dream

Experiments

Future work

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Experiments

GoalsCheck that

Various personalities can be builtThere is a gain in configurabilityPerformances for functionally equivalent CMs are comparablePerformances can be better when CMs are adequately configured

ExperimentsJoram, an open-source implementation of the JMS APILightweight Probabilistic Broadcast (LPBCast)Staged Event-Driven Architecture (SEDA)

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Joram

Router

Atomic Reactor

Agent Factory

Agent Repository

MessageT

oNotif

NotifT

oMessage

ConduitRouter

Causal Sorter

DestinationResolver

ChannelOut ChannelIn

DestinationResolver

ChannelOut ChannelIn

AtomicityProtocol

Engine

Repository

Network 1 Network 2

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Performances (1)

Compare performance of the same application running on Joram agent server and its Dream based implementation

Four Agent serversEach server hosts an agentAgents are organized in a virtual ringA message is forwarded by each agent around the ringMeasure

Number of rounds made by the message per secondMemory footprint

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Performances (2)

Nb of Rounds / sec Memory footprint

(KB)0 kB 1 kB

Joram 325 255 4 x 1447

Dream (non-reconf) 329 260 4 x 1580

Dream (reconf) 318 250 4 x 1587Dream non-reconf

Optimized bindingInterface object bypassed

No lifecycle interceptorNon stoppable application

Julia has no execution cost and low memory cost

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Configurability assessment (1)

Allow changing non functional propertiesCausal orderingAtomic reaction

Allow changing the architecture

Allow changing the concurrency model

Allow building an architecture for mobile devices

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Configurability assessment (2)

An Agent Server for mobile devices

Router

Atomic Reactor

Agent Factory

Agent Repository

MessageT

oNotif

NotifT

oMessage

TCPChannelIn(Pull)

TCPChannelOut(Push)

RepositoryAtomicityProtocol

Engine

ChannelOut(Pull)

TCPChannelIn

(Push)

Conduit

Network (details not shown)

RemoteRepresentative

Towards other agent servers

Mobile device Proxy

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SEDA (Staged Event-Driven Architecture)

UC Berkeley project (SOSP 2001, USITS 2003)

Dedicated to the construction of highly concurrent Internet services

Service = network of event-driven stages

StageEvent queue (incoming events)Event handlerThread pool

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SEDA architecture

Event Handler

Thread Pool

Controller

Event Queue

Outgoing Events

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SEDA-Dream architecture

PumpEvent

Queue EventHandler

Stage

Activity manager

Task(thread)

taskManager

threadManager

taskControllerFunctional interfaces

batchingAttribute

ActivityManager

Stage

StagePumpTask

Task(thread)

Task(thread)

Scheduler

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Configurability assessment

Event handlers have direct control over threadsAllows avoiding the use of locks, …

Activity managers can be shared between several stages

Common scheduling policy for accessing shared state

Every architectural element is a componentReconfigurationOrdered queues

Allows changing the concurrency model

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Outline

Motivations

Dream

Experiments

Future work

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Future work

Improving DreamPersistency, transactionsImproving resource management

Integrating Dream with other projects (CLIF, LeWYS)

Binding factory for Julia

Building other personalitiesSynchronous middleware (requires Jonathan concepts)Group communication library (with JGroups as a basis)Implementing various publish/subscribe middleware

www.objectweb.org Architecture Meeting - D32 - 07/08/2004

Questions?