1 IMPLEMENTING AN ACTIVE FUNCTIONALITY SERVICE ON DIFFERENT PLATFORMS Candidate: Antollini, Juan José Advisor: Cilia, Mariano Cilia, Mariano Universidad.

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IMPLEMENTING ANIMPLEMENTING AN ACTIVE FUNCTIONALITY ACTIVE FUNCTIONALITY

SERVICE SERVICE ON DIFFERENT PLATFORMSON DIFFERENT PLATFORMS

Candidate:Candidate:Antollini, Juan JoséAntollini, Juan José

Advisor:Advisor: Cilia, MarianoCilia, Mariano

Universidad Nacional del Centro de la Provincia de Buenos AiresUniversidad Nacional del Centro de la Provincia de Buenos AiresFacultad de Ciencias ExactasFacultad de Ciencias Exactas

Tandil, Argentina - Tandil, Argentina - JulyJuly, 2005, 2005

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OrganizationOrganization

MotivationMotivation Main PillarsMain Pillars ImplementationImplementation Adaptation for Different PlatformsAdaptation for Different Platforms Conclusions & Future WorkConclusions & Future Work

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MotivationMotivation

Today we are living a technology convergence Today we are living a technology convergence leading to an increasing information flowleading to an increasing information flow

This requires new paradigms for its appropriate This requires new paradigms for its appropriate administration and processingadministration and processing

Emerging applications:Emerging applications: Ambient intelligence, Ubiquitous computing, Supply-Ambient intelligence, Ubiquitous computing, Supply-

chain management, Auto-ID, e-businesschain management, Auto-ID, e-business These apps are characterized by the reaction to These apps are characterized by the reaction to

situations of interestsituations of interest Monitoring situations of interestMonitoring situations of interest React accordinglyReact accordingly

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Active DBMSActive DBMS

One approach was the inclusion of powerful One approach was the inclusion of powerful active active rule-rule-processing capabilities processing capabilities

Reactive mechanisms were introduced in the form of Reactive mechanisms were introduced in the form of Event-Condition-Action rules in database systemsEvent-Condition-Action rules in database systems

Avoid unnecessary pollingAvoid unnecessary polling Data is stored in the database, situations of interest Data is stored in the database, situations of interest

(events) are detected, appropriate reactions are executed(events) are detected, appropriate reactions are executed

aD BM S

STIMULI

DATABASE

REACTIVE MECHANISM

EFFECT

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Distributed Reactive SystemsDistributed Reactive Systems But not all applications need a full-fledge database, just want to use But not all applications need a full-fledge database, just want to use

the reactive functionalitythe reactive functionality Distributed Reactive Systems respond to stimuli to bring desirable Distributed Reactive Systems respond to stimuli to bring desirable

effects in their environmenteffects in their environment Three different approachesThree different approaches

PollingPolling Embedded codeEmbedded code Self-signaling capabilitiesSelf-signaling capabilities

STIMULI

EFFECTREACTIVE SYSTEM

STIMULI

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Proposed ApproachProposed Approach

The reaction to events on the application-side is The reaction to events on the application-side is normally hard-coded and has been difficult to normally hard-coded and has been difficult to adapt to new requirements quicklyadapt to new requirements quickly

The goal of this work is to provide a flexible The goal of this work is to provide a flexible platform for platform for Reactive FunctionalityReactive Functionality in open in open distributed and heterogeneous environmentsdistributed and heterogeneous environments

Decoupled from database systemsDecoupled from database systems Offering an autonomous and flexible serviceOffering an autonomous and flexible service Can be combined in many different ways and used in Can be combined in many different ways and used in

a variety of environmentsa variety of environments

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A Three Step ProcessA Three Step Process Rule Definition:Rule Definition:

An ECA-Rule is the entity that encapsulates all the desired An ECA-Rule is the entity that encapsulates all the desired functionality required for this reactive systemfunctionality required for this reactive system

Service Configuration:Service Configuration: According to the rule defined in the previous step, the appropriate According to the rule defined in the previous step, the appropriate

services are located through a Service Platformservices are located through a Service Platform Once the corresponding services are located, the rule is Once the corresponding services are located, the rule is

decomposed and passed to these servicesdecomposed and passed to these services Service Run-time:Service Run-time:

Once the Services have been configured and started the Once the Services have been configured and started the corresponding services “wait” until specified events are signaledcorresponding services “wait” until specified events are signaled

When they are detected, those services are triggered by receiving When they are detected, those services are triggered by receiving this notification and they start processing according to the rule this notification and they start processing according to the rule definitiondefinition

All the elementary services rely on a notification service for the All the elementary services rely on a notification service for the dissemination of datadissemination of data

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Active Functionality ServiceActive Functionality Service

Main building blocksMain building blocks ECA Rule DefinitionECA Rule Definition Elementary ServicesElementary Services Service Platform IndependenceService Platform Independence Event Dissemination MechanismEvent Dissemination Mechanism Ontology (or Common Vocabulary)Ontology (or Common Vocabulary) Plug-insPlug-ins Service Manager (ECA Manager)Service Manager (ECA Manager) Repository ServiceRepository Service

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The Big PictureThe Big PictureRule definition

RULE wayToWorkONIF

THEN

EngineStarted DriverIdentification = “Paul”

AND IsWorkingDay LoadDriverPreferences(”Paul”)

ECA-Manager

Service Registry andRule Repository

EventCompositor

ConditionEvaluation

ActionExecution

Service Platform

Rul

e de

finiti

on

Se

rvic

e C

onfig

ura

tion

Run

-tim

e Ontology representation

ECA Rule API

API

Event Dissemination

Plug-ins

Elementary Services

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ECA Rule Definition APIECA Rule Definition API

Advanced users:Advanced users: ECA-rule parserECA-rule parser

Non-technical users:Non-technical users: User-friendly interfaceUser-friendly interface

RULE wayToWorkONIF

THEN



Rule Identifier

Event

Condition

Action

Rule Definition X

OK Cancel

Ontology-basedrule representation

PARSER

FORMPROCESSING

API

Rule definition

RULE wayToWorkONIF

THEN



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ECA-RulesECA-Rules Event:Event:

A logic expression that includes boolean operators (A logic expression that includes boolean operators (ANDAND, , OROR, , NOTNOT) and comparisons operators () and comparisons operators (==, , !=!=, , <<,,<=<=, , > , >=)> , >=)

They are composed by They are composed by references references and and valuesvalues. The references . The references are replaced at run-time and then evaluatedare replaced at run-time and then evaluated

Condition:Condition: A condition that is evaluated. If true, follows the series of stepsA condition that is evaluated. If true, follows the series of steps It is not mandatory and reflects a deeper level of filtering before It is not mandatory and reflects a deeper level of filtering before

executing any actionexecuting any action It is also comprised by It is also comprised by logic expressions logic expressions It allows the use of plug-insIt allows the use of plug-ins

Action:Action: The action that takes place when the event of interest arrives The action that takes place when the event of interest arrives

and the condition evaluation finishes successfullyand the condition evaluation finishes successfully A set of actions have been provided. More actions can be addedA set of actions have been provided. More actions can be added It can also operate with plug-insIt can also operate with plug-ins

Rule definition

RULE wayToWorkONIF

THEN



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ECA ManagerECA Manager

Plays the role of a representative of the Active Plays the role of a representative of the Active Functionality ServiceFunctionality Service

Responsible for rule registration:Responsible for rule registration:1.1. Decomposing the rule,Decomposing the rule,

2.2. Searching and contacting the elementary services,Searching and contacting the elementary services,

3.3. Configuring the elementary services andConfiguring the elementary services and

4.4. Deploying the elementary servicesDeploying the elementary services

It also offers operations to activate, deactivate It also offers operations to activate, deactivate and unregister rulesand unregister rules

Service Registry andRule Repository

ECA-Manager

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Elementary Services (1)Elementary Services (1)

Each component was designed according to the Each component was designed according to the properties of distributed heterogeneous systemsproperties of distributed heterogeneous systems

They are responsible for:They are responsible for: Complex event detection,Complex event detection, Event filtering,Event filtering, Condition evaluation, andCondition evaluation, and Action executionAction execution

Elementary services expose two kinds of generic and Elementary services expose two kinds of generic and very simple interfaces:very simple interfaces:1.1. A configuration interface used for administration purposes, such A configuration interface used for administration purposes, such

as registration, activation, de-activation, etcas registration, activation, de-activation, etc2.2. A service interface to receive event notificationsA service interface to receive event notifications

EventCompositor

ConditionEvaluation

ActionExecution

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Separation of logic:Separation of logic: Service Logic Service Logic which: the code that represents the which: the code that represents the

operation of the service itselfoperation of the service itself Functional Logic: Functional Logic: a wrapper that makes the service a wrapper that makes the service

logic work within a frameworklogic work within a framework

They are contacted and administered through They are contacted and administered through the use of a Service Platformthe use of a Service Platform

They are combined through the use of a They are combined through the use of a common notification mechanismcommon notification mechanism

EventCompositor

ConditionEvaluation

ActionExecution

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Functional Logic Service LogicFunctional Logic Service Logic

EventCompositor

ConditionEvaluation

ActionExecution

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Notification Service (NS)Notification Service (NS)

Event-based systems need an event dissemination Event-based systems need an event dissemination mechanism to deliver relevant events to interested mechanism to deliver relevant events to interested consumersconsumers

Events are disseminated as notifications by a Events are disseminated as notifications by a publish/subscribe notification servicepublish/subscribe notification service

The publish/subscribe paradigm plays an important role The publish/subscribe paradigm plays an important role in this architecture providing the following advantages:in this architecture providing the following advantages: It allows asynchronous communication and decouples event It allows asynchronous communication and decouples event

producers and consumersproducers and consumers The notification contains required event information and its The notification contains required event information and its

contextcontext It provides a simple and powerful generic communication modelIt provides a simple and powerful generic communication model Events are the ones that directly trigger rule executionEvents are the ones that directly trigger rule execution

EventCompositor

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NS: Concept-based AddressingNS: Concept-based Addressing Subscriptions are raised to a higher level of Subscriptions are raised to a higher level of

expressivenessexpressiveness It provides a higher level of abstraction to describe the It provides a higher level of abstraction to describe the

interests of event producers and consumersinterests of event producers and consumers It is achieved by supporting from the ground up It is achieved by supporting from the ground up

ontologiesontologies (or common vocabulary) which provide the (or common vocabulary) which provide the base for correct data and event interpretationbase for correct data and event interpretation

Metadata information and conversion functions to Metadata information and conversion functions to simplify and enrich their interaction are providedsimplify and enrich their interaction are provided

Event consumers specify the context to which events Event consumers specify the context to which events need to be converted before they are delivered for client need to be converted before they are delivered for client processingprocessing

It allows abstractions from NS particularitiesIt allows abstractions from NS particularities

EventCompositor

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Plug-ins (1)Plug-ins (1) Conceived to increase the functionality of the system by Conceived to increase the functionality of the system by

the aid of external applications (i.e. a Database System)the aid of external applications (i.e. a Database System) Every plug-in is composed by a Every plug-in is composed by a sentence sentence part and a part and a

configuration configuration partpart The statement syntax provides a mean to express The statement syntax provides a mean to express

ontology concepts that will be resolved according to ontology concepts that will be resolved according to incoming notificationsincoming notifications

Ontology references must be written inside opening and Ontology references must be written inside opening and closing braces (“[“ “]”) and must contain concept names closing braces (“[“ “]”) and must contain concept names supported by the ontologysupported by the ontology

The configuration part is used to tune the external The configuration part is used to tune the external applicationapplication

This approach allows users to create their own plug-ins This approach allows users to create their own plug-ins in a straightforward fashionin a straightforward fashion

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Plug-ins (2)Plug-ins (2)

Two types:Two types: Application-specificApplication-specific for particular application (i.e. calendar) for particular application (i.e. calendar) Generic plug-insGeneric plug-ins (i.e. databases) (i.e. databases)

Data

Convert(context defined

by user)

Convert(context definedby programmer)

Base Software (generic use)i.e. Database

Particular Applicationi.e. Calendar

Plu

g-i

nIn

com

ing

dat

a

Data ’

AlreadyConverted

Data

Data ’

Base Software Specific Application

2020

Plug-ins (3)Plug-ins (3)

• How to write plug-ins:How to write plug-ins:1.1. Ontology specific concepts must be createdOntology specific concepts must be created2.2. A new plug-in class extending the A new plug-in class extending the PlugInIntfPlugInIntf

interface must be codedinterface must be coded3.3. A new configuration class extending the A new configuration class extending the

ConfigurationIntfConfigurationIntf interface must be coded interface must be coded4.4. The plug-in must be registered into the The plug-in must be registered into the

repository. One or more keywords and a repository. One or more keywords and a plug-in configuration (if needed) must be plug-in configuration (if needed) must be added to the plug-in repositoryadded to the plug-in repository

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Service PlatformsService Platforms

The use of Service Platforms allows:The use of Service Platforms allows: Life-cycle management for the different servicesLife-cycle management for the different services Remote access to servicesRemote access to services

The same functionality implemented on two The same functionality implemented on two platforms:platforms: J2EE (enterprise applications)J2EE (enterprise applications)

A robust platform designed for distributed or client-server A robust platform designed for distributed or client-server interaction. It provides the ease for persistence, interaction. It provides the ease for persistence, asynchronous communications and remote access to objectsasynchronous communications and remote access to objects

OSGi (small devices)OSGi (small devices) Intended for (remotely deployable) service-oriented Intended for (remotely deployable) service-oriented

applications. It is a lightweight platform where different applications. It is a lightweight platform where different services can be deployed, installed and executed allowing services can be deployed, installed and executed allowing simple sharing and interaction among themsimple sharing and interaction among them

EventCompositor

ConditionEvaluation

ActionExecution

Service Platform

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J2EEJ2EE

Defines three kinds of Enterprise Java Beans Defines three kinds of Enterprise Java Beans (EJB), each one with definite purposes and (EJB), each one with definite purposes and activities:activities: Session beansSession beans Entity beansEntity beans Message-driven beansMessage-driven beans

Services were adapted to each one of these Services were adapted to each one of these EJB’sEJB’s

EventCompositor

ConditionEvaluation

ActionExecution

Service Platform

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Session & Entity BeansSession & Entity Beans

Session beans:Session beans: ECA-Manager wrapped as a Session BeanECA-Manager wrapped as a Session Bean An ECA-Manager instance is held An ECA-Manager instance is held inside inside the Session Beanthe Session Bean It complies with the Session façade patternIt complies with the Session façade pattern

Entity beans:Entity beans: Every rule definition and every plug-in implementation are Every rule definition and every plug-in implementation are

stored in a stored in a Repository Service Repository Service in order to maintain information in order to maintain information about the active functionality serviceabout the active functionality service

This persistence is achieved by the use of Entity BeansThis persistence is achieved by the use of Entity Beans Three Entity Beans:Three Entity Beans:

RuleDefRuleDef: stores every rule definition deployed: stores every rule definition deployed PlugInPlugIn: stores a set of instructions each plug-in understands and : stores a set of instructions each plug-in understands and

references to their implementing codereferences to their implementing code PlugInConfigurationPlugInConfiguration: stores a configuration pattern associated to : stores a configuration pattern associated to

every plug-in nameevery plug-in name

EventCompositor

ConditionEvaluation

ActionExecution

Service Platform

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Message-driven BeansMessage-driven Beans

The Condition and Action services were The Condition and Action services were composed as Message-driven Beanscomposed as Message-driven Beans

Commonly MDBs are created declaratively but Commonly MDBs are created declaratively but we can not have a unique MDB to attend we can not have a unique MDB to attend all all the the possible rules and also we can not deploy possible rules and also we can not deploy beforehand a number beforehand a number n n of MDBs and assign of MDBs and assign each one a different rule to attendeach one a different rule to attend

Each condition and action services Each condition and action services must must be be deployed deployed dynamically dynamically every time a new rule is every time a new rule is registeredregistered

EventCompositor

ConditionEvaluation

ActionExecution

Service Platform

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MDB Service ConfigurationMDB Service Configuration

RULE wayToWorkONIF

THEN



ECA-Manager

Concept

BasedJMS

ConditionMDB

J2EE Server

RULE wayToWorkONIF

THEN



EventCompositor

ConditionEvaluation

ActionExecution

Service Platform

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MDB Class HierarchyMDB Class HierarchyThe Concept-based class hierarchy for the Message-driven beans servicesThe Concept-based class hierarchy for the Message-driven beans services

EventCompositor

ConditionEvaluation

ActionExecution

Service Platform

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MDB Service Run-timeMDB Service Run-time

CActionMDB

JMS

Concept-basedMDB

CCondition

MDB

Concept-basedMDB

E CB

Interaction between the services and the concept-basedInteraction between the services and the concept-basedimplementation at run-timeimplementation at run-time

ACC

CB

EventCompositor

ConditionEvaluation

ActionExecution

Service Platform

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OSGiOSGi OSGi is a lightweight framework for (remotely) deploying OSGi is a lightweight framework for (remotely) deploying

and executing service-oriented applicationsand executing service-oriented applications Oscar is an open source implementation of the OSGi Oscar is an open source implementation of the OSGi

specificationspecification OSGi works via dynamically loaded components, called OSGi works via dynamically loaded components, called

bundlesbundles Every bundle needs at least a Bundle Activator (to Every bundle needs at least a Bundle Activator (to

manage the life-cycle of every installed bundle) class manage the life-cycle of every installed bundle) class and a manifest fileand a manifest file

Commonly the steps required to create any bundle Commonly the steps required to create any bundle comprise:comprise:1.1. Write a bundle activator class in JavaWrite a bundle activator class in Java2.2. Create a Manifest file as a text fileCreate a Manifest file as a text file3.3. Build a JAR file that contains the compiled activator class the Build a JAR file that contains the compiled activator class the

Manifest file and any required libraryManifest file and any required library

EventCompositor

ConditionEvaluation

ActionExecution

Service Platform

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BundlesBundles

The following set of bundles was built, The following set of bundles was built, installed and shared:installed and shared:

1.1. Repository ServiceRepository Service2.2. Concept-Based Notification ServiceConcept-Based Notification Service3.3. Action ServiceAction Service4.4. Condition ServiceCondition Service5.5. ECA-Manager ServiceECA-Manager Service6.6. Complementary Services:Complementary Services:

• Inspector ServiceInspector Service• Web Form ServiceWeb Form Service

EventCompositor

ConditionEvaluation

ActionExecution

Service Platform

3030

Bundle OrganizationBundle Organization

RepositoryService

Concept-BasedNotification Service

Ontology.*

ActionService

Ontology.*

ConditionService

Ontology.*

ECAManagerService

Ontology.*

Imported packageExported packageProvided service Required service

EventCompositor

ConditionEvaluation

ActionExecution

Service Platform

3131

Using The Active Functionality Using The Active Functionality ServiceService

Event

3232

ConclusionsConclusions

The Active Functionality Service was extended:The Active Functionality Service was extended: Rule Definition APIRule Definition API

Web FormWeb Form Text ParserText Parser

Service Platform IndependenceService Platform Independence J2EEJ2EE OSGiOSGi Service logic and Functional logic separationService logic and Functional logic separation

Proof-of-concepts plug-insProof-of-concepts plug-ins DatabaseDatabase CalendarCalendar

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Future WorkFuture Work

J2EE: EJB 2.1 SpecificationJ2EE: EJB 2.1 Specification OSGi: Dynamic service assembleOSGi: Dynamic service assemble Static analysis of rulesStatic analysis of rules Run-time visualization toolsRun-time visualization tools Accommodate to real-time features where Accommodate to real-time features where

different performance tests can be applieddifferent performance tests can be applied Provide authoring and authentication in Provide authoring and authentication in

components and notification servicescomponents and notification services

1 IMPLEMENTING AN ACTIVE FUNCTIONALITY SERVICE ON DIFFERENT PLATFORMS Candidate: Antollini, Juan José Advisor: Cilia, Mariano Cilia, Mariano Universidad.

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