JBoss Bridging academia and industry through Open Source

JBoss

Bridging academia and industry

through Open Source

JBoss™ : A Few Facts

JBoss 3. is an application server based upon J2EE 1.3

• LGPL (Lesser GPL) licence: JBoss use is FREE

• A standard in the market– 2 million downloads in 2002– Over 1 million downloads in first 4 months ’03– 70% of JBoss users use it in production (Java

Developers Journal poll/May ’03)

JBoss™ : A Few Facts

• Quality– JavaWorld Editors’Choice Award as best Java Application

Server in 2002, beating BEA Weblogic and IBM Websphere

– SDTimes 10 top innovators– Few bugs in production, Open Source– Academia involvement

• Fully supported by JBoss Group

JBoss Group Overview

• JBoss Group was founded by Marc Fleury and Scott Stark in 2001 to provide supporting services around the FREE JBoss application server.

• The company brings together the core developers of JBoss to form a new type of open-source consultancy, offering an unmatched « Back Office » operations model, where expert developers spend

– 50% of their time in development– 50% of their time providing services

• Manpower:– Employees: 2(‘01), 7(‘02), 30(‘03)– Developer community (RW passwords): 30(‘01), 50(‘02), 80(‘03)

• Profitable, self-funded “pay as you grow” strategy, with 125% average monthly growth rate (at a standard deviation of 428%)

CUSTOMERS(the tip of the iceberg)

JBoss based on academic work

• JBoss includes software developed in academia• java-groups: Bela Ban (Cornell/Fujitsu)

– Group communication

• javassist: Shigeru Chiba (Tokyo Inst. Tech)– Bytecode engineering

• Oswego: Doug Lea– Concurrent package

• Jacorb: Gerald Brose (Uni Berlin/Xtradyne)– IIOP engine

Academic work is based on JBoss

• NRMI: Tilovich, Smaragdakis (Georgia Tech)– Pass by copy- restore semantics

• ROC: Candea, Fox, Patterson (Stanford/Berkeley)

– Recovery Oriented Computing/ High Availability

• GRID: Los Alamos Nat labs– GRID distribution and monitoring

• Are you next?– Aspect orientation makes it easy

Is JBoss for you?

• Rapid prototyping based on JBoss– Give a reference implementation of your research

• The market will pick what it wants with Open Source

• Give your research a large audience

• LGPL requirement

JBoss 4.0: Availability

• Developer Release: June 2003

• Production Release: Fourth Quarter 2003

• JBOSS 4.0 AN AOP APPLICATION

DYNAMIC AOP:MIDDLEWARE

NIRVANA?

• JBoss 4.0 brings enterprise Java to a broader range of developers, borrowing from framework features of Visual Basic, .NET and CORBA, as well as J2EE, giving them a more intuitive way to interact with the system.

• Application developers do not have to worry about system architecture. The system architect can manipulate and integrate legacy/standard Java applications into JBoss 4.0. USES RUNTIME AOP.

• JBoss 4.0 combines the simplicity of standard Java with the power of enterprise Java.

• GUI used OOP, Middleware uses AOP

JBoss 4.0Architectural overview

• Microkernel design– Independent cycling and loading

• Hot Deployment of services and applications– Unified ClassLoaders, total Class visibility/cyclability– Service Archives (SARs) for easy configuration and net deployment

• AOP-enabled Services– Persistence, cache, transactions, acidity, remoteness, security– Orthogonal aspects weaved in at run time under the objects– In use in JBoss since 2.x series– Ease of debugging == STABLE– Generalized for public AOP consumption in the JBoss 4.x series– NO COMPILER, FULL DYNAMIC DESIGN (bytecode engineering)

• CONTAINER DESIGN MADE EASY

HTTP Grid loading

Computer 1

Computer 1

Computer 2

Computer 2

http

WebServer

FileFile

JBossMXJBossMX

JBossMXJBossMX JBossMXJBossMX

JBossMXJBossMX

CLASSES

Unified ClassLoaders

• Shared classes and cycling of classes

JBossMX

REPOSITORY

Deployer

JBossAOP a new generation

• System level aspects are by definition cross cutting to the applications (they are in fact orthogonal aspects).

• Use Java, straight java and some XML• Define pointcuts easily

– Either XML in class (useful for persistence, JSR 175)– Either XML in logical scope (e.g. instance (acidity,

locking), class, application (security), VM (monitoring), cluster (ROC))

– Context based constructs are possible, thread association (Observer/Observable, READ-AHEAD)

– DYNAMIC AOP ENABLES COMPLETE OBLIVION use of Advisable interface for cache, NO user input

public class POJO {

private int privField;

public float pubField;

public static String pubStaticField;

public POJO() {}

public void somemethod() {

privField = 10;

}

}

Public class POJORef {

{

POJO p = new POJO();

p.pubField = 5;

p.somemethod();

}

}

public class POJO {

private int privField;

public float pubField;

public static String pubStaticField;

public POJO() {}

public void somemethod() {

privField = 10;

}

}

Public class POJORef {

{


p.pubField = 5;

p.somemethod();

}

}

Fields, Methods, and Constructs

POJO

Pluggable Cross-Cutting Functionality

• New behavior can be attached by writing a simple Interceptor class and inserting it into the chain of invocation

Tracing ObserverCaller Notifications

MonitoringMetrics

• POJO

Implements

Advisable

DYNAMIC!

Orthogonal interceptorsAspect orientation

Aspect Oriented Programming DESIGN

Interceptors

• Implement the org.jboss.aop.Interceptor interface

• Invocation object encapsulates method args or field values

• Hold reference to interceptor chain

• Driver of interception

• Resolves metadata

public interface Interceptor {

public String getName();

public InvocationResponse invoke(Invocation invocation) throws Throwable;

}

public interface Interceptor {

public String getName();

public InvocationResponse invoke(Invocation invocation) throws Throwable;

}

Metadata and Metatags

• XDoclet and JSR-175• Metatags can define pre-packed Aspects• Pluggable Java language keywords• AOP is the glue• Required interceptors automatically added when keyword applied

/**

*

* @jboss-aop.metadata group=“transaction” trans-attribute=“RequiresNew”

*/

public void somePOJOmethod() { … }

/**

*


*/

public void somePOJOmethod() { … }

Dynamic API

• Every POJO filtered through AOP has an extended interface

• At classloading time, bytecode manipulation forces AOP POJOs to implement a standard AOP interface.

• AOP interface allows you to define Instance-level metadata

• Allows you to insert interceptors for a particular instance at runtime

{


Advised obj = (Advised)p; //Typecast

obj.insertInterceptor(new MetricsInterceptor());

…

}

{


Advised obj = (Advised)p; //Typecast

obj.insertInterceptor(new MetricsInterceptor());

…

}

AOP for Middleware

• AOP simplifies applications with high degrees of reuse of cross-cutting concerns

• Application Servers by definition provide cross-cutting SYSTEM-LEVEL aspects

• Middleware is thus a perfect fit for AOP

• The middleware aspects are themselves the killer application of AOP

JBoss 4: Pre-packaged Aspects

• J2EE a la carte, EJB like but no EJB API

– Transaction demarcation

– Role-based Security

– Remoting – choose at runtime, SOAP, RMI, Sockets, IIOP

– Clustered Remoting – invocation failover

• Beyond J2EE

– Transactional, ACID, Objects. Our Transactional Cache

– Replicated Objects. Our Distributed Cache

– Transctional Locking. Expanded Java “synchronized”

• Persistence

– JBossDO – JDO on JBoss

J2EE a la carte

/**


*/

public void somepojoMethod() { … }

/**

* @jboss-aop.permission role-name="Administrator,Tester"

*/

public void securedPojoMethod {…}

/**


*/

public void somepojoMethod() { … }

/**

* @jboss-aop.permission role-name="Administrator,Tester"

*/

public void securedPojoMethod {…}

Remoting

• Declare POJO remoted at runtime, as in .NET REMOTE• Hooks into JBoss Remoting project (Jeff Haynie, Tom Elrod)• URI based protocols (soap, socket, rmi)• ONE WAY >>> JMS + MDB from a development standpoint

// Server

POJO remote = new POJO("hello");

Dispatcher.singleton.registerTarget(“objName", remote);

// Client

POJO proxy =

(POJO)Remoting.createRemoteProxy(“objName",

POJO.class,

“soap://localhost:8080");

// Server

POJO remote = new POJO("hello");

Dispatcher.singleton.registerTarget(“objName", remote);

// Client

POJO proxy =

(POJO)Remoting.createRemoteProxy(“objName",

POJO.class,

“soap://localhost:8080");

Clustered Remoting

• Invocation failover with any protocol

POJO pojo = new POJO("hello");

POJO proxy = (POJO)ClusteredRemoting.registerClusteredObject(

“objName",

pojo,

"DefaultPartition",

new RoundRobin(),

“socket://localhost:5150");

POJO pojo = new POJO("hello");

POJO proxy = (POJO)ClusteredRemoting.registerClusteredObject(

“objName",

pojo,

"DefaultPartition",

new RoundRobin(),

“socket://localhost:5150");

Interceptors for clustering

Client side proxy for clustering

package org.jboss.invocation.jrmp.interfaces;

/**** JRMPInvokerProxy, local to the proxy and is capable of delegating to local and JRMP implementations* 2002/04/08: Sacha Labourey* <ol>* <li>Pass a value with the invocation that allows any server side interceptor to know * when a call result from a failover (and the number of tries)</li>* </ol>*/public class JRMPInvokerProxyHA extends JRMPInvokerProxy implements Externalizable{ // Public -------------------------------------------------------- protected ArrayList targets = null;

protected LoadBalancePolicy loadBalancePolicy;

protected transient long currentViewId = 0; public static final HashSet colocation = new HashSet();

package org.jboss.invocation.jrmp.interfaces;

/**** JRMPInvokerProxy, local to the proxy and is capable of delegating to local and JRMP implementations* 2002/04/08: Sacha Labourey* <ol>* <li>Pass a value with the invocation that allows any server side interceptor to know * when a call result from a failover (and the number of tries)</li>* </ol>*/public class JRMPInvokerProxyHA extends JRMPInvokerProxy implements Externalizable{ // Public -------------------------------------------------------- protected ArrayList targets = null;

protected LoadBalancePolicy loadBalancePolicy;

protected transient long currentViewId = 0; public static final HashSet colocation = new HashSet();

The HA version contains a list of invokers

The HA version contains a list of invokers


public Object getRemoteTarget()

{

if (targets.size() == 0)

{

return null;

}

synchronized (targets)

{

return loadBalancePolicy.chooseTarget(targets);

}

}

/**

* Returns wether we are local to the originating container or not.

*/

public boolean isLocal(Invocation invocation)

{

return colocation.contains(invocation.getObjectName());

}

public Object getRemoteTarget()

{

if (targets.size() == 0)

{

return null;

}

synchronized (targets)

{

return loadBalancePolicy.chooseTarget(targets);

}

}

/**

* Returns wether we are local to the originating container or not.

*/

public boolean isLocal(Invocation invocation)

{

return colocation.contains(invocation.getObjectName());

}

Pluggable load balance policies are

responsible for picking the target

Pluggable load balance policies are

responsible for picking the target


public Object invoke(Invocation invocation) throws Exception { // we give the opportunity, to any server interceptor, to know if this a // first invocation to a node or if it is a failovered call int failoverCounter = 0; invocation.setValue ("FAILOVER_COUNTER", new Integer(failoverCounter), invocation.AS_IS); // optimize if calling another bean in same EJB-application if (isLocal(invocation)) { return InvokerInterceptor.getLocal().invoke(invocation); } else { // We are going to go through a Remote invocation, switch to a Marshalled Invocation MarshalledInvocation mi = new MarshalledInvocation(invocation); // Set the transaction propagation context mi.setTransactionPropagationContext(getTransactionPropagationContext()); mi.setValue("CLUSTER_VIEW_ID", new Long(currentViewId)); Invoker target = (Invoker)getRemoteTarget();

public Object invoke(Invocation invocation) throws Exception { // we give the opportunity, to any server interceptor, to know if this a // first invocation to a node or if it is a failovered call int failoverCounter = 0; invocation.setValue ("FAILOVER_COUNTER", new Integer(failoverCounter), invocation.AS_IS); // optimize if calling another bean in same EJB-application if (isLocal(invocation)) { return InvokerInterceptor.getLocal().invoke(invocation); } else { // We are going to go through a Remote invocation, switch to a Marshalled Invocation MarshalledInvocation mi = new MarshalledInvocation(invocation); // Set the transaction propagation context mi.setTransactionPropagationContext(getTransactionPropagationContext()); mi.setValue("CLUSTER_VIEW_ID", new Long(currentViewId)); Invoker target = (Invoker)getRemoteTarget();

We still collocate if we are local

We still collocate if we are local

DEBUG IS EASY!

while (target != null) { try { HARMIResponse rsp = (HARMIResponse)((MarshalledObject)target.invoke(mi)).get(); if (rsp.newReplicants != null) { setTargets(rsp.newReplicants); currentViewId = rsp.currentViewId; } return rsp.response; } // ALL CATCH JUST GOES ON catch (java.rmi.ConnectException ce){}

// If we reach here, this means that we must fail-over remoteTargetHasFailed(target); target = (Invoker)getRemoteTarget(); failoverCounter++; mi.setValue ("FAILOVER_COUNTER", new Integer(failoverCounter), invocation.AS_IS); } // if we get here this means list was exhausted throw new java.rmi.RemoteException("Service unavailable."); } }

while (target != null) { try { HARMIResponse rsp = (HARMIResponse)((MarshalledObject)target.invoke(mi)).get(); if (rsp.newReplicants != null) { setTargets(rsp.newReplicants); currentViewId = rsp.currentViewId; } return rsp.response; } // ALL CATCH JUST GOES ON catch (java.rmi.ConnectException ce){}

// If we reach here, this means that we must fail-over remoteTargetHasFailed(target); target = (Invoker)getRemoteTarget(); failoverCounter++; mi.setValue ("FAILOVER_COUNTER", new Integer(failoverCounter), invocation.AS_IS); } // if we get here this means list was exhausted throw new java.rmi.RemoteException("Service unavailable."); } }

Server piggy-backs information about the

topology

Server piggy-backs information about the

topology

We fail over here by taking a new target and

looping on the while (target !=null)

We fail over here by taking a new target and

looping on the while (target !=null)

Transactional Caching

• POJOs become ACID• State changes become transactional• Done with Field interception• Pessimistic cache• Snapshot Isolation

Version 4

Replicated Cache

• Field interception again

• State changes queued and replicated at transaction commit

• Only fields that have changed are replicated

DistributedTxCache cache = new DistributedTxCache(cacheSize, lockTimeoutInMillis, cacheName );

Address address = new Address(“Boston”, “MA”);

Person person = new Person(“Bill”, 31, address);

Cache.put(“bill”, person);

tm.begin();

person.address.city = “Bedford”;

person.age = 32;

tm.commit();

DistributedTxCache cache = new DistributedTxCache(cacheSize, lockTimeoutInMillis, cacheName );

Address address = new Address(“Boston”, “MA”);

Person person = new Person(“Bill”, 31, address);

Cache.put(“bill”, person);

tm.begin();

person.address.city = “Bedford”;

person.age = 32;

tm.commit();

QED & QA

• DYNAMIC AOP BASED REFLECTIVE MIDDLEWARE IS SUPERIOR TO COMPILER BASED MIDDLEWARE GENERATION.

• Ease of coding• Ease of debugging• Ease of deployment• Ease of testing• Leads to stable, easy to use Middleware that weaves system aspects.• Intuitive system-developer interface

– Is UML the natural UI language to specify pointcuts?– Runtime analysis of application topology enables iterative development.

• A new age of SYSTEM-DESIGN?– What system aspects are next? – Try providing a reference implementation for your research as aspect for JBoss– People will test it!

Come help us!

• TELL US about your work ([email protected].)

• Prototype on JBoss

• Contribute to JBoss

• Reach millions with your research

• Be used by millions

• “All your grad students are belong to us”

• Join the bazaar without leaving the Cathedral

Documents

JBoss Bridging academia and industry through Open Source