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 {

{

POJO p = new POJO();

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() { … }

/**

*

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

*/

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

{

POJO p = new POJO();

Advised obj = (Advised)p; //Typecast

obj.insertInterceptor(new MetricsInterceptor());

…

}

{

POJO p = new POJO();

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

/**

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

*/

public void somepojoMethod() { … }

/**

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

*/

public void securedPojoMethod {…}

/**

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

*/

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* <p><b>2002/04/08: Sacha Labourey</b>* <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* <p><b>2002/04/08: Sacha Labourey</b>* <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

Client side proxy for clustering

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

Client side proxy for clustering

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 (marc@jboss.org.)

• 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