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© JBoss Inc. 2006
JBoss Clustering An Overview
Bela Ban ([email protected])Lead JGroups, Manager Clustering Group
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© JBoss Inc. 2006
Topics
• What is clustering?• JBoss/JEMS Clustering Components
JGroups, JBoss Cache, HA-JNDI, SLSBs, SFSBs, HTTP session replication, Entity beans, EJB3 and POJO Clustering
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Why JBoss Clustering?
• Transparent No stub re-compiling! Client doesn’t know about clustering
aspect Cluster is maintained automatically Modular/stack approach
• Open source No extra cost to activate clustering Fairly robust 24/7 production support
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Clustering Terminology
• Scalability I want to handle x times the number of concurrent access than
what I have now• High availability
Services are accessible with reasonable (and predictable) response times at any time
E.g., 99.999 (5 Nines in Telco)• Load balancing
A way to obtain high availability and better performance by dispatching incoming requests to different servers
Session affinity (or stickiness)• Failover
Process can continue when it is re-directed to a “backup” node because the original one fails
State needs to be available on backup• Fault tolerance
A service that guarantees strictly correct behavior despite system failure
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Clustering Overview
Load Balancer
State Replication
Failover
R1
R1
R2
R2
R3
R3
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JBoss Thin Client Clustering
• Front end load balancer Software
• Apache httpd and JBossWeb Apache with mod_jk/mod_proxy JBossWeb (Tomcat on steroids)
Hardware• F5 Big IP
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JBoss Fat Client Clustering
• Client uses smart proxy retrieved from JNDI• HA smart proxy
Based on Remoting (EJB3.0) or RMI (EJB2.1) Has load balancing policy, e.g., Round-Robin Has failover capability (sticky), e.g., detect call
failure
• HA smart proxy has logic inside• Logic is pluggable, users can provide their
own Failover policy Load balancing, e.g. based on load or weight
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Running JBoss Cluster – Basic Steps
• Use JBoss’ “all” configuration run.bat -c all ./run.sh -c all
• The “all” configuration contains everything needed for clustering: It has all the libraries for clustering
• JGroups.jar, jboss-cache.jar Clustered beans (cluster-service.xml) HA-JNDI HTTP session replications (tc5-cluster-
service.xml) Farming HA-JMS
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Clustering divided in 3 parts
• Client-cluster communication Formerly HA-RMI, no HA-Remoting Load balancing and failover logic for fat
clients
• State replication (inside cluster) JBoss Cache
• HTTP session, SFSBs, DistributedState
• Cluster communication (inside cluster) Method calls across all cluster nodes
• Cache invalidation, HA-JNDI, Farming
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Clustering Stack
JGroups
JBossCache
DRM
HA
-JN
DI
HT
TP
SF
SB
En
tity
Hibernate
Distributed RPC,
Membership
Me
ssa
gin
g
HAServices
DRM
Fa
rmin
gHA-
SingletonH
A-
Re
mo
ting
Dis
trib
ute
d
Sta
te
jBp
m
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What is JGroups?
• A reliable group messaging library• Reliable messaging
Sequence ordering• FIFO or total ordering
Flow control Acknowledgement Fragmentation
• Manage group membership Join Leave Shun
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What is JBoss Cache?
• An in-memory, replicated, transactional, persistent, and fine-grained cache system
• Uses JGroups as the messaging layer• Ideal for state replication
Transactional Persistent (and passivation) Fine-grained field-level replication Sub-partitioning, Buddy Replication
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HA-JNDI
• Clustered JNDI
Node 1
HA-JNDI
JNDI
Node 2
JNDI
Node 3
HA-JNDI
JNDI
HA-JNDI
Partition "Main"
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• Local proxies Local proxies have direct reference to container localInvoke() creates invocation in container
• Remote proxies Remote proxies create invocation on client (method, args,
ObjectName) Communicate via Remoting framework
HA Smart Proxies
Client JVM
Dispatcher
Dispatcher
Server JVM
011101
Typed Interface
Remote Proxy
RemotingConnectorRemotingConnector
AOP ContainerInvocation
Port 3873ClientClient
dynamicInvoke(Invocation)
localInvoke(Method, args)
Local clientLocal client
Typed Interface
Local Proxy
JBoss Remoting
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JBoss Remoting
• JBoss Remoting is a framework with a single, simple API for making network based invocations and other network related services.
• Client – the external API access point for client code.• Client/Server Invoker – protocol specific implementation. For example,
SocketClientInvoker and SocketServerInvoker.• Invocation Handler – end target interface implemented by user that
receives the invocation from the client.
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SFSB Configuration in EJB 2
<enterprise-beans> <session> <ejb-name> ClusteredSessionBean </ejb-name> <jndi-name> ClusteredSessionBean </jndi-name> <clustered>True</clustered> <cluster-config> <partition-name>MyPartition</partition-name> <home-load-balance-policy> org.jboss.ha.framework.interfaces.RoundRobin </home-load-balance-policy> <bean-load-balance-policy> org.jboss.ha.framework.interfaces.FirstAvailable </bean-load-balance-policy> </cluster-config> </session>
<enterprise-beans> <session> <ejb-name> ClusteredSessionBean </ejb-name> <jndi-name> ClusteredSessionBean </jndi-name> <clustered>True</clustered> <cluster-config> <partition-name>MyPartition</partition-name> <home-load-balance-policy> org.jboss.ha.framework.interfaces.RoundRobin </home-load-balance-policy> <bean-load-balance-policy> org.jboss.ha.framework.interfaces.FirstAvailable </bean-load-balance-policy> </cluster-config> </session>
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import org.jboss.ejb3.remoting.Clustered;
@Stateful
@Clustered (loadBalancePolicy = FirstAvailable.class, partition = ”MyPartition”)
public class ClusteredSessionBean implements ClusteredSession {
}
import org.jboss.ejb3.remoting.Clustered;
@Stateful
@Clustered (loadBalancePolicy = FirstAvailable.class, partition = ”MyPartition”)
public class ClusteredSessionBean implements ClusteredSession {
}
SFSB Configuration in EJB3
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Entities
• Use JBoss Cache as Hibernate’s 2nd level cache Default cache in ejb3-entity-cache-service.xml
• jboss.cache:service=EJB3EntityTreeCache Configure in META-INF/hibernate.cfg.xml per app
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Entities
<hibernate-configuration>
<session-factory>
<!-- Clustered cache with TreeCache -->
<property name="cache.provider_class">org.jboss.ejb3.entity.TreeCacheProviderHook</property>
<!– Object Name of cache to use -->
<property name="treecache.mbean.object_name">jboss.cache:service=EJB3EntityTreeCache</property>
<!-- Define cached entities and collections -->
<class-cache class="org.jboss.ejb3.tutorial.clusteredentity.bean.Customer" usage="transactional"/>
<class-cache class="org.jboss.ejb3.tutorial.clusteredentity.bean.Contact" usage="transactional"/>
<collection-cache collection="org.jboss.ejb3.tutorial.clusteredentity.bean.Customer.contacts" usage="transactional"/>
</session-factory>
</hibernate-configuration>
<hibernate-configuration>
<session-factory>
<!-- Clustered cache with TreeCache -->
<property name="cache.provider_class">org.jboss.ejb3.entity.TreeCacheProviderHook</property>
<!– Object Name of cache to use -->
<property name="treecache.mbean.object_name">jboss.cache:service=EJB3EntityTreeCache</property>
<!-- Define cached entities and collections -->
<class-cache class="org.jboss.ejb3.tutorial.clusteredentity.bean.Customer" usage="transactional"/>
<class-cache class="org.jboss.ejb3.tutorial.clusteredentity.bean.Contact" usage="transactional"/>
<collection-cache collection="org.jboss.ejb3.tutorial.clusteredentity.bean.Customer.contacts" usage="transactional"/>
</session-factory>
</hibernate-configuration>
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Future
@Entity
@Replicated(mode=asynchronous,type=BuddyReplication,BackupCopies=1)
public class Pojo {
@id
long key;
@transient
int cacheID;
}
@Entity
@Replicated(mode=asynchronous,type=BuddyReplication,BackupCopies=1)
public class Pojo {
@id
long key;
@transient
int cacheID;
}
• Common set of annotations @Replicated, @Singleton, @N-lton, @Farmed,
@Remote
• Integration into EJB3 (detach and attach extended to replication)
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HTTP Session Replication
• JBossWeb• Replication granularity
Session Modified attributes Modified fields
• Implemented using JBoss Cache
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Granularity: SESSION
• Entire http session is replicated• User defines whether getAttribute()
call marks a session as dirty If attribute value is mutable, the
application can modify session state without calling setAttribute()
Operates blindly (application may not have changed the object)
After each HTTP request the entire session is serialized and replicated
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Granularity: SESSION
// … if replication triggered by getAttribute() is disabled:
Pojo pojo = (Pojo)session.getAttribute(“pojo”);
pojo.setName(“Ben”);
session.setAttribute(“pojo”, pojo); // Done manually to replicate the session
// … if replication triggered by getAttribute() is enabled:
Pojo pojo = (Pojo)session.getAttribute(“pojo”); // Session will be replicated
return pojo.getName(); // Pojo was not actually changed
// … if replication triggered by getAttribute() is disabled:
Pojo pojo = (Pojo)session.getAttribute(“pojo”);
pojo.setName(“Ben”);
session.setAttribute(“pojo”, pojo); // Done manually to replicate the session
// … if replication triggered by getAttribute() is enabled:
Pojo pojo = (Pojo)session.getAttribute(“pojo”); // Session will be replicated
return pojo.getName(); // Pojo was not actually changed
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Granularity: ATTRIBUTE
• Only attributes marked as dirty are replicated. More efficient than session granularity User still needs to manage object relationship
• Can still configure whether getAttribute() marks the attribute as dirty
Pojo pojo = (Pojo)session.getAttribute(“pojo”);
pojo.setName(“Ben”);
session.setAttribute(“pojo”, pojo); // Only attribute “pojo” gets replicated!
Pojo pojo = (Pojo)session.getAttribute(“pojo”);
pojo.setName(“Ben”);
session.setAttribute(“pojo”, pojo); // Only attribute “pojo” gets replicated!
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Granularity: FIELD
• Replication is on Pojo field level where Pojo has to be instrumented with AOP Annotation or XML
• Object relationships are maintained• Available beginning with JBoss 4.0.4
Person joe = (Person)session.getAttribute(“joe”);
joe.setName(“joe”); // Only this field gets replicated.
Person mary = (Person)session.getAttribute(“mary”);
mary.setAge(41); // Only this field gets replicated.
Address addr = new Address(“San Jose”, 95123);
joe.setAddress(addr);
mary.setAddress(addr); // addr only gets replicated once; shared ref is maintained
Person joe = (Person)session.getAttribute(“joe”);
joe.setName(“joe”); // Only this field gets replicated.
Person mary = (Person)session.getAttribute(“mary”);
mary.setAge(41); // Only this field gets replicated.
Address addr = new Address(“San Jose”, 95123);
joe.setAddress(addr);
mary.setAddress(addr); // addr only gets replicated once; shared ref is maintained
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Granularity: FIELD
• When a Pojo object size is huge, e.g., a long List of size 100K, field level replication is efficient!
Subsription subs = (Subscription)session.getAttribute(“subscription”);// What if list is size of 100K?List mailingList = (List)subs.getMailingList(); Person joe = findSubscriber(“joe”, mailingList);joe.getAddress().setZip(94086); // Only replicates this field!!
Subsription subs = (Subscription)session.getAttribute(“subscription”);// What if list is size of 100K?List mailingList = (List)subs.getMailingList(); Person joe = findSubscriber(“joe”, mailingList);joe.getAddress().setZip(94086); // Only replicates this field!!
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Clustering – Configuration
• Session replication is enabled per web application in WEB-INF/web.xml
• Add <distributable/> to your webapp• JBoss specific stuff (async vs sync
replication) goes into WEB-INF/jboss-web.xml
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Links
• Details on Clustering Documentation
• http://docs.jboss.com JBoss AS chapters 16 (Clustering) & 17
(JBossCache and JGroups) http://www.jboss.com/products/jbosscache http://www.jboss.com/products/jgroups
Webinars• http://www.jboss.com/services/
online_education Training
• http://www.jboss.com/services/training/clustering (next: Berlin March 21-24)
© JBoss Inc. 2006
Questions ?
