JBoss Cache

Cache A place to temporarily store data that is expensive or difficult to compute or retrieve. Caches should be fast to access. May or may not exhibit “enterprise” features such as transactions

JBoss Cache Cluster A collection of homogenous services, grouped such that characteristics of high availability and load balancing can be achieved. Distributed cache? Similar to a cache, except that stores could be distributed across multiple physical or virtual machines. May or may not mirror contents.

JBoss Cache Why cache? Benefits: Removal of data retrieval or calculation bottlenecks Concerns/pitfalls: Cached data validity Cluster-wide coherence “Over-caching” Don’t cache unless you know you have a bottleneck “Measure. Don’t guess.”

JBoss Cache Why cluster? HA - Fault tolerance is critical 24/7 world Global user base SLAs Scaling horizontally Need to deal with predicted and unpredicted spikes Planned increase of capacity Coherence of state and performance of maintaining

JBoss Cache Data grids and clustering Hardware is cheap. Both CPUs and memory Grid computing is becoming easier to implement Compute grid frameworks like GridGain Clouds - Amazon EC2 Work stealing patterns Data availability becomes important Data retrieval bottleneck impact increases drastically with grid size Cost of keeping caches coherent increases with cluster size Not as much as data retrieval bottlenecks though

JBoss Cache Simple API for caching data Either local, replicated or distributed Support for eviction of unused elements Cache loading/storing to disk to free up memory Chaining caches, remote caches using TcpCacheLoader Support for JTA transactions Listeners and notifications, JMX manageability Multiple locking schemes (optimistic,pessimistic)‏

JBoss Cache Flavors Core cache - for caching simple objects, primitives POJO cache - Optimised for caching large and complex objects with relationships Object relationships maintained, even after replication or persistence Fine-grained replication Minimal API

JBoss Cache Searchable cache Adds efficient querying capabilities to the core cache − Uses Lucene to maintain indexes − In-memory distributed object database, anyone?

JBoss Cache Who uses JBoss Cache? JBoss Application Server - Clustering HTTP and EJB sessions, JPA entities Hibernate - entity caching SEAM - clustering contexts and caching JSF generated content JBoss Portal Lucene/Hibernate Search - cluster-wide indexes

JBoss Cache Benchmarks Just because we’re a distributed cache doesn’t mean we cannot be used as a standalone in-memory cache as well. Tracking JSR the JCACHE spec. Fast − Highly concurrent − Rich eviction and cacheloading strategies − Queryable −

JBoss Cache Architecture Implementing JBoss/Tomcat Fine- Configuration Http Session Replication Http session clustering with Tomcat Configuration

JBoss Cache Goal What is JBoss Cache? TreeCache TreeCacheAOP requires JBossAOP Stores and replicates values from a tree structure (hence the name)‏ Each value is associated with a path and key Stores and replicates values from a tree structure (hence the name)‏ Each value is associated with a path and key

JBoss Cache What is JBoss Cache? Uses JGroups as underlying transport stack Available as stand-alone or embeddable (MBean) TreeCacheAOP requires JbossAOP runtime Can be used with other app servers as well Can manage caching and replication on full Java objects (POJOs)‏ Object oriented cache

JBoss Cache. JBoss Cache Key Feature‏ Local and Replication mode Synchronous and Asychronous Fine grained field-level replication using TreeCacheAOP component. No need to declare POJO Serializable

JBoss Cache Local and Replication mode Each node has a name and Can be navigated recursively from node to node or using a fully qualified name (/a/d/g)‏ Multiple roots per cache allowed Locking Isolation level per node TreeCache Architecture

JBoss Cache Aop is a modular way of defining and applying cross-cutting concerns Current release 1.1 Definition: Advice, Aspect, Jointpoint, Interceptor, and Pointcut Define a rich set of metadata language as pointcut Supports dynamic Aop JBoss Aop Features

JBoss Cache Adding cache interceptor at runtime Declare POJO to be instrumented Dynamic Aop

JBoss Cache Use JBossAop’s dynamic aop feature A subclass of TreeCache all the features of TreeCache Eviction policy and replication pojo TreeCacheAop

JBoss Cache Fine-grained field-level caching with POJO style Object graph Polymorphism Inheritance Automatic Collections class support List, Map, and Set A proxy is generated for the Collections. TreeCacheAop

JBoss Cache TreeCacheAop API Plain cache API put(FQN name, Object key, Object value)‏ Object get(FQN name, Object key)‏ remove(FQN name, Object key)‏

JBoss Cache TreeCacheAop Mapping JBoss Cache Configuration Object relationship management has replySync-service.xml reference counting Object instance that is referenced more than once is moved to an internal area.

JBoss Cache Replication Granularity Level: New Http Session Replication Goal Session Replication is on per http sessionobject. It is a blob of hash map. Replication mode - Synchronous or Asynchronous User can define whether a getAttribute is dirty or not. Provide persistency and memory usage control

JBoss Cache Implemented using TreeCache API Pojo pojo = (Pojo)session.getAttribute(“pojo”); pojo.setName(“Ben”); Session.setAttribute(“pojo”, pojo); // Need to do this manually and replicates the session

JBoss Cache We use Cache mechanisms for Web fault tolerance and load balancing. We use Cache mechanisms for EJB fault tolerance and load balancing. AOP makes Cluster and Cache transparent. Summary