Terracotta is an open-source Java clustering technology. It creates a virtual, durable Java heap that is shared across a cluster of Java Virtual Machines. This is done by dynamically instrumenting bytecode at load time to intercept calls to read and write fields, and also to enter and exit monitor locks. Information about these calls is then transmitted to the Terracotta Server (which can also be clustered) and out to other nodes in the cluster as needed. The advantage of this approach is that many Java programs can be clustered without code changes by providing just external Terracotta configuration. Many performance optimizations are performed to minimize communication and locking costs. Terracotta is commonly used for session sharing in web applications, distributed caching, and distributed workflow processing.

This presentation will give an overview of the Terracotta technology, how it's implemented, and common use cases that can benefit from the technology. We will look at some code and cluster some Java applications during the presentation.

Alex Miller is a Sr. Engineer with Terracotta Inc, the makers of the open-source Java clustering product Terracotta. Prior to Terracotta, Alex worked at BEA Systems on the AquaLogic product line and was Chief Architect at MetaMatrix. His interests include Java, concurrency, distributed systems, query languages, and software design. Alex enjoys writing his blog at http://tech.puredanger.com and has spoken at a number of Java user group meetings and conferences.