Constructs

Overview

Ehcache-constructs builds on top of ehcache to create implementations for common caching patterns.

All implementations use ehcache as the backing cache. They also share a common purpose - to create very high performance Java applications.

Pattern Implementations

General Purpose Caching

BlockingCache - a cache which blocks subsequent threads until the first read thread populates a cache entry
SelfPopulatingCache - a read-through cache. A cache that populates elements as they are requested without requiring the caller to know how the entries are populated. It also enables refreshes of cache entries without blocking reads on the same entries.
UpdatingSelfPopulatingCache - a read-through cache. A cache that populates elements as they are requested without requiring the caller to know how the entries are populated. The cache entry is automatically updated on subsequent reads.
SelfPopulatingCollectionsCache - a SelfPopulatingCache that adds threading safety where it is known in advance that all entries will be collections.

Web Caching

Servlet 2.3 caching filters that cache HTTP/S responses:

CachingFilter - an abstract, extensible caching filter.
SimplePageCachingFilter - a concrete implementation which caches pages based on the request URI and Query String.
SimplePageFragmentCachingFilter - a concrete implementation which caches page fragments based on the request URI and Query String.

Asynchronous Command Executor

This is the trusty old command pattern with a twist: asynchronous behaviour, fault tolerance and caching.

Quality Features

Ehcache-constructs has the following features:

Fast - performance benchmarks are used throughout unit testing
Simple - each pattern implementation is as simple as it can be.
Small foot print. Both in terms of size and memory requirements.
Minimal dependencies.
Fully documented. See the online Documentation and the online JavaDoc.
Comprehensive unit test coverage. See the online clover test report.
Scalable on large multi-cpu servers. Each construct is concurrency tested with unit tests.
Available under the Apache 1.1 license. Ehcache's copyright and licensing has been reviewed and approved by the Apache Software Foundation, making ehcache suitable for use in Apache projects.
Production tested. All versions of ehcache are production tested for several weeks on a large and very busy eCommerce site before release.

Now Separately Distributed

Ehcache-constructs is now separately packaged. Ehcache itself is now very mature. Most of the changes now are creating implementations to solve common caching problems. Splitting out constructs allows for a different release cycle. Also there is the Unix maxim, do one thing and do it well.

News Highlights

15 August 2005 Announcing ehcache-constructs-0.6. A subproject of ehcache, ehcache-constructs builds on top of ehcache to create implementations for common caching patterns. All implementations use ehcache as the backing cache. They also share a common purpose - to create very high performance Java applications. New in this version is a fault-tolerant AsynchronousCommandExecutor, which will asynchronously execute arbitrary commands, optionally retrying on a defined array of Exception types a defined number of times at a defined interval.

23 November 2004 ehcache-constructs 0.5 released. This is the first release. The constructs package was previously distributed with ehcache. Much of it is very mature. .5 represents a halfway point between starting and a 1.0 release, which is about right.

See the release notes and full changelog here.

Downloads

Download here.

Contributions

The ehcache project gratefully acknowledges the contribution of wotif.com, who granted a license to the authors to in respect of code developed at wotif.com for the purpose of making it available to the community under an Apache open source license.

novell

The ehcache project gratefully acknowledges the contriubtion of Novell, Inc, who granted a license to the authors of the AsynchronousCommandExecutor and associated code for the purposes of making it available to the communtiy under an Apache open source license.

Thanks also to:

ThoughtWorks for free legal assistance in formalising the granting of code from wotif.com to the open source community. Copies of the executed deeds are available should anyone need to audit the grant.
Cenqua for the free open source license of the test coverage tool Clover.
Atlassian for the free open source licenses of JIRA, an issue tracking tool and Confluence, a wiki.
Ironflare for permission to embed the excellent Orion application server in the testing infrastructure for use as a Servlet 2.3 container. Orion is not distributed in the binary. It is not a dependency for using ehcache-constructs. Commercial use of Orion requires a license.

Finally, thanks to those who have contributed to the project. Those people are acknowledged in the traditional way with an @author tag in the source code.

About the ehcache-constructs name

Doug Lea in his book Concurrent Programming in Java talks about concurrency support constructs. One meaning of a construct is "an abstract or general idea inferred or derived from specific instances". Just like patterns emerge from noting the similarities of problems and gradually finding a solution to classes of them, so to constructs are general solutions to commond problems. With ehcache-constructs, concrete, extensible implementations are offered to solve these common problems.