Sneak peek into the JCache API (JSR 107)

Abhishek GuptaFebruary 11th, 2015Last Updated: February 10th, 2015

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This post covers the JCache API at a high level and provides a teaser – just enough for you to (hopefully) start itching about it ;-)

In this post ….

JCache overview
JCache API, implementations
Supported (Java) platforms for JCache API
Quick look at Oracle Coherence
Fun stuff – Project Headlands (RESTified JCache by Adam Bien) , JCache related talks at Java One 2014, links to resources for learning more about JCache

What is JCache?

JCache (JSR 107) is a standard caching API for Java. It provides an API for applications to be able to create and work with in-memory cache of objects. Benefits are obvious – one does not need to concentrate on the finer details of implementing the Caching and time is better spent on the core business logic of the application.

JCache components

The specification itself is very compact and surprisingly intuitive. The API defines high level components (interfaces) some of which are listed below

Caching Provider – used to control Caching Managers and can deal with several of them,
Cache Manager – deals with create, read, destroy operations on a Cache
Cache – stores entries (the actual data) and exposes CRUD interfaces to deal with the entries
Entry – abstraction on top of a key-value pair akin to a java.util.Map

Hierarchy of JCache API components

JCache Implementations

JCache defines the interfaces which of course are implemented by different vendors a.k.a Providers.

Oracle Coherence
Hazelcast
Infinispan
ehcache
Reference Implementation – this is more for reference purpose rather than a production quality implementation. It is per the specification though and you can be rest assured of the fact that it does in fact pass the TCK as well

From the application point of view, all that’s required is the implementation to be present in the classpath. The API also provides a way to further fine tune the properties specific to your provider via standard mechanisms.

You should be able to track the list of JCache reference implementations from the JCP website link

JCache provider detection

JCache provider detection happens automatically when you only have a single JCache provider on the class path
You can choose from the below options as well

Java Platform support

Compliant with Java SE 6 and above
Does not define any details in terms of Java EE integration. This does not mean that it cannot be used in a Java EE environment – it’s just not standardized yet.
Could not be plugged into Java EE 7 as a tried and tested standard
Candidate for Java EE 8

Project Headlands: Java EE and JCache in tandem

By none other than Adam Bien himself !
Java EE 7, Java SE 8 and JCache in action
Exposes the JCache API via JAX-RS (REST)
Uses Hazelcast as the JCache provider
Highly recommended !

Oracle Coherence

This post deals with high level stuff w.r.t JCache in general. However, a few lines about Oracle Coherence in general would help put things in perspective

Oracle Coherence is a part of Oracle’s Cloud Application Foundation stack
It is primarily an in-memory data grid solution
Geared towards making applications more scalable in general
What’s important to know is that from version 12.1.3 onwards, Oracle Coherence includes a reference implementation for JCache (more in the next section)

JCache support in Oracle Coherence

Support for JCache implies that applications can now use a standard API to access the capabilities of Oracle Coherence
This is made possible by Coherence by simply providing an abstraction over its existing interfaces (NamedCache etc). Application deals with a standard interface (JCache API) and the calls to the API are delegated to the existing Coherence core library implementation
Support for JCache API also means that one does not need to use Coherence specific APIs in the application resulting in vendor neutral code which equals portability
How ironic – supporting a standard API and always keeping your competitors in the hunt ;-) But hey! That’s what healthy competition and quality software is all about !
Talking of healthy competition – Oracle Coherence does support a host of other features in addition to the standard JCache related capabilities.
The Oracle Coherence distribution contains all the libraries for working with the JCache implementation