Getting started with Spring and Hazelcast

by Enes Akar — Apr 5, 2012
This article is a getting-started tutorial on integrating hazelcast into a Spring project.
Part 1: First Create Spring project (if you have already skip to Part 2)
1- Create a maven project.
mvn archetype:generate -DgroupId=spring_hazelcast -DartifactId=spring_hazelcast  

2- Add spring dependencies into pom.
3- Create a TestBean.
3- Create beans.xml in your source root (src/main/java/beans.xml)
4- Test your Spring app.
If you see “success” printed, now we can integrate hazelcast.

Part 2: Integrate Hazelcast
1- Add hazelcast dependencies
2- Add hz name spaces, hazelcast configuration and an hazelcast map bean to beans xml.
In hz:map definition, “id” is spring bean id, name refers to hazelcast map’s name.

3- Test hazelcast.

You can download and browse the getting started project here:

Distribute Grails with Hazelcast

by Enes Akar — Apr 3, 2012

Distribute Grails with Hazelcast


In this article I will try to integrate my two favorite technology: grails and hazelcast.
(Bias: I am currently work for Hazelcast)

Ruby on Rails gained popularity among people who seeks productivity on web programming.
Java is often criticisized on being heavy for rapid development.
But richness of Java community has given birth to flexible and dynamic JVM languages like Groovy.
Grails is somewhat synthesis of power of Java (with the help of Groovy) and productivity of Rails with philosophy “convention over configuration”.
Another technology which amazes me is Hazelcast.
I remember the days which I first meet socket programming, RMI; in university.
And when I first tried the Hazelcast my first reaction is “How “Distributing your data over machines” could be so easy.
Single jar, no dependency, distribute your data over maps, queues, topics…

So I have decided to integrate these two technology, write a simple plugin so anyone can easily distribute data over memory by hazelcast.
Here introductory on using this plugin.
How to Install Plugin

Run the command:
install-plugin hazelgrails

You will see hazelcast.xml in conf directory under plugins directory.
You can configure hazelcast in details. 
For available options have a look at:

To see hazelcast logs add following to Config.groovy:
info ‘com.hazelcast’
Use Hazelcast as Hibernate 2nd Level Cache
In DataSource.groovy replace the following line in hibernate configuration block.
cache.region.factory_class = ‘com.hazelcast.hibernate.HazelcastCacheRegionFactory’
For more details about 2nd level cache configuration have a look at:

Test The  Plugin

Create an Grails application and install the plugin. Then create a domain and two controllers.
create-domain-class com.hazelgrails.Customer
create-controller com.hazelgrails.Server1
create-controller com.hazelgrails.Server2

As you see, Customer is serializable. Hazelcast requires the objects to be serializable in order to distribute them in cluster.

Now create the war file (command “grails war”) but copy the file with different name (app2.war). 
You may deploy the wars into different machines in the same network, or to different servers (Tomcat, Jetty) in same machine or even into the same Tomcat.
For simplicity I have run the current app by “grails run-app” and I have deployed the war to an external Tomcat.
And test them:

Cities:[2:New York, 1:London] 
Timestamps:[1333447087796, 1333447112863]
Cities:[2:New York, 1:London] 
First customer name:tom, age:20 
Timestamps:[1333447087796, 1333447112863]

In practice, if you see the following then you can conclude the nodes formed a cluster succesfully. (you should add “info ‘com.hazelcast’” into Config.groovy)
Members [2] {
        Member []
        Member [] this

Usage Examples
There are two new methods defined for domain classes.
saveHz() method, first persists the domain object (like original save()) then puts it to hazelcast map.
getHz() method tries to find object with given id first in hazelcast map, if not found then tries to find it in datasource.
Hazelcast create a distributed map for each domain class. 
So by using saveHz() and getHz() you can get your objects from distributed memory instead of getting by database operations.
Also by injecting hazelService, you can create hazelcast instances.
Here the usage exampples: