Friday, August 12, 2011

RESTful Transactions in the Cloud: Now they're for real

A few months back Mark posted on the subject of REST, transactions and the cloud. Well now you can test the validity of his claims for yourselves. RedHat recently announced their OpenShift initiative for deploying applications into the cloud and we have put together a demonstration to show how easy it is to perform end to end transactional requests whilst remaining RESTful/RESTlike throughout and using little more than a JAX-RS container, an HTTP client library and a transaction coordinator.

As our starting point we use an implementation of the draft specification for a RESTful interface to 2-Phase-Commit transactions which we refer to as REST-AT.

The demonstration starts out by showing local clients (written in various languages such as javascript and Ruby) and local (JAX-RS) web services interacting transactionally using HTTP for all communications. The transaction coordinator that implements REST-AT is written using JAX-RS and also runs locally.

The push to cloud based deployments demands that providers support piecemeal migration of applications into the cloud infrastructure. REST-AT together with OpenShift makes the realisation of this goal, at least for transactional services, a relatively painless exercise. The demonstration code and accompanying video shows how to migrate the transaction coordinator component leaving clients and services outside of the infrastructure. We achieve this by using the OpenShift JBoss AS7 cartridge and deploy REST-AT as a war into the application server that this cartridge provides. In a later post we will show how to migrate Java and Ruby services into the OpenShift infrastructure using the AS7 and Ruby cartridges, respectively.

To begin using OpenShift a good starting point would be to watch the various getting started videos (look for the Zero to Cloud in 30 minutes track or go directly to the demo video). To start using REST-AT check out the quickstarts and the sources for the demo.

Using JBossTS in OpenShift Express


I just wanted to let you know that you can use transactions in Red Hat's new OpenShift Express tool. Having had some hand's on time with the system I can safely say its one of the most exciting new projects I have seen in a while.

It makes deploy applications into the cloud so easy, plus as it supports deploying applications onto AS7 you can benefit from all the cool features that have been added there.

As AS7 features transactions (naturally!) I decided to kick the tyres of Openshift Express a little harder by not just using JPA, EJB, JTA and JSF, but also utilise one of the JBoss Transactions extension features - TXOJ. You can watch my video of this here, and the source code is available here.

Safe to say it was extremely simple to get this up and running, if you follow the video you can too!

For those who don't like videos though, here's a little cheat sheet I put together to get it running:

1. You need an openshift express domain, go to: to get one
2. rhc-create-app -a txapp -t jbossas-7.0
3. cd txapp
4. svn export
5. mv jee_transactional_app/* .
6. rmdir jee_transactional_app
7. Add an openshift profile to your pom.xml:
8. git add src pom.xml
9. git commit -a -m “jee_transactional_app” && git push
10. Open up firefox and go to http://txapp-<YOUR_DOMAIN>

I hope you enjoy using Openshift Express and also can add a few Transactional Objects to your applications!