This post is part of Who's at Google I/O, a series of guest blog posts written by developers who are appearing in the Developer Sandbox at Google I/O. It's also cross-posted to the Google Code blog which has similar posts for all sorts of Google developer products.
Elastic Path develops a very flexible enterprise ecommerce platform. Many global brands rely on the Elastic Path platform to power their ecommerce solutions.
Many ecommerce sites are actually complex web applications. Catalog management, shopping cart functionality, promotion engine, order fulfillment, and backend integrations are just some of the challenges involved in running a full-fledged online store.
Since 2008, our Java-based platform has been the ecommerce backbone of a couple of online stores that are being migrated to run on App Engine. Like many complex web applications, these stores used to run in a multi-server environment (Apache Tomcat with a MySQL database) hosted in a colocation center.
As the diagram above shows, our goal is to have Elastic Path running entirely on the App Engine cloud. The storefronts have already been migrated, and the database and remaining parts of the Elastic Path platform will be fully on the cloud soon.
Why are we doing this? There are many benefits to being on App Engine:
- Increased security
- Easier deployments and operations
- Built-in monitoring
Our migration’s high-level approach was to move everything except the persistence layer onto App Engine, and then resolve issues with the technical limitations such as the class whitelist and request length. We also had to modify some third-party libraries to work around App Engine’s restrictions on operations such as class loading, threads, and sockets.
We didn’t migrate the persistence layer because Elastic Path uses a relational database; converting our entire object graph to the Datastore is not feasible now. We are working closely with Google on alternatives. In the interim, we are still using a MySQL database and have kept our persistence layer running within a Tomcat application in the colo. We implemented a creative solution: the non-persistence layers of Elastic Path run on App Engine and communicate with the Tomcat-hosted persistence services via Spring Remoting. The back-and-forth remoting was expensive and impacted the performance of our application so we implemented some data caching. For this, we turned to App Engine’s Memcache, which improved performance by an order of magnitude (less than 2 seconds average response times vs. 2 minutes or more without Memcache).
Other App Engine technologies we use heavily include AppStats for performance tuning, URL Fetch for the Spring Remoting described above, and the fantastic Maven GAE plugin that we use for packaging and automated deployments. As we continue to push our platform up to the cloud, we hope to utilize more of App Engine’s cool features. If you’d like to learn more about Elastic Path, how we are migrating our Java platform to run on the cloud, and how you might be able to migrate your application to App Engine, drop by our booth in the App Engine section of the Developer Sandbox. See you there!
Eddie Chan is an ecommerce developer at Elastic Path Software in beautiful Vancouver, Canada. He and his brilliant team work closely with Google and are currently focused on migrating existing online stores to App Engine.
Posted by Scott Knaster, Editor