I’m developing a Java/Spring web application deployed on JBoss 4.2.2 that makes heavy use of memcached in order to reduce the latency experienced by the user. The user interacts with data that is (unbeknownst to them) in the cache. In order to make changes permanent a message is placed on a queue that is picked up by an MDB. The message is just the key used to access the data in the cache. The MDB takes the data out of the cache and then saves it to the database. This greatly improves the user experience because they do not have to wait for the next page to load while costly database writes occur. So far, so good.
In this case I am unfortunately duplicating data by separating the reads from the writes. The data lives in the Hibernate session used by the read-only app server in order to load the data in the first place. It also has to be loaded in the write-only app server in order for that Hibernate session to work with it, which brings me to the point of this post: Is there any way that I can use Terracotta to pool my Hibernate-managed objects into one pool used by both the read-only and write-only app servers? I think I would like to pool my Hibernate second-level cache. It seems like Terracotta can get the job done.
That said, I’m anxious to explore this topic more when Orion Letizi from Terracotta Tech comes to speak at the Boston Scalability User Group next Wednesday on May 28th. The meeting starts at 6 p.m. at the IBM Innovation Center in Waltham, MA. Of course there will be pizza and soda (sponsored by Terracotta - thank you!) so come to the meeting to have some food and explore what Terracotta can do for your project. All the details, including directions, are on the Boston Scalability User Group web site. Remember, there will be pizza!