Hi Emmanuel, I guess some classes would result similar in an Infinispan based mass indexer, bit this is coupled to which are the efficient strategies to get a continuous flow of Documents. It mostly depends on how you're going to store structured entities in Infinispan? The whole graph needed by a DocumentBuilder is found on the same key? (i.e. no lazy loading?) Sure a non-tuned implementation would not be hard, but we might find out that to make it fast it needs a larger set of changes maybe up to the API. Some classes would be reused with minimal changes, as whatever the source is I'd still recommend to use the multiple-parallel-queues idea, so at least these: ProducerConsumerQueue, MassIndexerProgressMonitor, Executors even the coordinator BatchCoordinator could work unchanged; All classes in org.hibernate.search.backend.impl.batchlucene would also work unchanged. I can't really abstract-away Hibernate from the MassIndexerImpl and the 2 Runnable types it spawns, the strategies it uses are tailored for Hibernate: exploit caches, fight delay on lazyloading, detach-reattach to session at thread switches, pool the Session(s). I guess you could rename it to HibernateMassIndexerImpl? Another implementation could easily combine the other classes as common utilities but I'd bet the main strategy would be different. you say "aside from the MassIndexer interface", note I'm exposing cacheMode(org.hibernate.CacheMode cacheMode) on the interface. I've seen consistent performance differences in enabling/disabling the caches, in some models clearly faster enabling it, in others disabling it, so I need some way to set this. We could change that to a boolean, as only IGNORE/NOT_IGNORE the caches are interesting options. Other implementations could then ignore this setting if caching doesn't make sense to them. After having made the API "hibernate free" we can change the factory to return a different impl whatever the storage engine is. (we call it "storage engine" ?) Sanne 2009/10/25 Emmanuel Bernard <emmanuel(a)hibernate.org&gt;: > Hey Sanne, > MassIndexerImpl is 100% dependent of Hibernate Core (you pass a > SessionFactory). > How realistic and doable is it to abstract that a bit. For example, > would an > Infinispan based mass indexer make sense? If yes, what's reusable > in your > impl (I mean aside from the MassIndexer interface). > > Emmanuel >