Does titan (graph database) support update notifications?

Question

Context:

I'm using Titan v1.0.0, on AWS infrastructure and want to support failover/fault tolerance. AWS will take care of DynamoDb storage backend but it seems necessary to have several titan instances serviced by an (ELB) load balancer. (Feel free to correct this assertion)

I'm using a nodeJs library to get to gremlin, and gremlin to access Titan.

Question

I'd like to receive updates in the nodeJs app when someone adds/updates/removes a vertex/edge/their properties covered by a certain query. This is equivalent to the observer pattern or continuous query functionality in some DBs/caches.

Anyone know if this is possible? Looking at the transaction log stuff it may be possible but I'm not sure. EventStrategy/EventGraph both seem to only work for the local instance transaction.

An illustration of the problem (assume instances 'A' and 'B' have a pinned session). If NodeJsA makes an update via TitanA, I want TitanB to pick that up and notify NodeJsB.

[NodeJsA]\             /[TitanA]\
          \           /          \
           [ELB (AWS)]            [DynamoDb (AWS)]
          /           \          /
[NodeJsB]/             \[TitanB]/

Polling is a fall back option but I'd rather not go there.

Answer 1

Titan does not have any features that directly accomplish what you're asking for (neither does TinkerPop). I think you've already mentioned the closest options that you have: the Titan transaction log and EventStrategy. In both cases, I think you'd have a bit of work to do and would have to complicate your architecture a bit to accommodate such a feature.