Thanks, Johan. My concern relates to the "transaction interleaving" that might occur...which could definitely result in unexpected consequences, could it not?
If I create a transaction on a specific thread, can I safely assume that it is independent from a transaction that is started on another thread? In general, each servlet request will be handled on a separate thread, and we will have a background pool of worker threads for other tasks, all of which will occasionally need to access Neo. I just want to make sure I fully understand the transactioning model and its implications. Rick -----Original Message----- From: user-boun...@lists.neo4j.org [mailto:user-boun...@lists.neo4j.org] On Behalf Of Johan Svensson Sent: Wednesday, December 16, 2009 4:49 AM To: Neo user discussions Subject: Re: [Neo] Best practices for using Neo within a web application Hi, On Tue, Dec 15, 2009 at 2:44 PM, Rick Bullotta <rick.bullo...@burningskysoftware.com> wrote: > Hello, all. > > I was wondering if there was any guidance/best practices for leveraging Neo > in a scenario where multiple servlets in a web application will have the > need to read/insert/update/delete nodes and relationships simultaneously. > We are working at getting such information up on the wiki (there are some info but it is spread out over different pages and needs to be completed/updated). > In particular: > > > > 1) Must/should the NeoService be a singleton shared amongst all > servlets? Yes or better is not to have singletons and instead use inversion of control and inject the NeoService where it is needed. > > 2) When best to create transactions - on each invocation? > Wrap each request in a transaction, this work well in most scenarios. > 3) How do the threading implications of the servlet's service() method > affect transactions and unintentional transaction nesting? Should be no problem since trying to start a transaction when there is already one running will do nothing and use the current running transaction. See http://wiki.neo4j.org/content/Neo_Transactions (flat nested transactions). > > 4) Is there any advantage to using additional EmbeddedReadOnlyNeo > instances in cases where access is truly read only? > No. If on the same JVM pass around the normal EmbeddedNeo instance to read only requests also. > > > In some cases, there may be a desire to have multiple web applications in > the same web app server (Tomcat, JBoss, etc.) accessing a common Neo graph > structure. In this case, what are the options? We were thinking that the > only option is RemoteNeo between the web apps, or some other RPC layer > invoking methods in classes that reside in the "master" web app that > actually has a NeoService instance. > Was a while since I worked with Tomcat/JBoss but I take it the problem you have is that each web app has its own class loader? If you somehow could put the Neo4j classes and dependencies on a common class loader used by all web apps that problem should go away (but I don't really know this kind of stuff, anyone else?). Regards, -Johan _______________________________________________ Neo mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user _______________________________________________ Neo mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
