On Wed, Dec 16, 2009 at 3:30 PM, Rick Bullotta <rick.bullo...@burningskysoftware.com> wrote: > 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
Yes you can. Once a transaction is started (NeoService.beginTx) the transaction will be associated with the current thread. I just checked the javadoc and wiki documentation, none of them really explains this in a clear way so thanks for pointing this out. Regards, -Johan > 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
