CODEWITHSUNDEEP
gremlingremlin-server
Lanre Adeoluwa
Lanre Adeoluwa

Reputation: 31

How to programmatically create a new graph instance at runtime on Gremlin Server

I have a Java Project that connects to a Gremlin Server. I want to create 5 new graph instances of Neo4j at runtime? How can i do this on Gremlin Server please?

Also, I have heard about session and sessionless states in Gremlin Server but don't really understand the purpose of this?! Can someone please touch on this but more importantly, to show how to use a session state and a sessionless state in my Java project on Gremlin Server?

Many thanks in advance.

For example: 

List<GraphTraversalSource> graphs;

for (int x= 0 ;  x < 5 ; x++) {
 graph = Neo4jGraph.open();
 g = graph.traversal(); 
 graphs.add(g);
}

Upvotes: 0

Views: 426

Answers (1)

stephen mallette
stephen mallette

Reputation: 46226

The short answer is that Gremlin Server doesn't allow for programmatic graph creation - graphs are configured up front prior to Gremlin Server starting.

The longer answer is that Gremlin Server is a bit of a reference implementation of the Gremlin Server Protocol, which means that depending on the TinkerPop-enabled graph database you use you might get a different answer to your question. For example, DS Graph and JanusGraph both have options for dynamic graph construction. Neo4j and TinkerGraph on the other hand utilize the raw reference implementation of Gremlin Server and therefore don't have that kind of functionality.

That last point about the reference implementation leads to yet a longer answer. You can submit a script to create graphs like Neo4jGraph or TinkerGraph but it won't add them to the global list of graphs that Gremlin Server holds (which you've tried to simulate in your pseudocode with graphs.add(g)). That of course means that you won't be able to access those newly created Graph instances on future requests........unless, you use a session. The reason that TinkerPop has both sessionless and sessioned based requests is that sessions tend to be more expensive to the server because they maintain more state between requests and they bind requests to a single Gremlin Server rather than spreading requests across a cluster. TinkerPop recommends using sessionless for almost all use cases and to reserve sessioned requests for some fairly narrow use cases (like tools - a Gremlin-based visualization UI).

There are likely some ways to extend Gremlin Server for your purposes (JanusGraph did it with their packaging of Gremlin Server), but it would require you to get knowledgeable on the code itself. I could probably provide you some additional guidance but StackOverflow probably isn't the right place to do that. Feel free to ask questions on the gremlin-users mailing list if you'd like to discuss that option in greater detail.

Upvotes: 2

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