The Web Semantic

I recently ran across a project called ja.net that provides support for compilation of Java to .Net.  Since neo4j has such a dependency clean kernel, I decided to try ja.net as a way of making neo4j usefull under .Net. (no slight against the RESTful interfaces, but perhaps you’d like to run neo4j on .net as an embedded graph DB under .Net). Here’s my VS2010 with the neo4j.dll referenced, and the object browser showing the EmbeddedGraphDB class as a first class .Net object:

Step #1 Download stuff

Download the neo4j kernel source and expand into a working directory. http://neo4j.org/download

Download the geronimo JTA spec src jar and expand under neo4j’s src/main/java directory. 

Install Ja.net from http://www.janetdev.org/. 

Step #2 Compile neo4j kernel using Ja.Net

C:\neo4j-kernel-1.0\src>c:\opt\java\Ja.NET\bin\javac -bam:neo4j.dll main

You can compile first then using the “bam” command to create the dll, or do it in one pass as I’ve done here.  You’ll see warnings, most look like compiler warnings, one may be of concern.  For now let’s just experiment.  No garauntees, promises, etc. 

Step #3 Create a C# console app, reference your newly created .dll, and give neo4j on .net a run.  Here’s my sample code:

class Program
{
static void Main(string[] args)
{
var graphDb = new EmbeddedGraphDatabase("graphdb");
var tx = graphDb.beginTx();
try
{
var firstNode = graphDb.createNode();
var secondNode = graphDb.createNode();
var relationship = firstNode.createRelationshipTo(
secondNode, DynamicRelationshipType.withName("KNOWS"));
firstNode.setProperty("message", "Hello, ");
secondNode.setProperty("message", "world!");
relationship.setProperty("message", "brave Neo4j ");
var i = graphDb.getAllNodes().iterator();
while (i.hasNext()) {
    var n = ((Node)i.next());
    if (n.hasProperty("message"))
    Console.WriteLine(n.getProperty("message"));
}
Console.WriteLine("bye");
tx.success();
}
finally
{
   tx.finish();
   graphDb.shutdown();
}
Console.ReadLine();
}