How do I access a .net resource for an IKVM-ported java library

Question

I am using IKVM to port some java libraries into my c# project. The library api (StanfordNLP) requires that a file be loaded to train the statistical models used by the nlp functions. Loading the file from the file system has worked well for weeks, but I would now like to add the file as an embedded resource in a dll, rather than retrieving it from the file system.

The problem is that the java api is not finding the .net embedded resource.

Here is a snippet of code that works when retrieving a file from the file system:

public class SNLPModel
{
   public LexicalizedParser LP;

   public SNLPModel()
   {
      // Using a relative file path in the target build directory
      LP = LexicalizedParser.loadModel("models-stanford\\englishPCFG.ser.gz");
   }
}

But when I make the "englishPCFG.ser.gz" file an embedded resource in visual studio (using VS2012), and change the code to match:

public class SNLPModel
{
   public LexicalizedParser LP;

   public SNLPModel()
   {
        // Using this line of code to verify that the file is being loaded as
        // an embedded resource. Running in debug, I have verified that it is, and
        // noted its complete name.
        string[] s = System.Reflection.Assembly.GetExecutingAssembly()
                        .GetManifestResourceNames();

        java.io.InputStream modelFile = java.lang.ClassLoader
              .getSystemResourceAsStream
              ("FeatureExtraction.StanfordNLP_Models.englishPCFG.ser.gz");

        java.io.ObjectInputStream x = new java.io.ObjectInputStream(modelFile);

        LP = LexicalizedParser.loadModel(x);
   }
}

the InputStream object, modelFile, is always returned null. I have tried various forms of the resource string, replaceing the first two dots (".") with forward slash ("/"), backslash ("\") and double backslash ("\\"). I am beginning to suspect that java.io cannot access the .net resource. It would not be surprising that the java api does not recognize the .net resources, but I thought IKVM might provide a bridge. I have seen a reference to something called IKVM.Internals.VirtualFileSystem, but only the one reference (http://old.nabble.com/Manual-by-name-embedded-resource-lookup--td31162421.html) and haven't found any IKVM dlls that actually contain the class.

Any help would be much appreciated. I am using:

c#.NET 4.5

Visual Studio 2012

Latest Stanford NLP java libraries

IKVM 7.0.4335.0

Answer 1

There is no automatic support for this in IKVM, but it is really easy to do it yourself:

var asm = Assembly.GetExecutingAssembly();
var stream = asm.GetManifestResourceStream("FeatureExtraction.StanfordNLP_Models.englishPCFG.ser.gz");
var inp = new ikvm.io.InputStreamWrapper(stream);
var x = new java.io.ObjectInputStream(inp);

Answer 2

The hint to the right solution is in the extension of the file that you embed.

If it is plain serialized java object (like english-left3words-distsim.tagger) you can load it like this

let model = "../english-left3words-distsim.tagger"
use fs = new FileStream(model, FileMode.Open)
use isw = new ikvm.io.InputStreamWrapper(fs)
let tagger = edu.stanford.nlp.tagger.maxent.MaxentTagger(isw)

but if your model has extension .gz this mean that file is gzipped, and you have to wrap input stream into java.util.zip.GZIPInputStream before deserialization

let model = "../englishRNN.ser.gz"
use fs = new FileStream(model, FileMode.Open)
use isw = new ikvm.io.InputStreamWrapper(fs)

use ois =
    if model.EndsWith(".gz")
    then
        let gzs = new java.util.zip.GZIPInputStream(isw)
        new java.io.ObjectInputStream(gzs)
    else new java.io.ObjectInputStream(isw)
let lp = edu.stanford.nlp.parser.lexparser.LexicalizedParser.loadModel(ois)