RE: JESS: Call Jess from C++ via JNI

[Friedman-Hill, Ernest]

 To restate: you have three libraries you want to use:

- One (Jess) is written in Java;

- One (BWAPI) can be accessed from Java by using an existing JNI interface,

- And the third (BWSAL) is currently available only in native code.

Your current plan is to write a JNI wrapper for some or all of BWSAL and write 
your application in Java. This makes perfect sense to me.

It might be even easier to use JNA (http://jna.java.net/) instead of writing a 
specific wrapper, but that depends on various details. Worth looking at, anyway.


From: owner-jess-us...@sandia.gov [mailto:owner-jess-us...@sandia.gov] On 
Behalf Of Hunter McMillen
Sent: Saturday, October 01, 2011 12:52 PM
To: jess-users
Subject: Re: JESS: Call Jess from C++ via JNI

Well I am trying to create an agent to compete in the Starcraft AI competition 
for next year, the API that the agents all use is called BWAPI: 
http://code.google.com/p/bwapi/, but this is also a standard library that some 
of the agents use that would be really useful for for my agent called BWSAL: 
http://code.google.com/p/bwsal/. Anyway there is a native interface that 
someone created for BWAPI, which I was planning on using in my code, so my plan 
was to create a native interface for BWSAL, that way I could do all the Jess 
interaction inside of Java, then call associated methods in C++ via JNI. Does 
this sound far-fetched?

On Thu, Sep 29, 2011 at 5:10 PM, Socrates Frangis 
mailto:soc.fran...@gmail.com>> wrote:
What framework are you using? Curious to see how it is invoking JNI.


"using this I think I can only interact with Jess in my Java program then pass 
data from my Java code to C++"
-Unless your framework has an API supporting JESS specifically, i doubt that is 
the case.  It should be providing a 'simpler' implementation to access your 
java classes but that would just eliminate the cryptic path declaration and 
still give you an interface to what youre playing with.

Overall opinion, given the chance that your framework may inhibit full controll 
of the Rete engine or using JESS (and for the learning experience) i would 
recommend sticking with your current implementation.  Rule engines require 
precise attention to detail and i wouldn't risk the chance of losing fidelity.


On Wed, Sep 28, 2011 at 2:22 PM, Hunter McMillen 
mailto:mcmil...@gmail.com>> wrote:
Sorry to pester you with more questions.

The way I am currently doing things in invoking a JVM from C++ to call Java 
code that calls/interacts with Jess code, but it turns out that someone has 
actually created a java native interface for the api/framework I am using to 
make my agent, using this I think I can only interact with Jess in my Java 
program then pass data from my Java code to C++, I was wondering if you thought 
this would be a better solution than invoke a JVM from C++

Thanks
Hunter


On Tue, Sep 27, 2011 at 12:03 PM, Friedman-Hill, Ernest 
mailto:ejfr...@sandia.gov>> wrote:
This is all perfectly reasonable so far. When you create the JVM you'll need to 
tell it where jess.jar is, along with any other jars you use, with the "-cp" 
flag or the "java.class.path" property.

Once you have this working, you'll presumably want to connect things a little 
more tightly. You can use the JNI API to write the equivalent of your 
three-line main() in C++ pretty easily; you'll want to put together a C++ 
version "executeCommand()" that controls the Rete instance, passes a script 
along, executes it, and gets the Value back, decoding it as needed.



From: owner-jess-us...@sandia.gov 
[mailto:owner-jess-us...@sandia.gov] On 
Behalf Of Hunter McMillen
Sent: Monday, September 26, 2011 8:51 PM
To: jess-users
Subject: JESS: Call Jess from C++ via JNI

Hello everyone,

 I am working on a project where I am using a C++ framework and API to create a 
game agent. My agent has to be flexible so it can react to/predict events that 
occur inside the game environment, Jess has the kind of flexibility that I need 
for my agent to be good,  but I am having trouble connecting to Jess from C++ 
and that is where I was hoping someone could help me out.

What I am doing right now
I have a C++ program that starts a Java Virtual Machine and searches for a Java 
class file name "TestJNIJessInvoke"

Inside of "TestJNIJessInvoke.java" I define a simple function in Jess, and try 
to call that function then print the result
import jess.*;
public class TestJNIJessInvoke
{
public static void main(String[] args) throws JessException
{
Rete r = new Rete();
r.executeCommand("(deffunction square (?n) (return (* ?n ?n)))");
Value v = r.executeCommand("(square 3)");

System.out.println(v.intValue(r.getGlobalContext()));
}
}

But when I try to compile and link the C++ file with:
cl
   -I"C:\Program Files\Java\jdk1.7.0\include"
   -I"C:\Program Files\Java\jdk1.7.0\include\win32"
  

Re: JESS: Call Jess from C++ via JNI

[Hunter McMillen]

Well I am trying to create an agent to compete in the Starcraft AI
competition for next year, the API that the agents all use is called BWAPI:
http://code.google.com/p/bwapi/, but this is also a standard library that
some of the agents use that would be really useful for for my agent called
BWSAL: http://code.google.com/p/bwsal/. Anyway there is a native interface
that someone created for BWAPI, which I was planning on using in my code, so
my plan was to create a native interface for BWSAL, that way I could do all
the Jess interaction inside of Java, then call associated methods in C++ via
JNI. Does this sound far-fetched?

On Thu, Sep 29, 2011 at 5:10 PM, Socrates Frangis wrote:

> What framework are you using? Curious to see how it is invoking JNI.
>
>
> "using this I think I can only interact with Jess in my Java program then
> pass data from my Java code to C++"
> -Unless your framework has an API supporting JESS specifically, i doubt
> that is the case.  It should be providing a 'simpler' implementation to
> access your java classes but that would just eliminate the cryptic path
> declaration and still give you an interface to what youre playing with.
>
> Overall opinion, given the chance that your framework may inhibit full
> controll of the Rete engine or using JESS (and for the learning experience)
> i would recommend sticking with your current implementation.  Rule engines
> require precise attention to detail and i wouldn't risk the chance of losing
> fidelity.
>
>
> On Wed, Sep 28, 2011 at 2:22 PM, Hunter McMillen wrote:
>
>> Sorry to pester you with more questions.
>>
>> The way I am currently doing things in invoking a JVM from C++ to call
>> Java code that calls/interacts with Jess code, but it turns out that someone
>> has actually created a java native interface for the api/framework I am
>> using to make my agent, using this I think I can only interact with Jess in
>> my Java program then pass data from my Java code to C++, I was wondering if
>> you thought this would be a better solution than invoke a JVM from C++
>>
>> Thanks
>> Hunter
>>
>>
>> On Tue, Sep 27, 2011 at 12:03 PM, Friedman-Hill, Ernest <
>> ejfr...@sandia.gov> wrote:
>>
>>> **
>>> This is all perfectly reasonable so far. When you create the JVM you'll
>>> need to tell it where jess.jar is, along with any other jars you use, with
>>> the "-cp" flag or the "java.class.path" property.
>>>
>>> Once you have this working, you'll presumably want to connect things a
>>> little more tightly. You can use the JNI API to write the equivalent of your
>>> three-line main() in C++ pretty easily; you'll want to put together a C++
>>> version "executeCommand()" that controls the Rete instance, passes a script
>>> along, executes it, and gets the Value back, decoding it as needed.
>>>
>>>
>>>  --
>>> *From:* owner-jess-us...@sandia.gov [mailto:owner-jess-us...@sandia.gov]
>>> *On Behalf Of *Hunter McMillen
>>> *Sent:* Monday, September 26, 2011 8:51 PM
>>> *To:* jess-users
>>> *Subject:* JESS: Call Jess from C++ via JNI
>>>
>>>  Hello everyone,
>>>
>>>   I am working on a project where I am using a C++ framework and API to
>>> create a game agent. My agent has to be flexible so it can react to/predict
>>> events that occur inside the game environment, Jess has the kind
>>> of flexibility that I need for my agent to be good,  but I am having trouble
>>> connecting to Jess from C++ and that is where I was hoping someone could
>>> help me out.
>>>
>>>  *What I am doing right now*
>>> I have a C++ program that starts a Java Virtual Machine and searches for
>>> a Java class file name "TestJNIJessInvoke"
>>>
>>>  Inside of "TestJNIJessInvoke.java" I define a simple function in Jess,
>>> and try to call that function then print the result
>>>  import jess.*;
>>> public class TestJNIJessInvoke
>>> {
>>> public static void main(String[] args) throws JessException
>>> {
>>> Rete r = new Rete();
>>> r.executeCommand("(deffunction square (?n) (return (* ?n ?n)))");
>>> Value v = r.executeCommand("(square 3)");
>>>
>>>  System.out.println(v.intValue(r.getGlobalContext()));
>>> }
>>> }
>>>
>>>  But when I try to compile and link the C++ file with:
>>> *cl *
>>> *   -I"C:\Program Files\Java\jdk1.7.0\include" *
>>> *   -I"C:\Program Files\Java\jdk1.7.0\include\win32" *
>>> *   TestJNIJessInvoke.cpp *
>>> *   -link "C:\Program Files\Java\jdk1.7.0\lib\jvm.lib"*
>>>  *
>>> *
>>> I get a class loader exception:
>>>  *Exception in thread "main" java.lang.NoClassDefFoundError: jess/Rete*
>>> *at TestJNIJessInvoke.main(TestJNIJessInvoke.java:6)*
>>> *Caused by: java.lang.ClassNotFoundException: jess.Rete*
>>> *at java.net.URLClassLoader$1.run(URLClassLoader.java:366)*
>>> *at java.net.URLClassLoader$1.run(URLClassLoader.java:355)*
>>> *at java.security.AccessController.doPrivileged(Native Method)*
>>> *at java.net.URLClassLoader.findClass(URLClassLoader.java:354)*
>>> *at java