Hi, Jeff. If it helps, I get the same behavior on both computers. I
cannot seem to get the library to run its code. However, if I might
add a new wrinkle: This time I changed the JNI to this:
public class NativeCodeClass {
static {
try{
System.loadLibrary("SolverLibrary");
} catch (UnsatisfiedLinkError e) {
System.exit(0);
}
}
public native String validatePassword(String username, String
password);
}
In theory, this will make the JRE completely crash if it cannot find
the SolverLibrary. The JRE did not crash but the communication between
server and client still did not function... I am totally lost now. If
you have any suggestions, I'd be happy to hear them. Thanks for all
your help thus far. Best, Darin
On Nov 3, 2:47 pm, Darin <[email protected]> wrote:
> Hi, Jeff. Again, thanks for the responses. I have researched what the
> classpath means (and I assume you mean the directory or directories
> where the JRE looks for possible libraries to use) and I have manually
> set the classpath to be the directory where the library resides.
> Unfortunately, that still did not change anything.
>
> To the best of my knowledge, the server itself isn't supposed to run
> the code. According to the GWT website (please correct me if I am
> wrong, and it is very possible that I am wrong), the code is executed
> as Javascript from within the browser. The Javascript that is already
> theoretically executing from within the browser is supposed to execute
> the native code. For some reason, it finds the code on the computer on
> which I am developing the app, but cannot find the native code when I
> copy it directly to another machine (into the directory where Apache
> looks for its source files). I have copied the SolverLibrary into
> every subdirectory of the main Apache library that I can find but the
> native code still refuses to execute. I'm going to try installing
> Eclipse and GWT on the server machine and see if that helps. Wish me
> luck...
>
> Best, Darin
>
> On Nov 3, 2:14 pm, Jeff Chimene <[email protected]> wrote:
>
> > Hi Darin:
>
> > After re-reading your first post, I think you're already in a client-server
> > environment. I am confused by the following:> I am running Windows XP and
> > using Apache as my http server. Any ideas for
>
> > where I should put the native library so
>
> > > that the Javascript can find it?
>
> > Your Apache installation probably doesn't run Java
> > I think the reason it works in hosted mode is that your hosted mode server
> > is a Java server: Tomcat.
>
> > On Tue, Nov 3, 2009 at 2:59 PM, Jeff Chimene <[email protected]> wrote:
>
> > > On Tue, Nov 3, 2009 at 2:36 PM, Darin <[email protected]> wrote:
>
> > >> Hi, Jeff.
>
> > >> Thank you so much for responding to my question.
>
> > >> Perhaps I'm getting confused by the jargon. The "SolverLibrary" that I
> > >> wrote is written in C/C++ and compiled by Visual Studio into a DLL.
> > >> This DLL is supposed to be run only on the server. The GWT code was
> > >> written in Eclipse and follows essentially the documentation on the
> > >> GWT web site. At the moment, the C/C++ DLL is only checking whether a
> > >> username and password sent it by the client exists within a file on
> > >> the server (nothing fancy; there is no reason to do this in C/C++
> > >> other than to see if it will work) though I have plans to make much
> > >> more complicated native functions once I get this to work. I am not
> > >> sure where the "classpath" is. There is an environment variable in
> > >> Windows called the "PATH"; is that what you mean? I do call the
> > >> library via RPC. The calling code is as follows (written in Java in
> > >> Eclipse using GWT):
>
> > >> public class SecurityServiceImpl extends RemoteServiceServlet
> > >> implements SecurityService {
>
> > >> private static NativeCodeClass nativeCode=new NativeCodeClass();
> > >> private CompressClass compression=new CompressClass();
> > >> �...@override
> > >> public CompressedMessage validatePassword(CompressedMessage m) {
> > >> String message=compression.Decompress(m);
> > >> String username=message.substring(0,message.indexOf(','));
> > >> String password=message.substring(message.indexOf(',')
> > >> +1,message.length());
> > >> String returnString=nativeCode.validatePassword(username,
> > >> password);
> > >> CompressedMessage
> > >> replyMessage=compression.Compress(returnString);
> > >> return replyMessage;
> > >> }
> > >> }
>
> > >> Again, thanks for your help. Any other suggestions would be welcome.
> > >> Best, Darin
>
> > >> All the above has to run on the server (because it uses classes defined
> > >> in
> > > SolverLibrary). You'll want to modify the above to handle requests from
> > > your
> > > client for solver library routines. The code you've posted so far will
> > > only
> > > run as Javascript on the client when SolverLibrary exists as Javascript;
> > > which condition is not true. The above code will run (as Java) on the
> > > client
> > > in Hosted mode (because SolverLibrary will be loaded by the Java run-time
> > > in
> > > Hosted mode); which is no good for what you want in the Long Run.
>
> > > On Nov 3, 7:27 am, Jeff Chimene <[email protected]> wrote:
> > >> > Darin:
>
> > >> > There is one other possibility. You mention that you "... tested the
> > >> > compiled code (including the native
> > >> > code) inside the Mozilla browser and it also runs as it should."
>
> > >> > What's happening is that the Java run-time is able to load and run your
> > >> > library in hosted mode. But, that doesn't mean that you can compile
> > >> > this
> > >> > library to Javascript. Try putting the library into the classpath,
> > >> modify
> > >> > your code to instantiate whatever classes you need, and compile (rather
> > >> than
> > >> > run in hosted mode). You cannot use LoadLibrary on the client side:
> > >> there is
> > >> > no Java runtime.
>
> > >> > On Mon, Nov 2, 2009 at 4:37 PM, Darin <[email protected]> wrote:
>
> > >> > > Hello.
>
> > >> > > I have written a GWT project that uses native code. The class that
> > >> > > calls the code looks like this:
>
> > >> > > public class NativeCodeClass {
> > >> > > static {
> > >> > > System.loadLibrary("SolverLibrary");
> > >> > > }
> > >> > > public native String validatePassword(String username, String
> > >> > > password);
> > >> > > }
>
> > >> > > When I compile and run this inside of Eclipse (hosted mode), the
> > >> > > native code runs (assuming that I uncheck the "Use Google App
> > >> > > Engine")
> > >> > > just fine. I have also tested the compiled code (including the native
> > >> > > code) inside the Mozilla browser and it also runs as it should.
> > >> > > Unfortunately, when I deploy my code to the server, the Javascript
> > >> > > does not seem to be able to find my native library (SolverLibrary)
> > >> > > even though the Javascript is definitely working. I have tried
> > >> > > copying
> > >> > > the library to every conceivable location that I could think of but
> > >> > > have thus far failed. I am running Windows XP and using Apache as my
> > >> > > http server. Any ideas for where I should put the native library so
> > >> > > that the Javascript can find it?
>
> > >> > > Disclaimer: I am a definite newbie with GWT and amathematicianby
> > >> > > trade. If I am doing something outrageously stupid, I apologize for
> > >> > > wasting everyone's time, but please let me know what I'm doing wrong
> > >> > > so that I don't wind up smashing my computer and scaring my son.
> > >> > > Thanks, Darin
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