Hello again, everyone.
Tomcat is now installed and running. Unfortunately, I am getting
exactly the same behavior as before. The code to process the returned
value on the client is as follows:
securityService.validatePassword(message, new
AsyncCallback<CompressedMessage>(){
@Override
public void onFailure(Throwable caught) {
displayErrorBox("Server error","Unable to
contact the server.");
return;
}
@Override
public void onSuccess(CompressedMessage result) {
String
replyString=compression.Decompress(result);
and so on...
I am getting the top error box every time: "Unable to contact the
server".Technically, Tomcat is not throwing an error; it just can't
seem to process the RPC. This is the same behavior that it was
exhibiting before when I was using the C version of the Apache server.
With respect to jhulford's suggestion: I changed the java.library.path
in Tomcat using the command
-Djava.library.path=C:\Program Files\Apache Software Foundation\Tomcat
6.0\webapps\ROOT
Then I stopped and restarted the Tomcat service and got exactly the
same behavior. (That was depressing because I really thought that was
going to work.) And I'm out of ideas again... Anything else I should
try?
Best, Darin
On Nov 4, 1:17 pm, Darin <[email protected]> wrote:
> Hi, guys. Thanks again everyone for your help. (Sorry if the thanking
> gets repetitive, but I've seen so many impatient and ungrateful
> nimrods on forum pages like these that I'd prefer to be overly polite
> than seem unappreciative.)
>
> From your responses, I believe that I may have a solution to the
> problem. The Apache server that I downloaded was the C version of the
> server which, it appears, does not support Java at all. When I
> download and install Tomcat, hopefully one issue will go away.
> However, there is the other issue that the Java is calling native code
> from a directory that the Java environment will not be aware of. This
> may be slightly harder to remedy, but if I understand "jhulford"
> correctly, it is possible to determine what the java.library.path is
> and place the C/C++ dll there. I will research this and get back to
> everyone with the results.
>
> Best, Darin
>
> On Nov 4, 6:39 am, Jeff Chimene <[email protected]> wrote:
>
> > On Wed, Nov 4, 2009 at 7:03 AM, Darin <[email protected]> wrote:
>
> > > Hi, Adrian and Jeff.
>
> > > Thanks again for the help from both of you. I greatly appreciate it.
>
> > No prob.
>
> > I'm still looking for two answers:
> > 1. What error are you getting when running using Apache?
> > 2. What Java server are you using outside development mode? Apache doesn't
> > support Java. When in development mode, you're using Tomcat. Even when
> > compiling and running, you're still (probably) using Tomcat (unless you're
> > using -noserver, and it doesn't sound like you are).
>
> > > I have two files in the server. One of them is SecurityServiceImpl and
> > > the code looks like this (skipping the includes, etc.):
> > > 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;
> > > }
> > > }
> > > The other file is called NativeCodeClass and the code looks like this:
> > > public class NativeCodeClass {
> > > static {
> > > System.loadLibrary("SolverLibrary");
> > > }
> > > public native String validatePassword(String username, String
> > > password);
> > > }
>
> > > I have doublechecked that both of these files are definitely in the
> > > server code (and these are the only files in the server code). When I
> > > run the code from within hosted mode, this code works (i.e. finds the
> > > SolverLibrary and checks the entered password, etc.). And (here comes
> > > the important part), when I compile it and run it from within the
> > > browser by pressing the Compile/Browse button from inside hosted mode,
> > > it works just fine as well inside Mozilla. It fails when I copy the
> > > directories to another place on the hard drive. Unless I am seriously
> > > confused (and I have to admit that this is a possibility), if the
> > > problem was one where the native code was executing inside of
> > > Javascript, it could not run correctly from inside the browser after
> > > the Compile/Browse step.
>
> > > It occurs to me that maybe my RPC calls to the server are not
> > > functioning correctly when I try to move the folders to somewhere else
> > > on the hard drive. Is there an obvious reason why that might happen?
> > > Thanks for all your help.
>
> > > Darin
>
> > > On Nov 4, 1:56 am, Adrian <[email protected]> wrote:
> > > > Hi guys,
>
> > > > I think Darin might not be up to speed with the differences between
> > > > server side and client side stuff and also how web environment differs
> > > > from the desktop environment. You might know this already but if not
> > > > it might clear a few things up.
>
> > > > When developing an application with GWT in Eclipse you need to be
> > > > aware of two distinct parts, the client side and the server
> > > > side.Eclipse should setup a couple packages for these parts when you
> > > > create a GWT project so you don't get confused. The client side is
> > > > compiled from java to javascript that is designed to run only in a
> > > > browser. That means the resulting javascript has all the limitations
> > > > enforced by the browser, which includes no way to run native code. So
> > > > GWT compiles the java in the client package to javascript, which is
> > > > run in the browser once the browser requests it from your webserver
> > > > (apache in this case). Because apache isn't a java application server
> > > > (like tomcat, jetty etc) it cannot directly run the server side java
> > > > (stuff in the server package).
>
> > > > Things get a little confusing when you're running in hosted mode
> > > > because a lot of fancy stuff is happening in the background so it
> > > > appears the java code you have written for the client is running
> > > > directly, it basically skips the compiling to javascript step and runs
> > > > the client code as java. Because java has the ability to run native
> > > > code it will appear to work, however once compiled to javascript it
> > > > wont because javascript doesn't have the functionality (mainly for
> > > > security reasons).
>
> > > > Also don't be fooled by javascript's name, it is a very different
> > > > language than java!
>
> > > > So, you can't run native code from javascript in a browser, but you
> > > > can run it from java on the server side. A possibly solution could be
> > > > to use GWT's Remote Procedure Calls to run the native code on the
> > > > server, then get the results sent to back to the client.
>
> > > > Hope that helps,
> > > > Adrian
>
> > > > On Nov 4, 1:25 pm, Jeff Chimene <[email protected]> wrote:
>
> > > > > On Tue, Nov 3, 2009 at 3:47 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)
>
> > > > > Yes
>
> > > > > > and I have manually
> > > > > > set the classpath to be the directory where the library resides.
> > > > > > Unfortunately, that still did not change anything.
>
> > > > > I didn't expect it would.
>
> > > > > > To the best of my knowledge, the server itself isn't supposed to run
> > > > > > the code.
>
> > > > > The code that you posted originally (the call to LoadLibrary) should
> > > only
> > > > > run on the server. It might also run on the client in hosted mode, but
> > > > > that's not what you want in the Long Run.
>
> > > > > 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.
>
> > > > > Correct, as long as you;re not trying to call LoadLibrary.
>
> > > > > The Javascript that is already
>
> > > > > > theoretically executing from within the browser is supposed to
> > > execute
> > > > > > the native code.
>
> > > > > I don't know what you mean by "native code". Do you mean the compiled
> > > C++
> > > > > code in SolverLibrary? If so. the browser will not execute that native
> > > code
> > > > > (at least not via GWT compiled Javascript)
>
> > > > > 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...
>
> > > > > I think we're back to the issue that Apache doesn't have a JRE, so
> > > > > it's
> > > not
> > > > > finding the code that calls LoadLibrary. I think that what's happening
> > > is
> > > > > that in hosted mode, you're using Tomcat, a Java server which will
> > > > > find
> > > and
> > > > > execute the code that calls LoadLibrary. When you move to GWT noserver
> > > mode,
> > > > > then you're using Apache.
>
> > > > > What is the error you get when you run the code using an Apache server
> > > > > instance?
>
> > > > > > 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
>
> ...
>
> read more »
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