JNI and multithreading

Hello all
We have developed a Java application that invokes C functions of a third-party
vendor via JNI.
One of the clients of our application is a servlet that invokes our
application in a multithreaded manner. We instantiate the JNI
in the init() method of the servlet, and the functions of our application
are invoked in the doPost() method.
The software from the third-party software expects requests in a multithreaded
manner from the C application, but it reports an error, stating that it received
requests from a single-threaded application.
Is this due to the JNI compoenent?
Is there a way of creating C threads from Java?
We need to maintain a one-to-one mapping between the C and Java threads.
Thanks in advance
Kind regards

The software from the third-party software expects
requests in a multithreaded
manner from the C application, but it reports an
error, stating that it received
requests from a single-threaded application.Do you have multiple versions of the external library for single and multi-threaded? Maybe you are simply linking the wrong one.
Is this due to the JNI compoenent?Possibly. If the Java thread model does not match the underlying thread model, you might have this sort of problem.
Is there a way of creating C threads from Java?
We need to maintain a one-to-one mapping between the C
and Java threads.This depends what the underlying thread model of the VM is. If the VM uses native threads, then each Java thread uses exactly one C thread (and the VM may use additional C threads). If the VM uses "green" threads, then all Java threads map to a single C thread. Native threads are the only option on Windows, but green threads were the default on Unix platforms until recently. (I do not remember exactly when Solaris and Linux switched to native threads; I think 1.2 for Linux and 1.3 for Solaris). HP/UX and other "unofficial" platforms may still be using green threads, in which case you have a problem. You would have to control all access to the native library with synchronization.

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JNIEXPORT jobject JNICALL Java_CustomerInfo_nGetCustomerAccountInfo(JNIEnv *env, jobject customerInfo, jstring accountNumber, jstring iniFileName)
jboolean isCopy;
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jobject accountInfoObj = NULL;
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jmethodID ctorID = NULL;
// Pointer to the interface for the ClsAccount COM object
_clsAccount *pClsAccount = NULL;
HRESULT hr;
BSTR bstrIniFileName(L"");
try
const char *nativeAccountNumber = NULL;
if (accountNumber != NULL)
nativeAccountNumber = env->GetStringUTFChars(accountNumber, &isCopy);
else
jclass newExcCls;
env->ExceptionDescribe();
env->ExceptionClear();
newExcCls = env->FindClass("java/lang/IllegalArgumentException");
env->ThrowNew(newExcCls, "accountNumber passed in was null !");
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// Initialization
variantt varConnectionSucceeded = variantt(false);
variantt varGetAccountInfoSucceeded = variantt(false);
variantt varAccountNumber = variantt(nativeAccountNumber);
bstrt bstrLastPaymentDate = bstrt();
bstrt bstrLastErrorMessage = bstrt();
bstrt bstrLastErrorNumber = bstrt();
jlong jTotalDue = NULL;
jlong jEstablishedDueDay = NULL;
jlong jLastPaymentAmount = NULL;
jstring jLastPaymentDate = NULL;
jstring jLastErrorMessage = NULL;
jstring jLastErrorNumber = NULL;
jthrowable jException = NULL;
const char *chLastPaymentDate = NULL;
const char *chLastErrorMessage = NULL;
const char *chLastErrorNumber = NULL;
long long totalDue;
long long lastPaymentAmount;
long establishedDueDateDay;
//Convert string from Java string to C string to VB string
const char *nativeIniFileName = NULL;
if (iniFileName != NULL)
nativeIniFileName = env->GetStringUTFChars(iniFileName, &isCopy);
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jclass newExcCls;
env->ExceptionDescribe();
env->ExceptionClear();
newExcCls = env->FindClass("java/lang/IllegalArgumentException");
env->ThrowNew(newExcCls, "iniFileName passed in was null");
return NULL;
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if (hr == S_OK)
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jLastErrorNumber = env->NewStringUTF(chLastErrorNumber);
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delete[] chLastErrorNumber;
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// Find the Java class and the ID of its constructor
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ctorID = env->GetMethodID(accountInfoCls, "<init>", "(JJJLjava/lang/String;Ljava/lang/String;Ljava/lang/String;)V");
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CoUninitialize();
　
catch (_com_error &e)
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pClsAccount->Release();
catch (...)
pClsAccount->Release();
return accountInfoObj;
Edited by: Cthulhu76 on Jan 5, 2010 9:18 AM

0x49202400 JavaThread "ContainerBackgroundProcessor[StandardEngine[Catalina]]" daemon [_thread_blocked, id=5340, stack(0x49bf0000,0x49c40000)]
0x48a7e800 JavaThread "Thread-1" [_thread_in_native, id=5976, stack(0x48f00000,0x48f50000)]
0x48a0dc00 JavaThread "Low Memory Detector" daemon [_thread_blocked, id=3072, stack(0x48c60000,0x48cb0000)]
0x48a09000 JavaThread "CompilerThread0" daemon [_thread_blocked, id=4988, stack(0x48c10000,0x48c60000)]
0x48a07c00 JavaThread "Attach Listener" daemon [_thread_blocked, id=3124, stack(0x48bc0000,0x48c10000)]
0x48a07000 JavaThread "Signal Dispatcher" daemon [_thread_blocked, id=2572, stack(0x48b70000,0x48bc0000)]
0x489f5c00 JavaThread "Finalizer" daemon [_thread_blocked, id=5752, stack(0x48b20000,0x48b70000)]
0x489f4c00 JavaThread "Reference Handler" daemon [_thread_blocked, id=2596, stack(0x48ad0000,0x48b20000)]
0x003c6000 JavaThread "main" [_thread_in_native, id=4252, stack(0x00820000,0x00870000)]
Other Threads:
0x489f0400 VMThread [stack: 0x48a80000,0x48ad0000] [id=5624]
0x48a18800 WatcherThread [stack: 0x48cb0000,0x48d00000] [id=1192]
VM state:not at safepoint (normal execution)
VM Mutex/Monitor currently owned by a thread: None
Heap
def new generation total 36288K, used 12762K [0x02940000, 0x050a0000, 0x07800000)
eden space 32256K, 34% used [0x02940000, 0x0343af58, 0x048c0000)
from space 4032K, 37% used [0x04cb0000, 0x04e2ba28, 0x050a0000)
to space 4032K, 0% used [0x048c0000, 0x048c0000, 0x04cb0000)
tenured generation total 483968K, used 7518K [0x07800000, 0x250a0000, 0x42940000)
the space 483968K, 1% used [0x07800000, 0x07f57958, 0x07f57a00, 0x250a0000)
compacting perm gen total 14080K, used 14016K [0x42940000, 0x43700000, 0x46940000)
the space 14080K, 99% used [0x42940000, 0x436f0320, 0x436f0400, 0x43700000)
No shared spaces configured.
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0x76b70000 - 0x76b7b000      C:\WINDOWS\system32\PSAPI.DLL
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0x4a6a0000 - 0x4a6ac000      C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\MMI\WEB-INF\lib\CustomerInfoProxy.dll
0x77670000 - 0x777a9000      C:\WINDOWS\system32\ole32.dll
0x77d00000 - 0x77d8b000      C:\WINDOWS\system32\OLEAUT32.dll
0x7c420000 - 0x7c4a7000      C:\WINDOWS\WinSxS\x86_Microsoft.VC80.CRT_1fc8b3b9a1e18e3b_8.0.50727.4053_x-ww_E6967989\MSVCP80.dll
0x78130000 - 0x781cb000      C:\WINDOWS\WinSxS\x86_Microsoft.VC80.CRT_1fc8b3b9a1e18e3b_8.0.50727.4053_x-ww_E6967989\MSVCR80.dll
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0x4bc50000 - 0x4bc6c000      C:\WINDOWS\system32\DBNETLIB.DLL
0x71f60000 - 0x71f64000      C:\WINDOWS\system32\security.dll
0x76c90000 - 0x76cb7000      C:\WINDOWS\system32\msv1_0.dll
0x76cf0000 - 0x76d0a000      C:\WINDOWS\system32\iphlpapi.dll
0x761b0000 - 0x76243000      C:\WINDOWS\system32\crypt32.dll
0x76190000 - 0x761a2000      C:\WINDOWS\system32\MSASN1.dll
0x4bcf0000 - 0x4bcff000      C:\Program Files\Common Files\System\Ole DB\SQLOLEDB.RLL
0x4a8a0000 - 0x4a8aa000      C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\MMI\WEB-INF\lib\MIGI.DLL
0x73570000 - 0x736c2000      C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\MMI\WEB-INF\lib\MSVBVM60.DLL
0x4a950000 - 0x4a9e2000      C:\Program Files\Common Files\System\ado\msado15.dll
0x74a50000 - 0x74a6a000      C:\WINDOWS\system32\MSDART.DLL
0x4c850000 - 0x4c8c9000      C:\Program Files\Common Files\System\Ole DB\oledb32.dll
0x4dbb0000 - 0x4dbc1000      C:\Program Files\Common Files\System\Ole DB\OLEDB32R.DLL
VM Arguments:
jvm_args: -Dcatalina.home=C:\Program Files\Apache Software Foundation\Tomcat 5.5 -Dcatalina.base=C:\Program Files\Apache Software Foundation\Tomcat 5.5 -Djava.endorsed.dirs=C:\Program Files\Apache Software Foundation\Tomcat 5.5\common\endorsed -Djava.io.tmpdir=C:\Program Files\Apache Software Foundation\Tomcat 5.5\temp -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djava.util.logging.config.file=C:\Program Files\Apache Software Foundation\Tomcat 5.5\conf\logging.properties -Djava.library.path=C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\MMI\WEB-INF\lib vfprintf -Xms512m -Xmx1024m
java_command: <unknown>
Launcher Type: generic
Environment Variables:
JAVA_HOME=C:\Program Files\Java\jdk1.6.0_07
[error occurred during error reporting (printing environment variables), id 0xc0000005]
--------------- S Y S T E M ---------------
OS: Windows Server 2003 family Build 3790 Service Pack 2
CPU:total 4 (4 cores per cpu, 1 threads per core) family 6 model 7 stepping 6, cmov, cx8, fxsr, mmx, sse, sse2, sse3, ssse3
Memory: 4k page, physical 2097151k(2097151k free), swap 4194303k(4194303k free)
vm_info: Java HotSpot(TM) Client VM (10.0-b23) for windows-x86 JRE (1.6.0_07-b06), built on Jun 10 2008 01:14:11 by "java_re" with MS VC++ 7.1
time: Mon Dec 28 15:24:00 2009
elapsed time: 600 seconds

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a)User goes to Login.jsp, enters user and password
b) User submits to LoginServlet
c) login calls JNI code that connects to a powerbuilder(Yes I know this is ugly) PBNI code module (this is a .dll) that authenticates the user with the database
d) the servlet then redirects to another .jsp page
e) user then submits to LogoutServlet - also a JNI call to a powerbuilder PBNI code module
f) REPEAT STEPS a-e over a few times (inconsistent) and then the call to the JNI code hangs
2)
a) users does NOT goto Login.jsp, but rather calls LoginServlet and passes the userid and password as GET parms
b) user does NOT get redirected to a page (redirect code commented out)
c) user calls LogoutServlet
d) repeat steps a-c at will and no failure, no hanging
The only difference is that in case 1 (with JSP), there is a redirect and it afffected the JNI call by haniging inside JNI code.
In case 2 (without JSP) there is still a JNI call, but it does not hang. In addition, when it hangs and I stop Tomcat, the logs show cleanup entries that say:
Oct 19, 2004 9:17:09 AM org.apache.catalina.core.StandardWrapper unload
INFO: Waiting for 1 instance(s) to be deallocated
Oct 19, 2004 9:17:10 AM org.apache.catalina.core.StandardWrapper unload
INFO: Waiting for 1 instance(s) to be deallocated
Oct 19, 2004 9:17:11 AM org.apache.catalina.core.StandardWrapper unload
INFO: Waiting for 1 instance(s) to be deallocated
Is this a threading issue in Tomcat???
On would assume that the JNI code is not cleaning up after itself, but I don't believe this is the case,
and even if it was, why would I get the tomcat log cleanup entries above???
What do those cleanup entries imply about the state of Tomcat????

hi ,
I met the same problem this morning, and searched the www.google.com in order to solve it, as a result, your article was shown on my screen. :)
Till now I have read some technical information and solved my problems. Maybe the solution be useful to you:
==============================
error message : (Environment : Tomcat 5, Windows 2003, Mysql5)
2006-3-29 11:53:48 org.apache.catalina.core.StandardWrapper unload
message: Waiting for 2 instance(s) to be deallocated
==============================
cause: the number of connection to database exceeded.another word,too many connections.
==============================
solution: close the connection when it becomes useless for your program. :)
==============================
ps. Sorry for my weak English . hehe ....

Problem with JNI and Parallel Port dll

Hi. I'm doing some testes with JNI. Firs i followed the netbeans tutorial for doing a C programa that prints somthing for java.. like.. "Hello java from C".
So i tried to load a dll from my dll. Like, I have this dll to use the parallel port on windows Xp. So i created a dll to access it an comunicates eoth java.
I did everything just fine.
When I start my Java app, the first thing it does is to load this parallel port dll and configure the functions of it.
After that .. I get this error
EXCEPTION_FLT_STACK_CHECK (0xc0000092) at pc=0x0093d269, pid=2284, tid=3000
Can someone explain why ?
(Sorry if i wasn't clear enough, english is not my native language, so ask if you don't understand something.. )

hi ,
I met the same problem this morning, and searched the www.google.com in order to solve it, as a result, your article was shown on my screen. :)
Till now I have read some technical information and solved my problems. Maybe the solution be useful to you:
==============================
error message : (Environment : Tomcat 5, Windows 2003, Mysql5)
2006-3-29 11:53:48 org.apache.catalina.core.StandardWrapper unload
message: Waiting for 2 instance(s) to be deallocated
==============================
cause: the number of connection to database exceeded.another word,too many connections.
==============================
solution: close the connection when it becomes useless for your program. :)
==============================
ps. Sorry for my weak English . hehe ....

Problem with JNI and Tomcat in windows

Hello guys...
I have the following problem.
I used Tomcat 4 and I have following ApiEncriptacion class, in package com.servipag.sts;
package com.servipag.sts;
class ApiEncriptacion
     public native String encripta(String texto, String ubicacionLlavePublica, String semilla);
     static
          System.loadLibrary("apisdark");
     public native String desencripta(String texto, String ubicacionLlavePrivada);
     static
          System.loadLibrary("apisdark");
the LD_LIBRARY_PATH is set in following dir c:\tomcat\bice
the dll this in the following path = c:\tomcat\bice\apisdark.dll
I run Tomcat at the following way..
C:\jdk1.4\bin\java.exe -jar -Djava.library.path="c:\tomcat\bice" -Duser.dir="C:\Tomcat" "C:\Tomcat\bin\bootstrap.jar" start
but, still appear the error:
java.lang.UnsatisfiedLinkError: encripta
     at com.servipag.sts.ApiEncriptacion.encripta(Native Method)
     at com.servipag.sts.ServiciosServiPagImpl.rescatarFirma(ServiciosServiPagImpl.java:2143)
     at com.servipag.sts.ServiciosServiPagImpl.pagarCuenta(ServiciosServiPagImpl.java:310)
     at org.apache.jsp.SBCO_0005flogin_0005fbice_0005f4$jsp._jspService(SBCO_0005flogin_0005fbice_0005f4$jsp.java:265)
     at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:107)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
     at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:201)
     at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:381)
     at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:473)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:243)
     at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
     at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:190)
     at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
     at org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve.java:246)
     at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
     at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
     at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2343)
     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
     at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
     at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170)
     at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
     at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:170)
     at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
     at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:468)
     at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
     at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
     at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
     at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
     at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:1012)
     at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:1107)
     at java.lang.Thread.run(Thread.java:536)
please help me
Luis Navarro.
Chile

ApiEncripatcion.h
/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class ApiEncriptacion */
#ifndef IncludedApiEncriptacion
#define IncludedApiEncriptacion
#ifdef __cplusplus
extern "C" {
#endif
* Class: ApiEncriptacion
* Method: encripta
* Signature: (Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;
JNIEXPORT jstring JNICALL Java_ApiEncriptacion_encripta
(JNIEnv *, jobject, jstring, jstring, jstring);
* Class: ApiEncriptacion
* Method: desencripta
* Signature: (Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;
JNIEXPORT jstring JNICALL Java_ApiEncriptacion_desencripta
(JNIEnv *, jobject, jstring, jstring);
#ifdef __cplusplus
#endif
#endif
ApiEncriptacion.c
#include "jni.h"
#include <stdio.h>
#include "files.h"
#include "hex.h"
#include "rsa.h"
#include "randpool.h"
USING_NAMESPACE(CryptoPP)
USING_NAMESPACE(std)
void GenerateRSAKey(unsigned int keyLength, const char privFilename, const char pubFilename, const char *seed);
char RSAEncryptString(const char pubFilename, const char seed, const char message);
char RSADecryptString(const char privFilename, const char *ciphertext);
JNIEXPORT jstring JNICALL
Java_ApiEncriptacion_encripta(JNIEnv *env, jobject obj, jstring texto, jstring ubicacionLlavePublica, jstring semilla)
     try
          char *ciphertext = RSAEncryptString(ubicacionLlavePublica, semilla, texto);
          delete [] ciphertext;
          return(ciphertext);
     catch(CryptoPP::Exception &e)
          return ("");
     catch(std::exception &e)
          return ("");
     catch(...)
          return ("");
JNIEXPORT jstring JNICALL
Java_ApiEncriptacion_desencripta(JNIEnv *env, jobject obj, jstring texto, jstring ubicacionLlavePrivada)
     try
          char *decrypted = RSADecryptString(ubicacionLlavePrivada, texto);
          return(decrypted);
     catch(CryptoPP::Exception &e)
          return ("");
     catch(std::exception &e)
          return ("");
     catch(...)
          return ("");
int main()
     return(0);
void GenerateRSAKey(unsigned int keyLength, const char privFilename, const char pubFilename, const char *seed)
     RandomPool randPool;
     randPool.Put((byte *)seed, strlen(seed));
     RSAES_OAEP_SHA_Decryptor priv(randPool, keyLength);
     HexEncoder privFile(new FileSink(privFilename));
     priv.DEREncode(privFile);
     privFile.MessageEnd();
     RSAES_OAEP_SHA_Encryptor pub(priv);
     HexEncoder pubFile(new FileSink(pubFilename));
     pub.DEREncode(pubFile);
     pubFile.MessageEnd();
char RSAEncryptString(const char pubFilename, const char seed, const char message)
     FileSource pubFile(pubFilename, true, new HexDecoder);
     RSAES_OAEP_SHA_Encryptor pub(pubFile);
     if (strlen(message) > pub.MaxPlainTextLength())
          cerr << "message too long for this key\n";
          abort();
     RandomPool randPool;
     randPool.Put((byte *)seed, strlen(seed));
     char outstr = new char[2pub.CipherTextLength()+1];
     pub.Encrypt(randPool, (byte *)message, strlen(message), (byte *)outstr);
     HexEncoder hexEncoder;
     hexEncoder.Put((byte *)outstr, pub.CipherTextLength());
     hexEncoder.MessageEnd();
     hexEncoder.Get((byte *)outstr, 2*pub.CipherTextLength());
     outstr[2*pub.CipherTextLength()] = 0;
     return outstr;
char RSADecryptString(const char privFilename, const char *ciphertext)
     FileSource privFile(privFilename, true, new HexDecoder);
     RSAES_OAEP_SHA_Decryptor priv(privFile);
     HexDecoder hexDecoder;
     hexDecoder.Put((byte *)ciphertext, strlen(ciphertext));
     hexDecoder.MessageEnd();
     SecByteBlock buf(priv.CipherTextLength());
     hexDecoder.Get(buf, priv.CipherTextLength());
     char *outstr = new char[priv.MaxPlainTextLength()+1];
     unsigned messageLength = priv.Decrypt(buf, (byte *)outstr);
     outstr[messageLength] = 0;
     return outstr;

JNI and Tomcat running on Linux

Hi all!
I have a small problem with calling a native library from my Tomcat running on a linux.
The code is simple enough
System.loadLibrary(myLibrary);I know that when libmyLibrary.so isn't in the java.library.path I get an error at this line. When it is in the path it goes past this line with out problems but on the next line
myFunction(); that is a function within myLibrary i get something like
java.lang.UnsatisfiedLinkError: myFunction()The thing is. This exact code when either executed in a standalone java application or from a Tomcat running on windows works with out problem. Tomcat on linux doesn't.
myLibrary uses other libraries on a different path and my guess is that tomcat for some reason won't allow access to those. The security manager however doesn't give me any errors, nor does tomcat itself other than the UnsatisfiedLinkError.
Anyone running Tomcat on linux and using native libraries or perhaps just knows alot about this?
Please help. Thanks!

Are you sure you are not running into a class loader issue? Does this occur the very first LoadLibrary call or after the first successfull call?
It could be that your JNI or bridge has already been loaded by another class loader in the tomcat class loader hierarchy and this would result in the UnsatisfiedLinkError.
Check out: http://www.onjava.com/pub/a/onjava/2004/06/30/classloader2.html

JNI and Oracle 9i

HI !!!! Please, is there anybody outthere ?
We have a problem about using a packege that use a dll to cript-decprit data and java store procedure. We need to put in db oracle 9i the function to cript and decript data.So we need to use this. But using a dll with loadlibrary in oracle java store procedure seems impossibile!!!
Please,can you help us ?
Is there anybody whi have an idea ?
thank's,
andrea

Hi.
No, it isn't possibile ! IOracle don't let us to load library with JNI, jaust to avoid to waste db file or other. It seems a security policy of oracle itself, that limitate JVM.
But, it's incredible, we could use .dll ora c or c++ file in db, if we choose to not use java!! But, the package to manage security in our enterprise application is of the third part, not ours. So, how can we use a .jar library to cript and decript data in oracle ? Note that, we had this cripta and decripta under WLS, but we nedd to process one hundred thousand of data per day !! And http connection,...collapse we timeout problem....we want to put in java store procedure....or other, please! Help us!!!
thanks!
andrea

JNI and Websphere 3.5

Hi there,
I have an application that makes use of JNI technology.
Basically, so as to work, the app must access a C++ DLL library via JNI, that in my case is a set of classes packaged in a jar file.
The app works just fine when is run locally, but I?m really in trouble to set up WebSphere properly so that I can web access the app with servlet and jsp.
I haven?t been succesful getting consistent info anywhere.
Could anybody give me detailed instructions on how to do that?
IBM instructions lack further details, they just don?t help, they?re made for experts!
Thanks!

I have solved the previous problem, and fallen into another.
Now this is quite a wierd one. Basically, as the servlet is run from the browser, the servlet calls the business classes. The business classes use other java classes that have native methods to call a DLL library.
A have put the JNI java classes in the websphere class path, not in the web app classpath, as descrived in the IBM redbooks, and I also created the 'path' variable from the web project in WebSphere in reference to the DLL.
When I go to the browser and call the servlet, the app works, once I get all the info on the jsp that came from the DLL. Now, if any other call is done through the web browser, the dll is no more instantiated!
Neither from the same machine nor from anywhere else!
Has anybody ever seen such a thing?
I just don?t know what else to do, and have not found any more instructions.
Please, any info on it is very much welcome.
Thanks a lot.

JNI and J2ME

Hello all. These days i've been asked to make a little aplication for a PDA and while looking for information about j2me it says jni its not supported. But the app i need to make needs to use some library written in C, and my question is if there is any way o making an application in j2me that can use those libraries.
Thanks all.

Yes i've found a compiler for my target platform and compiling and running the C libraries doesnt seem a problem at the time. My main problem is that I can't call them from my java application because jni is not supported and i dont know how to import them.
Thanks for your answer
Message was edited by:
trospito

JNI and multithreading

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