Error while creating jvm in DLL

Thu Feb 7 09:39:00 GMT 2008

Hi,
I’ve written a custom odbc driver to execute some complex queries using
Tomcat Server.
MS ACCESS loads the dll (through system DSN) I created and links the table
to oracle using my odbc drier.
The problem:
Inside the dll I’m creating a jvm which talks to the tomcat server.
When I run a sample application locally it works just fine (in the sense,
the jvm gets created and connection to tomcat etc etc.)
But when I try to run it through ODBC bridge, the dll is not able to create
the JVM: 
It throws an exception : 
#
# An unexpected error has been detected by HotSpot Virtual Machine:
#
# EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x10004e86, pid=4184,
tid=4716
#
# Java VM: Java HotSpot(TM) Client VM (1.5.0-b64 mixed mode)
# Problematic frame:
# C [aces_odbc_driver.dll+0x4e86]
#
Stack: [0x00040000,0x00080000), sp=0x0007ecf0, free space=251k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native
code)
C [aces_odbc_driver.dll+0x4e86]
C [aces_odbc_driver.dll+0x1ad2d]
C [ODBC32.dll+0x9260]
C [ODBC32.dll+0x3004]
C [ODBC32.dll+0x2fbc]
C [ODBC32.dll+0x328f9]
C [JdbcOdbc.dll+0x4c6d]
j sun.jdbc.odbc.JdbcOdbc.driverConnect(J[B[B)V+0
j sun.jdbc.odbc.JdbcOdbc.SQLDriverConnect(JLjava/lang/String;)V+93
j 
sun.jdbc.odbc.JdbcOdbcConnection.initialize(Ljava/lang/String;Ljava/util/Properties;I)V+984
j 
sun.jdbc.odbc.JdbcOdbcDriver.connect(Ljava/lang/String;Ljava/util/Properties;)Ljava/sql/Connection;+129
j 
java.sql.DriverManager.getConnection(Ljava/lang/String;Ljava/util/Properties;Ljava/lang/ClassLoader;)Ljava/sql/Connection;+165
j 
java.sql.DriverManager.getConnection(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)Ljava/sql/Connection;+41
j SimpleSelect.main([Ljava/lang/String;)V+23
I’ was trying to use a simple java program to test the functionality. 
Here is the sample java code.
import java.net.URL;
import java.sql.*;
class SimpleSelect {
 public static void main (String args[]) {
 	String url = "jdbc:odbc:aptest";
 	String query = "SELECT * FROM emp";
 	try {
 		// Load the jdbc-odbc bridge driver
 		Class.forName ("sun.jdbc.odbc.JdbcOdbcDriver");
 		DriverManager.setLogStream(System.out);
 		// Attempt to connect to a driver. Each one
 		// of the registered drivers will be loaded until
 		// one is found that can process this URL
 		Connection con = DriverManager.getConnection (
 			url, "abc", "abc");
 		// If we were unable to connect, an exception
 		// would have been thrown. So, if we get here,
 		// we are successfully connected to the URL
<Here is the code in the myodbc dll for which the DSN is created>
typedef _JNI_IMPORT_OR_EXPORT_ jint (JNICALL *JNI_JVMPROC) (JavaVM **,void
**,void *);
	JNI_JVMPROC ProcAdd;
	if(env == NULL || jvm == NULL) 
	{
		options[0].optionString = "-Djava.class.path=”required path given for
jars”	
	//	options[1].optionString = "-verbose:jni";
		
		vm_args.version = JNI_VERSION_1_2;
		vm_args.options = options;
		vm_args.nOptions = 1;
		
		vm_args.ignoreUnrecognized = JNI_TRUE;
		
		//		JNI_GetDefaultJavaVMInitArgs(&vm_args);
		
 if (!getcwd(buffer, 512)) { /* returns null if path is too long */
 cout << "Path name is too long \n" ;
 }
 else {
 cout << "Current Working Directory is " << buffer;
 }
		cout << "\n\n**************Loading jvm.dll library****************\n\n";
		hinstLib = LoadLibrary("jvm.dll");
		if (hinstLib == NULL) 
		{
		cout << "\n\n**************Failed Loading jvm.dll
library****************\n\n";
		}
		ProcAdd = (JNI_JVMPROC) GetProcAddress(hinstLib, "JNI_CreateJavaVM"); 
		if(ProcAdd != NULL ) {
			cout << "------------Proc address got is : --------" << ProcAdd;
		}
		res = (ProcAdd) (&jvm,(void**)&env,&vm_args); 	
		//res = JNI_CreateJavaVM(&jvm,(void**)&env,&vm_args);
		cout <<res;
		if (res < 0) 
		{
			cerr<< "\n\n Can't create Java VM FROM Swapnil" << endl;
			if (env->ExceptionOccurred()) 
			{
				env->ExceptionDescribe();
				env->ExceptionClear();
			}
			cout<< "Destroying JVM" << endl;
			jvm->DestroyJavaVM();
		}
	}
I tried using the simple way of creating the jvm also but didn’t work out.
The same code works when I load the dll directly in a sample program 
I checked the path , environment variables as well. The only problem is jvm
is not created when I try to invoke it from dll through ODBC32.dll
Any help would be appreciated.
-----
Swapnil Kale  Think before you print
________________________________________
:working:
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