ClassNotFoundException thrown in IKVM.Runtime.dll for JDBC

Hello,

I'm new to ChemAxon software and am modifying the JChemBaseSearch example found in the "JChem .NET API 5.3.8.9" directory. I made a few modifications to the code to use the installed JDBC drivers and our db connection parameters. I'm able to connect to our SQL Server database through the Microsoft JDBC SQL Server driver from the other Marvin and JChem applications but when I attempt to connect through the JChemBaseSearch .Net application I get a class not found error even through the path to the jdbc jar file is in the ClassPath environment variable.

I also attempted to initiate the load through this call

Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");

but got the following error.

"A first chance exception of type 'java.lang.ClassNotFoundException' occurred in IKVM.Runtime.dll"

Any guidance would be greatly appreciated.

Thanks,

Molly

Hello Molly,

Please see this example: http://www.chemaxon.com/dotNET/examples/jchem/JChemBaseSearch/DataAccess.cs.html

Unfortunately Class.forName() is not as simple in .NET as in Java, because of the strong named assemblies. Instead, we use something like this:

DriverManager.registerDriver(new com.microsoft.sqlserver.jdbc.SQLServerDriver());

Hope this helps,

Gabor Vasko

DriverManager.registerDriver(new com.microsoft.sqlserver.jdbc.SQLServerDriver());

Thanks, I tried that initially but I'm getting an error on the driver name at compile time saying the type or namespace is not recognized. Is there some other place to reference or register the driver? I have the full path to the sqljdbc.jar file in the CLASSPATH now.

Two possible solutions:

1/ Try to use JTDS driver which has already been provided with the installer (recommended).

2/ Try to convert the jar file with ikvmc.exe (Program Files/ChemAxon/JChem .NET API ... folder): ikvmc -out:sqljdbc.dll -target:library sqljdbc.jar

After that the dll should be referenced from your project.

We encountered some problems in the past using the MS driver, that is why we provide the JTDS driver.

Classpath: Jar files cannot be used from .NET wihtout the conversion.

Gabor Vasko

I was able to get option 2 to work using sqljdbc4.jar as the source. I had to remove and then add references to the existing IKVM assemblies to avoid a version conflict issue that occurred when I added the reference to the sqljdbc4.dll but everything works now. Thank you!

Thank you for your response.

Hello,

I downloaded the most recent .Net examples (JChem_NET_API_5_5_0_1510) and opened the JChemBaseSearch example. I added a reference to the jtds-1.2.2.dll but when I compile, I get the following error: Found conflicts between different versions of the same dependent assembly. (the details are copied in below.)

Note: Via JCMan.exe, I can connect to a SQL Server 2008 with the following driver connection string: com.microsoft.sqlserver.jdbc.SQLServerDriver.

However, when I try the jtds driver in Visual Studio or, if I use a sqljdbc4.dll generated using ikvmc.exe from the target library of the same driver jar file referenced in the jcman connection string above, I get a similar conflict error message.

Any suggestions would be much appreciated.

Thanks, Molly

*************************************************************************************************************

error CS1705: Assembly 'jtds-1.2.2, Version=5.5.0.1510, Culture=neutral, PublicKeyToken=d25ce09139c726a9' uses 'IKVM.OpenJDK.Core, Version=0.42.1.72, Culture=neutral, PublicKeyToken=d25ce09139c726a9' which has a higher version than referenced assembly 'IKVM.OpenJDK.Core, Version=0.42.1.42, Culture=neutral, PublicKeyToken=d25ce09139c726a9'

error CS1705: Assembly 'jtds-1.2.2, Version=5.5.0.1510, Culture=neutral, PublicKeyToken=d25ce09139c726a9' uses 'IKVM.OpenJDK.Jdbc, Version=0.42.1.72, Culture=neutral, PublicKeyToken=d25ce09139c726a9' which has a higher version than referenced assembly 'IKVM.OpenJDK.Jdbc, Version=0.42.1.42, Culture=neutral, PublicKeyToken=d25ce09139c726a9'

c:\WINDOWS\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets(1360,9): warning MSB3247: Found conflicts between different versions of the same dependent assembly.

Dear Molly,

next Monday is a bank Holiday, on Tuesday Gabor will take a look at the issue.

Viktor

Dear Molly,

Could you please check what versions of JChem .NET API are installed on your machine?

I suppose there are multiple installations, however, it should work.

Please try to remove and add all JChem .NET API assembly references.

Best regards,

Gabor Vasko

Hi Molly,

we could reproduce the problem, when having multiple versions of JChem .NET API present on the machine. Please also verify if the GAC contains any older versions.

1. Go to C:\Windows\assembly

2. Verify the following dlls:

IKVM.* should be 0.42.1.72

JChem should be 5.5.0.150

jtds-1.2.2 should be 5.5.0.1510

You can remove unnecessary versions, by right click uninstall.

We also look into the problem why it is trying to resolve a different version, than it has referenced, because as Gabor described it should work even with multiple versions installed.

Best regards,

Tamas.

Thanks for relaying this information. I'm out of the office this week but will remove previous versions of the ChemAxon .Net API when I return to the office on Monday.

Molly

I removed the previous versions of the .Net API and the example compiled and ran as expected. Thanks.