Sharing sqljdbc_auth.dll among multiple war files in Tomcat server running at the same time

Question

Following is my use-case:

I have started using Camunda Platform and am accessing the Camunda process engine using a Custom Application written in java. So basically there are 2 applications or war files in Tomcat server. Initially I was using the inbuilt h2 database for the Camunda application and SQL server database for my Custom Application and was using integrated authentication mechanism which worked perfectly fine. Now I have replicated the h2 database to SQL server database and am again using integrated authentication for the process engine to connect to SQL Server.

Problem: After deploying the 2 wars, when I restart the Tomcat server, the sqljdbc_auth.dll present in the tomcat bin folder gets loaded successfully by the Camunda application and process engine successfully accepts requests, accesses the database and gives correct responses on the Camunda Web applications(Cockpit,Tasklist,Admin) but when I try to login on my Custom application then I get the following error: " null.null Failed to load the sqljdbc_auth.dll cause : Native Library C:\Users\Aakanksha\Desktop\BACKUP\$CAMUNDA_HOME\server\apache-tomcat-8.0.24\bin\sqljdbc_auth.dll already loaded in another classloader "

I do understand why this is happening and have followed the following solutions already:

Sol.1 -

1. Added the sqljdbc4.jar file to $TOMCAT_HOME/lib folder

2. Added the sqljdbc_auth.dll file to $TOMCAT_HOME/bin folder

Sol.2 - Added sqljdbc4.jar and sqljdbc_auth.dll file to separate war files i.e. WEBINF/lib folders.

Sol.3 -

1. Removed the dll file from $TOMCAT_HOME/bin folder and added the same to Windows/System32

2. Added this path to the PATH Environment variable

Sol.4 - Added the dll file to Java/JDK/bin folder.

Sol.1, Sol.3 and Sol.4 - The dll files was loaded and used successfully by one war but not the other with the same error. Sol.2 - lead to error " com.microsoft.sqlserver.jdbc.AuthenticationJNI. Failed to load the sqljdbc_auth.dll cause : no sqljdbc_auth in java.library.path "

Both of my applications are running at the same time and have different SQL Server databases to make connections to. Is it even possible for 2 wars running at the same instant to use a shared dll for making connection to different databases?

Kindly share your suggestions and ideas.

Answer 1

I was having the same issue. We changed our war files to use jndi lookups from tomcat configuration. That works great we now can deploy multiple war files.

For more information see

http://www.baeldung.com/spring-persistence-jpa-jndi-datasource

Johan