Hello
Just wanted to share my findings when trying to integrate NetXMS with Grafana.
Whatever I did I couldn't get a connection between them. The data source always gave an error stating "HTTP Error Internal Server Error"
If I tried to open the web service page (http://192.168.222.44:8080/websvc) directly it gave me a this error: {"description":"Internal error","error":46}
Just for the record, now that the issue is fixed, I still get the error 46 message if I try to connect directly.
I asked for help and Victor was kind enough to take a look at things for me.
First we tried the Curl trick posted at the bottom of this wiki page.
https://wiki.netxms.org/wiki/Web_service_API
The catalina.out file in Tomcat log folder showed that authentication was successful, so it wasn't a case of mistyped password or wrong user.
Then further down he saw something about missing javax classes.
Turns out that using Java 11 with Tomcat was the issue.
I removed Java 11 and installed Java 8 and the issue was resolved.
So, check if you are using a compatible Java version 
PS: Victor mentioned that it might work with Java 10 by adding --add-modules java.xml.bind to JVM command line
I hope this is helpful for others as well!
tfn
