In case someone is interested, I found out how to solve my problem.
The solution was to create a web dynamic project in eclipse and to initialize the knowledge base in a servlet. Then I created a web service in this project and sent the external event in the exposed method. I exported my project as a .war file using eclipse and put it into the webapps folder of my Tomcat installation.
I'm not sure that this architecture is pertinent and it would be interesting to discuss but at least it works.