Out of the box, the session timeout is set to 20 minutes for the user login. Below is the procedure to increase the session timeout more than 20 minutes.
1. In the Business Objects Installation server, navigate to <INSTALL DIR>\Tomcat\webapps\BOE\WEB-INF
2. Take a backup and open web.xml file in a text editor.
3. Search for the "session-timeout". The default value is 20 minutes.
4. Change it to the required value and save the file.
5. Restart the Apache Tomcat for BI4 service.