When you go over Corticon's User's Guide sooner or later you will notice that both Tomcat and JRE are bundled with the eServer installation. The choice is quite interesting but understandable - not everyone who go over the tutorial know Java or Tomcat. So for them it's a blessing that they don't have to mess up with installation of Java or Tomcat.
For others, who considers themselves seasoned Java/Web developers - just remember about this fact so that you don't get the conflicts in your environment.
One thing I still are not quite comfortable with - they use eServer and ccServer terms. I don't know yet what is what. I guess I'll figure it out when I do the further reading.