Apache Tomcat is an open source web servlet container and JSP Java EE
Axelor recommends using the Tomcat application server 7+ available here .
Download Core distribution for your operating system. Then just unzip the archive into an appropriate directory.
Example:
$ wget http://mir2.ovh.net/ftp.apache.org/dist/tomcat/tomcat-7/v7.0.50/bin/apache-tomcat-7.0.50.tar.gz
$ tar -xzf apache-tomcat-7.0.50.tar.gz
$ mv apache-tomcat-7.0.50 <path.to.tomcat>/tomcat
<Path.to.tomcat> is a directory that will contain the sources of Tomcat. It must have previously been created.