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This work comes from a corporate environment where isolation, control and ease of upgrade with a fallback are very important. Also, allows for fast horizontal or vertical scaling where multiple Tomcat instances are run on the same machine. This is the fundation for understanding and moving towards cloud techniques such as Tomcat based
Also this also sets your application to moving towards cloud containor implementations like LXC or Docker.
The key concept here is that we setup Tomcat and Java as an isolated package. There is no install and you may take your package to another system just by using tar and then untaring provided you rely on the same serveradmin account with matching GUID's across systems.
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