> Each JAR / WAR is a self-contained application that can run anywhere where there's a JVM (which is pretty much everywhere).
Jar could be self contained or it could depend on 100s of other jars so it is not as straightforward as one assume.
War required a Java application containers to be deployed which is outside a War not inside. Also J2EE deployments can get pretty complicated with its infamous XML usage for configuring anything.
JVM is not everywhere by default or work without config by default for non trivial application. It is complex software which can lead to myriad classpath/ version issues related to jar files if not installed very carefully.
Containers are like that as well. You can have a container for your application, that doesn't really do anything unless you can connect to your database which runs in another container.
Jar could be self contained or it could depend on 100s of other jars so it is not as straightforward as one assume.
War required a Java application containers to be deployed which is outside a War not inside. Also J2EE deployments can get pretty complicated with its infamous XML usage for configuring anything.
JVM is not everywhere by default or work without config by default for non trivial application. It is complex software which can lead to myriad classpath/ version issues related to jar files if not installed very carefully.