Does someone know how for example tomcat is able to check or retrieve xml schemas defined in the configuration? I mean, the tomcat configuration and other configuration for other products says to to try to find it on the internet and obviously there is no internet access on a server (for access out).

Take this for example from a message queue product:

<beans
xmlns="http://www.springframework.org/schema/beans"
xmlns:amq="http://activemq.apache.org/schema/core"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans

How will this message queue product be able to check the schema definitions to see if the xml document contains valid tags when it says that the xmlns is at a site on the internet and the server dont have access to that site, is the schema bundled with the product in some way, and if it is, how does the product know where to look for the schema definitions ?

Edit: Just saw this one http://stackoverflow.com/questions/1...ace-attributes, but it still doesnt explain how the tomcat or other configurations are able to verify which tags are valid, i mean, how does for example tomcat know where the schema definitions are defined?

Edit2: This http://stackoverflow.com/questions/5...schemalocation, is conflicting with what i just wrote above it seems

It depends on XML parser if it validate with schema and how to react on invalid data. I don't known about your sample, but it is possible that application which use xml data ignore schema and use other build-in simple validation during data retrieval.