What does a Servlet 3.0 compatible web-app declaration in web.xml do?
java, jetty, servlet-3.0, web-applications
Solution
You should be able to simply swap the schema declaration from 2.4 to 3.0.
Scientific method
Initially I set off to prove it by doing `diff` between 2.4 and 2.5 and another one comparing 2.5 and 3.0.
I have convinced myself that the differences between 2.4 and 2.5 are only additive and the name space have shifted from `j2ee` to `javaee`.
However xsd schema for 3.0 is smaller then 1/3rd of the other two versions. Not sure how to proceed in this case (any ideas welcome!)
You can download all schemas from here and do the comparison yourself:
- web xml v2.4 xsd schema
- web.xml v2.5 xsd schema
- web.xml v3.0 xsd schema
Not so scientific method
Here are the what's new articles describing each new version of the standard:
- What's new in Servlet 2.4
- What's new in Servlet 2.5
- What's new in Servlet 3.0
If you read in, the changes to `web.xml` descriptor mentioned in the articles are minute.
What I would do is simply list all the elements in your original `web.xml` and confirm that they do exist in this document describing the 3.0 schema.
Hope this helps!
Problem
I am deploying a web application that is declared in web.xml and deployed as a .war file. I am deploying on Jetty 9.1.x (but I think this question is not container specific). My web.xml file is quite old and declares itself as a Servlet 2.4 application: ``` <web-app version="2.4" id="my_app" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=" http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> ``` My configuration actually declares some Servlet 3.0 only features, like a default error page. These features do not validate according to the schema, but the features seem to work correctly. Since I am using 3.0 features, I would like to change the declaration to be correct: ``` <web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0"> ``` But I am scared to do this because I don't understand what the difference will be to Jetty. Will changing the declaration have any effect on the runtime behavior of Jetty? Does Jetty treat a 2.4 app somehow differently than a 3.0 app?