Where i can find valid values for the version attribute of the web-app element in web.xml?

Question

Typical web.xml looks like this:

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
        "http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<web-app version="2.4">
  <display-name>Archetype Created Web Application</display-name>
</web-app>

How can I find out which values are valid for the version attribute of <web-app>?

<web-app version="?">

Is it 2.5 or may be 3.0?

Does someone know a URL with the schema or DTD for web.xml validation? URL's for DTD of different web-app versions are different is there some source where I can see full list?

//doctype for servlet 2.3
<!DOCTYPE web-app
    PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
    "http://java.sun.com/dtd/web-app_2_3.dtd">

//doctype for servlet 2.2
<!DOCTYPE web-app PUBLIC
  "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN"
  "http://java.sun.com/j2ee/dtds/web-app_2_2.dtd">

Answer 1

You can try this url:

http://www.oracle.com/webfolder/technetwork/jsc/xml/ns/javaee/index.html

Here you can find

http://www.oracle.com/webfolder/technetwork/jsc/xml/ns/javaee/web-app_3_0.xsd

http://www.oracle.com/webfolder/technetwork/jsc/xml/ns/javaee/web-app_2_5.xsd