XSD reference (or DTD reference) learning for the Web. xml file

1. Why Web. XML has different versions of the XSD reference:

　　JDK dependent change;

or the servlet (JAVA EE) itself API changes;

2. Why there is a difference between DTD and XSD two versions

As I saw in this article, the author seems to have copied an API note:

　

There is, ways to specify, the schema for a, the Web. xml file (Deployment descriptor). Dtd-document Type definitionxsd-xml Schema definitionthe XSD version is preferred since JSP 2.0/servlets 2.4 (eg:to MCAT 5.5). Note that the XML encoding can is specified as Iso-8859-1, UTF-8, or any other valid encoding in either version, and Shoul D match the actual encoding of your text file. XSD Example for JSP 2.1/servlets 2.5 (Tomcat 6.0): <?xml version= "1.0" encoding= "iso-8859-1"? ><web-app xmlns= "HT Tp://java.sun.com/xml/ns/j2ee "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_5.xsd "version=" 2.5 "></web-app>xsd Example for JSP 2.0/servlets 2.4 (Tomcat 5.5): <?xml version= "1.0" encoding= "iso-8859-1"? ><web-app xmlns= "http: Java.sun.com/xml/ns/j2ee "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 "version=" 2.4 "></web-app>dtd example for JSP 1.2/ Servlets 2.3 (Tomcat 5): <?xml version= "1.0" encoding= "iso-8859-1"?> <! DOCTYPE Web-app Public "-//sun Microsystems, INC.//DTD Web Application 2.3//en" "Http://java.sun.com/dtd/web-app_2_3.d TD "><web-app></web-app>

　

Here, too, the DTD is the way of early support, using XSD as much as possible later. Why XSD becomes a trend, here's a good note on "How to use XSD", "dtd,xsd differences and Applications in XML".

DTD versus xsd: DTDs are written using non-XML syntax.

DTDs are not extensible, namespaces are not supported, and only a very limited number of data types are available.

3. Web. xml Several versions of the list

Web. XML v2.3

<? XML version= "1.0" encoding="iso-8859-1"?> <! DOCTYPE Web-app Public "-//sun Microsystems, INC.//DTD Web Application 2.3//en" "Http://java.sun.com/dtd/web-app_2_3. DTD " > <web-app></web-app>

Web. XML v2.4

<Web-app id="Webapp_9" version="2.4" xmlns= "HTTP://JAVA.SUN.COM/XML/NS/J2EE"

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" >

</Web-app>

Web. XML v2.5

<? XML version= "1.0" encoding="UTF-8"?>

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_2_5.xsd"

version="2.5">

</Web-app>

Web. Xml v3.0

<? XML version= "1.0" encoding="UTF-8"?>

<Web-app version="3.0" 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" >

</Web-app>

XSD reference (or DTD reference) learning for the Web. xml file