The Document Headerand Schema Declarations
An XML document may start with a tag that specifies the version of XML in use:
<?xml version="1.0" encoding="UTF-8"?>
This tag identifies the document as an XML document that adheres to Version 1.0 of the XML specification and uses the UTF-8 character encoding. EJB vendors usually support this character encoding.
In EJB 2.1, the element following the XML header (the
<ejb-jar> element) is the root element of
the deployment descriptor. This element declares the
document’s XML namespace and the location of the XML
schema that can be used to validate its contents. A complete
<ejb-jar> element looks like this:
<?xml version="1.0" encoding="UTF-8"?> <ejb-jar 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/ejb-jar_2_1.xsd" version="2.1"> ... </ejb-jar>
In EJB 2.0, a DOCTYPE element follows the document header and specifies the DTD that defines the document’s contents:
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE ejb-jar PUBLIC "-//Sun Microsystems, Inc.//DTD Enterprise JavaBeans 2.0//EN" "http://java.sun.com/dtd/ejb-jar_2_0.dtd"> <ejb-jar> ... </ejb-jar>
In both EJB 2.1 and 2.0, the schema definition provides a URL from which you (or, more importantly, tools processing the deployment descriptor) can download the schema used to validate the XML document; this means that the EJB server deploying the bean can download the ...