Problem in xml header syntax!!

Question

Greetings,
I'm testing hibernate framework, I'm writing this mapping xml file. Regardless the fact it is a hibernate example, this is a normal xml file problem. When I write that xml to the JBuilder editor, I get an error msg. I don't know why! and this is actually the question, how to make the xml below valid?
I'd like to share my experience about this file. The problem is in the line
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
and this is the key to the hidden solution!! is this line like import statement so the editor doesn't see it? when I delete it, the editor then says: that <hibernate-mapping>, <class> etc must be declared!!
Thanks in advance for help
below is the xml file code:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="hello.Message" table="MESSAGES">
<id name="id" column="MESSAGE_ID">
<generator class="increment"/>
</id>
<property name="text" column="MESSAGE_TEXT"/>
<many-to-one name="nextMessage" cascade="all" column="NEXT_MESSAGE_ID"/>
</class>
</hibernate-mapping>

Answer 1

In my experience with XML (and not hibernate), the set of messages "{every tag name} must be declared" usually means you have not turned on validation properly in whatever is parsing your data. I don't know the magic incantation to parse with a DTD, so I cannot help you with a solution, just with a clarification of the problem.
Dave Patterson