General Structure of XML Documents - Page 3
December 2, 2002
The following listing shows the general tree structure of a content document for the simple CMS application:
Here is the DTD for the above:
<!DOCTYPE CONTENT[
<!ELEMENT CONTENT (TITLE,AUTHORS,PAGE,BODY)>
<!ATTLIST CONTENT TYPE CDATA #REQUIRED>
<!ATTLIST CONTENT SUBTYPE CDATA #REQUIRED>
<!ELEMENT TITLE (#PCDATA)>
<!ELEMENT AUTHORS (FNAME,MNAME,LNAME)>
<!ELEMENT FNAME (#PCDATA)>
<!ELEMENT MNAME (#PCDATA)>
<!ELEMENT LNAME (#PCDATA)>
<!ELEMENT PAGE (#PCDATA)>
<!ATTLIST PAGE URL CDATA #IMPLIED>
<!ELEMENT BODY (#PCDATA)>
]>
All documents imported into this simple CMS database must follow this skeleton structure; the documents
will differ only in the <body> element's subtree structure. The equivalent XML template looks like this:
<content type="__type__" subtype="__subtype__">
<title>__title__</title>
<authors>
<author>
<fname>__firstname__</fname>
<mname>__middlename__</mname>
<lname>__lastname__</lname>
</author>
</authors>
<page url="__url__"/> <!-- Attribute 'url' is optional -->
<body>
__body_of_content__
</body>
</content>
Values for attributes and tags are shown as field markers, in bold. For example, the value of type is
indicated by the marker __type__. When a document is added to the database, only the above tags will be
parsed. Everything in the <body> element will be stored as a block of XML-like markup. The XML PI that
starts every XML file will be stripped off.
The resulting <body> block will be parsed later by an application component that knows how to process the
particular document type/subtype. That component is not talked about here though.
Such components are not dicussed in this chapter.
Example 1: Non-fiction Book (Beginning Stages)
This example represents a non-fiction book. The following XML listing (nonfic01.xml) is broken up into
sections in order to explain the tags:
<?xml version="1.0" ?>
Each document must start with the root element <content> and include two attributes – type and
subtype (subtype can be a blank string). The resulting combination of attribute values will determine the
structure of the sub-document within the <body>...</body> tag block.
<content type="nonfiction" subtype="book">
The combination of type, subtype, and the title must be unique. In other words, for a given
type/subtype combination, all relevant documents must have a unique title:
<title>Web Development Methodologies</title>
Note, however, that titles can be repeated in a different type/subtype combination.
Each document may have one or more contributors. For each author, use one <author>...</author>
block. This block defines two authors:
<authors>
<author>
<fname>mary</fname>
<mname>elizabeth</mname>
<lname>smith</lname>
</author>
<author>
<fname>john</fname>
<mname>q</mname>
<lname>doe</lname>
</author>
</authors>
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General Structure of XML Documents - - Page 4
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