| |
|
| |
 |
Elements and attributes: modeling relational data in XML, part 1
is parsed differently from this document:
<customer>
<address>123 Somewhere
Street</address>
<city>Randomtown</city>
<state>WV</state>
<zip>25423</zip>
<name>Fred Q.
Anybody</name>
</customer>
|
This can make parsing difficult, depending on the parser library you use. You have to manually check all the child elements of the customer element to determine which one has the piece of information (the customer's name, for example) that is being searched for. Generating XML documents with this structure is also more difficult—the elements containing the data points must be serialized to the target document in exactly the right order, or the document does not validate against its DTD or schema.
On the other hand, attributes in an XML document are not order sensitive in much the same way that named columns are not order sensitive in a relational database table. Thus, the following two documents are parsed exactly the same way:
<customer
name="Fred Q. Anybody"
address="123 Somewhere Street"
city="Randomtown"
state="WV"
zip="25423" />
|
and
<customer
name="Fred Q. Anybody"
address="123 Somewhere Street"
city="Randomtown"
state="WV"
zip="25423" />
|
Because these two documents parse the same way, they both validate against the same DTD or schema. Creating documents is easier as well, because you can add attributes to the XML document in any order convenient to you.
Differences in document size
Because of the way XML documents are serialized to text, attribute values use fewer characters than their equivalent element representations. For example, compare our two sample documents (assuming that all white space is removed to minimize document size):
<customer>
<name>Fred Q.
Anybody</name>
<address>123 Somewhere
Street</address>
<city>Randomtown</city>
<state>WV</state>
<zip>25423</zip>
</customer>
|
Subscribers who liked this article also read:If you're interested in this topic, these articles may be helpful:
|
|
