Java Enterprise Best Practices

Use Elements Sparingly, Attributes Excessively

After giving you two recommendations about organization, I will now make what might seem like a counterintuitive suggestion: use elements infrequently and, instead, use attributes whenever possible.

To get a better idea of what I’m talking about, take a look at the XML fragment in Example 5-3.

Example 5-3. An element-heavy document fragment

<person>
  <firstName>Adam</firstName>
  <lastName>Duritz</lastName>
  <address type="home">
    <street>102 Elizabeth Lane</street>
    <street>Apartment 23</street>
    <city>Los Angeles</city>
    <state>California</state>
    <zipCode>92013</zipCode>
  </address>
</person>

To optimize this XML, you should try and convert as much as possible into attributes. The rule of thumb here is that any single-valued content can be turned into an attribute, while multivalued content must stay as elements. So, the firstName and lastName elements can be converted into attributes; each will always have only one value. Hence, the XML can be modified to look as follows:

               <person firstName="Adam" lastName="Duritz">
                 <address type="home">
    <street>102 Elizabeth Lane</street>
    <street>Apartment 23</street>
    <city>Los Angeles</city>
    <state>California</state>
    <zipCode>92013</zipCode>
  </address>
</person>

The address element could not be converted to an attribute. First, it has its own content, and second, there could be multiple addresses for the same person (a home address, work address, and so forth). Within that element, you can perform the same ...