6-2 Programming XML for Oracle WebLogic Server
6.2 Increasing Performance of XML Validation
If the performance of your XML application decreases due to a parser validation issue, and you need to validate your XML documents, you might improve the performance
of your application by writing your own customized code that validates the data as it is being received or parsed, rather than using the setValidating method of the
DocumentBuilderFactory or SaxParserFactory.
When you turn on validation while parsing an XML document with SAX or DOM, the parser might do more validation of the document than you really need, thus
decreasing the overall performance of the application. Instead, consider choosing certain points during the parsing of the document when you want to check that the
XML document is valid, and add your own Java code at those points.
For example, assume you are writing an application that uses the WebLogic XML Streaming API to processes an XML purchase order. Because you know that the first
element of the document should be purchase_order, you can quickly verify that the document appears to be valid by pulling the first element off the stream and
checking its name. This check does not ensure that the entire XML document is valid, of course, but you can continue checking for known elements as you pull elements
from the stream. These quick checks are much faster than using the standard setValidating methods.
6.3 When to Use XML Schemas or DTDs
There are two ways to describe the structure of an XML document: DTDs and XML Schemas.
The current trend is to use Schemas to describe XML documents. Schemas are much more expressive than DTDs because the set of available data types to describe XML
elements is much richer and you can describe more specifically what is valid in an XML document. In addition, you can only use Schemas, and not DTDs, in SOAP
messages. Because SOAP is the main messaging protocol used in Web services, consider using Schemas to describe any XML documents that might be used as either
input or output parameters to Web services.
Still, DTDs have a few advantages. DTDs are more widely supported than Schemas, although that is changing rapidly. Because DTDs are less expressive than Schemas,
they are easier to write and manage.
However, Oracle recommends that you use Schemas to describe your XML documents.
6.4 Configuring External Entity Resolution for Maximum Performance
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