Sun's Streaming Parser Implementation

The Sun Java System Application Server (SJSAS) PE 9.0 package includes Sun Microsystem's JSR 173 (StAX) implementation, called the Sun Java Streaming XML Parser (SJSXP). The SJSXP is a high-speed, non-validating, W3C XML 1.0 and Namespace 1.0-compliant streaming XML pull parser built upon the Xerces2 codebase.

In Sun's SJSXP implementation, the Xerces2 lower layers, particularly the Scanner and related classes, have been redesigned to behave in a pull fashion. In addition to the changes the lower layers, the SJSXP includes additional StAX-related functionality and many performance-enhancing improvements. The SJSXP is implemented in appserv-ws.jar and javaee.jar, both of which are located in the <javaee.home>/lib directory.

Included with this J2EE tutorial are StAX code samples, located in the <javaee.tutorial.home>/examples/stax directory, that illustrate how Sun's SJSXP implementation works. These samples are described in the Sample Code section, later in this chapter.

Before proceeding with the sample code, there are two important aspects of the SJSXP about which you should be aware:

Reporting CDATA Events

The javax.xml.stream.XMLStreamReader implemented in the SJSXP does not report CDATA events. If you have an application that needs to receive such events, configure the XMLInputFactory to set the following implementation-specific "report-cdata-event" property:

XMLInputFactory factory = XMLInptuFactory.newInstance();
factory.setProperty("report-cdata-event", Boolean.TRUE);

SJSXP Factories Implementation

Most applications do not need to know the factory implementation class name. Just adding the javaee.jar and appserv-ws.jar files to the classpath is sufficient for most applications because these two jars supply the factory implementation classname for various SJSXP properties under the META-INF/services directory--for example, javax.xml.stream.XMLInputFactory, javax.xml.stream.XMLOutputFactory, and javax.xml.stream.XMLEventFactory--which is the third step of a lookup operation when an application asks for the factory instance. See the javadoc for the XMLInputFactory.newInstance() method for more information about the lookup mechanism.

However, there may be scenarios when an application would like to know about the factory implementation class name and set the property explicitly. These scenarios could include cases where there are multiple JSR 173 implementations in the classpath and the application wants to choose one, perhaps one that has superior performance, contains a crucial bug fix, or suchlike.

If an application sets the SystemProperty, it is the first step in a lookup operation, and so obtaining the factory instance would be fast compared to other options; for example:

javax.xml.stream.XMLInputFactory --> 
com.sun.xml.stream.ZephyrParserFactory
javax.xml.stream.XMLOutputFactory --> 
com.sun.xml.stream.ZephyrWriterFactor
javax.xml.stream.XMLEventFactory --> 
com.sun.xml.stream.events.ZephyrEventFactory