com.ibm.di.parser
Class XMLSaxParser

java.lang.Object
  com.ibm.di.parser.ParserImpl
      com.ibm.di.parser.XMLSaxParser

All Implemented Interfaces:

ParserInterface, VersionInfoInterface

public class XMLSaxParser
extends ParserImpl

A class reading Entries in XML format. XML Sax Parser doesn't support writing. This parser uses a SAX2 parser to read an XML document. For every start-tag read from the input document the parser concatenates this tag name with its parent tag name into a currentTag value. The currentTag value holds the path to the current position in the XML document. When character data is read an attribute is either created or appended to using the currentTag name and the character data as the value. Data collection is only done when a group tag is found (e.g. when any of the group tag values are found). When an end-tag is encountered the parser will first check to see if the currentTag matches the GroupTag configured for the parser, and if it does, the current entry is added to a queue which is read by the readEntry() method. Since SAX2 is event driven, this class creates a thread that performs the XML parsing and notifies the parser class when an entry is ready for consumption. The currentTag is composed of tag names concatenate with the "@" character. The GroupTag specifies which tag-path marks the boundary for an entry. If specified as a string not starting with an asterix, the tag is checked for equality with the currentTag. If the GroupTag starts with "*" then the currentTag is checked for containment of the GroupTag (e.g. "Root@Entry@X" matches "*Root@Entry" but not "Root@Entry"). You can specify multiple group tags by comma-separating the tags (e.g. a,b@x etc) Big Data Blue Data 12 88 Blue Data Using "Root@Entry" as the GroupTag, the above XML document would yield two entries with the following attributes: ENTRY [ "Root@Entry@attribute": [ "Big Data", "Blue Data" ] ] ENTRY [ "Root@Entry@attribute#name": [ "big" "blue" ] "Root@Entry@attribute@size": [ "12" ] "Root@Entry@attribute@age": [ "88" ] "Root@Entry@attribute": [ "Blue Data" ] ] The saxRemovePrefix parameter is a convenience parameter that cause the parser to remove a specific prefix. If the parser was configured with "Root@Entry@" for the saxRemovePrefix the entries would be simpler like "attribute@size" rather than "Root@Entry@attribute@size". The Parser creates Sax Content handler thread. It parses the XML document and in its endElement method puts the Entry object in XMLSaxParser's queue and notifies XMLSaxParser to read the entry. After reading XMLSaxParser deletes the Entry object from queue. Sax Content Handler thread waits in startElement method for Entry to be read. XMLSaxParser, upon request for readEntry, trigger SaxContentHandler thread to go ahead.

Field Summary

Fields inherited from class com.ibm.di.parser.ParserImpl

_debug, myConfiguration

Constructor Summary

XMLSaxParser()
Constructor

Method Summary

void	closeParser() Stops the Sax Content Handler thread.
String	getVersion() Return version information
void	initParser() Initializes queue object, reads configuration parameters, creates SaxContentHandler thread and starts the thread.
Entry	readEntry() readEntry() uses the queue object to check for new entries provided by the xml-parser thread.
void	registerScriptBeans(ScriptEngine se) Not used
void	writeEntry(Entry entry) Not supported

Methods inherited from class com.ibm.di.parser.ParserImpl

debug, debugMode, flush, getClassInstance, getContext, getDebug, getInputStream, getOutputStream, getParam, getParser, getReader, getWriter, isDeltaSupported, logmsg, setConfiguration, setContext, setDebug, setInputStream, setInputStream, setInputStream, setOutputStream, setOutputStream, setParam, setParser

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

XMLSaxParser

public XMLSaxParser()

Constructor

Method Detail

registerScriptBeans

public void registerScriptBeans(ScriptEngine se)
                         throws Exception

Not used

Specified by:

registerScriptBeans in interface ParserInterface

Overrides:

registerScriptBeans in class ParserImpl

Parameters:

se - The script engine

Throws:

Exception

initParser

public void initParser()
                throws Exception

Initializes queue object, reads configuration parameters, creates SaxContentHandler thread and starts the thread.

Specified by:

initParser in interface ParserInterface

Overrides:

initParser in class ParserImpl

Throws:

Exception - if getInputStream() and getReader() both returns null.

closeParser

public void closeParser()
                 throws Exception

Stops the Sax Content Handler thread.

Specified by:

closeParser in interface ParserInterface

Overrides:

closeParser in class ParserImpl

Throws:

Exception

readEntry

public Entry readEntry()
                throws Exception

readEntry() uses the queue object to check for new entries provided by the xml-parser thread. The object found in the queue governs when an entry is ready, an end-of-file has been reached or if there is an error parsing the document. The method simply checks the class type for the object and decides what to do next.

Returns:

The next Entry in the XML document.

Throws:

Exception

writeEntry

public void writeEntry(Entry entry)
                throws Exception

Not supported

Parameters:

entry - The entry to write

Throws:

Exception

getVersion

public String getVersion()

Return version information

Returns:

String