uk.ac.starlink.vo

Class DalResultXMLFilter

java.lang.Object

org.xml.sax.helpers.XMLFilterImpl

uk.ac.starlink.vo.DalResultXMLFilter

All Implemented Interfaces:

ContentHandler, DTDHandler, EntityResolver, ErrorHandler, XMLFilter, XMLReader

public class DalResultXMLFilter
extends XMLFilterImpl

SAX filter which ignores any tables in a VOTable document, except those in a RESOURCE which has type="results". This is suitable for getting the basic table from the result of an SIA or SSA service. Under some circumstances the results can come with a large amount of non-result information (for instance massive numbers of small footprint tables from http://www.stecf.org/hst-vo/hst_ssa?), which can have a very serious impact on performance when trying to build a DOM. So if all you are interested in is the results table which the SIA/SSA protocol says has to be there, using this filter can save a lot of unnecessary processing.

In many cases, you can just use the getDalResultTable(uk.ac.starlink.votable.VOElementFactory, org.xml.sax.InputSource) utility method.

See Also:

Simple Spectral Access Protocol, Simple Image Access Protocol

Constructor Summary

Constructors

Constructor and Description
DalResultXMLFilter(XMLReader parent, Namespacing namespacing) Constructor.

Method Summary

Modifier and Type	Method and Description
void	characters(char[] ch, int start, int length)
void	endElement(String namespaceURI, String localName, String qName)
void	endPrefixMapping(String prefix)
static StarTable	getDalResultTable(VOElementFactory vofact, InputSource inSrc) Utility method which can return the single results table from a DAL-type response.
void	ignorableWhitespace(char[] ch, int start, int length)
static VOElement	parseDalResult(VOElementFactory vofact, InputSource inSrc) Utility method which uses an instance of this class to turn a SAX InputSource into a DOM.
void	processingInstruction(String target, String data)
void	skippedEntity(String name)
void	startElement(String namespaceURI, String localName, String qName, Attributes atts)
void	startPrefixMapping(String prefix, String uri)

Methods inherited from class org.xml.sax.helpers.XMLFilterImpl

endDocument, error, fatalError, getContentHandler, getDTDHandler, getEntityResolver, getErrorHandler, getFeature, getParent, getProperty, notationDecl, parse, parse, resolveEntity, setContentHandler, setDocumentLocator, setDTDHandler, setEntityResolver, setErrorHandler, setFeature, setParent, setProperty, startDocument, unparsedEntityDecl, warning

Methods inherited from class java.lang.Object

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

Constructor Detail

DalResultXMLFilter

public DalResultXMLFilter(XMLReader parent,
                          Namespacing namespacing)

Constructor.

Parameters:

parent - parent SAX reader

namespacing - VOTable namespacing policy to employ

Method Detail

startElement

public void startElement(String namespaceURI,
                         String localName,
                         String qName,
                         Attributes atts)
                  throws SAXException

Specified by:

startElement in interface ContentHandler

Overrides:

startElement in class XMLFilterImpl

Throws:

SAXException

endElement

public void endElement(String namespaceURI,
                       String localName,
                       String qName)
                throws SAXException

Specified by:

endElement in interface ContentHandler

Overrides:

endElement in class XMLFilterImpl

Throws:

SAXException

startPrefixMapping

public void startPrefixMapping(String prefix,
                               String uri)
                        throws SAXException

Specified by:

startPrefixMapping in interface ContentHandler

Overrides:

startPrefixMapping in class XMLFilterImpl

Throws:

SAXException

endPrefixMapping

public void endPrefixMapping(String prefix)
                      throws SAXException

Specified by:

endPrefixMapping in interface ContentHandler

Overrides:

endPrefixMapping in class XMLFilterImpl

Throws:

SAXException

characters

public void characters(char[] ch,
                       int start,
                       int length)
                throws SAXException

Specified by:

characters in interface ContentHandler

Overrides:

characters in class XMLFilterImpl

Throws:

SAXException

ignorableWhitespace

public void ignorableWhitespace(char[] ch,
                                int start,
                                int length)
                         throws SAXException

Specified by:

ignorableWhitespace in interface ContentHandler

Overrides:

ignorableWhitespace in class XMLFilterImpl

Throws:

SAXException

processingInstruction

public void processingInstruction(String target,
                                  String data)
                           throws SAXException

Specified by:

processingInstruction in interface ContentHandler

Overrides:

processingInstruction in class XMLFilterImpl

Throws:

SAXException

skippedEntity

public void skippedEntity(String name)
                   throws SAXException

Specified by:

skippedEntity in interface ContentHandler

Overrides:

skippedEntity in class XMLFilterImpl

Throws:

SAXException

parseDalResult

public static VOElement parseDalResult(VOElementFactory vofact,
                                       InputSource inSrc)
                                throws IOException

Utility method which uses an instance of this class to turn a SAX InputSource into a DOM. The DOM will lack non-results tables.

Parameters:

vofact - factory which can generate VOTable DOMs

inSrc - source of the SAX stream

Throws:

IOException

getDalResultTable

public static StarTable getDalResultTable(VOElementFactory vofact,
                                          InputSource inSrc)
                                   throws IOException

Utility method which can return the single results table from a DAL-type response. This is the single table within the RESOURCE element marked with type="results", as described by the SIA and SSA standards. The QUERY_STATUS INFO element is checked; in case of ERROR, an exception is thrown.

Parameters:

vofact - factory which can generate VOTable DOMs

inSrc - source of the SAX stream

Returns:

result table, never null

Throws:

IOException - in case of error, including an ERROR-valued QUERY_STATUS in the response, or no suitable table found