uk.ac.starlink.votable
Class VOSerializer

java.lang.Object
  extended by uk.ac.starlink.votable.VOSerializer

public abstract class VOSerializer
extends Object

Class which knows how to serialize a table's fields and data to VOTable elements. For writing a full VOTable document which contains a single table the VOTableWriter class may be more convenient, but this class can be used in a more flexible way, by writing only the elements which are required.

Obtain an instance of this class using the makeSerializer(uk.ac.starlink.votable.DataFormat, uk.ac.starlink.table.StarTable) method.


Method Summary
static char ensureLegalXml(char c)
          Returns a legal XML character corresponding to an input character.
static String formatAttribute(String name, String value)
          Turns a name,value pair into an attribute assignment suitable for putting in an XML start tag.
static String formatText(String text)
          Performs necessary special character escaping for text which will be written as XML CDATA.
 DataFormat getFormat()
          Returns the data format which this object can serialize to.
 StarTable getTable()
          Returns the table object which this object can serialize.
static VOSerializer makeFitsSerializer(StarTable table, FitsTableSerializer fitser)
          Constructs a FITS-type VOSerializer.
static VOSerializer makeSerializer(DataFormat dataFormat, StarTable table)
          Returns a serializer capable of serializing a given table to given data format, using the default VOTable output version.
static VOSerializer makeSerializer(DataFormat dataFormat, VOTableVersion version, StarTable table)
          Returns a serializer capable of serializing a given table to a given data format using a given VOTable version.
 void writeDescription(BufferedWriter writer)
          Writes any DESCRIPTION element associated with this serializer's table.
abstract  void writeFields(BufferedWriter writer)
          Writes the FIELD headers corresponding to this table on a given writer.
abstract  void writeHrefDataElement(BufferedWriter xmlwriter, String href, DataOutput streamout)
          Writes this serializer's table data to a <DATA> element containing a <STREAM> element which references an external data source (optional method).
 void writeHrefTableElement(BufferedWriter xmlwriter, String href, DataOutput streamout)
           
abstract  void writeInlineDataElement(BufferedWriter writer)
          Writes this serializer's table data as a self-contained <DATA> element.
 void writeInlineTableElement(BufferedWriter writer)
          Writes this serializer's table as a complete TABLE element.
 void writeParams(BufferedWriter writer)
          Writes any PARAM and INFO elements associated with this serializer's table.
 void writePostDataXML(BufferedWriter writer)
          Outputs any content of the TABLE element following the DATA element and the TABLE end tag.
 void writePreDataXML(BufferedWriter writer)
          Outputs the TABLE element start tag and all of its content before the DATA element.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

getFormat

public DataFormat getFormat()
Returns the data format which this object can serialize to.

Returns:
output format

getTable

public StarTable getTable()
Returns the table object which this object can serialize.

Returns:
table to write

writeFields

public abstract void writeFields(BufferedWriter writer)
                          throws IOException
Writes the FIELD headers corresponding to this table on a given writer.

Parameters:
writer - destination stream
Throws:
IOException

writeInlineDataElement

public abstract void writeInlineDataElement(BufferedWriter writer)
                                     throws IOException
Writes this serializer's table data as a self-contained <DATA> element. If this serializer's format is binary (non-XML) the bytes will get written base64-encoded into a STREAM element.

Parameters:
writer - destination stream
Throws:
IOException

writeHrefDataElement

public abstract void writeHrefDataElement(BufferedWriter xmlwriter,
                                          String href,
                                          DataOutput streamout)
                                   throws IOException
Writes this serializer's table data to a <DATA> element containing a <STREAM> element which references an external data source (optional method). The binary data itself will be written to an output stream supplied separately (it will not be inline). If this serializer's format is not binary (i.e. if it's TABLEDATA) an UnsupportedOperationException will be thrown.

Parameters:
xmlwriter - destination stream for the XML output
href - URL for the external stream (output as the href attribute of the written <STREAM> element)
streamout - destination stream for the binary table data
Throws:
IOException

writeInlineTableElement

public void writeInlineTableElement(BufferedWriter writer)
                             throws IOException
Writes this serializer's table as a complete TABLE element. If this serializer's format is binary (non-XML) the bytes will get written base64-encoded into a STREAM element.

Parameters:
writer - destination stream
Throws:
IOException

writeHrefTableElement

public void writeHrefTableElement(BufferedWriter xmlwriter,
                                  String href,
                                  DataOutput streamout)
                           throws IOException
Throws:
IOException

writeParams

public void writeParams(BufferedWriter writer)
                 throws IOException
Writes any PARAM and INFO elements associated with this serializer's table. These should generally go in the RESOURCE element in which the table will be contained.

Parameters:
writer - destination stream
Throws:
IOException

writeDescription

public void writeDescription(BufferedWriter writer)
                      throws IOException
Writes any DESCRIPTION element associated with this serializer's table. This should generally go just inside the TABLE element itself. If there's no suitable description text, nothing will be written.

Parameters:
writer - destination stream
Throws:
IOException

writePreDataXML

public void writePreDataXML(BufferedWriter writer)
                     throws IOException
Outputs the TABLE element start tag and all of its content before the DATA element. Other items legal where a TABLE can appear may be prepended if required.

Parameters:
writer - output stream
Throws:
IOException

writePostDataXML

public void writePostDataXML(BufferedWriter writer)
                      throws IOException
Outputs any content of the TABLE element following the DATA element and the TABLE end tag.

Parameters:
writer - output stream
Throws:
IOException

formatAttribute

public static String formatAttribute(String name,
                                     String value)
Turns a name,value pair into an attribute assignment suitable for putting in an XML start tag. The resulting string starts with, but does not end with, whitespace. Any necessary escaping of the strings is taken care of.

Parameters:
name - the attribute name
value - the attribute value
Returns:
string of the form ' name="value"'

formatText

public static String formatText(String text)
Performs necessary special character escaping for text which will be written as XML CDATA.

Parameters:
text - the input text
Returns:
text but with XML special characters escaped

ensureLegalXml

public static char ensureLegalXml(char c)
Returns a legal XML character corresponding to an input character. Certain characters are simply illegal in XML (regardless of encoding). If the input character is legal in XML, it is returned; otherwise some other weird but legal character (currently the inverted question mark, "¿") is returned instead.

Parameters:
c - input character
Returns:
legal XML character, c if possible

makeSerializer

public static VOSerializer makeSerializer(DataFormat dataFormat,
                                          StarTable table)
                                   throws IOException
Returns a serializer capable of serializing a given table to given data format, using the default VOTable output version.

Parameters:
dataFormat - one of the supported VOTable serialization formats
table - the table to be serialized
Returns:
serializer
Throws:
IOException

makeSerializer

public static VOSerializer makeSerializer(DataFormat dataFormat,
                                          VOTableVersion version,
                                          StarTable table)
                                   throws IOException
Returns a serializer capable of serializing a given table to a given data format using a given VOTable version.

Parameters:
dataFormat - one of the supported VOTable serialization formats
version - specifies the version of the VOTable standard to which the output will conform
table - the table to be serialized
Returns:
serializer
Throws:
IOException

makeFitsSerializer

public static VOSerializer makeFitsSerializer(StarTable table,
                                              FitsTableSerializer fitser)
                                       throws IOException
Constructs a FITS-type VOSerializer. Since a FitsTableSerializer is required for this, if one is already available then supplying it directly here will be more efficient than calling makeSerializer which will have to construct another, possibly an expensive step.

Parameters:
table - table for serialization
fitser - fits serializer
Throws:
IOException

Copyright © 2004 CLRC: Central Laboratory of the Research Councils. All rights reserved.