Class VOSerializer

java.lang.Object
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.

Author:
Mark Taylor (Starlink)
  • Method Details

    • getFormat

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

      public uk.ac.starlink.table.StarTable getTable()
      Returns the table object which this object can serialize.
      Returns:
      table to write
    • getVersion

      public VOTableVersion getVersion()
      Returns the version of the VOTable standard for which this serializer will write.
      Returns:
      VOTable version
    • setCompact

      public void setCompact(boolean isCompact)
      Controls whitespace formatting for TABLEDATA format; no effect for other DataFormats.
      Parameters:
      isCompact - if true, add whitespace round TR/TD elements
    • isCompact

      public boolean isCompact()
      Indicates compactness of whitespace formatting for TABLEDATA format; no effect for other DataFormats.
      Returns:
      if true, add whitespace round TR/TD elements
    • 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
    • writeInlineDataElementUTF8

      public abstract void writeInlineDataElementUTF8(OutputStream out) throws IOException
      Writes this serializer's table data as a self-contained <DATA> element to an output stream using UTF8 encoding. This may be substantially faster than the otherwise equivalent writeInlineDataElement(java.io.BufferedWriter) method.
      Parameters:
      out - output stream
      Throws:
      IOException
    • writeHrefDataElement

      public abstract void writeHrefDataElement(BufferedWriter xmlwriter, String href, OutputStream 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
    • writeInlineTableElementUTF8

      public void writeInlineTableElementUTF8(OutputStream out) throws IOException
      Writes this serializer's table as a complete TABLE element to an output stream using UTF8 encoding. If this serializer's format is binary (non-XML) the bytes will get written base64-encoded into a STREAM element.

      This may be substantially faster than the otherwise equivalent writeInlineTableElement(java.io.BufferedWriter) method.

      Parameters:
      out - output stream
      Throws:
      IOException
    • writeHrefTableElement

      public void writeHrefTableElement(BufferedWriter xmlwriter, String href, OutputStream 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 TABLE element.
      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
    • writeServiceDescriptors

      public void writeServiceDescriptors(BufferedWriter writer) throws IOException
      Writes the service descriptor parameters of this serializer's table as a sequence of zero or more RESOURCE elements. Each has attributes type="meta" and utype="adhoc:service".
      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
    • getRowCount

      public long getRowCount()
      Returns the number of rows that this serializer will write, if known. The default implementation returns getTable().getRowCount(), but this may be overridden if that value is known to be unreliable.
      Returns:
      number of rows iterated over by getRowSequence, or -1 if not known
    • getRowSequence

      public uk.ac.starlink.table.RowSequence getRowSequence() throws IOException
      Returns the row sequence that this serializer will write.
      Returns:
      row sequence
      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, uk.ac.starlink.table.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, uk.ac.starlink.table.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(uk.ac.starlink.table.StarTable table, uk.ac.starlink.fits.FitsTableSerializer fitser, VOTableVersion version) 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
      version - output VOTable version
      Returns:
      serializer
      Throws:
      IOException