uk.ac.starlink.table
Class StreamTableSink

java.lang.Object
  extended byuk.ac.starlink.table.StreamTableSink
All Implemented Interfaces:
TableSink

public abstract class StreamTableSink
extends Object
implements TableSink

TableSink which turns its accepted data into a one-pass table and does something with it (calls scanTable(uk.ac.starlink.table.StarTable) on it). This effectively allows you to 'push' table data by writing it to this TableSink rather than 'pulling' it by implementing a RowSequence; the latter may be a less obvious or more fiddly way to work. Note however this will only work for scanTable implementations which need only a single pass of the data.

See TableSink for usage rules.

Since:
8 Aug 2007

Constructor Summary
StreamTableSink()
           
 
Method Summary
 void acceptMetadata(StarTable meta)
          Takes delivery of a row-less StarTable object which defines the metadata of the table to be transmitted.
 void acceptRow(Object[] row)
          Takes delivery of one row of data.
 void endRows()
          Signals that there are no more rows to be transmitted.
protected abstract  void scanTable(StarTable table)
          Does something or other with the table whose data is being pushed into this sink.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

StreamTableSink

public StreamTableSink()
Method Detail

scanTable

protected abstract void scanTable(StarTable table)
                           throws IOException
Does something or other with the table whose data is being pushed into this sink. The only data access which will work is a single call to uk.ac.starlink.table. Subsequent getRowSequence calls will result in a UnrepeatableSequenceException. This method is called in a separate thread than the one in which the accept* calls are made; but any exceptions thrown here are passed back to the latter thread.

Parameters:
table - table to consume
Throws:
IOException

acceptMetadata

public void acceptMetadata(StarTable meta)
                    throws TableFormatException
Description copied from interface: TableSink
Takes delivery of a row-less StarTable object which defines the metadata of the table to be transmitted. If the number of rows that will be transmitted via subsequent calls to acceptRow is known, this value should be made available as the row count of meta (StarTable.getRowCount()); if it is not known, the row count should be -1. However, this object should not attempt to read any of meta's cell data.

The data to be transmitted in subsequent calls of acceptRow must match the metadata transmitted in this call in the same way that rows of a StarTable must match its own metadata (number and content clases of columns etc). If this sink cannot dispose of a table corresponding to meta then it may throw a TableFormatException - this may be the case if for instance meta has columns with types that this sink can't deal with.

Specified by:
acceptMetadata in interface TableSink
Parameters:
meta - table metadata object
Throws:
TableFormatException - if this sink cannot accept table rows matching the given metadata

acceptRow

public void acceptRow(Object[] row)
               throws IOException
Description copied from interface: TableSink
Takes delivery of one row of data. row is an array of objects comprising the contents of one row of the table being transmitted. The number and classes of the elements of row are described by the metadata object previously accepted.

Specified by:
acceptRow in interface TableSink
Parameters:
row - table data row
Throws:
IOException

endRows

public void endRows()
             throws IOException
Description copied from interface: TableSink
Signals that there are no more rows to be transmitted.

Specified by:
endRows in interface TableSink
Throws:
IOException

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