weka.experiment
Class DatabaseResultListener

java.lang.Object
  |
  +--weka.experiment.DatabaseUtils
        |
        +--weka.experiment.DatabaseResultListener

All Implemented Interfaces:

ResultListener, java.io.Serializable

Direct Known Subclasses:

DatabaseResultProducer

public class DatabaseResultListener

extends DatabaseUtils

implements ResultListener

DatabaseResultListener takes the results from a ResultProducer and submits them to a central database.

Author:

Len Trigg (trigg@cs.waikato.ac.nz)

See Also:

Serialized Form

Field Summary

protected FastVector	m_Cache Stores the cached values
protected java.lang.Object[]	m_CacheKey Stores the key for which the cache is valid
protected int	m_CacheKeyIndex Stores the index of the key column holding the cache key data
protected java.lang.String	m_CacheKeyName Holds the name of the key field to cache upon, or null if no caching
protected boolean	m_Debug True if debugging output should be printed
protected ResultProducer	m_ResultProducer The ResultProducer to listen to
protected java.lang.String	m_ResultsTableName The name of the current results table

Fields inherited from class weka.experiment.DatabaseUtils

DRIVERS, EXP_INDEX_TABLE, EXP_RESULT_COL, EXP_RESULT_PREFIX, EXP_SETUP_COL, EXP_TYPE_COL, m_Connection, m_DatabaseURL, m_Statement, PROPERTIES, PROPERTY_FILE

Constructor Summary

DatabaseResultListener()
Sets up the database drivers

Method Summary

void	acceptResult(ResultProducer rp, java.lang.Object[] key, java.lang.Object[] result) Submit the result to the appropriate table of the database
java.lang.String	cacheKeyNameTipText() Returns the tip text for this property
java.lang.String[]	determineColumnConstraints(ResultProducer rp) Determines if there are any constraints (imposed by the destination) on any additional measures produced by resultProducers.
java.lang.String	getCacheKeyName() Get the value of CacheKeyName.
java.lang.String	globalInfo() Returns a string describing this result listener
protected boolean	isCacheValid(java.lang.Object[] key) Checks whether the current cache contents are valid for the supplied key.
protected boolean	isKeyInCache(ResultProducer rp, java.lang.Object[] key) Returns true if the supplied key is in the key cache (and thus we do not need to execute a database query).
boolean	isResultRequired(ResultProducer rp, java.lang.Object[] key) Always says a result is required.
protected void	loadCache(ResultProducer rp, java.lang.Object[] key) Executes a database query to fill the key cache
void	postProcess(ResultProducer rp) Perform any postprocessing.
void	preProcess(ResultProducer rp) Prepare for the results to be received.
void	setCacheKeyName(java.lang.String newCacheKeyName) Set the value of CacheKeyName.
protected void	updateResultsTableName(ResultProducer rp) Determines the table name that results will be inserted into.

Methods inherited from class weka.experiment.DatabaseUtils

arrayToString, connectToDatabase, createExperimentIndex, createExperimentIndexEntry, createResultsTable, databaseURLTipText, disconnectFromDatabase, execute, experimentIndexExists, getDatabaseURL, getResultFromTable, getResultSet, getResultsTableName, isConnected, isKeyInTable, putResultInTable, setDatabaseURL, tableExists, typeName

Methods inherited from class java.lang.Object

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

Field Detail

m_ResultProducer

protected ResultProducer m_ResultProducer

The ResultProducer to listen to

m_ResultsTableName

protected java.lang.String m_ResultsTableName

The name of the current results table

m_Debug

protected boolean m_Debug

True if debugging output should be printed

m_CacheKeyName

protected java.lang.String m_CacheKeyName

Holds the name of the key field to cache upon, or null if no caching

m_CacheKeyIndex

protected int m_CacheKeyIndex

Stores the index of the key column holding the cache key data

m_CacheKey

protected java.lang.Object[] m_CacheKey

Stores the key for which the cache is valid

m_Cache

protected FastVector m_Cache

Stores the cached values

Constructor Detail

DatabaseResultListener

public DatabaseResultListener()
                       throws java.lang.Exception

Sets up the database drivers

Throws:

java.lang.Exception - if an error occurs

Method Detail

globalInfo

public java.lang.String globalInfo()

Returns a string describing this result listener

Returns:

a description of the result listener suitable for displaying in the explorer/experimenter gui

preProcess

public void preProcess(ResultProducer rp)
                throws java.lang.Exception

Prepare for the results to be received.

Specified by:

preProcess in interface ResultListener

Parameters:

rp - the ResultProducer that will generate the results

Throws:

java.lang.Exception - if an error occurs during preprocessing.

postProcess

public void postProcess(ResultProducer rp)
                 throws java.lang.Exception

Perform any postprocessing. When this method is called, it indicates that no more results will be sent that need to be grouped together in any way.

Specified by:

postProcess in interface ResultListener

Parameters:

rp - the ResultProducer that generated the results

Throws:

java.lang.Exception - if an error occurs

determineColumnConstraints

public java.lang.String[] determineColumnConstraints(ResultProducer rp)
                                              throws java.lang.Exception

Determines if there are any constraints (imposed by the destination) on any additional measures produced by resultProducers. Null should be returned if there are NO constraints, otherwise a list of column names should be returned as an array of Strings. In the case of DatabaseResultListener, the structure of an existing database will impose constraints.

Specified by:

determineColumnConstraints in interface ResultListener

Parameters:

rp - the ResultProducer to which the constraints will apply

Returns:

an array of column names to which resutltProducer's results will be restricted.

Throws:

java.lang.Exception - if an error occurs.

acceptResult

public void acceptResult(ResultProducer rp,
                         java.lang.Object[] key,
                         java.lang.Object[] result)
                  throws java.lang.Exception

Submit the result to the appropriate table of the database

Specified by:

acceptResult in interface ResultListener

Parameters:

rp - the ResultProducer that generated the result

key - The key for the results.

result - The actual results.

Throws:

java.lang.Exception - if the result couldn't be sent to the database

isResultRequired

public boolean isResultRequired(ResultProducer rp,
                                java.lang.Object[] key)
                         throws java.lang.Exception

Always says a result is required. If this is the first call, prints out the header for the Database output.

Specified by:

isResultRequired in interface ResultListener

Parameters:

rp - the ResultProducer wanting to generate the result

key - The key for which a result may be needed.

Returns:

true if the result should be calculated.

Throws:

java.lang.Exception - if the database couldn't be queried

updateResultsTableName

protected void updateResultsTableName(ResultProducer rp)
                               throws java.lang.Exception

Determines the table name that results will be inserted into. If required: a connection will be opened, an experiment index table created, and the results table created.

Parameters:

rp - the ResultProducer

Throws:

java.lang.Exception - if an error occurs

cacheKeyNameTipText

public java.lang.String cacheKeyNameTipText()

Returns the tip text for this property

Returns:

tip text for this property suitable for displaying in the explorer/experimenter gui

getCacheKeyName

public java.lang.String getCacheKeyName()

Get the value of CacheKeyName.

Returns:

Value of CacheKeyName.

setCacheKeyName

public void setCacheKeyName(java.lang.String newCacheKeyName)

Set the value of CacheKeyName.

Parameters:

newCacheKeyName - Value to assign to CacheKeyName.

isCacheValid

protected boolean isCacheValid(java.lang.Object[] key)

Checks whether the current cache contents are valid for the supplied key.

Parameters:

key - the results key

Returns:

true if the cache contents are valid for the key given

isKeyInCache

protected boolean isKeyInCache(ResultProducer rp,
                               java.lang.Object[] key)
                        throws java.lang.Exception

Returns true if the supplied key is in the key cache (and thus we do not need to execute a database query).

Parameters:

rp - the ResultProducer the key belongs to.

key - the result key

Returns:

true if the key is in the key cache

Throws:

java.lang.Exception - if an error occurs

loadCache

protected void loadCache(ResultProducer rp,
                         java.lang.Object[] key)
                  throws java.lang.Exception

Executes a database query to fill the key cache

Parameters:

rp - the ResultProducer the key belongs to

key - the key

Throws:

java.lang.Exception - if an error occurs