org.mmbase.module.builders
Class Vwmtasks

java.lang.Object
  |
  +--org.mmbase.module.core.MMTable
        |
        +--org.mmbase.module.core.MMObjectBuilder
              |
              +--org.mmbase.module.builders.Vwmtasks

All Implemented Interfaces:

java.lang.Runnable

public class Vwmtasks

extends MMObjectBuilder

implements java.lang.Runnable

Virtual Web Master task builder. This builder holds the tasks that need to be performed by the various VWMs (which are registered in the VWMS builder). It also rusna taskscheduler that periodically cehcks whether any new tasks need to be handled
Task nodes have a number of fields that define if, when, and how a task is to be performed. These fields are :
Requested Machine: the machine on which the task is to be performed (wantedcpu)
VWM: the name of the vwm (as known in the VWMS builder) trhat should perform the task
Status : the state of the task (i.e. requesting, claimed, error, done)
Claiming Machine : the cpu that claimed the task for performance (claimedcpu)
Wanted Time : time at which to start the task
Changed Time : time at which the task was last changed
Expire Time : time at which the task expires
Task : name of the task
Id : unknown
Data : field for including properties/parameters

Version:

5-Apr-2001

Author:

Arjan Houtman, Pierre van Rooden (javadocs)

Field Summary

boolean	replaceCache
static int	SLEEP_TIME The interval (in seconds) between checks for new nodes by the task scheduler.
static int	STATUS_CLAIMED Status value for a task that is being performed
static int	STATUS_DONE Status value for a task that was succesfully performed
static int	STATUS_ERROR Status value for a task that failed to be performed
static int	STATUS_REQUEST Status value for a task that requests to be performed
static int	STATUS_TIMEOUT Status value for a task that timed out

Fields inherited from class org.mmbase.module.core.MMObjectBuilder

broadcastChanges, database, DEFAULT_ALINEA, DEFAULT_EOL, description, descriptions, fields, nodeCache, obj2type, OBJ2TYPE_MAX_SIZE, oType, REPLACE_CACHE, searchAge, sortedDBLayout, TEMPNODE_DEFAULT_SIZE, TemporaryNodes, virtual

Fields inherited from class org.mmbase.module.core.MMTable

mmb, tableName

Constructor Summary

Vwmtasks()

Method Summary

java.lang.String	getGUIIndicator(MMObjectNode node) What should a GUI display for this node.
java.lang.String	getGUIIndicator(java.lang.String field, MMObjectNode node) What should a GUI display for this node/field combo.
protected void	getVwmTasks() Task scheduling routine.
MMObjectNode	preCommit(MMObjectNode node) This method is called just before an actual write to the database is performed.
void	run() VWM maintenance scheduler.
void	start() Starts the thread for the task scheduler
void	stop() Stops the thread for the task scheduler Sets the kicker field to null, which causes the run method to terminate.

Methods inherited from class org.mmbase.module.core.MMObjectBuilder

addField, addLocalObserver, addRemoteObserver, buildSet, checkAddTmpField, commit, convertMMNode2SQL, count, create, createAlias, created, deleteNodeCache, drop, equals, equals, executeFunction, executeFunction, fieldLocalChanged, getAge, getAliasedNode, getAncestors, getCacheNumbers, getCacheSize, getCacheSize, getClassName, getConfigFile, getDBByte, getDBKey, getDBState, getDBText, getDBType, getDefaultTeaser, getDefaultUrl, getDescendants, getDescription, getDescription, getDescriptions, getEditFields, getField, getFieldNames, getFields, getFields, getFullTableName, getFunctionParameters, getHardNode, getHardNode, getHTML, getInitParameter, getInitParameters, getList, getLocaleGUIIndicator, getLocaleGUIIndicator, getMachineName, getMaintainer, getNewNode, getNewTmpNode, getNextField, getNextField, getNode, getNode, getNode, getNode, getNodes, getNodeType, getNumberFromName, getObjectType, getObjectValue, getParentBuilder, getPluralName, getPluralName, getPluralNames, getQuery, getQuery, getQuery, getRelations_main, getSearchAge, getShort, getShortedByte, getShortedText, getSingularName, getSingularName, getSingularNames, getSmartPath, getSortedFields, getSortedListFields, getTableName, getTmpNode, getURLEncode, getValue, getVersion, getWAP, getXMLPath, hashCode, hostname_function, init, insert, insert, insertDone, isExtensionOf, isNodeCached, isVirtual, nodeLocalChanged, nodeRemoteChanged, preEdit, process, putTmpNode, readSearchResults, removeField, removeNode, removeRelations, removeTmpNode, replace, safeCache, safeCommit, safeInsert, search, search, search, searchIn, searchIn, searchIn, searchList, searchList, searchNumbers, searchVector, searchVector, searchVector, searchVector, searchVectorIn, searchVectorIn, searchVectorIn, searchVectorIn, searchWithWhere, sendFieldChangeSignal, setDBLayout_xml, setDefaults, setDescription, setDescriptions, setInitParameter, setMaintainer, setMMBase, setParentBuilder, setPluralNames, setSearchAge, setSingularNames, setTableName, setValue, setValue, setVersion, setXMLPath, setXMLValues, signalNewObject, testValidData, toString, toString, toXML, updateFields, waitUntilNodeChanged, wrap

Methods inherited from class org.mmbase.module.core.MMTable

size

Methods inherited from class java.lang.Object

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

Field Detail

STATUS_REQUEST

public static final int STATUS_REQUEST

Status value for a task that requests to be performed

STATUS_CLAIMED

public static final int STATUS_CLAIMED

Status value for a task that is being performed

STATUS_DONE

public static final int STATUS_DONE

Status value for a task that was succesfully performed

STATUS_TIMEOUT

public static final int STATUS_TIMEOUT

Status value for a task that timed out

STATUS_ERROR

public static final int STATUS_ERROR

Status value for a task that failed to be performed

SLEEP_TIME

public static final int SLEEP_TIME

The interval (in seconds) between checks for new nodes by the task scheduler.

replaceCache

public boolean replaceCache

Constructor Detail

Vwmtasks

public Vwmtasks()

Method Detail

start

public void start()

Starts the thread for the task scheduler

stop

public void stop()

Stops the thread for the task scheduler Sets the kicker field to null, which causes the run method to terminate.

run

public void run()

VWM maintenance scheduler. Calls the getVwmTasks() method, after which the thread sleeps for a number of seconds as set in SLEEP_TIME.

Specified by:

run in interface java.lang.Runnable

preCommit

public MMObjectNode preCommit(MMObjectNode node)

This method is called just before an actual write to the database is performed. It sets the last changed time to the current time (so the scheduler will select this node).

Overrides:

preCommit in class MMObjectBuilder

Parameters:

node - The node to be committed.

Returns:

the node to be committed (after changes have been made).

getGUIIndicator

public java.lang.String getGUIIndicator(MMObjectNode node)

What should a GUI display for this node. Returns the contents of the task field (the task's description).

Overrides:

getGUIIndicator in class MMObjectBuilder

Parameters:

node - The node to display

Returns:

the display of the node as a String

getGUIIndicator

public java.lang.String getGUIIndicator(java.lang.String field,
                                        MMObjectNode node)

What should a GUI display for this node/field combo. Returns a descriptive text for the status field, or a formatted date struing in case of a time-value.

Overrides:

getGUIIndicator in class MMObjectBuilder

Parameters:

node - The node to display

field - the name field of the field to display

Returns:

the display of the node's field as a String, null if not specified

getVwmTasks

protected void getVwmTasks()

Task scheduling routine. This routine selects all tasks that are to be performed. In order to be selected, a task should be new or recently changed, it's status should indicate that it needs a request, and the desired machine to execute the code should match this machine. The tasks are passed to the VWM that is associated with the task.