anon.infoservice
Class Database

java.lang.Object
  java.util.Observable
      anon.infoservice.Database

All Implemented Interfaces:

anon.util.IXMLEncodable

public final class Database
extends java.util.Observable
implements anon.util.IXMLEncodable

This class is the generic implementation of a database. It is used by the database implementations for the different services. It is also a registry for all databases used in the context of this application. Instances of this class are observable. Observers of the instances are notified, if an entry is added, renewed or removed from the database or if the whole database is cleared. The observers will always get a DatabaseMessage object as the argument of the update() method. The DatabaseMessage will identify the reason of the notification, see the DatabaseMessage class for more information.

Nested Class Summary

static interface

Database.IWebInfo

Field Summary

Fields inherited from interface anon.util.IXMLEncodable

FIELD_XML_ELEMENT_CONTAINER_NAME, FIELD_XML_ELEMENT_NAME, XML_ATTR_ID, XML_ATTR_LANGUAGE, XML_ATTR_VERSION

Method Summary

void	addObserver(java.util.Observer a_observer) Adds an observer to this database.
static org.w3c.dom.Document	dumpToXML(java.lang.Class[] classesToDump)
AbstractDatabaseEntry	getEntryById(java.lang.String entryId) Returns the DatabaseEntry with the given ID.
java.lang.Class	getEntryClass() Returns the DatabaseEntry class for that this Database is registered.
java.util.Hashtable	getEntryHash()
java.util.Vector	getEntryList() Returns a snapshot of all values in the serviceDatabase.
java.util.Enumeration	getEntrySnapshotAsEnumeration() Returns a snapshot of all entries in the Database as an Enumeration.
static Database	getInstance(java.lang.Class a_DatabaseEntryClass) Gets the Database for the specified database entries.
int	getNumberOfEntries() Returns the number of DatabaseEntries in the Database.
AbstractDatabaseEntry	getRandomEntry() Returns a random entry from the database.
java.util.Vector	getSortedEntryList(anon.util.Util.Comparable c)
int	getTimeoutListSize()
org.w3c.dom.Document	getWebInfos()
org.w3c.dom.Document	getWebInfos(java.lang.String a_ID)
boolean	isEntryIdInTimeoutList(java.lang.String a_entryId)
static void	loadFromExternalDatabase_int()
static void	loadFromExternalDatabase()
int	loadFromXml(org.w3c.dom.Element a_dbNode) Adds all database entries that are subnodes of the given element to the database.
int	loadFromXml(org.w3c.dom.Element a_dbNode, boolean a_bVerify) Adds all database entries that are subnodes of the given element to the database.
static void	registerDistributor(IDistributor a_distributor) Registers a distributor that forwards new database entries.
static boolean	registerExternalDatabase(java.lang.String a_driverName, java.lang.String a_dbURL)
boolean	remove(AbstractDatabaseEntry a_deleteEntry) Removes an entry from the database.
boolean	remove(java.lang.String a_entryID) Removes an entry from the database.
void	removeAll() Removes all entries from the database.
static void	restoreFromXML(org.w3c.dom.Document xmlAllDBs, java.lang.Class[] classesToRestore)
static void	shutdownDatabases()
org.w3c.dom.Element	toXmlElement(org.w3c.dom.Document a_doc) If the entries of this database implement IXMLEncodable and has a proper value for the field XML_ELEMENT_CONTAINER_NAME, this database is transformed into an XML element.
org.w3c.dom.Element	toXmlElement(org.w3c.dom.Document a_doc, java.lang.String a_xmlContainerName) Creates an XML node with all database entries, but only for those entries that implement IXMLEncodable.
boolean	update(AbstractDatabaseEntry newEntry) Updates an entry in the database.
boolean	update(AbstractDatabaseEntry newEntry, boolean a_bDistribute) Updates an entry in the database.

Methods inherited from class java.util.Observable

clearChanged, countObservers, deleteObserver, deleteObservers, hasChanged, notifyObservers, notifyObservers, setChanged

Methods inherited from class java.lang.Object

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

Method Detail

registerDistributor

public static void registerDistributor(IDistributor a_distributor)

Registers a distributor that forwards new database entries.

Parameters:

a_distributor - a distributor that forwards new database entries

registerExternalDatabase

public static boolean registerExternalDatabase(java.lang.String a_driverName,
                                               java.lang.String a_dbURL)

getInstance

public static Database getInstance(java.lang.Class a_DatabaseEntryClass)
                            throws java.lang.IllegalArgumentException

Gets the Database for the specified database entries. Creates the Database if it does not exist already.

Parameters:

a_DatabaseEntryClass - the DatabaseEntry class for that the method returns the corresponding Database object

Returns:

the Database object that contains DatabaseEntries of the specified type

Throws:

java.lang.IllegalArgumentException - if the argument is no valid DatabaseEntry class

restoreFromXML

public static void restoreFromXML(org.w3c.dom.Document xmlAllDBs,
                                  java.lang.Class[] classesToRestore)

dumpToXML

public static org.w3c.dom.Document dumpToXML(java.lang.Class[] classesToDump)

shutdownDatabases

public static void shutdownDatabases()

update

public boolean update(AbstractDatabaseEntry newEntry)
               throws java.lang.IllegalArgumentException

Updates an entry in the database. If the entry is an unknown or if it is newer then the one stored in the database for this service, the new entry is stored in the database and forwarded to all neighbour infoservices.

Parameters:

newEntry - The database entry to update.

Returns:

if the database has been changed

Throws:

java.lang.IllegalArgumentException - if the database entry is not of the type the Database can store

update

public boolean update(AbstractDatabaseEntry newEntry,
                      boolean a_bDistribute)
               throws java.lang.IllegalArgumentException

Updates an entry in the database. If the entry is an unknown or if it is newer then the one stored in the database for this service, the new entry is stored in the database and forwarded to all neighbour infoservices.

Parameters:

newEntry - The database entry to update.

a_bDistribute - distribute to other InfoServices if distributor object is set; should be default

Returns:

if the database has been changed

Throws:

java.lang.IllegalArgumentException - if the database entry is not of the type the Database can store

getEntryClass

public java.lang.Class getEntryClass()

Returns the DatabaseEntry class for that this Database is registered.

Returns:

the DatabaseEntry class for that this Database is registered

remove

public boolean remove(java.lang.String a_entryID)

Removes an entry from the database.

Parameters:

a_entryID - The ID of the entry to remove. If it is not in the database, nothing is done.

Returns:

if the database has been changed

remove

public boolean remove(AbstractDatabaseEntry a_deleteEntry)

Removes an entry from the database.

Parameters:

a_deleteEntry - The entry to remove. If it is not in the database, nothing is done.

Returns:

if the database has been changed

removeAll

public void removeAll()

Removes all entries from the database.

loadFromXml

public int loadFromXml(org.w3c.dom.Element a_dbNode)

Adds all database entries that are subnodes of the given element to the database. The class must have a constructor with a single argument, a org.w3c.dom.Element, so that this is successful.

Parameters:

a_dbNode - The xml node that contains db entries.

Returns:

number of updated entries

loadFromXml

public int loadFromXml(org.w3c.dom.Element a_dbNode,
                       boolean a_bVerify)

Adds all database entries that are subnodes of the given element to the database. The class must have a constructor with a single argument, a org.w3c.dom.Element, so that this is successful.

Parameters:

a_dbNode - The xml node that contains db entries.

a_signatureDocumentClass - if set to a value greater -1, the document is verified against certificates of the given class before getting loaded

Returns:

number of updated entries

toXmlElement

public org.w3c.dom.Element toXmlElement(org.w3c.dom.Document a_doc)

If the entries of this database implement IXMLEncodable and has a proper value for the field XML_ELEMENT_CONTAINER_NAME, this database is transformed into an XML element.

Specified by:

toXmlElement in interface anon.util.IXMLEncodable

Parameters:

a_doc - a Document

Returns:

the database as XML Element or null if transformation was not possible

toXmlElement

public org.w3c.dom.Element toXmlElement(org.w3c.dom.Document a_doc,
                                        java.lang.String a_xmlContainerName)

Creates an XML node with all database entries, but only for those entries that implement IXMLEncodable.

Parameters:

a_doc - The XML document, which is the environment for the created XML node.

a_xmlContainerName - the name of the XML element that should contain the entries

Returns:

the newly created XML node.

getEntryHash

public java.util.Hashtable getEntryHash()

getEntryList

public java.util.Vector getEntryList()

Returns a snapshot of all values in the serviceDatabase.

Returns:

A Vector with all values which are stored in the serviceDatabase.

getSortedEntryList

public java.util.Vector getSortedEntryList(anon.util.Util.Comparable c)

getEntrySnapshotAsEnumeration

public java.util.Enumeration getEntrySnapshotAsEnumeration()

Returns a snapshot of all entries in the Database as an Enumeration.

Returns:

a snapshot of all entries in the Database as an Enumeration

getNumberOfEntries

public int getNumberOfEntries()

Returns the number of DatabaseEntries in the Database.

Returns:

the number of DatabaseEntries in the Database

getEntryById

public AbstractDatabaseEntry getEntryById(java.lang.String entryId)

Returns the DatabaseEntry with the given ID. If there is no DatabaseEntry with this ID is in the database, null is returned.

Parameters:

entryId - The ID of the database entry.

Returns:

The entry with the specified ID or null, if there is no such entry.

getRandomEntry

public AbstractDatabaseEntry getRandomEntry()

Returns a random entry from the database. If there are no entries in the database, null is returned.

Returns:

A random entry from the database or null, if the database is empty.

addObserver

public void addObserver(java.util.Observer a_observer)

Adds an observer to this database. The observer will obtain an initial message including a snapshot of the current database (this message is also sent, if the observer was already observing the database).

Overrides:

addObserver in class java.util.Observable

Parameters:

a_observer - The observer to add to this database.

isEntryIdInTimeoutList

public boolean isEntryIdInTimeoutList(java.lang.String a_entryId)

getTimeoutListSize

public int getTimeoutListSize()

getWebInfos

public org.w3c.dom.Document getWebInfos(java.lang.String a_ID)

getWebInfos

public org.w3c.dom.Document getWebInfos()

loadFromExternalDatabase

public static void loadFromExternalDatabase()

loadFromExternalDatabase_int

public static void loadFromExternalDatabase_int()
                                         throws java.sql.SQLException

Throws:

java.sql.SQLException