abs.ixi.client.io

Class DefaultPersistenceMechanism

java.lang.Object

abs.ixi.client.io.DefaultPersistenceMechanism

All Implemented Interfaces:

UndeliveredStanzaManager.PersistenceMechanism

public class DefaultPersistenceMechanism
extends Object
implements UndeliveredStanzaManager.PersistenceMechanism

Default implementation of UndeliveredStanzaManager.PersistenceMechanism interface. User packets generated on a client are queued up and marked delivered only when a ACK is received from the server. The packets for which ACK has been received are removed from the queue. Typically, when underlying network connection is broken ACK packets are not recceived; if ACK is not received from the server witin stipulated time, the SDK will try to resend undelivered packets to server.

While undelieverd packets are queued up in writer's queue, it may happen that SDK is off-loaded from memory (there could be many possible reasons such as power failure on underlying device, application was killed forcefully, device shutdown, application may crash due to a programming bug etc) and if the SDK is off-loaded from memory, undelivered message queues will be wiped out too. Therefore it is importatnt to persist undelivered messsages to avoid message loss.

XMPP as a protocol does not recommend a mechanism to avoid undelievred message loss. However Stringflow SDK provides a default mechanism to persist undelivered messages on to a file. This class is the default implementation in which message are written on to a file. The packets are serialized before getting written to a file. It is application developer's responsibility to ensure that SDK has enough permissions to be able to create/write file on the underlying file system.

UndeliveredStanzaManager.PersistenceMechanism is an injectable interface; application developers can inject an implementation of UndeliveredStanzaManager.PersistenceMechanism interface which, instead of DefaultPersistenceMechanism, will be used to persist packets.

Author:

Yogi

Constructor Summary

Constructors

Constructor and Description
DefaultPersistenceMechanism(String dirPath) Instantiate DefaultPersistenceMechanism object with a directory path in which files will be created.

Method Summary

Modifier and Type	Method and Description
List<Stanza>	readAll() Read all the stanzas from persistent store and delete them.
void	remove(int count) Remove number of stanza from persistent store.
void	truncateUndeliverStanzas() Delete All stanzas from store.
void	write(List<Stanza> stanzas) Write a stanza to persistent store.
void	write(Stanza stanza) Write a stanza to persistent store.

Methods inherited from class java.lang.Object

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

Constructor Detail

DefaultPersistenceMechanism

public DefaultPersistenceMechanism(String dirPath)
                            throws Exception

Instantiate DefaultPersistenceMechanism object with a directory path in which files will be created. If the given path name does not exist, a directory representing the path will be created. If the given path name exist but represents a regualr file not a directory a FileNotFoundException exception will be thrown.

Parameters:

dirPath - directory path on the file system in which data files will be stored. The may or may not exist; it could be relative or absolute path

Throws:

Exception - if there is permission issue or any other error while setting up the files and directories

Method Detail

write

public void write(Stanza stanza)
           throws IOException

Description copied from interface: UndeliveredStanzaManager.PersistenceMechanism

Write a stanza to persistent store. It is recommended that stanza packets are serialized before writting them to the persistent store.

Specified by:

write in interface UndeliveredStanzaManager.PersistenceMechanism

Parameters:

stanza - stanza

Throws:

IOException - IOException

write

public void write(List<Stanza> stanzas)
           throws IOException

Description copied from interface: UndeliveredStanzaManager.PersistenceMechanism

Write a stanza to persistent store. It is recommended that stanza packets are serialized before writting them to the persistent store.

Specified by:

write in interface UndeliveredStanzaManager.PersistenceMechanism

Parameters:

stanzas - stanzas

Throws:

IOException - IOException

remove

public void remove(int count)
            throws IOException

Description copied from interface: UndeliveredStanzaManager.PersistenceMechanism

Remove number of stanza from persistent store.

Specified by:

remove in interface UndeliveredStanzaManager.PersistenceMechanism

Parameters:

count - stanzaCount

Throws:

IOException - IOException

readAll

public List<Stanza> readAll()
                     throws IOException

Description copied from interface: UndeliveredStanzaManager.PersistenceMechanism

Read all the stanzas from persistent store and delete them.

Specified by:

readAll in interface UndeliveredStanzaManager.PersistenceMechanism

Returns:

List list

Throws:

IOException - IOException

truncateUndeliverStanzas

public void truncateUndeliverStanzas()

Description copied from interface: UndeliveredStanzaManager.PersistenceMechanism

Delete All stanzas from store.

Specified by:

truncateUndeliverStanzas in interface UndeliveredStanzaManager.PersistenceMechanism