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xmlBlaster 2.2.0 API | |||||||||
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java.lang.Object org.xmlBlaster.contrib.mime.DropIfNotDeliverableUniqueOnly
public class DropIfNotDeliverableUniqueOnly
Sometimes we need to support this subscribe pattern: A client only wants the newest message with this details:
- Initial connect and subscribe: send current newest (or given history depth) - If it is online it is a normal subscription - If it is offline don't add messages to callback queue - If it comes online again check if current message was delivered, if not send it initially (if redeliverNewestOnReconnect==false which is default; else on reconnect the newest is always send. Note: You can't use both variants simultaneously as it operates on the session Map)
If a client callback goes to polling, this plugin removes all existing subscriptions.
The client needs to add a filter Qos to its SubscribeQos to activate the plugin.
and needs to re-subscribe on relogin if desired.
The message uniqueness is checked per topic, but if you pass a client property "_uniqueGroupId" this is used to check uniqueness: Messages with the same "_uniqueGroupId" value are compared to decide if delivered already. This is like a sub-group of the topic and is for your convenience only as it could be solved by having a separate topic for each "_uniqueGroupId".
This makes only sense if the client is operating in fail save mode (-dispatch/callback/retries -1) and reconnects with the same publicSessionId > 0 (-session.name jack/session/1) so that its session is found again.
Configuration example (put to xmlBlaster.properties):
MimeAccessPlugin[DropIfNotDeliverableUniqueOnly][1.0]=\ org.xmlBlaster.contrib.mime.DropIfNotDeliverableUniqueOnly,dropper.types=*,uniqueGroupIdKeyName=_myuniqueGroupIddropper.types=* is default and activates the plugin for any published message where a subscriber has set this filter,
<qos> <multiSubscribe>false</multiSubscribe> <local>false</local> <initialUpdate>false</initialUpdate> <updateOneway>false</updateOneway> <notify>false</notify> <persistent>false</persistent> <filter type='DropIfNotDeliverableUniqueOnly'> <![CDATA[_]]> </filter> </qos>
The query statement '_' is ignored by this plugin.
This plugin is a singleton and loaded once only for multiple subscribers configuring it
Example to try on command line
export CLASSPATH=$XMLBLASTER_HOME/lib/xmlBlaster.jar Start the server: java org.xmlBlaster.Main Start a sniffer GUI to see what happens: cd ~/xmlBlaster build SimpleReader Start the subscriber which wants the newest and unique message only: java javaclients.HelloWorldSubscribe -session.name subscriber/session/1 -disconnect false -multiSubscribe false -initialUpdate true -unSubscribe false -dispatch/callback/retries -1 -filter.type DropIfNotDeliverableUniqueOnly -filter.query _ (Avoid disconnect as it cleans up the session) (example to get first ten of history: -historyNumUpdates 10 -historyNewestFirst false) Start the publisher for two groupIds: java javaclients.HelloWorldPublish -clientProperty[_uniqueGroupId] weather.south
Field Summary | |
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private Global |
glob
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private static java.util.logging.Logger |
log
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private java.lang.String |
ME
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static java.lang.String |
MIME_TYPES
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private java.lang.String[] |
mimeTypes
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private PluginInfo |
pluginInfo
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private boolean |
redeliverNewestOnReconnect
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private java.lang.String |
uniqueGroupIdKeyName
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Constructor Summary | |
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DropIfNotDeliverableUniqueOnly()
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Method Summary | |
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java.lang.String[] |
getMimeExtended()
Get the content MIME version number for which this plugin applies |
java.lang.String[] |
getMimeTypes()
Get the content MIME type for which this plugin applies, currently { "*" }. |
java.lang.String |
getName()
Get a human readable name of this filter implementation |
java.lang.String |
getType()
Return plugin type for Plugin loader |
java.lang.String |
getVersion()
Return plugin version for Plugin loader |
void |
init(Global glob,
PluginInfo pluginInfo)
This method is called by the PluginManager (enforced by I_Plugin). |
void |
initialize(ServerScope serverScope)
This is called after instantiation of the plugin |
boolean |
match(SessionInfo receiver,
MsgUnit msgUnit,
Query query)
Check if the filter rule matches for this message. |
void |
shutdown()
Cleans up the resource. |
void |
toAlive(I_DispatchManager dispatchManager,
ConnectionStateEnum oldState)
|
void |
toAliveSync(I_DispatchManager dispatchManager,
ConnectionStateEnum oldState)
|
void |
toDead(I_DispatchManager dispatchManager,
ConnectionStateEnum oldState,
XmlBlasterException xmlBlasterException)
|
void |
toPolling(I_DispatchManager dispatchManager,
ConnectionStateEnum oldState)
|
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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private final java.lang.String ME
private Global glob
private static java.util.logging.Logger log
private java.lang.String[] mimeTypes
private PluginInfo pluginInfo
public static final java.lang.String MIME_TYPES
private java.lang.String uniqueGroupIdKeyName
private boolean redeliverNewestOnReconnect
Constructor Detail |
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public DropIfNotDeliverableUniqueOnly()
Method Detail |
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public void initialize(ServerScope serverScope)
initialize
in interface I_AccessFilter
glob
- The Global handle of this xmlBlaster server instance.public void init(Global glob, PluginInfo pluginInfo) throws XmlBlasterException
init
in interface I_Plugin
XmlBlasterException
I_Plugin.init(org.xmlBlaster.util.Global,org.xmlBlaster.util.plugin.PluginInfo)
public java.lang.String getType()
getType
in interface I_Plugin
public java.lang.String getVersion()
getVersion
in interface I_Plugin
public java.lang.String getName()
getName
in interface I_AccessFilter
public java.lang.String[] getMimeTypes()
getMimeTypes
in interface I_AccessFilter
public java.lang.String[] getMimeExtended()
getMimeExtended
in interface I_AccessFilter
public boolean match(SessionInfo receiver, MsgUnit msgUnit, Query query) throws XmlBlasterException
I_AccessFilter
Note that you are not allowed to manipulate the content or XmlKey or QoS of a message with your plugin as this would affect all other subscribers (you are working on a reference to the original message). You can find out the publisher name like msgUnit.getQosData().getSender()
match
in interface I_AccessFilter
receiver
- The session object describing the receiver, is never null.msgUnit
- The message to check, is never null.query
- The query containing the filter rule on subscribe/get usually
the client defines his own rule which is passed here.XmlBlasterException
- Is thrown on problems, for example if the MIME type
does not fit to message content.public void shutdown()
I_Plugin
shutdown
in interface I_AccessFilter
shutdown
in interface I_Plugin
public void toAlive(I_DispatchManager dispatchManager, ConnectionStateEnum oldState)
toAlive
in interface I_ConnectionStatusListener
public void toAliveSync(I_DispatchManager dispatchManager, ConnectionStateEnum oldState)
toAliveSync
in interface I_ConnectionStatusListener
public void toDead(I_DispatchManager dispatchManager, ConnectionStateEnum oldState, XmlBlasterException xmlBlasterException)
toDead
in interface I_ConnectionStatusListener
xmlBlasterException
- Can be nullpublic void toPolling(I_DispatchManager dispatchManager, ConnectionStateEnum oldState)
toPolling
in interface I_ConnectionStatusListener
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