Type	NEW
Priority	HIGH
Status	CLOSED

Topic	State charts and configuration of message and topic lifecycles
Des cription	In xmlBlaster we define a topic as a single key oid whereas a message instances are the single messages published (probably with identical oid). The message instances build a history queue of a topic. Message lifecycle overview Every message key oid defines a topic. You publish any number of messages with the same oid, those MsgUnit instances are distinguished by the unique receive timestamp. The messages are queryable from the history queue. The history queue only contains references to the real messageUnit. Every subscription puts a reference of a messageUnit into the client specific callback queue, from where the messages are sent to the client. The real messageUnit (the meat) is handled by the cache implementation. The pointers on the cache entries are reference counted. If no weak reference exists anymore the cache entry is destroyed. If a cache entry is swapped to harddisk, the weak references are set to null by the Java virtual machine. In this case, the access forces a lookup and the message is swapped back to the cache. The logical states of a topic (= messages with same key oid) The above states break down to internal conditions. Internal conditions of a topic: state Is visible? XPATH queries are possible has BigXmlDom entry Referenced by history queue Referenced by callback queue Has EXACT subscriptions (*) alive true true true true alive true true true false alive true true false true alive true true false false alive true false true true alive true false true false alive true false false true unreferenced true false false false invalid false true true true invalid false true true false invalid false true false true invalid false true false false invalid false false true true softErased false false true false unconfigured false false false true start/dead false false false false (*) XPATH subscriptions don't prevent the topic from going to DEAD Possible states of a message instance:
Configure	The configuration of topics and messages are done by publishing a message and setting certain publish QoS tags: NOTE: Configuration parameters are specified on command line (-someValue 17) or in the xmlBlaster.properties file (someValue=17). See requirement "util.property" for details. Columns named Impl tells you if the feature is implemented. Columns named Hot tells you if the configuration is changeable in hot operation.
See API	org.xmlBlaster.util.qos.MsgQosSaxFactory
See REQ	interface.publish
See REQ	engine.message
See TEST	org.xmlBlaster.test.topic.TestTopicLifeCycle

This page is generated from the requirement XML file xmlBlaster/doc/requirements/engine.message.lifecycle.xml

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