Duplicate Detection Methods for a webMethods Messaging Trigger
Integration Server ensures exactly-once processing by performing duplicate detection and by providing the ability to retry trigger services. Duplicate detection determines whether the current document is a copy of one previously processed by the webMethods messaging trigger. Duplicate documents can be introduced in to the webMethods system when:
The publishing client publishes the same document more than once.
During publishing or retrieval of guaranteed documents, the sending resource loses connectivity to the destination resource before receiving a positive acknowledgement for the document. The sending resource will redeliver the document when the connection is restored.
Note: Exactly-once processing and duplicate detection are performed for guaranteed documents only.
Integration Server uses duplicate detection to determine the document’s status. The document status can be one of the following:
New. The document is new and has not been processed by the
webMethods messaging trigger.
Duplicate. The document is a copy of one already processed the
webMethods messaging trigger.
In Doubt. Integration Server cannot determine the status of the document. The
webMethods messaging trigger may or may not have processed the document before.
To resolve the document status, Integration Server evaluates, in order, one or more of the following:
Redelivery count indicates how many times the transport has redelivered the document to the
webMethods messaging trigger.
Document history database maintains a record of all guaranteed documents processed by
webMethods messaging triggers for which exactly-once processing is configured.
Document resolver service is a service created by a user to determine the document status. The document resolver service can be used instead of or in addition to the document history database.
The steps that
Integration Server performs to determine a document’s status depend on the exactly-once properties configured for the subscribing trigger. For more information about configuring exactly-once properties, see
Configuring Exactly-Once Processing
for a webMethods Messaging Trigger
.
Note: For detailed information about exactly-once processing for webMethods messaging triggers, see Publish-Subscribe Developer’s Guide.
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