Chapter 25. Configuring Duplicate Message Detection

To enable duplicate message detection for sent messages, you need to set the value of the org.apache.activemq.artemis.api.core.Message.HDR_DUPLICATE_DETECTION_ID property, which resolves to _AMQ_DUPL_ID, to a unique value. When the target server receives the messages, if the _AMQ_DUPL_ID property is set, it will check its memory cache to see if it has already received a message with the value of that header. If it has, then this message will be ignored. See Configuring the Duplicate ID Cache for more information.

The value of the _AMQ_DUPL_ID property can be of type byte[] or SimpleString if you are using the core API. If you are using JMS, it must be a String.

The following example shows how to set the property for core API.

SimpleString myUniqueID = "This is my unique id";   // Can use a UUID for this

ClientMessage message = session.createMessage(true);
message.setStringProperty(HDR_DUPLICATE_DETECTION_ID, myUniqueID);

SimpleString myUniqueID = "This is my unique id";   // Can use a UUID for this

ClientMessage message = session.createMessage(true);
message.setStringProperty(HDR_DUPLICATE_DETECTION_ID, myUniqueID);

The following example shows how to set the property for JMS clients.

String myUniqueID = "This is my unique id";   // Can use a UUID for this

Message jmsMessage = session.createMessage();
message.setStringProperty(HDR_DUPLICATE_DETECTION_ID.toString(), myUniqueID);

String myUniqueID = "This is my unique id";   // Can use a UUID for this

Message jmsMessage = session.createMessage();
message.setStringProperty(HDR_DUPLICATE_DETECTION_ID.toString(), myUniqueID);

The server maintains caches of received values of the _AMQ_DUPL_ID property that is sent to each address. Each address maintains its own address cache.

The cache is fixed in terms of size. The maximum size of cache is configured using the id-cache-size attribute. The default value of this parameter is 20000 elements. If the cache has a maximum size of n elements, then the (n + 1)th ID stored will overwrite the element 0 in the cache. The value is set using the following management CLI command:

/subsystem=messaging-activemq/server=default:write-attribute(name=id-cache-size,value=SIZE)

/subsystem=messaging-activemq/server=default:write-attribute(name=id-cache-size,value=SIZE)

The caches can also be configured to persist to disk. This can be configured by setting the persist-id-cache attribute using the following management CLI command.

/subsystem=messaging-activemq/server=default:write-attribute(name=persist-id-cache,value=true)

/subsystem=messaging-activemq/server=default:write-attribute(name=persist-id-cache,value=true)

If this value is set to true, then each ID will be persisted to permanent storage as they are received. The default value for this parameter is true.