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FAQ: In Ultra Messaging, can messages be sent using an event queue?
No. Application messages are not sent using the event queue or encapsulated in source events that are delivered to the application callback.  


Let us take the LBM_SRC_EVENT_SEQUENCE_NUMBER_INFO callback as an example. This source event callback informs the application of the sequence numbers used for a message via the lbm_src_event_sequence_number_info_t_stct​ structure. When an application, which has configured this callback, sends a message, there is a check in the sending sequence to determine if an event queue has been specified. If an event queue is specified (and the source is not a smart source), the necessary information for the sequence number structure is garnered and placed in the event queue. In both cases, messages will be batched and sent on the transport as configured by the application. 

This represents the high-level code flow:


determine the sequence number information ​
if (event queue) {
enqueue the information
} else {
deliver the event to the application callback​
batch the message as needed
send the message on the transport



More Information
Event queues encapsulate data provided to application callbacks.  Unlike the source callback event, the receiver callback can include a pointer to the message that has been retrieved from the transport for the topic (or pattern). 

Applies To
Product: Ultra Messaging
Problem Type: Performance
User Type: Developer
Project Phase: Configure; Implement
Product Version:
Operating System:
Other Software:



Last Modified Date:1/6/2020 5:43 AMID:611742
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