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Pacing or once-only-msg in messaging systems Disclosure Number: IPCOM000239519D
Publication Date: 2014-Nov-13
Document File: 1 page(s) / 27K

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The Prior Art Database


This invention introduce the concept of a "once in group" message. When producing application delivers a series of messages in to the messaging middleware, which are identified as being in a single group, as each message enters the middleware, if there are earlier messages in the group that have yet to be consumed they are removed in preference of the newest message. For each message placed on a queue, if flagged with the "once in group" QoS, the messaging middleware identifies other messages in the group which are already present on the queue/topic and removes those in preference to the newest message.

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Pacing or once-only-msg in messaging systems

Messaging systems provide varying levels of quality-of-service (QoS). The most common being understood as "at least once", "no more than once" and "exactly once". When using a pub/sub paradigm, a number of messaging providers also provide the concept of retained messages in which, per-topic, the latest message is always held for later retrieval by a consuming application, without the need to hold the full history of messages. Retained messaging is often popular for holding the current state of an entity - a popular example being stock prices.

    However, not all applications suit the use of pub/sub and therefore retained. Often extra care needs to be taken when writing consuming applications to realise if the retained message has changed from the last time a retrieval was attempted. Additionally, without the application writers providing additional data within the message, eg sequence numbers, there is no mechanism to identify how many message may have been missed since the last retrieval was attempted.

    Furthermore, in distributed pub/sub environments all copies of retained publications are passed between all messaging engines, which can potentially overload the transmission messages when it is adequate for just the most recent message to arrive.

    Outside of the use of retained pub/sub the existing QoS mechanism available tend to fall in to persistent (each message exactly once) and non-persistent (best effort). Many applications require better than non-persistent so opt for a persistent mechanism, however it is sometimes sufficient that some, or even just one, of the message in some identifiable group be available.

    Introduce the concept of a "once in group" message. When producing application delivers a series of messages in to the messaging middlewa...