Created question in FIWARE Q/A platform on 06-12-2015 at 15:12
Please, ANSWER this question AT http://stackoverflow.com/questions/34118219/orion-context-broker-delivery-guarantees

Question:
Orion Context Broker delivery guarantees?

Description:
Thinking of 'production' usage of Orion Context Broker, I wonder what kind of guarantees are provided by the Orion Context Broker in terms of delivery of messages – both from producer and consumer perspective? In particular, keeping in mind various possible failure scenarios (CB failure/restart, network transient failure, consumer failure/restart, etc), as well as possibility of resource congestion in the CB. Few examples:

1) if a context update operation succeeds, is it guaranteed that consequent queries will return the latest data (e.g., even if CB failed right after acknowledging the update request, and then restarted)?

2) if a consumer subscribed for certain context information, is it guaranteed that it will receive all the relevant updates – exactly once, at least once, or even at all? (e.g., in case of transient network failure between CB and the consumer)

3) if a consumer updated its subscription, is it guaranteed that the consequent updates will accurately reflect it? (e.g., if CB failed right after acknowledging the subscription request, and then restarted)

4) if a consumer is subscribed for context changes ('onchange', no throttling), and there are multiple consequent updates from the producer affecting the same attribute, is it guaranteed that each of the changes will be sent (or some might be skipped – e.g., due to too many notifications that CB needs to send during a certain period of time), in any particular order?

etc...

Thanks!