Hi, Storm does only guarantee exactly once *within* the system. If you write to an external consumer you need to ensure that writes are idempotent or de-duplicate externally.
About Tridents internals, start to read the documentation here: https://storm.apache.org/documentation/Transactional-topologies.html If you have further questions, don't hesitate to follow up on this thread. -Matthias On 01/12/2016 06:26 AM, Ajay wrote: > Hi, > > We are evaluating storm with Trident to process events from Kafka in an > exactly once manner so that the consumer application need not worry > about the de-duplication logic. > > > One of the sample use case could be as below: > > 1) Read an event from Kafka > 2) Parse the JSON > 3) Process the data > 4) Write it to dynamo db and Apache solr > > So I want to understand how does the Trident handles exactly once > semantics when the processing updates one or more distributed systems > like in this case. What happens if write to one of them fails. > > Also wish to know the implementation details of how Trident supports > exactly once semantics. > > Thanks > Ajay
signature.asc
Description: OpenPGP digital signature
