DDD is Domain-Driven Design , it is a methodology that include ubiquitous language, root entity , value object and aggregations..
DCI: Data, Context, Interactions is a programming paradigm invented by Trygve Reenskaug.
how can I combine with them in a new system?
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If you read through this https://msdn.microsoft.com/en-us/library/jj554200.aspx I believe the DCI notion of a "context" would be synonymous with a "process manager". Instead of the process manager calling methods on the aggregates, it would apply roles to the aggregates and coordinate using those. A "bounded context" could have several "process managers" aka "contexts". What do you think?
This is a subject of on going discussion, and something you'll probably find better answers to at the object-composition Google group where it has been discussed earlier. Also there is an effort to port the canonical DDD sample to DCI at the DCI github page.
Long story overly short though: DCI fits within a Bounded Context, where you'd then have a DCI context per use case.