Prior to product version 1.17, MDM operations supported bulk processing of records only; typically on a batch schedule and for many implementations this works perfectly fine. However the ability to process individual records was missing. For example where data integration is transactional (via ESB etc.) it is often desirable to normalise, match and merge records as they arrive and not wait until the next batch cycle.
The new Real-time MDM Actions introduced in product version 1.17 provide support for exactly this use case and allow individual MDM operations to be invoked via Process Builder or via the REST API. Further to this Visual Workflow (or Force.com Flow) can be used to orchestrate processing across multiple actions in line with custom business logic – such Flows can then be exposed via the REST API as custom flow actions.