EMA C++ RDM Usage Guide : 2 Domain Model Overview : 2.6 General Enterprise Message API Concepts : 2.6.1 Snapshot and Streaming Requests
 
2.6.1 Snapshot and Streaming Requests
Many domains generally support issuing a request message with or without setting the ReqMsg.InterestAfterRefresh flag. When the flag is set, the request is known as a “streaming” request, meaning that the refresh will be followed by updates.
When a snapshot request is made, the refresh should have a StreamState of StreamState::NonStreamingEnum. When the final part of the refresh is received, the stream is considered closed (the final refresh is indicated by the RefreshMsg.Complete flag on the RefreshMsg). The consumer should be prepared to receive status messages or update messages between the first and final parts of the refresh (if the domain supplies only single part refresh messages, like Market Price, no updates would be delivered on the stream).
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