A stream of messages to be read. Messages can be awaited await reader.MoveNext(), that returns true if there is a message available and false if there are no more messages (i.e. the stream has been closed).

On the client side, the last invocation of MoveNext() either returns false if the call has finished successfully or throws RpcException if call finished with an error. Once the call finishes, subsequent invocations of MoveNext() will continue yielding the same result (returning false or throwing an exception).

On the server side, MoveNext() does not throw exceptions. In case of a failure, the request stream will appear to be finished (MoveNext will return false) and the CancellationToken associated with the call will be cancelled to signal the failure.

MoveNext() operations can be cancelled via a cancellation token. Cancelling an individual read operation has the same effect as cancelling the entire call (which will also result in the read operation returning prematurely), but the per-read cancellation tokens passed to MoveNext() only result in cancelling the call if the read operation haven't finished yet.