Data communications may be carried out in a distributed computing environment that includes computers coupled for data communications through communications adapters and an active messaging interface (‘AMI’). Such data communications may be carried out by: issuing, by a sender to a receiver, an eager SEND data communications instruction to transfer SEND data, the instruction including information describing data location at the sender and data size; transmitting, by the sender to the receiver, the SEND data as eager data packets; discarding, by the receiver in dependence upon data flow conditions, eager data packets as they are received from the sender; and transferring, in dependence upon the data flow conditions, by the receiver from the sender's data location to a receive buffer by remote direct memory access (“RDMA”), the SEND data.