Editing Message passing (section)

===Hybrids===
Synchronous communication can be built on top of asynchronous communication by using a [[Synchronizer (algorithm)|Synchronizer]]. For example, the α-Synchronizer works by ensuring that the sender always waits for an acknowledgement message from the receiver. The sender only sends the next message after the acknowledgement has been received. On the other hand, asynchronous communication can also be built on top of synchronous communication. For example, modern [[microkernel]]s generally only provide a [[Microkernel#Inter-process communication|synchronous messaging]] primitive{{Citation needed|date=April 2015}} and asynchronous messaging can be implemented on top by using [[Thread (computing)|helper threads]].