Non-blocking APIs
The client of a non-blocking API gets the results without being blocked for a significant amount of time, thus allowing the client to do something else during the period when the results are being prepared. So, the notion of a non-blocking API implies a highly responsive application. The processing of the request (that is, getting the results) can be done synchronously or asynchronously – it does not matter to the client. In practice, though, typically, the application uses asynchronous processing to facilitate an increased throughput and improved performance of the API.
The term non-blocking came into use with the java.nio package. The non-blocking input/output (NIO) provides support for intensive input/output (I/O) operations. It describes how the application is implemented: it does not dedicate an execution thread to each of the requests but provides several lightweight worker threads that do the processing asynchronously and concurrently.
