REST web services: synchronous or asynchrous?

Question

What is the default behavior of REST web services - synchronous or asynchronous?
If it's synchronous then can we create asynchronous?

Answer 1

"Synchronous" or "Asynchronous" is the behaviour of the client that is requesting the resource. It has nothing to do with REST webservice, its structure, or the supporting server.

Synchronous behaviour:

• Client constructs an HTTP structure, sends over the socket connection.
• Waits for the response HTTP.

Asychronous behaviour:

• Client constructs HTTP structure, sends the request, and moves on.
• There's another thread that is waiting on the socket for the response. Once response arrives, the original sender is notified (usually, using a callback like structure).