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).

Answer 2

@Thrustmaster has explained it well. I just wanted to add a point to make it sound simpler.

REST web service is nothing but an HTTP call. You make a HTTP request to a URL and get a HTTP response back. How to handle the request and response is up to the caller.

Answer 3

REST services has not nothing to do with being Synchronous or asynchronous.

Client Side: Clients calling must support asynchronous to achieve it like AJAX in browser.

Server Side: Multi- Thread environment / Non blocking IO are used to achieve asynchronous service.

Answer 4

I think this might be a good help for you to understand the RESTful web services in Java:

• Building RESTful Web Services with JAX-RS

You can control the client being synchronous or asynchronous from the client side. An example - using AJAX .

Answer 5

Yes you can have Asynchronous as well as Synchronous Web Service. You can use any of the frameworks like Restlet, JAXB, JAX-RS.