Which is better in this case - sync or async web service?

Question

I'm setting up a web service in Axis2 whose job it will be to take a bunch of XML and put it on to a queue to be processed later. I understand its possible to set up a client to invoke a synchronous web service asynchronously by creating a using an "invokeNonBlocking" operation on the "Call" instance. (ref http://onjava.com/pub/a/onjava/2005/07/27/axis2.html?page=4)

So, my question is, is there any advantage to using an asynchronous web service in this case? It seems redundant because 1) the client isn't blocked and 2) the service has to accept and write the xml to queue regardless if it's synchronous or asynchronous

Answer 1

A "sync call" seems appropriate, I agree.

If the request from the client isn't time consuming, then I don't see the advantage either in making the call asynchronous. From what I understand of the situation in question here, the web-service will perform its "processing" against the request some time in the future.

If, on the contrary, the request had required a time consuming process, then an async call would haven been appropriate.

Answer 2

After ruminating some more about it, I'm thinking that the service should be asynchronous. The reason is that it would put the task of writing the data to the queue into a separate thread, thus lessening the chances of a timeout. It makes the process more complicated, but if I can avoid a timeout, then it's got to be done.

Answer 3

In my opinion, asynchronous is the appropriate way to go. A couple of things to consider:

1. Do you have multiple clients accessing this service at any given moment?
2. How often is this process occurring?

It does take a little more effort to implement the async methods. But I guarantee, in the end you will be much happier with the result. For one, you don't have to manage threading. Your primary concern might just be the volatility of the data in the que (i.e. race/deadlock conditions).