In addition, the librares also support a range of asynchronous methods that can be used to store, update and retrieve values without having to explicitly wait for a response.

The asynchronous methods use a Future object or its appropriate implementation which is returned by the initial method call for the operation. The communication with the Couchbase server will be handled by the client libraries in the background so that the main program loop can continue. You can recover the status of the operation by using a method to check the status on the returned Future object. For example, rather than synchronously getting a key, an asynchronous call might look like this:

GetFuture getOp = client.asyncGet("someKey");

A list of the asynchronous methods are shown in Table 4.3, “Java Client Library Asynchronous Method Summary”.

This will populate the Future object GetFuture with the response from the server. The Future object class is defined here. The primary methods are:

For example, you can use the timeout method to obtain the value or cancel the operation:

GetFuture getOp = client.asyncGet("someKey");

Object myObj;

try {
    myObj = getOp.get(5, TimeUnit.SECONDS);
} catch(TimeoutException e) {
    getOp.cancel(false);
}

Alternatively, you can do a blocking wait for the response by using the get() method:

Object myObj;

myObj = getOp.get();