CODEWITHSUNDEEP
javaweb-servicesalgorithmjakarta-eewebservice-client
shafi khan
shafi khan

Reputation: 85

java implementation : polling a web service

Please find below my requirement.

Requirement : Poll a web service. Two crucial parameters of polling max_timeout, polling_interval are configured in properties file. Overall objective is to spend for a time of overall in obtaining the response. If we get the response with in max_timeout, we can return the response to client. Otherwise we will throw an error saying that the operation is unsuccessful.

Below is the code snippet I have written.

int maxTimeOut = 10;
int interval   = 2;

int iterations = maxTimeOut/interval;
boolean success = false;

for (int i = 0; i < iterations; i++)
{
    System.out.println("Number of iteration = " + i);
    try
    {
        Thread.sleep(interval * 1000);
        System.out.println("Waited for " + interval + " seconds");

        success =  getWSResponse(i);
        System.out.println("CALL" + ((success) ? "SUCCESSFUL" : "FAIL"));

        if(success) break;

    }catch (InterruptedException ie)
    {
        System.out.println(ie.getMessage());
    }
}

//Send the success flag to client

Could you correct me if this is the proper implementation of polling. I am little bit concerned that this code assumes that webservice call returns in no time. If this takes 2-3 seconds (usually it does ), then we would be spending more than max_timeout overall for POLLING alone. How could we fix this. Is there any better approach than this.

Upvotes: 2

Views: 8887

Answers (2)

Nrj
Nrj

Reputation: 6831

If polling just means that the webservice is up and running, in your poll code you can try to open a connection to the webservice (with connection timeout) .If you are successfully able to connect, this means the webservice is up.

HttpURLConnection connection = null;
URL url = new URL("URL");
connection = (HttpURLConnection) url.openConnection();
connection .setConnectTimeout(timeout);//specify the timeout and catch the IOexception
connection.connect();

EDIT

Alternatively, you can call the webservice using an executor (see java.util.concurrent.ExecutorService) in a task with timeout and can decide accordingly. Sample : 

// Make the ws work a time-boxed task
            final Future<Boolean> future= executor.submit(new Callable<Boolean>() {         
                @Override
                public Boolean call() throws Exception {
                    // get ws result
                       return getWSResponse();
                }
            });
try {
                boolean result = future.get(max_wait_time, TimeUnit.SECONDS);
            } catch (TimeoutException te) {
throw e;
}

Upvotes: 1

light_303
light_303

Reputation: 2111

you can combine the use of a ScheduledExecutorService with the HttpURLConnection-Timeout to poll in a given delay - and abort the task if it takes any longer.

Upvotes: 2

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