Java

Using IMAP IDLE to Wait for Updates

This example demonstrates how to use the IMAP IDLE functionality in Chilkat. Java

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    boolean success = false;

    CkImap imap = new CkImap();

    // ....
    // ....
    // ....

    // Select an IMAP mailbox
    success = imap.SelectMailbox("INBOX");
    if (success != true) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // After a mailbox has been selected, IDLE may begin.
    // Idling tells the IMAP server to push unsolicited updates for the selected
    // mailbox to the connected client (which is your application).
    success = imap.IdleStart();
    if (success != true) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // Once idling has started, your code still has to periodically check to see
    // if any updates have arrived.  However, this is significantly different
    // then what normally occurs when checking email.  The IdleCheck does NOT
    // send a message to the IMAP server.  It simply checks the connection to see
    // if any data has arrived.  If so, it can be consumed and the client (your app)
    // can react appropriately.  

    // Note: It is recommended that idling only run for a max of 20 minutes before stopping and
    // re-starting the IDLE.  This is to maintain a minimum low level of activity so that 
    // the IMAP server does not disconnect (which it may do if it considers the connection to 
    // be truly inactive, i.e. forgotten).

    // To check the connection for IDLE updates, call IdleCheck.  The 1st argument indicates how
    // long we're willing to wait. We'll wait 1 millisecond:
    String idleResultXml;
    idleResultXml = imap.idleCheck(1);
    if (imap.get_LastMethodSuccess() != true) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // See the online reference documentation for details regarding the XML that is returned.
    // Your application code would parse the XML to determine what action to take.
    // If the XML contains "<idle></idle>", then no updates are available and your application
    // would call IdleCheck again at some point in the future.

    // If updates are available, the IDLE must be terminated by calling IdleDone, like this:
    success = imap.IdleDone();
    if (success != true) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // Once the IDLE is terminated, your application can make calls to fetch email, etc.
    // Any attempt to communicate with the IMAP server prior to terminating the IDLE will
    // result in failure.

    // IMPORTANT: Please realize that your application code will be structured differently than shown here.
    // The call to IdleCheck will likely be in a function/procedure that is periodically called
    // after the IdleStart has been called from some other location in your app
  }
}