PowerBuilder

Using IMAP IDLE to Wait for Updates

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

integer li_rc
long li_Success
oleobject loo_Imap
string ls_IdleResultXml

li_Success = 0

loo_Imap = create oleobject
li_rc = loo_Imap.ConnectToNewObject("Chilkat.Imap")
if li_rc < 0 then
    destroy loo_Imap
    MessageBox("Error","Connecting to COM object failed")
    return
end if

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

//  Select an IMAP mailbox
li_Success = loo_Imap.SelectMailbox("INBOX")
if li_Success <> 1 then
    Write-Debug loo_Imap.LastErrorText
    destroy loo_Imap
    return
end if

//  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).
li_Success = loo_Imap.IdleStart()
if li_Success <> 1 then
    Write-Debug loo_Imap.LastErrorText
    destroy loo_Imap
    return
end if

//  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:

ls_IdleResultXml = loo_Imap.IdleCheck(1)
if loo_Imap.LastMethodSuccess <> 1 then
    Write-Debug loo_Imap.LastErrorText
    destroy loo_Imap
    return
end if

//  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:
li_Success = loo_Imap.IdleDone()
if li_Success <> 1 then
    Write-Debug loo_Imap.LastErrorText
    destroy loo_Imap
    return
end if

//  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.


destroy loo_Imap