Rust

Using IMAP IDLE to Wait for Updates

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

let imap = chilkat::Imap::new();

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

// Select an IMAP mailbox
if imap.select_mailbox("INBOX").is_err() {
    println!("{}", imap.last_error_text());
    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).
if imap.idle_start().is_err() {
    println!("{}", imap.last_error_text());
    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:
let idle_result_xml = imap.idle_check(1).unwrap_or_default();
if !imap.last_method_success() {
    println!("{}", imap.last_error_text());
    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:
if imap.idle_done().is_err() {
    println!("{}", imap.last_error_text());
    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.