Unable to create a in app local notification in Android.

hi. this is my code for local in app notification.

but the background service is not working properly for more than one notification at a time in a session. this also deletes my previous notification and the latest ones are displayed when i try it.

ExampleService.js

var service = Ti.Android.currentService;
var serviceIntent = service.getIntent();
var timestamp = new Date(serviceIntent.getStringExtra('timestamp'));
if (new Date() > timestamp) {
    // Grab extra data sent with the intent
    var title = serviceIntent.getStringExtra('title');
    var message = serviceIntent.getStringExtra('message');
 
    // Create an intent that launches the application
    var intent = Ti.Android.createIntent({
        action : Ti.Android.ACTION_MAIN,
        packageName: 'com.mycompany.myapp'
    });
    intent.flags |= Ti.Android.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED | Ti.Android.FLAG_ACTIVITY_SINGLE_TOP;
    intent.addCategory(Ti.Android.CATEGORY_LAUNCHER);
 
    // Create notification
    var notification = Ti.Android.createNotification({
        contentIntent : Ti.Android.createPendingIntent({intent : intent}),
        contentTitle : title,
        contentText : message,
    });
 
    notify_id = 1;
    // Send the notification
    // notify_id is dynamically generated for multiple notifications; 
    Ti.Android.NotificationManager.notify(notify_id, notification);
 
    // Stop the service once the notification is sent
    Ti.Android.stopService(serviceIntent);
}

index.js

var intent = Ti.Android.createServiceIntent({
        url : 'ExampleService.js'
    });
    intent.putExtra('title' , 'Richard III');
    intent.putExtra('message' , 'Now is the winter of our discontent...');
    intent.putExtra('timestamp', new Date(new Date().getTime() + 30 * 1000));
    Ti.Android.startService(intent);

please help me out for the same.