IPP Notification Subscriptions Event Notification

Subscription Operations Create-Printer-Subscription –creates a subscription for printer events Create-Job-Subscription –creates a subscription for job events Implicit Job-Subscription with Job creation –creates a subscription for job events

Subscription Request Attributes (Partial) notify-recipient –the url of the notification recipient –the scheme specifies the delivery method notify-events –one or more keywords that are event names notify-format –a MIME media type -- the format of the event notification

Subscription Response Attributes (Partial) subscription-id –integer for identifying a subscription notify-lease-expiration-time –integer time at which subscription lease expires notify-server-up-time –current integer time on Printer.

Event Notification Event is delivered –when event in notify-events occurs –to notify-recipient –with contents of notify-format containing a fixed set of attributes

Event Notification Attributes Delivered (e.g.) printer-uri subscription-id request-id (i.e. a sequence number) trigger-event trigger-time printer-state (for printer events) job-state (for job events)

Event Notification Delivery Methods Three delivery methods to specified url –mailto: mail the event notification –indp: use ipp over http to send event notification –ipp: use ipp to get (poll) accumulated event notifications

ipp: The Printer –saves each event for a fix amount of time –supports the Get-Notifications operation –does not send events with this delivery method to anyone –expects clients to fetch event notifications with Get-Notifications

ipp: Get-Notifications Request request –like Get-Printer-Attributes –specifies events by notify-recipient url –events from all subscriptions with the specified url job-id –events from all subscriptions associated with the job subscription-id Issue as to whether to support all 3

ipp: Get-Notifications Response Response –operation attributes contains event-lease-time-interval –number of seconds until future events start disappearing recommended-time-interval –number of seconds a client should wait until next Get- Notifications request –one notification group per event each group contains the fixed attributes

ipp: Issues Should the scheme be ipp? Does using ipp for notification of Printer events conflict or complement its use for creating jobs on a Printer ? Do the lease and recommended times make polling a reasonable substitute for notification?

ipp: Issues –Is it reasonable for Get-Notifications to have an option whereby the Printer does not send an immediate response? Rather it sends event notifications as they occur over several seconds in a strung out response? Does a client receive them spread out in time? Can proxies deal with this? Does putting each group of events in a separate Multipart MIME have any value?

indp: The notify-recipient –acts like a Printer (http server) –receives an ipp request –operation is Send-Notifications contains one notification attributes group per event each group contains standard attributes each group may also contain two optional attributes –human-readable-report –human-readable-report-format

indp Issues If a client prints to a Printer outside a corporate firewall, can a Printer notify a client inside the firewall with this delivery method?

mailto: The Printer –sends (smtp) to the specified url –the format may human readable, e.g. text/plain with a recommendation that it contain the fixed attributes machine readable, e.g. application/ipp multi-part, an allowed default for a printer that wants to send multi-media event notifications.

mailto: Issues Mailto is the most universal and the one that will go into a corporate firewall. Is it sufficient for notification, or should we support one or both of ipp and indp?