IPP Notification

1. IPP Notification • Subscriptions • Event Notification

2. 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

3. 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

4. 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.

5. 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

6. Event NotificationAttributes 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)

7. Event NotificationDelivery 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

8. 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

9. 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

10. 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

11. 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?

12. 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?

13. 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

14. 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?

15. mailto: • The Printer • sends email (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.

16. 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?