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 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)

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

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 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.

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?