IPP Mail Archive: RE: IPP>NOT latest notify-poll document[wi

IPP Mail Archive: RE: IPP>NOT latest notify-poll document[wi

RE: IPP>NOT latest notify-poll document[window of events NEED NOT be a constant for Printer]

From: Hastings, Tom N (hastings@cp10.es.xerox.com)
Date: Wed Mar 08 2000 - 13:02:51 EST

  • Next message: Hastings, Tom N: "IPP> OPS - Ok that the 'any-value' out-of-band value has an attribute value?"

    I think that the time window should be able to be different for different
    Subscription objects, depending on the events that are wanted.

    Not a fixed time for all events for the Printer.

    Introduction

    IPP printers that support the OPTIONAL IPP notification extension [ipp-ntfy]
    either a) accept, store, and use notification subscriptions to generate
    event Notification reports and implement one or more delivery methods for
    notifying interested parties, or b) support a subset of these tasks and farm
    out the remaining tasks to a Notification Delivery Service. The 'ipp' event
    notification delivery method specified in this document defines a
    Get-Notifications operation that may be used in a variety of notification
    scenarios. Its primary intended use is for clients that want to be
    Notification Recipients. However, the Get-Notifications operation may also
    be used by Notification Delivery Services for subsequent distribution to the
    Ultimate Notification Recipients.

    When a Printer supports the 'ipp' delivery method, it holds each
    Notification event for a certain length of time \. The amount of time is
    called the "lease time" and it is the same for all events in a Printer. If
    a Notification Recipient does not want to miss events, the time between
    consecutive pollings of Subscription objects must be less than the lease
    time. The Get-Notifications request indicates whether the client wants to
    receive all pending events Notifications for (1) any Subscription for which
    the client is the owner, (2) any Subscription associated with a particular
    Job or (3) a particular Subscription object. With the Get-Notifications
    operation, the Printer returns all existing Notifications along with two
    time intervals. One specifies the length of the lease for all future events
    and the other specifies the recommended interval to wait to the next
    Get-Notifications operation. The second time interval is less than the
    first..
     
    The Printer may keep the channel open if the recommended interval is
    sufficiently short, but in any case the client performs a new
    Get-Notifications operation each time it wants more Notifications. Since the
    time interval between consecutive client requests is normally less than the
    lease time, consecutive responses will normally contain some events that are
    identical. The later ones in the previous response will become the
    earliest in the next response. The client is expected to filter out these
    duplicates, which is easy to do because of the sequence number in each
    Notification. The reason for not removing the Notifications from the
    Subscription object with every Get-Notifications request, is so that
    multiple Notification Recipients can be polling the same subscription object
    and so the Get-Notification operation satisfies the rule of idempotency.
    The former is useful if someone is logged in to several desktops at the same
    time and wants to see the same events at both places. The latter is useful
    if the network loses the response.

    -----Original Message-----
    From: Herriot, Robert [mailto:Robert.Herriot@pahv.xerox.com]
    Sent: Tuesday, March 07, 2000 19:47
    To: ipp@pwg.org
    Subject: IPP>NOT lastest notify-poll document

    I just downloaded the latest notify-poll document.

    It is

    ftp://ftp.pwg.org/pub/pwg/ipp/new_NOT/ipp-notify-poll-000306-rev.doc

    We may discuss the issues at the IPP teleconference tomorrow.

    Bob Herriot



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