I've attached the notes and agreements regarding the Notification
Requirements document and the 3 notification specifications that were
reviewed at the IPP WG meeting, 7/7-99-7/8/99 in Copenhagen.
We will discuss these on the DL and at the upcoming IPP telecon, Wed,
7/14/99, 1-3pm EDT (10-12 PDT).
I've also copied these agreements to:
ftp://ftp.pwg.org/pub/pwg/ipp/new_NOT/notification-agreements-990708.docftp://ftp.pwg.org/pub/pwg/ipp/new_NOT/notification-agreements-990708.pdfftp://ftp.pwg.org/pub/pwg/ipp/new_NOT/notification-agreements-990708.txt
Notes and Agreements on Notification, 7/7/99-7/8/99
From: Bob Herriot and Tom Hastings
Date: 07/08/1999
File: notification-agreements-990708.doc
Bob Herriot led the IPP review of the Notification Requirements document
and the Notification specs at the 7/7/99-7/8/99 IETF IPP WG meeting on
Copenhagen. He generated the following notes and agreements that were
reached. The unnumbered issues are new issues raised. The number
issues refer to the numbered issues in the specifications.
As always, these agreements are being sent to the IPP DL for further
discussion and final consensus.
Notification requirements
The following agreements were reached and issues raised on the
"Notification Requirements" Internet-Draft <draft-ietf-ipp-not-02.txt>,
dated June 24, 1999:
ftp://ftp.pwg.org/pub/pwg/ipp/new_NOT/ipp-notification-requirements-990624.p
df
1. Section 2.15 need better wording for subscription, e.g.
@ any set of traps for a specific job and
@ any set of traps for a printer and jobs with no control over
which jobs.
2. ISSUE: Section 2.19 Queued notification definition is flawed. Look
at Jini for ideas.
3. ISSUE: Section 2.20 Is it "Reliable Transport" or just Reliable that
is important?
4. Section 3. item 3 last sentence doesn't make sense. Also reword to
include printer subscription for all events and for specific job
events.
5. Section 3 item 6. Strike the word "that"
6. Section 3 item 8 and 9, combine that 9, which qualifies 8 comes first
and is part of the same item.
7. Section 3 item 11: change "must" to "may".
8. Section 3 item 13 change "Event Source" to "Notification Source"
9. Section 3 item 14: remove. It is not an IPP issue. It is a value-add
implementation issue.
10. Section 4, item 3, change "form" to "firm".
11. Section 4, item 4, why is "type" "email" instead of "queued"
12. Section 4, item 7, delete word "audit" and change "accounting" to
"usage statistics".
13. There is no requirement for batching events or keeping them
separate. Note that sequence numbering of events is harder with
batching. We decided to abandon batching and send events one by one.
Notification Specification
The following agreements were reached and issues raised on the "IPP
Event Notification" document, dated May 18, 1999:
ftp://ftp.pwg.org/pub/pwg/ipp/new_NOT/ipp-notification-990518.pdf
14. Move section 3 to just before section 1 so that model is defined
before details.
15. Events are not limited by scheme of delivery method.
16. Who is "device-trigger-date-time" optional for. Isn't it required
if the printer implements current-date-time?
17. Section 3. B is subscribed to by "first" party not "third" party.
18. Section 3 change "device" to "printer".
19. Rename "event report" to "notification"
Section 4: New Subscription Operation attributes
20. Section 4: #2 need more details for "restart" operation. E.g. how
does sequence number get communicated. Explain how job-description
attributes say how to generate a new subscription. Reference to ipp-
ops-set1 should be updated to IPP/1.1.
21. ISSUE 1, yes you might have to drop events. Subscriber cannot state
whether to allow dropping of events, but an implementation may allow
an admin to configure policy on what to drop, but it is beyond the
protocol. There should not be an event-dropping event because it
would just add to the congestion and might not get delivered.
Instead, a subscriber SHOULD start a separate timer for renewing
leases in order to be really robust.
22. Section 4.1.1 fix 2nd paragraph. Maybe delete it.
23. Section 4.1. keep http but remove issue
24. Section 4.1 move SNMP traps to some separate document
25. Section 4.1 remove ndps-notify
26. Section 4.1 remove sense-notify
27. ISSUE: Why does Jini have synchronous notify using RMI, i.e.,
notify event report is delivered to the Notification Recipient as a
request and the Notification Recipient returns a response? Should we
change the notification delivery for IPP to be a request with a
response? For which delivery methods? Is this a Quality of Service
option that the subscriber can choose?
28. ISSUE: For TCP/IP, what about leaving notification connection open
versus having to reestablish a connection for each event?
29. ISSUE: Ok to add an octet stream for an attribute for
subscription, like Marshalled object in Jini? It provides a way for
a subscriber to pass opaque parameters to the recipient of the event.
30. Need to get back a 1setOf sequence numbers in CreateJob/PrintJob
response, if we can subscribe to more than one event in an operation.
Section 5: Event Report Content
31. There is no requirement for batching events or keeping them
separate. Note that sequence numbering of events is harder with
batching. We decided to abandon batching and send events one by one
in each report. In order to reduce the number of event reports
sent, each event is defined to be disjoint. So the 'job-completed'
event does not include 'job-state-changed' events. Also 'job-
created' event does not include 'job-state-changed' events. Also
'job-state-reasons-changed' is merged with 'job-state-changed' event
(see 34 below). Etc. Same for Printer events.
32. Issue 7: yes, have a sequence number and put it into the 32-bit
"request-id" field. The event sequence number will be kept by event
for each Job and Printer object. So change "job-trigger-events"
(1setOf type2 keyword) to "job-trigger-events" (type2 keyword). Same
for "printer-trigger-events".
33. Request-id is not zero any longer. It is an integer sequence number
(0:MAX).
34. Probably should remove state-reason change event and have state-
change return events for state and/or state-reason changes. The
values returned should include previous-state, state, state-reasons,
plus reasons-added and reason-deleted (instead of previous reasons).
The latter sentence describes ideas not fully resolved.
35. Device-powered-up/down should be printer-shutdown and printer-
restarted. Actually they should be merged into the state-change
event. Likewise, printer-accepting-jobs should be a state-change
event rather than config change. The document needs to be more
precise about which event is associated with each attribute change.
36. Jobs are missing an event for monitor non-job-state changes, such
as job-name or job-template attribute changes.
37. Remove last 3 printer events ('device-config-change', 'ready-for-
job', and 'ready-for-just-in-time-job') for job submission because
they make sense only in the printer subscription (Subscribe-Printer)
case. But a later discussion to combine the two notification specs
into a single spec may make it ok to leave these events in.
38. Issue 10 is moot because we have only single values for event
reports.
39. Talk with Larry about multipart/report and other alternatives
40. Security issues not addressed.
Printer Notification
The following agreements were reached and issues raised on the IPP Event
Notification document: Job Independent Subscriptions, dated May 19,
1999:
ftp://ftp.pwg.org/pub/pwg/ipp/new_NOT/ipp-notification-printer-990519.pdf
41. Section 1: Subscription should be generated by server, not client.
This is correct in section 4 but not in summary. Fix summary.
42. Section 2: Pictures should eliminate job-creation subscriptions.
They confuse the printer subscription. Change arrow from "job-
creation subscriptions" to "job submissions".
43. Drop D and E and use words to describe them as examples of A.
44. Subscription leasing times should be handled by the client, i.e. It
has an alarm.
45. Section 4.1. The second sentence needs rewording to clarify
antecedent of "it" and "its".
46. ISSUE: Does a client need to be able to get a list of current
subscriptions? (Carl-Uno's issue)
47. Issue 1: A printer MAY suppress sending duplicate notifications
(same events to same notification recipient), but it MUST allow
duplication subscriptions so that Unsubscribe-Printer (Unsubscribe-
Job) doesn't unsubscribe both subscriptions. Since the sequence
number is kept by event for each object, rather than for each
subscription, duplicate notifications will get the same sequence
number, so the recipient can tell if the duplicates aren't
suppressed. Eventually, an older duplicate due to a subscriber crash
and restart will be aged out using the lease mechanism, if the
implementation doesn't filter out duplicate notifications. A
subscriber could record the subscription ID locally so that if the
subscriber crashes and is restarted, it can renew the old
subscription, rather than creating a new subscription.
48. Section 4.1 add "event-sequence-numbers" (1setOf integer (0:MAX)
attribute to the Subscribe-Printer response. This is an attribute
that is parallel to the "notify-events" (1setOf type2 keyword)
operation attribute. Sequence numbers are kept for each event for
each Job and Printer object. The returned value indicates the
sequence number returned for the last event delivery, for each event
being subscribed to. The next event delivery will supply a sequence-
number in the event report with a value one more than this value. An
event that has never occurred will return a sequence number value of
0 in the subscription response. Thus the first sequence number for
each event/object pair that is actually delivered to a Notification
Recipient will be 1.
49. Issue 2: Renew operation must not allow subscription-id to change.
Therefore, don't need "subscription-id" to come back, so remove it
from the response.
50. Renew has other errors, such as not .authorized and lease-denied.
51. Section 5.3 get rid of because client does renewal with alarm.
52. Issue 3: detailed-status-message solves the problem. Put in
implementer's guide.
53. Issue 4: maybe have unsubscribe ALL. Group undecided.
54. Issue 5: NO
55. Issue 6: Expect that subscriptions would survive, but low end might
lose everything. Rebooting tries to preserve lease and time of lease,
which should be no shorter than before the crash.
56. Issue 7: yes
57. Add Subscribe-Job operation that allows a client to add a
subscription to a previously submitted job. Change the name of the
Subscribe operation to Subscribe-Printer to clarify the target of
these two operations.
58. Add an OPTIONAL Unsubscribe-Job operation that would be useful for
a user to stop getting events from a Job, such as sheet-completions,
while the job was being processed. Add "subscription-id" operation
attribute to the create job operations that returns an implicit
subscription in create job operations (Create-Job, Print-Job, Print-
URI) so that an Unsubscribe-Job works, if Unsubscribe-Job operation
is supported.
Job Progress Attributes and Event Report Content
The following agreements were reached and issues raised on the "Job
Progress Attributes and Event Report Content" document, dated May 19,
1999:
ftp://ftp.pwg.org/pub/pwg/ipp/new_NOT/ipp-job-prog-attr-990519.pdf
This specification was not covered at the meeting. It contains the
following six issues which need to be resolved:
59. ISSUE - Should the "job-collation-type" (type2 enum) attribute
syntax be 'type2 keyword' to go with "multiple-document-
handling(type2 keyword)", instead of the Job MIB type2 enum syntax?
60. ISSUE - For the "job-collation-type" (type2 enum) attribute should
we use the out-of-band 'unknown' value, instead of this Job
Monitoring MIB '2' enum value for 'unknown'?
61. ISSUE - For "sheet-completed-copy-number" (integer(-2:MAX)) should
we change the lower limit to 0 and use the IPP out-of-bound values:
'unknown', instead of the '-2' value?
62. ISSUE - For "sheet-completed-document-number" (integer(-2:MAX))
should we change the lower limit to 0 and use the IPP out-of-bound
values: 'unknown' instead of the '-2' value?
63. ISSUE - For "impressions-interpreted" (integer(-2:MAX)) should we
change the lower limit to 0 and use the IPP out-of-bound values:
'unknown' instead of the '-2' value?
64. ISSUE - For "impressions-completed-current-copy" (integer(-2:MAX))
should we change the lower limit to 0 and use the IPP out-of-bound
values: 'unknown' instead of the '-2' value?