INTERNET-DRAFT Robert Herriot (editor) Xerox Corp. Carl Kugler IBM, Corp. Harry Lewis IBM, Corp. September 18, 2000 Internet Printing Protocol (IPP): The 'ippget' Event Notifications Delivery Method Copyright (C) The Internet Society (2000). All Rights Reserved. Status of this Memo: This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of [rfc2026]. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress". The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed as http://www.ietf.org/shadow.html. Abstract The notification extension document [ipp-ntfy] defines operations that a client can perform in order to create Subscription Objects in a Printer and carry out other operations on them. A Subscription Object represents a Subscription abstraction. The Subscription Object specifies that when one of the specified Events occurs, the Printer sends an asynchronous Event Notification to the specified Notification Recipient via the specified Delivery Method (i.e., protocol). The notification extension document [ipp-ntfy] specifies that each Delivery Method is defined in another document. This document is one such document, and it specifies the 'ippget' delivery method. Herriot, et al. Expires: March 18, 2001 [page 1] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 The 'ippget' Delivery Method is a 'pull and push' Delivery Method. That is, the Printer saves Event Notification for a period of time and expects the Notification Recipient to fetch the Event Notifications (the pull part). The Printer continues to send Event Notifications to the Notification Recipient as Events occur (the push part) if the client has selected the option to wait for additional Event Notifications. When a Printer supports this Delivery Method, it holds each Event Notification for an amount of time, called the Event Notification Lease Time. When a Notification Recipient wants to receive Event Notifications, it performs an IPP operation called 'Get-Notifications', which this document defines. This operation causes the Printer to return all Event Notifications held for the Notification Recipient. If the Notification Recipient has selected the option to wait for additional Event Notifications, the Printer continues sending Event Notifications to the Notification Recipient as additional Events occur. Herriot, et al. Expires: March 18, 2001 [page 2] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 The basic set of IPP documents includes: Design Goals for an Internet Printing Protocol [RFC2567] Rationale for the Structure and Model and Protocol for the Internet Printing Protocol [RFC2568] Internet Printing Protocol/1.1: Model and Semantics [RFC2911] Internet Printing Protocol/1.1: Encoding and Transport [RFC2910] Internet Printing Protocol/1.1: Implementer's Guide [ipp-iig] Mapping between LPD and IPP Protocols [RFC2569] Internet Printing Protocol/1.0 & 1.1: IPP Event Notification Specification [ipp-ntfy] The "Design Goals for an Internet Printing Protocol" document takes a broad look at distributed printing functionality, and it enumerates real-life scenarios that help to clarify the features that need to be included in a printing protocol for the Internet. It identifies requirements for three types of users: end users, operators, and administrators. It calls out a subset of end user requirements that are satisfied in IPP/1.0. A few OPTIONAL operator operations have been added to IPP/1.1. The "Rationale for the Structure and Model and Protocol for the Internet Printing Protocol" document describes IPP from a high level view, defines a roadmap for the various documents that form the suite of IPP specification documents, and gives background and rationale for the IETF working group's major decisions. The "Internet Printing Protocol/1.1: Model and Semantics" document describes a simplified model with abstract objects, their attributes, and their operations that are independent of encoding and transport. It introduces a Printer and a Job object. The Job object optionally supports multiple documents per Job. It also addresses security, internationalization, and directory issues. The "Internet Printing Protocol/1.1: Encoding and Transport" document is a formal mapping of the abstract operations and attributes defined in the model document onto HTTP/1.1 [RFC2616]. It defines the encoding rules for a new Internet MIME media type called "application/ipp". This document also defines the rules for transporting over HTTP a message body whose Content-Type is "application/ipp". This document defines a new scheme named 'ippget' for identifying IPP printers and jobs. The "Internet Printing Protocol/1.1: Implementer's Guide" document gives insight and advice to implementers of IPP clients and IPP objects. It is intended to help them understand IPP/1.1 and some of the considerations that may assist them in the design of their client and/or IPP object implementations. For example, a typical order of processing requests is given, including error checking. Motivation for some of the specification decisions is also included. Herriot, et al. Expires: March 18, 2001 [page 3] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 The "Mapping between LPD and IPP Protocols" document gives some advice to implementers of gateways between IPP and LPD (Line Printer Daemon) implementations. The "Event Notification Specification" document describes an extension to the IPP/1.0, IPP/1.1, and future versions. This extension allows a client to subscribe to printing related Events. Subscriptions are modeled as Subscription Objects. The Subscription Object specifies that when one of the specified Event occurs, the Printer sends an asynchronous Event Notification to the specified Notification Recipient via the specified Delivery Method (i.e., protocol). A client associates Subscription Objects with a particular Job by performing the Create-Job- Subscriptions operation or by submitting a Job with subscription information. A client associates Subscription Objects with the Printer by performing a Create-Printer-Subscriptions operation. Four other operations are defined for Subscription Objects: Get-Subscriptions- Attributes, Get-Subscriptions, Renew-Subscription, and Cancel- Subscription. Herriot, et al. Expires: March 18, 2001 [page 4] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 Table of Contents 1 Introduction ......................................................6 2 Terminology .......................................................6 3 Model and Operation ...............................................7 4 General Information ...............................................8 5 Get-Notifications operation ......................................10 5.1 Get-Notifications Request.......................................11 5.2 Get-Notifications Response......................................12 6 Additional Printer Description Attributes ........................19 6.1 begin-to-expire-time-interval" (integer(0:MAX)).................19 7 New Status Codes .................................................19 7.1 redirection-other-site (0x300)..................................20 8 Encoding .........................................................20 9 Conformance Requirements .........................................20 10 IANA Considerations ..............................................21 11 Internationalization Considerations ..............................21 12 Security Considerations ..........................................21 13 References .......................................................21 14 Authors' Addresses ...............................................22 15 Full Copyright Statement .........................................23 Herriot, et al. Expires: March 18, 2001 [page 5] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 1 Introduction The notification extension document [ipp-ntfy] defines operations that a client can perform in order to create Subscription Objects in a Printer and carry out other operations on them. A Subscription Object represents a Subscription abstraction. The Subscription Object specifies that when one of the specified Events occurs, the Printer sends an asynchronous Event Notification to the specified Notification Recipient via the specified Delivery Method (i.e., protocol). The notification extension document [ipp-ntfy] specifies that each Delivery Method is defined in another document. This document is one such document, and it specifies the 'ippget' delivery method. The 'ippget' Delivery Method is a 'pull and push' Delivery Method. That is, the Printer saves Event Notification for a period of time and expects the Notification Recipient to fetch the Event Notifications (the pull part). The Printer continues to send Event Notifications to the Notification Recipient as Events occur (the push part) if the client has selected the option to wait for additional Event Notifications. When a Printer supports this Delivery Method, it holds each Event Notification for an amount of time, called the Event Notification Lease Time. When a Notification Recipient wants to receive Event Notifications, it performs an IPP operation called 'Get-Notifications', which this document defines. This operation causes the Printer to return all Event Notifications held for the Notification Recipient. If the Notification Recipient has selected the option to wait for additional Event Notifications, the Printer the Printer continues to send Event Notifications to the Notification Recipient as Events occur. 2 Terminology This section defines the following terms that are used throughout this document: Capitalized terms, such as MUST, MUST NOT, REQUIRED, SHOULD, SHOULD NOT, MAY, NEED NOT, and OPTIONAL, have special meaning relating to conformance to this specification. These terms are defined in [RFC2911 Herriot, et al. Expires: March 18, 2001 [page 6] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 section 13.1 on conformance terminology, most of which is taken from RFC 2119 [RFC2119]. Event Notification Lease: The lease that is associated with an Event Notification. When the lease expires, the Printer discards the associated Event Notification. Event Notification Lease Time: The expiration time assigned to a lease that is associated with an Event Notification. Event Notification Attributes Group: The attributes group in a response that contains attributes that are part of an Event Notification. For other capitalized terms that appear in this document, see [ipp- ntfy]. 3 Model and Operation In a Subscription Creation Operation, when the value of the "notify- recipient-uri" attributes has the scheme 'ippget', the client is requesting that the Printer use the 'ippget' Delivery Method for the Event Notifications associated with the new Subscription Object. The client SHOULD choose a value for the address part of the "notify- recipient-uri" attribute that uniquely identifies the Notification Recipient. When an Event occurs, the Printer MUST generate an Event Notification and MUST assign it the Event Notification Lease Time. The Printer MUST hold an Event Notification for its assigned Event Notification Lease Time. The Printer MUST assign the same Event Notification Lease Time to each Event Notification. When a Notification Recipient wants to receive Event Notifications, it performs the Get-Notifications operation, which causes the Printer to return all unexpired Event Notifications held for the Notification Recipient. If the Notification Recipient has selected the option to wait for additional Event Notifications, the response to the Get- Notifications request continues indefinitely as the Printer continues to send Event Notifications in the response as Events occur. For the Get- Notification operation, the Printer sends only those Event Notifications that are generated from Subscription Objects whose "notify-recipient- Herriot, et al. Expires: March 18, 2001 [page 7] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 uri" equals the "notify-recipient-uri" Operation Attribute in the Get- Notifications operation. If a Notification Recipient performs the Get-Notifications operation twice in quick succession, it will receive nearly the same Event Notification both times because most of the Event Notifications are those that the Printer saves for a few seconds after the Event occurs. There are two possible differences. Some old Event Notifications may not be present in the second response because their Event Notification Leases have expired. Some new Event Notifications may be present in the second response but not the first response. When the Notification Recipient requests Event Notifications for per-Job Subscription Objects, the Notification Recipient typically performs the Get-Notifications operation within a second of performing the Subscription Creation operation. Because the Printer is likely to save Event Notifications for several seconds, the Notification Recipient is unlikely to miss any Event Notifications that occur between the Subscription Creation and the Get-Notifications operation. 4 General Information If a Printer supports this Delivery Method, the following are its characteristics. Table 1 - Information about the Delivery Method Document Method Conformance Delivery Method Realization Requirement 1.What is the URL scheme name ippget for the Delivery Method? 2.Is the Delivery Method RECOMMENDED REQUIRED, RECOMMENDED or OPTIONAL for an IPP Printer to support? 3.What transport and delivery IPP with one new operation. Herriot, et al. Expires: March 18, 2001 [page 8] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 protocols does the Printer use to deliver the Event Notification Content, i.e., what is the entire network stack? 4.Can several Event Yes. Notifications be combined into a Compound Event Notification? 5.Is the Delivery Method This Delivery Method is a pull and initiated by the Notification a push. Recipient (pull), or by the Printer (push)? 6.Is the Event Notification Machine Consumable content Machine Consumable or Human Consumable? 7.What section in this document Section 5 answers the following question? For a Machine Consumable Event Notification, what is the representation and encoding of values defined in section 9.1 of [ipp-ntfy] and the conformance requirements thereof? For a Human Consumable Event Notification, what is the representation and encoding of pieces of information defined in section 9.2 of [ipp-ntfy] and the conformance requirements thereof? 8.What are the latency and Same as IPP and the underlying HTTP reliability of the transport transport and delivery protocol? 9.What are the security aspects Same as IPP and the underlying HTTP of the transport and delivery transport protocol, e.g., how it is handled in firewalls? 10. What are the content length None restrictions? Herriot, et al. Expires: March 18, 2001 [page 9] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 11. What are the additional None values or pieces of information that a Printer sends in an Event Notification content and the conformance requirements thereof? 12. What are the additional None Subscription Template and/or Subscription Description attributes and the conformance requirements thereof? 13. What are the additional Printer Description attributes and the conformance None requirements thereof? 5 Get-Notifications operation This operation causes the Printer to return all Event Notifications held for the Notification Recipient. A Printer MUST support this operation. When a Printer performs this operation, it MUST return all and only those Event Notifications: a)Whose associated Subscription Object's "notify-recipient-uri" attribute equals the "notify-recipient-uri" Operation attribute AND b)Whose associated Subscription Object's "notify-recipient-uri" attribute has a scheme value of 'ippget' AND c)Whose Event Notification Lease Time has not yet expired AND d)Where the Notification Recipient is the owner of or has read- access rights to the associated Subscription Object. Herriot, et al. Expires: March 18, 2001 [page 10] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 The Printer MUST respond to this operation immediately with whatever Event Notifications it currently holds. If the Notification Recipient has selected the option to wait for additional Event Notifications, the Printer MUST continue to send Event Notifications as they occur until all of the associated Subscription Objects are cancelled. A Subscription Object is cancelled either via the Cancel-Subscription operation or by the Printer (e.g. the Subscription Object is cancelled when the associated Job completes). Note, the Printer terminates the operation in the same way that it normally terminates IPP operations. For example, if the Printer is sending chunked data, it can send a 0 length chunk to denote the end of the operation or it can close the connection. If the Notification Recipient wishes to terminate the Get-Notifications operation, it can close the connection. The Printer MUST accept the request in any state (see [RFC2911] "printer-state" and "printer-state-reasons" attributes) and MUST remain in the same state with the same "printer-state-reasons". Access Rights: If the policy of the Printer is to allow all users to access all Event Notifications, then the Printer MUST accept this operation from any user. Otherwise, the authenticated user (see [RFC2911] section 8.3) performing this operation MUST either be the owner of each Subscription Object identified by the "notify-recipient- uri" Operation attribute (as determined during a Subscription Creation Operation) or an operator or administrator of the Printer (see [RFC2911] Sections 1 and 8.5). Otherwise, the IPP object MUST reject the operation and return: 'client-error-forbidden', 'client-error-not- authenticated', or 'client-error-not-authorized' as appropriate. 5.1 Get-Notifications Request The following groups of attributes are part of the Get-Notifications Request: Group 1: Operation Attributes Natural Language and Character Set: The "attributes-charset" and "attributes-natural-language" attributes as described in [RFC2911] section 3.1.4.1. Target: The "printer-uri" (uri) operation attribute which is the target for this operation as described in [RFC2911] section 3.1.5. Herriot, et al. Expires: March 18, 2001 [page 11] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 Requesting User Name: The "requesting-user-name" (name(MAX)) attribute SHOULD be supplied by the client as described in [RFC2911] section 8.3. "notify-recipient-uri" (url): The client MUST supply this attribute. The Printer object MUST support this attribute. The Printer matches the value of this attribute (byte for byte with no case conversion) against the value of the "notify-recipient-uri" in each Subscription Object in the Printer. If there are no matches, the IPP Printer MUST return the 'client-error-not-found' status code. For each matched Subscription Object, the IPP Printer MUST return all unexpired Event Notifications associated with it. The Printer MUST send additional Event Notifications as Events occur if and only if the value of the "notify-no-wait" attribute is 'false' or not supplied by the client (see the next attribute below). Note: this attribute allows a subscribing client to pick URLs that are unique, e.g. the client's own URL or a friend's URL, which in both cases is likely the URL of the person's host. An application could make a URL unique for each application. "notify-no-wait" (boolean): The client MAY supply this attribute. The Printer object MUST support this attribute. If the value of this attribute is 'false', the Printer MUST send all un-expired Event Notifications (as defined in the previous attribute) and it MUST continue to send responses for as long as the Subscription Objects associated with the specified "notify-recipient-uri" continue to exist. If the value of this attribute is 'true', the Printer MUST send all un- expired Event Notifications (as defined in the previous attribute) and the Printer MUST conclude the operation without waiting for any additional Events to occur. If the client doesn't supply this attribute, the Printer MUST behave as if the client had supplied this attribute with the value of 'false'. 5.2 Get-Notifications Response The following groups of attributes are part of the Get-Notifications Response: Group 1: Operation Attributes Status Message: In addition to the REQUIRED status code returned in every response, the response OPTIONALLY includes a "status-message" (text(255)) and/or a "detailed-status-message" (text(MAX)) operation attribute as described in [RFC2911] sections 13 and 3.1.6. Herriot, et al. Expires: March 18, 2001 [page 12] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 The Printer can return any status codes defined in [RFC2911]. If the status code is not 'successful-', the Printer MUST NOT return any Event Notification Attribute groups. The following is a description of the important status codes: successful-ok: the response contains all Event Notification associated with the specified "notify-recipient-uri". If the specified Subscription Objects have no associated Event Notification, the response MUST contain zero Event Notifications. client-error-not-found: The Printer has no Subscription Object's whose "notify-recipient-uri" attribute equals the "notify- recipient-uri" Operation attribute. server-error-busy: The Printer is too busy to accept this operation. If the "suggested-ask-again-time-interval" operation attribute is present in the Operation Attributes of the response, then the Notification Recipient SHOULD wait for the number of seconds specified by the "suggested-ask-again- time-interval" attribute before performing this operation again. If the "suggested-ask-again-time-interval" Operation Attribute is not present, the Notification Recipient should use the normal network back-off algorithms for determining when to perform this operation again. redirection-other-site: The Printer does not handle this operation and requests the Notification Recipient to perform the operation with the uri specified by the "notify-ippget- redirect" Operation Attribute in the response.. Natural Language and Character Set: The "attributes-charset" and "attributes-natural-language" attributes as described in [RFC2911] section 3.1.4.2. The Printer MUST use the values of "notify-charset" and "notify- natural-language", respectively, from one Subscription Object associated with the Event Notifications in this response. Normally, there is only one matched Subscription Object, or the value of the "notify-charset" and "notify-natural-language" attributes is the same in all Subscription Objects. If not, the Printer MUST pick one Subscription Object from which to obtain the value of these attributes. The algorithm for picking the Subscription Object is implementation dependent. The choice of natural language is not critical because 'text' and 'name' values can override the "attributes-natural-language" Operation attribute. The Printer's choice of charset is critical because a bad choice may leave it unable to send some 'text' and 'name' values accurately. Herriot, et al. Expires: March 18, 2001 [page 13] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 "printer-up-time" (integer(0:MAX)): The value of this attribute is the Printer's "printer-up-time" attribute at the time the Printer sends this response. Because each Event Notification also contains the value of this attribute when the event occurred, the value of this attribute lets a Notification Recipient know when each Event Notification occurred relative to the time of this response. "suggested-ask-again-time-interval" (integer(0:MAX)): The value of this attribute is the number of seconds that the Notification Recipient SHOULD wait before trying this operation again when a)the Printer returns the 'server-error-busy' status code OR b)the Printer returns the 'successful-ok' status code and the client supplied the "notify-no-wait" attribute with a value of 'true'. This value is intended to help the client be a good network citizen. "notify-ippget-redirect" (uri): The value of this attribute is uri that the Notification Recipient MUST use for the Get-Notifications operation. This attribute is present in the Operation Attributes if and only if the status code has the value 'redirection-other-site'. Group 2: Unsupported Attributes See [RFC2911] section 3.1.7 for details on returning Unsupported Attributes. If the "subscription-ids" attribute contained subscription-ids that do not exist, the Printer returns them in this group as value of the "subscription-ids" attribute. Group 3 through N: Event Notification Attributes The Printer responds with one Event Notification Attributes Group per matched Event Notification. The initial matched Event Notifications are all un-expired Event Notification associated with the matched Subscription Objects. If the Notification Recipient has selected the option to wait for additional Event Notifications, the Printer the subsequent Event Notifications in the response are Event Notifications associated with the matched Subscription Objects as the corresponding Event occurs. From the Notification Recipient's view, the response appears as an initial burst of data, which includes the Operation Attributes Group and one Event Notification Attributes Groups per Event Notification that the Printer is holding. After the initial burst of data, if the Notification Recipient has selected the option to Herriot, et al. Expires: March 18, 2001 [page 14] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 wait for additional Event Notifications, the Notification Recipient receives occasional Event Notification Attribute Groups. Proxy servers may delay some Event Notifications or cause time-outs to occur. The client MUST be prepared to perform the Get-Notifications operation again when time-outs occur. Each Event Notification Group MUST start with an 'event- notification-attributes-tag' (see the section "Encodings of Additional Attribute Tags" in [ipp-ntfy]). Each attribute is encoded using the IPP rules for encoding attributes [RFC2910] and may be encoded in any order. Note: the Get-Jobs response in [RFC2911] acts as a model for encoding multiple groups of attributes. Each Event Notification Group MUST contain all of attributes specified in section 9.1 ("Content of Machine Consumable Event Notifications") of [ipp-ntfy] with exceptions denoted by asterisks in the tables below. The tables below are copies of the tables in section 9.1 ("Content of Machine Consumable Event Notifications") of [ipp-ntfy] except that each cell in the "Sends" column is a "MUST". For an Event Notification for all Events, the Printer includes the following attributes. Table 2 - Attributes in Event Notification Content Source Value Sends Source Object notify-subscription-id (integer(1:MAX)) MUST Subscription notify-printer-uri (uri) MUST Subscription notify-subscribed-event (type2 keyword) MUST Event Notification Herriot, et al. Expires: March 18, 2001 [page 15] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 Source Value Sends Source Object printer-up-time (integer(MIN:MAX)) MUST Printer printer-current-time (dateTime)* MUST Printer notify-sequence-number (integer (0:MAX)) MUST Subscription notify-charset (charset) MUST Subscription notify-natural-language (naturalLanguage) MUST Subscription notify-user-data (octetString(63)) ** MUST Subscription notify-text (text) MUST Event Notification attributes from the "notify-attributes" MUST Printer attribute *** attributes from the "notify-attributes" MUST Job attribute *** attributes from the "notify-attributes" MUST Subscription attribute *** Herriot, et al. Expires: March 18, 2001 [page 16] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 * The Printer MUST send "printer-current-time" if and only if it supports the "printer-current-time" attribute on the Printer object. ** If the associated Subscription Object does not contain a "notify-user-data" attribute, the Printer MUST send an octet-string of length 0. *** If the "notify-attributes" attribute is present on the Subscription Object, the Printer MUST send all attributes specified by the "notify-attributes" attribute. Note: if the Printer doesn't support the "notify-attributes" attribute, it is not present on the associated Subscription Object. For Event Notifications for Job Events, the Printer includes the following additional attributes. Table 3 - Additional Attributes in Event Notification Content for Job Events Source Value Sends Source Object job-id (integer(1:MAX)) MUST Job job-state (type1 enum) MUST Job job-state-reasons (1setOf type2 keyword) MUST Job job-impressions-completed MUST Job (integer(0:MAX)) * * The Printer MUST send the "job-impressions-completed" attribute in an Event Notification only for the combinations of Events and Subscribed Events shown in Table 4. Herriot, et al. Expires: March 18, 2001 [page 17] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 Table 4 - Combinations of Events and Subscribed Events for "job- impressions-completed" Job Event Subscribed Job Event 'job-progress' 'job-progress' 'job-completed' 'job-completed' 'job-completed' 'job-state-changed' For Event Notification for Printer Events, the Printer includes the following additional attributes. Table 5 - Additional Attributes in Event Notification Content for Printer Events Source Value Sends Source Object printer-state (type1 enum) MUST Printer printer-state-reasons (1setOf type2 MUST Printer keyword) printer-is-accepting-jobs (boolean) MUST Printer Herriot, et al. Expires: March 18, 2001 [page 18] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 6 Additional Printer Description Attributes 6.1 begin-to-expire-time-interval" (integer(0:MAX)) This attribute specifies the number of seconds that a Printer keeps an Event Notification that is associated with this Delivery Method. The Printer MUST support this attribute if it supports this Delivery Method. The value of this attribute is the minimum number of seconds that MUST elapse between the time the Printer creates an Event Notification object for this Delivery Method and the time the Printer discards the same Event Notification. For example, assume the following: 1. a client performs a Job Creation operation that creates a Subscription Object associated with this Delivery Method, AND 2. an Event associated with the new Job occurs immediately after the Subscription Object is created, AND 3. the same client or some other client performs a Get-Notifications operation N seconds after the Job Creation operation. Then, if N is less than the value of this attribute, the client performing the Get-Notifications operations can expect not miss any Event-Notifications, barring some unforeseen lack of memory space in the Printer. 7 New Status Codes The following status codes are defined as extensions for this Delivery Method and are returned as the status code of the Get-Notifications operation. Herriot, et al. Expires: March 18, 2001 [page 19] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 7.1 redirection-other-site (0x300) This status code means that the Printer doesn't perform that Get- Notifications operation and that the "notify-ippget-redirect" Operation Attribute in the response contains the uri that the Notification Recipient MUST use for performing the Get-Notifications operation. 8 Encoding The operation-id assigned for the Get-Notifications operation is: 0x001C and should be added to the next version of [RFC2911] section 4.4.15 "operations-supported". This notification delivery method uses the IPP transport and encoding [RFC2910] for the Get-Notifications operation with one extension: notification-attributes-tag = %x07 ; tag of 7 9 Conformance Requirements If the Printer supports the 'ippget' Delivery Method, the Printer MUST: 1.meet the conformance requirements defined in [ipp-ntfy]. 2.support the Get-Notifications operation defined in section 5. 3.support the "begin-to-expire-time-interval" attribute defined in section 6.1. 4.support the "redirection-other-site" status code defined 7.1 Herriot, et al. Expires: March 18, 2001 [page 20] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 10 IANA Considerations There is nothing to register. 11 Internationalization Considerations The IPP Printer MUST localize the "notify-text" attribute as specified in section 14 of [ipp-ntfy]. In addition, when the client receives the Get-Notifications response, it is expected to localize the attributes that have the 'keyword' attribute syntax according to the charset and natural language requested in the Get-Notifications request. 12 Security Considerations The IPP Model and Semantics document [RFC2911] discusses high-level security requirements (Client Authentication, Server Authentication and Operation Privacy). Client Authentication is the mechanism by which the client proves its identity to the server in a secure manner. Server Authentication is the mechanism by which the server proves its identity to the client in a secure manner. Operation Privacy is defined as a mechanism for protecting operations from eavesdropping. Unlike other Event Notification delivery methods in which the IPP Printer initiates the Event Notification, with the method defined in this document, the Notification Recipient is the client who s the Get- Notifications operation. Therefore, there is no chance of "spam" notifications with this method. Furthermore, such a client can close down the HTTP channel at any time, and so can avoid future unwanted Event Notifications at any time. 13 References [ipp-ntfy] R. Herriot, Hastings, T., Isaacson, S., Martin, J., deBry, R., Shepherd, M., Bergman, R., "Internet Printing Protocol/1.1: IPP Event Notification Specification", , June 30, 2000. Herriot, et al. Expires: March 18, 2001 [page 21] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 [rfc2026] S. Bradner, "The Internet Standards Process -- Revision 3", RFC 2026, October 1996. [RFC2616] R. Fielding, J. Gettys, J. Mogul, H. Frystyk, L. Masinter, P. Leach, T. Berners-Lee, "Hypertext Transfer Protocol - HTTP/1.1", RFC 2616, June 1999. [RFC2910] Herriot, R., Butler, S., Moore, P., Tuner, R., "Internet Printing Protocol/1.1: Encoding and Transport", RFC 2910, September 2000. [RFC2911] R. deBry, T. Hastings, R. Herriot, S. Isaacson, P. Powell, "Internet Printing Protocol/1.1: Model and Semantics", RFC 2911, September 2000. 14 Authors' Addresses Robert Herriot Xerox Corp. 3400 Hill View Ave, Building 1 Palo Alto, CA 94304 Phone: 650-813-7696 Fax: 650-813-6860 e-mail: robert.herriot@pahv.xerox.com Carl Kugler IBM P.O. Box 1900 Boulder, CO 80301-9191 Phone: Fax: e-mail: kugler@us.ibm.com Harry Lewis IBM P.O. Box 1900 Boulder, CO 80301-9191 Phone: 303-924-5337 FAX: e-mail: harryl@us.ibm.com Herriot, et al. Expires: March 18, 2001 [page 22] INTERNET-DRAFT IPP: The 'ippget' Delivery Method September 18, 2000 15 Full Copyright Statement Copyright (C) The Internet Society (2000). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Herriot, et al. Expires: March 18, 2001 [page 23]