INTERNET-DRAFT Robert Herriot (editor) Xerox Corporation Sylvan Butler Hewlett-Packard Paul Moore Microsoft Randy Turner Sharp Labs John Wenn Xerox Corporation February 17, 1998 Internet Printing Protocol/1.1: Encoding and Transport 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. Copyright Notice Copyright (C)The Internet Society (1998, 1999). All Rights Reserved. Abstract This document is one of a set of documents, which together describe all aspects of a new Internet Printing Protocol (IPP). IPP is an application level protocol that can be used for distributed printing using Internet tools and technologies. This document defines the rules for encoding IPP operations and IPP attributes into 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 'ipp' for identifying IPP printers and jobs. Finally, this document defines rules for supporting IPP/1.0 clients Herriot, Butler, [Page 1] Moore, Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 The full set of IPP documents includes: Design Goals for an Internet Printing Protocol [ipp-req] Rationale for the Structure and Model and Protocol for the Internet Printing Protocol [ipp-rat] Internet Printing Protocol/1.1: Model and Semantics [ipp-mod] Internet Printing Protocol/1.1: Encoding and Transport (this document) Internet Printing Protocol/1.1: Implementer's Guide [ipp-iig] Mapping between LPD and IPP Protocols [ipp-lpd] The document, "Design Goals for an Internet Printing Protocol", 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/1.1. Operator and administrator requirements are out of scope for version 1.1. The document, "Rationale for the Structure and Model and Protocol for the Internet Printing Protocol", describes IPP from a high level view, defines a roadmap for the various documents that form the suite of IPP specifications, and gives background and rationale for the IETF working group's major decisions. The document, "Internet Printing Protocol/1.1: Model and Semantics", 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 document "Internet Printing Protocol/1.1: Implementer's Guide", gives advice to implementers of IPP clients and IPP objects. The document "Mapping between LPD and IPP Protocols" gives some advice to implementers of gateways between IPP and LPD (Line Printer Daemon) implementations. Herriot, Butler, [Page 2] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 Table of Contents 1. Introduction.......................................................3 2. Conformance Terminology............................................4 3. Encoding of the Operation Layer...................................4 3.1 Picture of the Encoding.......................................4 3.2 Syntax of Encoding............................................7 3.3 Version-number................................................8 3.4 Operation-id..................................................8 3.5 Status-code...................................................8 3.6 Request-id....................................................8 3.7 Tags..........................................................9 3.7.1 Delimiter Tags...........................................9 3.7.2 Value Tags..............................................10 3.8 Name-Length..................................................12 3.9 (Attribute) Name.............................................12 3.10 Value Length.................................................14 3.11 (Attribute) Value............................................14 3.12 Data.........................................................15 4. Encoding of Transport Layer.......................................16 5. IPP URL Scheme....................................................16 6. Compatibility with IPP/1.0 Implementations........................18 7. Security Considerations...........................................19 7.1 Using IPP with TLS...........................................19 8. References........................................................20 9. Author's Address..................................................22 10.Other Participants:...............................................23 11.Appendix A: Protocol Examples.....................................23 11.1 Print-Job Request............................................23 11.2 Print-Job Response (successful)..............................24 11.3 Print-Job Response (failure).................................25 11.4 Print-Job Response (success with attributes ignored).........26 11.5 Print-URI Request............................................28 11.6 Create-Job Request...........................................29 11.7 Get-Jobs Request.............................................29 11.8 Get-Jobs Response............................................30 12.Appendix C: Registration of MIME Media Type Information for "application/ipp"....................................................31 13.Appendix D: Notices...............................................33 14.Appendix E: Changes from IPP /1.0.................................34 1. Introduction This document contains the rules for encoding IPP operations and describes two layers: the transport layer and the operation layer. The transport layer consists of an HTTP/1.1 request or response. RFC 2068 [rfc2068] describes HTTP/1.1. This document specifies the HTTP headers that an IPP implementation supports. The operation layer consists of a message body in an HTTP request or response. The document "Internet Printing Protocol/1.1: Model and Semantics" [ipp-mod] defines the semantics of such a message body and the supported values. This document specifies the encoding of an IPP Herriot, Butler, [Page 3] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 operation. The aforementioned document [ipp-mod] is henceforth referred to as the "IPP model document" 2. Conformance Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [rfc2119]. 3. Encoding of the Operation Layer The operation layer MUST contain a single operation request or operation response. Each request or response consists of a sequence of values and attribute groups. Attribute groups consist of a sequence of attributes each of which is a name and value. Names and values are ultimately sequences of octets The encoding consists of octets as the most primitive type. There are several types built from octets, but three important types are integers, character strings and octet strings, on which most other data types are built. Every character string in this encoding MUST be a sequence of characters where the characters are associated with some charset and some natural language. A character string MUST be in "reading order" with the first character in the value (according to reading order) being the first character in the encoding. A character string whose associated charset is US-ASCII whose associated natural language is US English is henceforth called a US-ASCII-STRING. A character string whose associated charset and natural language are specified in a request or response as described in the model document is henceforth called a LOCALIZED-STRING. An octet string MUST be in "IPP model document order" with the first octet in the value (according to the IPP model document order) being the first octet in the encoding Every integer in this encoding MUST be encoded as a signed integer using two's-complement binary encoding with big-endian format (also known as "network order" and "most significant byte first"). The number of octets for an integer MUST be 1, 2 or 4, depending on usage in the protocol. Such one-octet integers, henceforth called SIGNED-BYTE, are used for the version-number and tag fields. Such two-byte integers, henceforth called SIGNED-SHORT are used for the operation-id, status-code and length fields. Four byte integers, henceforth called SIGNED-INTEGER, are used for values fields and the sequence number. The following two sections present the operation layer in two ways @ informally through pictures and description @ formally through Augmented Backus-Naur Form (ABNF), as specified by RFC 2234 [rfc2234] 3.1 Picture of the Encoding The encoding for an operation request or response consists of: Herriot, Butler, [Page 4] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 ----------------------------------------------- | version-number | 2 bytes - required ----------------------------------------------- | operation-id (request) | | or | 2 bytes - required | status-code (response) | ----------------------------------------------- | request-id | 4 bytes - required ----------------------------------------------------------- | xxx-attributes-tag | 1 byte | ----------------------------------------------- |-0 or more | xxx-attribute-sequence | n bytes | ----------------------------------------------------------- | end-of-attributes-tag | 1 byte - required ----------------------------------------------- | data | q bytes - optional ----------------------------------------------- The xxx-attributes-tag and xxx-attribute-sequence represents four different values of "xxx", namely, operation, job, printer and unsupported. The xxx-attributes-tag and an xxx-attribute-sequence represent attribute groups in the model document. The xxx-attributes-tag identifies the attribute group and the xxx-attribute-sequence contains the attributes. The expected sequence of xxx-attributes-tag and xxx-attribute-sequence is specified in the IPP model document for each operation request and operation response. A request or response SHOULD contain each xxx-attributes-tag defined for that request or response even if there are no attributes except for the unsupported-attributes-tag which SHOULD be present only if the unsupported-attribute-sequence is non-empty. A receiver of a request MUST be able to process as equivalent empty attribute groups: a) an xxx-attributes-tag with an empty xxx-attribute-sequence, b) an expected but missing xxx-attributes-tag. The data is omitted from some operations, but the end-of-attributes-tag is present even when the data is omitted. Note, the xxx-attributes-tags and end-of-attributes-tag are called 'delimiter-tags'. Note: the xxx- attribute-sequence, shown above may consist of 0 bytes, according to the rule below. An xxx-attributes-sequence consists of zero or more compound-attributes. ----------------------------------------------- | compound-attribute | s bytes - 0 or more ----------------------------------------------- A compound-attribute consists of an attribute with a single value followed by zero or more additional values. Herriot, Butler, [Page 5] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 Note: a 'compound-attribute' represents a single attribute in the model document. The 'additional value' syntax is for attributes with 2 or more values. Each attribute consists of: ----------------------------------------------- | value-tag | 1 byte ----------------------------------------------- | name-length (value is u) | 2 bytes ----------------------------------------------- | name | u bytes ----------------------------------------------- | value-length (value is v) | 2 bytes ----------------------------------------------- | value | v bytes ----------------------------------------------- An additional value consists of: ----------------------------------------------------------- | value-tag | 1 byte | ----------------------------------------------- | | name-length (value is 0x0000) | 2 bytes | ----------------------------------------------- |-0 or more | value-length (value is w) | 2 bytes | ----------------------------------------------- | | value | w bytes | ----------------------------------------------------------- Note: an additional value is like an attribute whose name-length is 0. From the standpoint of a parsing loop, the encoding consists of: ----------------------------------------------- | version-number | 2 bytes - required ----------------------------------------------- | operation-id (request) | | or | 2 bytes - required | status-code (response) | ----------------------------------------------- | request-id | 4 bytes - required ----------------------------------------------------------- | tag (delimiter-tag or value-tag) | 1 byte | ----------------------------------------------- |-0 or more | empty or rest of attribute | x bytes | ----------------------------------------------------------- | end-of-attributes-tag | 2 bytes - required ----------------------------------------------- | data | y bytes - optional ----------------------------------------------- The value of the tag determines whether the bytes following the tag are: Herriot, Butler, [Page 6] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 @ attributes @ data @ the remainder of a single attribute where the tag specifies the type of the value. 3.2 Syntax of Encoding The syntax below is ABNF [rfc2234] except 'strings of literals' MUST be case sensitive. For example 'a' means lower case 'a' and not upper case 'A'. In addition, SIGNED-BYTE and SIGNED-SHORT fields are represented as '%x' values which show their range of values. ipp-message = ipp-request / ipp-response ipp-request = version-number operation-id request-id *(xxx-attributes-tag xxx-attribute-sequence) end-of- attributes-tag data ipp-response = version-number status-code request-id *(xxx-attributes-tag xxx-attribute-sequence) end-of- attributes-tag data xxx-attribute-sequence = *compound-attribute xxx-attributes-tag = operation-attributes-tag / job-attributes-tag / printer-attributes-tag / unsupported-attributes-tag version-number = major-version-number minor-version-number major-version-number = SIGNED-BYTE ; initially %d1 minor-version-number = SIGNED-BYTE ; initially %d0 operation-id = SIGNED-SHORT ; mapping from model defined below status-code = SIGNED-SHORT ; mapping from model defined below request-id = SIGNED-INTEGER ; whose value is > 0 compound-attribute = attribute *additional-values attribute = value-tag name-length name value-length value additional-values = value-tag zero-name-length value-length value name-length = SIGNED-SHORT ; number of octets of 'name' name = LALPHA *( LALPHA / DIGIT / "-" / "_" / "." ) value-length = SIGNED-SHORT ; number of octets of 'value' value = OCTET-STRING data = OCTET-STRING zero-name-length = %x00.00 ; name-length of 0 operation-attributes-tag = %x01 ; tag of 1 job-attributes-tag = %x02 ; tag of 2 printer-attributes-tag = %x04 ; tag of 4 unsupported- attributes-tag = %x05 ; tag of 5 end-of-attributes-tag = %x03 ; tag of 3 value-tag = %x10-FF SIGNED-BYTE = BYTE SIGNED-SHORT = 2BYTE Herriot, Butler, [Page 7] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 SIGNED-INTEGER = 4BYTE DIGIT = %x30-39 ; "0" to "9" LALPHA = %x61-7A ; "a" to "z" BYTE = %x00-FF OCTET-STRING = *BYTE The syntax allows an xxx-attributes-tag to be present when the xxx- attribute-sequence that follows is empty. The syntax is defined this way to allow for the response of Get-Jobs where no attributes are returned for some job-objects. Although it is RECOMMENDED that the sender not send an xxx-attributes-tag if there are no attributes (except in the Get-Jobs response just mentioned), the receiver MUST be able to decode such syntax. 3.3 Version-number The version-number MUST consist of a major and minor version-number, each of which MUST be represented by a SIGNED-BYTE. The protocol described in this document MUST have a major version-number of 1 (0x01) and a minor version-number of 1 (0x01). The ABNF for these two bytes MUST be %x01.01. 3.4 Operation-id Operation-ids are defined as enums in the model document. An operation- ids enum value MUST be encoded as a SIGNED-SHORT. Note: the values 0x4000 to 0xFFFF are reserved for private extensions. 3.5 Status-code Status-codes are defined as enums in the model document. A status-code enum value MUST be encoded as a SIGNED-SHORT. The status-code is an operation attribute in the model document. In the protocol, the status-code is in a special position, outside of the operation attributes. If an IPP status-code is returned, then the HTTP Status-Code MUST be 200 (successful-ok). With any other HTTP Status-Code value, the HTTP response MUST NOT contain an IPP message-body, and thus no IPP status- code is returned. 3.6 Request-id The request-id allows a client to match a response with a request. This mechanism is unnecessary in HTTP, but may be useful when application/ipp entity bodies are used in another context. Herriot, Butler, [Page 8] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 The request-id in a response MUST be the value of the request-id received in the corresponding request. A client can set the request-id in each request to a unique value or a constant value, such as 1, depending on what the client does with the request-id returned in the response. The value of the request-id MUST be greater than zero. 3.7 Tags There are two kinds of tags: @ delimiter tags: delimit major sections of the protocol, namely attributes and data @ value tags: specify the type of each attribute value 3.7.1 Delimiter Tags The following table specifies the values for the delimiter tags: Tag Value (Hex) Delimiter 0x00 reserved 0x01 operation-attributes-tag 0x02 job-attributes-tag 0x03 end-of-attributes-tag 0x04 printer-attributes-tag 0x05 unsupported-attributes-tag 0x06-0x0e reserved for future delimiters 0x0F reserved for future chunking-end-of-attributes- tag When an xxx-attributes-tag occurs in the protocol, it MUST mean that zero or more following attributes up to the next delimiter tag are attributes belonging to group xxx as defined in the model document, where xxx is operation, job, printer, unsupported. Doing substitution for xxx in the above paragraph, this means the following. When an operation-attributes-tag occurs in the protocol, it MUST mean that the zero or more following attributes up to the next delimiter tag are operation attributes as defined in the model document. When an job-attributes-tag occurs in the protocol, it MUST mean that the zero or more following attributes up to the next delimiter tag are job attributes or job template attributes as defined in the model document. When a printer-attributes-tag occurs in the protocol, it MUST mean that the zero or more following attributes up to the next delimiter tag are printer attributes as defined in the model document. When an unsupported-attributes-tag occurs in the protocol, it MUST mean that the zero or more following attributes up to the next delimiter tag are unsupported attributes as defined in the model document. The operation-attributes-tag and end-of-attributes-tag MUST each occur exactly once in an operation. The operation-attributes-tag MUST be the first tag delimiter, and the end-of-attributes-tag MUST be the last tag Herriot, Butler, [Page 9] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 delimiter. If the operation has a document-content group, the document data in that group MUST follow the end-of-attributes-tag. Each of the other three xxx-attributes-tags defined above is OPTIONAL in an operation and each MUST occur at most once in an operation, except for job-attributes-tag in a Get-Jobs response which may occur zero or more times. The order and presence of delimiter tags for each operation request and each operation response MUST be that defined in the model document. For further details, see section 3.9 "(Attribute) Name" and section 11 "Appendix A: Protocol Examples". A Printer MUST treat the reserved delimiter tags differently from reserved value tags so that the Printer knows that there is an entire attribute group that it doesn't understand as opposed to a single value that it doesn't understand. 3.7.2 Value Tags The remaining tables show values for the value-tag, which is the first octet of an attribute. The value-tag specifies the type of the value of the attribute. The following table specifies the "out-of-band" values for the value-tag. Tag Value (Hex) Meaning 0x10 unsupported 0x11 reserved for future 'default' 0x12 unknown 0x13 no-value 0x14-0x1F reserved for future "out-of-band" values. The "unsupported" value MUST be used in the attribute-sequence of an error response for those attributes which the printer does not support. The "default" value is reserved for future use of setting value back to their default value. The "unknown" value is used for the value of a supported attribute when its value is temporarily unknown. The "no- value" value is used for a supported attribute to which no value has been assigned, e.g. "job-k-octets-supported" has no value if an implementation supports this attribute, but an administrator has not configured the printer to have a limit. The following table specifies the integer values for the value-tag: Tag Value (Hex) Meaning 0x20 reserved 0x21 integer 0x22 boolean 0x23 enum 0x24-0x2F reserved for future integer types Herriot, Butler, [Page 10] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 NOTE: 0x20 is reserved for "generic integer" if it should ever be needed. The following table specifies the octetString values for the value-tag: Tag Value (Hex) Meaning 0x30 octetString with an unspecified format 0x31 dateTime 0x32 resolution 0x33 rangeOfInteger 0x34 reserved for collection (in the future) 0x35 textWithLanguage 0x36 nameWithLanguage 0x37-0x3F reserved for future octetString types The following table specifies the character-string values for the value- tag: Tag Value (Hex) Meaning 0x40 reserved 0x41 textWithoutLanguage 0x42 nameWithoutLanguage 0x43 reserved 0x44 keyword 0x45 uri 0x46 uriScheme 0x47 charset 0x48 naturalLanguage 0x49 mimeMediaType 0x4A-0x5F reserved for future character string types NOTE: 0x40 is reserved for "generic character-string" if it should ever be needed. NOTE: an attribute value always has a type, which is explicitly specified by its tag; one such tag value is "nameWithoutLanguage". An attribute's name has an implicit type, which is keyword. The values 0x60-0xFF are reserved for future types. There are no values allocated for private extensions. A new type MUST be registered via the type 2 registration process [ipp-mod]. The tag 0x7F is reserved for extending types beyond the 255 values available with a single byte. A tag value of 0x7F MUST signify that the first 4 bytes of the value field are interpreted as the tag value. Note, this future extension doesn't affect parsers that are unaware of this special tag. The tag is like any other unknown tag, and the value length specifies the length of a value which contains a value that the parser treats atomically. All these 4 byte tag values are currently unallocated except that the values 0x40000000-0x7FFFFFFF are reserved for experimental use. Herriot, Butler, [Page 11] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 3.8 Name-Length The name-length field MUST consist of a SIGNED-SHORT. This field MUST specify the number of octets in the name field which follows the name- length field, excluding the two bytes of the name-length field. If a name-length field has a value of zero, the following name field MUST be empty, and the following value MUST be treated as an additional value for the preceding attribute. Within an attribute-sequence, if two attributes have the same name, the first occurrence MUST be ignored. The zero-length name is the only mechanism for multi-valued attributes. 3.9 (Attribute) Name Some operation elements are called parameters in the model document [ipp-mod]. They MUST be encoded in a special position and they MUST NOT appear as an operation attributes. These parameters are: @ "version-number": The parameter named "version-number" in the IPP model document MUST become the "version-number" field in the operation layer request or response. @ "operation-id": The parameter named "operation-id" in the IPP model document MUST become the "operation-id" field in the operation layer request. @ "status-code": The parameter named "status-code" in the IPP model document MUST become the "status-code" field in the operation layer response. @ "request-id": The parameter named "request-id" in the IPP model document MUST become the "request-id" field in the operation layer request or response. All Printer and Job objects are identified by a Uniform Resource Identifier (URI) [rfc2396] so that they can be persistently and unambiguously referenced. The notion of a URI is a useful concept, however, until the notion of URI is more stable (i.e., defined more completely and deployed more widely), it is expected that the URIs used for IPP objects will actually be URLs [rfc1738] [rfc1808]. Since every URL is a specialized form of a URI, even though the more generic term URI is used throughout the rest of this document, its usage is intended to cover the more specific notion of URL as well. Some operation elements are encoded twice, once as the request-URI on the HTTP Request-Line and a second time as a REQUIRED operation attribute in the application/ipp entity. These attributes are the target URI for the operation and are called printer-uri and job-uri. Note: The target URI is included twice in an operation referencing the same IPP object, but the two URIs NEED NOT be literally identical. One can be a relative URI and the other can be an absolute URI. HTTP/1.1 allows clients to generate and send a relative URI rather than an absolute URI. A relative URI identifies a resource with the scope of the HTTP server, but does not include scheme, host or port. The Herriot, Butler, [Page 12] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 following statements characterize how URLs should be used in the mapping of IPP onto HTTP/1.1: 1. Although potentially redundant, a client MUST supply the target of the operation both as an operation attribute and as a URI at the HTTP layer. The rationale for this decision is to maintain a consistent set of rules for mapping application/ipp to possibly many communication layers, even where URLs are not used as the addressing mechanism in the transport layer. 2. Even though these two URLs might not be literally identical (one being relative and the other being absolute), they MUST both reference the same IPP object. 3. The URI in the HTTP layer is either relative or absolute and is used by the HTTP server to route the HTTP request to the correct resource relative to that HTTP server. The HTTP server need not be aware of the URI within the operation request. 4. Once the HTTP server resource begins to process the HTTP request, it might get the reference to the appropriate IPP Printer object from either the HTTP URI (using to the context of the HTTP server for relative URLs) or from the URI within the operation request; the choice is up to the implementation. 5. HTTP URIs can be relative or absolute, but the target URI in the operation MUST be an absolute URI. The model document arranges the remaining attributes into groups for each operation request and response. Each such group MUST be represented in the protocol by an xxx-attribute-sequence preceded by the appropriate xxx-attributes-tag (See the table below and section 11 "Appendix A: Protocol Examples"). In addition, the order of these xxx-attributes-tags and xxx-attribute-sequences in the protocol MUST be the same as in the model document, but the order of attributes within each xxx-attribute- sequence MUST be unspecified. The table below maps the model document group name to xxx-attributes-sequence: Model Document Group xxx-attributes-sequence Operation Attributes operations-attributes-sequence Job Template Attributes job-attributes-sequence Job Object Attributes job-attributes-sequence Unsupported Attributes unsupported- attributes-sequence Requested Attributes (Get- job-attributes-sequence Job-Attributes) Requested Attributes (Get- printer-attributes-sequence Printer-Attributes) Document Content in a special position as described above If an operation contains attributes from more than one job object (e.g. Get-Jobs response), the attributes from each job object MUST be in a separate job-attribute-sequence, such that the attributes from the ith job object are in the ith job-attribute-sequence. See Section 11 "Appendix A: Protocol Examples" for table showing the application of the rules above. Herriot, Butler, [Page 13] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 3.10 Value Length Each attribute value MUST be preceded by a SIGNED-SHORT, which MUST specify the number of octets in the value which follows this length, exclusive of the two bytes specifying the length. For any of the types represented by binary signed integers, the sender MUST encode the value in exactly four octets. For any of the types represented by character-strings, the sender MUST encode the value with all the characters of the string and without any padding characters. If a value-tag contains an "out-of-band" value, such as "unsupported", the value-length MUST be 0 and the value empty . the value has no meaning when the value-tag has an "out-of-band" value. If a client receives a response with a nonzero value-length in this case, it MUST ignore the value field. If a printer receives a request with a nonzero value-length in this case, it MUST reject the request. 3.11 (Attribute) Value The syntax types and most of the details of their representation are defined in the IPP model document. The table below augments the information in the model document, and defines the syntax types from the model document in terms of the 5 basic types defined in section 3 "Encoding of the Operation Layer". The 5 types are US-ASCII-STRING, LOCALIZED-STRING, SIGNED-INTEGER, SIGNED-SHORT, SIGNED-BYTE, and OCTET- STRING. Syntax of Attribute Encoding Value textWithoutLanguage, LOCALIZED-STRING. nameWithoutLanguage textWithLanguage OCTET_STRING consisting of 4 fields: a) a SIGNED-SHORT which is the number of octets in the following field b) a value of type natural-language, c) a SIGNED-SHORT which is the number of octets in the following field, d) a value of type textWithoutLanguage. The length of a textWithLanguage value MUST be 4 + the value of field a + the value of field c. nameWithLanguage OCTET_STRING consisting of 4 fields: a) a SIGNED-SHORT which is the number of octets in the following field b) a value of type natural-language, c) a SIGNED-SHORT which is the number of octets in the following field Herriot, Butler, [Page 14] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 Syntax of Attribute Encoding Value d) a value of type nameWithoutLanguage. The length of a nameWithLanguage value MUST be 4 + the value of field a + the value of field c. charset, US-ASCII-STRING. naturalLanguage, mimeMediaType, keyword, uri, and uriScheme boolean SIGNED-BYTE where 0x00 is 'false' and 0x01 is 'true'. integer and enum a SIGNED-INTEGER. dateTime OCTET-STRING consisting of eleven octets whose contents are defined by "DateAndTime" in RFC 1903 [rfc1903]. resolution OCTET_STRING consisting of nine octets of 2 SIGNED-INTEGERs followed by a SIGNED-BYTE. The first SIGNED-INTEGER contains the value of cross feed direction resolution. The second SIGNED- INTEGER contains the value of feed direction resolution. The SIGNED-BYTE contains the units value. rangeOfInteger Eight octets consisting of 2 SIGNED-INTEGERs. The first SIGNED-INTEGER contains the lower bound and the second SIGNED-INTEGER contains the upper bound. 1setOf X Encoding according to the rules for an attribute with more than 1 value. Each value X is encoded according to the rules for encoding its type. octetString OCTET-STRING The type of the value in the model document determines the encoding in the value and the value of the value-tag. 3.12 Data The data part MUST include any data required by the operation Herriot, Butler, [Page 15] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 4. Encoding of Transport Layer HTTP/1.1 [rfc2068] is the transport layer for this protocol. The operation layer has been designed with the assumption that the transport layer contains the following information: @ the URI of the target job or printer operation @ the total length of the data in the operation layer, either as a single length or as a sequence of chunks each with a length. It is REQUIRED that a printer implementation support HTTP over the IANA assigned Well Known Port 631 (the IPP default port), though a printer implementation may support HTTP over some other port as well. Each HTTP operation MUST use the POST method where the request-URI is the object target of the operation, and where the "Content-Type" of the message-body in each request and response MUST be "application/ipp". The message-body MUST contain the operation layer and MUST have the syntax described in section 3.2 "Syntax of Encoding". A client implementation MUST adhere to the rules for a client described for HTTP1.1 [rfc2068] . A printer (server) implementation MUST adhere the rules for an origin server described for HTTP1.1 [rfc2068]. An IPP server sends a response for each request that it receives. If an IPP server detects an error, it MAY send a response before it has read the entire request. If the HTTP layer of the IPP server completes processing the HTTP headers successfully, it MAY send an intermediate response, such as "100 Continue", with no IPP data before sending the IPP response. A client MUST expect such a variety of responses from an IPP server. For further information on HTTP/1.1, consult the HTTP documents [rfc2068]. An HTTP server MUST support chunking for IPP requests, and an IPP client MUST support chunking for IPP responses according to HTTP/1.1[rfc2068]. Note: this rule causes a conflict with non-compliant implementations of HTTP/1.1 that don't support chunking for POST methods, and this rule may cause a conflict with non-compliant implementations of HTTP/1.1 that don't support chunking for CGI scripts 5. IPP URL Scheme The IPP/1.1 specification defines a new scheme 'ipp' as the value of a URL that identifies either an IPP printer object or an IPP job object. The IPP attributes using the 'ipp' scheme are specified below. Because the HTTP layer does not support the 'ipp' scheme, a client MUST map 'ipp' URLs to 'http' URLs, and then follows the HTTP [RFC2068][RFC2069] rules for constructing a Request-Line and HTTP headers. The mapping is simple because the 'ipp' scheme implies all of the same protocol semantics as that of the 'http' scheme [RFC2068], except that it represents a print service and the implicit (default) port number that clients use to connect to a server is port 631. Herriot, Butler, [Page 16] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 In the remainder of this section the term 'ipp-URL' means a URL whose scheme is 'ipp' and whose implicit (default) port is 631. The term 'http-URL' means a URL whose scheme is 'http', and the term 'https-URL' means a URL whose scheme is 'https', A client and an IPP object (i.e. the server) MUST support the ipp-URL value in the following IPP attributes. job attributes: job-uri job-printer-uri printer attributes: printer-uri-supported operation attributes: job-uri printer-uri Each of the above attributes identifies a printer or job object. The ipp-URL is intended as the value of the attributes in this list, and for no other attributes. All of these attributes have a syntax type of 'uri', but there are attributes with a syntax type of 'uri' that do not use the 'ipp' scheme, e.g. 'job-more-info'. If a printer registers its URL with a directory service, the printer MUST register an ipp-URL. User interfaces are beyond the scope of this document. But if software exposes the ipp-URL values of any of the above five attributes to a human user, it is REQUIRED that the human see the ipp-URL as is. When a client sends a request, it MUST convert a target ipp-URL to a target http-URL for the HTTP layer according to the following rules: 1. change the 'ipp' scheme to 'http' 2. add an explicit port 631 if the URL does not contain an explicit port. Note: port 631 is the IANA assigned Well Known Port for the 'ipp' scheme. The client MUST use the target http-URL in both the HTTP Request-Line and HTTP headers, as specified by HTTP[RFC2068][RFC2069] . However, the client MUST use the target ipp-URL for the value of the "printer-uri" or "job-uri" operation attribute within the application/ipp body of the request. The server MUST use the ipp-URL for the value of the "printer- uri", "job-uri" or "printer-uri-supported" attributes within the application/ipp body of the response. For example, when an IPP client sends a request directly (i.e. no proxy) to an ipp-URL "ipp://myhost.com/myprinter/myqueue", it opens a TCP connection to port 631 (the ipp implicit port) on the host "myhost.com" and sends the following data: POST /myprinter/myqueue HTTP/1.1 Host: myhost.com:631 Content-type: application/ipp Transfer-Encoding: chunked ... Herriot, Butler, [Page 17] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 "printer-uri" "ipp://myhost.com/myprinter/myqueue" (encoded in application/ipp message body) ... As another example, when an IPP client sends the same request as above via a proxy "myproxy.com", it opens a TCP connection to the proxy port 8080 on the proxy host "myproxy.com" and sends the following data: POST http://myhost.com:631/myprinter/myqueue HTTP/1.1 Host: myhost.com:631 Content-type: application/ipp Transfer-Encoding: chunked ... "printer-uri" "ipp://myhost.com/myprinter/myqueue" (encoded in application/ipp message body) ... The proxy then connects to the IPP origin server with headers that are the same as the "no-proxy" example above. 6. Compatibility with IPP/1.0 Implementations IPP/1.1 implementations must be compatible with IPP 1.0 implementations, as defined in [ipp-mod-10] and [ipp-pro-10] documents. For compatibility with IPP/1.0 implementations, IPP objects (i.e. a server) MUST support additional schemes when communicating with IPP/1.0 clients as described in this section: @ If a server receives an IPP/1.0 request, it MUST return an IPP/1.0 response. That is, it MUST support both an http-URL and an https- URL in the target "printer-uri" and "job-uri" operation attributes in a request. The rules for attributes in a response is covered in the next two bullet items. @ When a server returns the printer attribute "printer-uri- supported", it MUST return all values of the attribute for an IPP/1.1 request. For an IPP/1.0 request, a server MUST return a subset of the attribute values, excluding those that are ipp-URLs, and including those that are http-URLs and https-URLs.. @ The table below shows the type of URL that a server returns for the "job-uri" and "job-printer-uri" job attributes for all operations based on how the job was created. Operation Job created via attribute s for a ipp secure ipp http https request ipp ipp No URL ipp No URL returned returned Herriot, Butler, [Page 18] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 secure ipp ipp ipp ipp ipp http http No URL http No URL returned returned https http https http https @ If a server registers a nonsecure ipp-URL with a name service, then it MUST also register an http-URL. If a printer supports a secure connection using SSL3, then it MUST register an https-URL. 7. Security Considerations The IPP Model document defines an IPP implementation with "privacy" as one that implements Transport Layer Security (TLS) [rfc2246]. TLS meets the requirements for IPP security with regards to features such as mutual authentication and privacy (via encryption). The IPP Model document also outlines IPP-specific security considerations and should be the primary reference for security implications with regards to the IPP protocol itself. The IPP Model document defines an IPP implementation with "authentication" as one that implements the standard way for transporting IPP messages within HTTP 1.1. These include the security considerations outlined in the HTTP 1.1 standard document [rfc2068] and Digest Access Authentication extension [rfc2069]. The current HTTP infrastructure supports HTTP over TCP port 80. IPP server implementations MUST offer IPP services using HTTP over the IANA assigned Well Known Port 631 (the IPP default port). IPP server implementations may support other ports, in addition to this port. See further discussion of IPP security concepts in the model document [ipp-mod]. 7.1 Using IPP with TLS An initial IPP request never uses TLS. The switch to TLS occurs either because the server grants the client's request to upgrade to TLS, or a server asks to switch to TLS in its response. Secure communication begins with a server's response to switch to TLS. During the TLS handshake, the original session is preserved. An IPP client that wants a secure connection MUST send "TLS/1.0" as one of the field-values of the Upgrade request header, e.g. "Upgrade: TLS/1.0" (see rfc2068 section 14.42). If the origin-server grants the upgrade request, it MUST respond with "101 Switching Protocols", and it Herriot, Butler, [Page 19] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 MUST include the header "Upgrade: TLS/1.0" to indicate what it is switching to. An IPP client MUST be ready to react appropriately if the server does not grant the upgrade request. Note: the 'Upgrade header' mechanism allows unsecured and secured traffic to share the same port (in this case, 631). With current technology, an IPP server can indicate that it wants an upgrade only by returning "401 unauthorized" or "403 forbidden". A server MAY give the client an additional hint by including an "Upgrade: TLS" header in the response. When an IPP client receives such a response, it can perform the request again with an Upgrade header with the "TLS/1.0" value. If a server supports TLS, it SHOULD include the "Upgrade" header with the value "TLS/1.0" in response to any OPTIONS request. Upgrade is a hop-by-hop header (rfc2068, section 13.5.1), so each intervening proxy which supports TLS MUST also request the same version of TLS/1.0 on its subsequent request. Furthermore, any caching proxy which supports TLS MUST NOT reply from its cache when TLS/1.0 has been requested (although clients are still recommended to explicitly include "Cache-control: no-cache"). Note: proxy servers may be able to request or initiate a TLS-secured connection, e.g. the outgoing or incoming firewall of a trusted subnetwork. Note: the initial connection (containing the Upgrade header) is not secure. Any client expecting a secure connection should first use a non-sensitive operation (e.g. an HTTP POST with an empty message body) to establish a secure connection before sending any sensitive data. 8. References [char] N. Freed, J. Postel: IANA Charset Registration Procedures, Work in Progress (draft-freed-charset-reg-02.txt). [dpa] ISO/IEC 10175 Document Printing Application (DPA), June 1996. [iana] IANA Registry of Coded Character Sets: ftp://ftp.isi.edu/in- notes/iana/assignments/character-sets. [ipp-iig] Hastings, Tom, et al., "Internet Printing Protocol/1.1: Implementer's Guide", draft-ietf-ipp-implementers-guide-00.txt, November 1998, work in progress. [ipp-lpd] Herriot, R., Hastings, T., Jacobs, N., Martin, J., "Mapping between LPD and IPP Protocols", draft-ietf-ipp-lpd-ipp- map-05.txt, November 1998. [ipp-mod-10] R. deBry, T. Hastings, R. Herriot, S. Isaacson, P. Powell, "Internet Printing Protocol/1.0: Model and Semantics", , November, 1998. Herriot, Butler, [Page 20] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 [ipp-mod] R. deBry, T. Hastings, R. Herriot, S. Isaacson, P. Powell, "Internet Printing Protocol/1.0: Model and Semantics", , February, 1999. [ipp-pro-10] Herriot, R., Butler, S., Moore, P., Turner, R., "Internet Printing Protocol/1.0: Encoding and Transport", draft- ietf-ipp-protocol-07.txt, November 1998. [ipp-pro] Herriot, R., Butler, S., Moore, P., Turner, R., "Internet Printing Protocol/1.1: Encoding and Transport", draft- ietf-ipp-protocol-v11-00-.txt, February 1999. [ipp-rat] Zilles, S., "Rationale for the Structure and Model and Protocol for the Internet Printing Protocol", draft-ietf-ipp- rat-04.txt, November 1998. [ipp-req] Wright, D., "Design Goals for an Internet Printing Protocol", draft-ietf-ipp-req-03.txt, November, 1998. [rfc822] Crocker, D., "Standard for the Format of ARPA Internet Text Messages", RFC 822, August 1982. [rfc1123] Braden, S., "Requirements for Internet Hosts - Application and Support", RFC 1123, October, 1989. [rfc1179] McLaughlin, L. III, (editor), "Line Printer Daemon Protocol" RFC 1179, August 1990. [rfc1543] Postel, J., "Instructions to RFC Authors", RFC 1543, October 1993. [rfc1738] Berners-Lee, T., Masinter, L., McCahill, M. , "Uniform Resource Locators (URL)", RFC 1738, December, 1994. [rfc1759] Smith, R., Wright, F., Hastings, T., Zilles, S., and Gyllenskog, J., "Printer MIB", RFC 1759, March 1995. [rfc1766] H. Alvestrand, " Tags for the Identification of Languages", RFC 1766, March 1995. [rfc1808] R. Fielding, "Relative Uniform Resource Locators", RFC1808, June 1995. [rfc1903] J. Case, et al. "Textual Conventions for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1903, January 1996. [rfc2046] N. Freed & N. Borenstein, Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types. November 1996, RFC 2046. [rfc2048] N. Freed, J. Klensin & J. Postel. Multipurpose Internet Mail Extension (MIME) Part Four: Registration Procedures. November 1996 (Also BCP0013), RFC 2048. Herriot, Butler, [Page 21] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 [rfc2068] R Fielding, et al, "Hypertext Transfer Protocol . HTTP/1.1" RFC 2068, January 1997. [rfc2069] J. Franks, et al, "An Extension to HTTP: Digest Access Authentication" RFC 2069, January 1997. [rfc2119] S. Bradner, "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119 , March 1997. [rfc2184] N. Freed, K. Moore, "MIME Parameter Value and Encoded Word Extensions: Character Sets, Languages, and Continuations", RFC 2184, August 1997. [rfc2234] D. Crocker et al., "Augmented BNF for Syntax Specifications: ABNF", RFC 2234. November 1997. [rfc2246] T. Dierks et al., "The TLS Protocol", RFC 2246. January 1999. [rfc2396] Berners-Lee, T., Fielding, R., Masinter, L., "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998. 9. Author's Address Paul Moore Robert Herriot (editor) Microsoft Xerox Corporation One Microsoft Way 3400 Hillview Ave., Bldg #1 Redmond, WA 98053 Palo Alto, CA 94304 Phone: 425-936-0908 Phone: 650-813-7696 Fax: 425-93MS-FAX Fax: 650-650-813-6860 Email: paulmo@microsoft.com Email: robert.herriot@pahv.xerox.com Randy Turner Sylvan Butler Sharp Laboratories Hewlett-Packard 5750 NW Pacific Rim Blvd 11311 Chinden Blvd. Camas, WA 98607 Boise, ID 83714 Phone: 360-817-8456 Phone: 208-396-6000 Fax: : 360-817-8436 Fax: 208-396-3457 Email: rturner@sharplabs.com Email: sbutler@boi.hp.com John Wenn Xerox Corporation 737 Hawaii St El Segundo, CA 90245 IPP Mailing List: ipp@pwg.org Phone: 310-333-5764 IPP Mailing List Subscription: Fax: 310-333-5514 ipp-request@pwg.org Herriot, Butler, [Page 22] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 IPP Web Page: Email: jwenn@cp10.es.xerox.com http://www.pwg.org/ipp/ 10. Other Participants: Chuck Adams - Tektronix Harry Lewis - IBM Ron Bergman - Dataproducts Tony Liao - Vivid Image Keith Carter - IBM David Manchala - Xerox Angelo Caruso - Xerox Carl-Uno Manros - Xerox Jeff Copeland - QMS Jay Martin - Underscore Roger deBry - IBM Larry Masinter - Xerox Lee Farrell - Canon Ira McDonald - High North Inc. Sue Gleeson - Digital Bob Pentecost - Hewlett-Packard Charles Gordon - Osicom Patrick Powell - Astart Technologies Brian Grimshaw - Apple Jeff Rackowitz - Intermec Jerry Hadsell - IBM Xavier Riley - Xerox Richard Hart - Digital Gary Roberts - Ricoh Tom Hastings - Xerox Stuart Rowley - Kyocera Stephen Holmstead Richard Schneider - Epson Zhi-Hong Huang - Zenographics Shigern Ueda - Canon Scott Isaacson - Novell Bob Von Andel - Allegro Software Rich Lomicka - Digital William Wagner - Digital Products David Kellerman - Northlake Jasper Wong - Xionics Software Robert Kline - TrueSpectra Don Wright - Lexmark Dave Kuntz - Hewlett-Packard Rick Yardumian - Xerox Takami Kurono - Brother Lloyd Young - Lexmark Rich Landau - Digital Peter Zehler - Xerox Greg LeClair - Epson Frank Zhao - Panasonic Steve Zilles - Adobe 11. Appendix A: Protocol Examples 11.1 Print-Job Request The following is an example of a Print-Job request with job-name, copies, and sides specified. The "ipp-attribute-fidelity" attribute is set to 'true' so that the print request will fail if the "copies" or the "sides" attribute are not supported or their values are not supported. Octets Symbolic Value Protocol field 0x0101 1.1 version-number 0x0002 Print-Job operation-id 0x00000001 1 request-id 0x01 start operation-attributes operation-attributes-tag 0x47 charset type value-tag 0x0012 name-length attributes- attributes-charset name charset 0x0008 value-length Herriot, Butler, [Page 23] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 Octets Symbolic Value Protocol field us-ascii US-ASCII value 0x48 natural-language type value-tag 0x001B name-length attributes- attributes-natural-language name natural- language 0x0005 value-length en-us en-US value 0x45 uri type value-tag 0x000B name-length printer-uri printer-uri name 0x0015 value-length ipp://forest/p printer pinetree value inetree 0x42 nameWithoutLanguage type value-tag 0x0008 name-length job-name job-name name 0x0006 value-length foobar foobar value 0x22 boolean type value-tag 0x0016 name-length ipp-attribute- ipp-attribute-fidelity name fidelity 0x0001 value-length 0x01 true value 0x02 start job-attributes job-attributes-tag 0x21 integer type value-tag 0x0006 name-length copies copies name 0x0004 value-length 0x00000014 20 value 0x44 keyword type value-tag 0x0005 name-length sides sides name 0x0013 value-length two-sided- two-sided-long-edge value long-edge 0x03 end-of-attributes end-of-attributes-tag %!PS... data 11.2 Print-Job Response (successful) Here is an example of a successful Print-Job response to the previous Print-Job request. The printer supported the "copies" and "sides" attributes and their supplied values. The status code returned is 'successful-ok'. Octets Symbolic Value Protocol field 0x0101 1.1 version-number 0x0000 successful-ok status-code 0x00000001 1 request-id Herriot, Butler, [Page 24] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 Octets Symbolic Value Protocol field 0x01 start operation-attributes operation-attributes-tag 0x47 charset type value-tag 0x0012 name-length attributes- attributes-charset name charset 0x0008 value-length us-ascii US-ASCII value 0x48 natural-language type value-tag 0x001B name-length attributes- attributes-natural- name natural-language language 0x0005 value-length en-us en-US value 0x41 textWithoutLanguage type value-tag 0x000E name-length status-message status-message name 0x000D value-length successful-ok successful-ok value 0x02 start job-attributes job-attributes-tag 0x21 integer value-tag 0x0006 name-length job-id job-id name 0x0004 value-length 147 147 value 0x45 uri type value-tag 0x0007 name-length job-uri job-uri name 0x0019 value-length ipp://forest/pin job 123 on pinetree value etree/123 0x23 nameWithoutLanguage type value-tag 0x0009 name-length job-state job-state name 0x0004 value-length 0x0003 pending value 0x03 end-of-attributes end-of-attributes-tag 11.3 Print-Job Response (failure) Here is an example of an unsuccessful Print-Job response to the previous Print-Job request. It fails because, in this case, the printer does not support the "sides" attribute and because the value '20' for the "copies" attribute is not supported. Therefore, no job is created, and neither a "job-id" nor a "job-uri" operation attribute is returned. The error code returned is 'client-error-attributes-or-values-not-supported' (0x040B). Octets Symbolic Value Protocol field 0x0101 1.1 version-number 0x040B client-error-attributes-or- status-code values-not-supported Herriot, Butler, [Page 25] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 Octets Symbolic Value Protocol field 0x00000001 1 request-id 0x01 start operation-attributes operation-attribute tag 0x47 charset type value-tag 0x0012 name-length attributes- attributes-charset name charset 0x0008 value-length us-ascii US-ASCII value 0x48 natural-language type value-tag 0x001B name-length attributes- attributes-natural-language name natural- language 0x0005 value-length en-us en-US value 0x41 textWithoutLanguage type value-tag 0x000E name-length status- status-message name message 0x002F value-length client-error- client-error-attributes-or- value attributes- values-not-supported or-values- not-supported 0x05 start unsupported-attributes unsupported-attributes tag 0x21 integer type value-tag 0x0006 name-length copies copies name 0x0004 value-length 0x00000014 20 value 0x10 unsupported (type) value-tag 0x0005 name-length sides sides name 0x0000 value-length 0x03 end-of-attributes end-of-attributes-tag 11.4 Print-Job Response (success with attributes ignored) Here is an example of a successful Print-Job response to a Print-Job request like the previous Print-Job request, except that the value of 'ipp-attribute-fidelity' is false. The print request succeeds, even though, in this case, the printer supports neither the "sides" attribute nor the value '20' for the "copies" attribute. Therefore, a job is created, and both a "job-id" and a "job-uri" operation attribute are returned. The unsupported attributes are also returned in an Unsupported Attributes Group. The error code returned is 'successful-ok-ignored-or- substituted-attributes' (0x0001). Octets Symbolic Value Protocol field 0x0101 1.1 version-number 0x0001 successful-ok-ignored-or- status-code Herriot, Butler, [Page 26] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 Octets Symbolic Value Protocol field substituted-attributes 0x00000001 1 request-id 0x01 start operation-attributes operation-attributes-tag 0x47 charset type value-tag 0x0012 name-length attributes- attributes-charset name charset 0x0008 value-length us-ascii US-ASCII value 0x48 natural-language type value-tag 0x001B name-length attributes- attributes-natural- name natural-language language 0x0005 value-length en-us en-US value 0x41 textWithoutLanguage type value-tag 0x000E name-length status-message status-message name 0x002F value-length successful-ok- successful-ok-ignored-or- value ignored-or- substituted-attributes substituted- attributes 0x05 start unsupported- unsupported-attributes attributes tag 0x21 integer type value-tag 0x0006 name-length copies copies name 0x0004 value-length 0x00000014 20 value 0x10 unsupported (type) value-tag 0x0005 name-length sides sides name 0x0000 value-length 0x02 start job-attributes job-attributes-tag 0x21 integer value-tag 0x0006 name-length job-id job-id name 0x0004 value-length 147 147 value 0x45 uri type value-tag 0x0007 name-length job-uri job-uri name 0x0019 value-length ipp://forest/pin job 123 on pinetree value etree/123 0x23 nameWithoutLanguage type value-tag 0x0009 name-length job-state job-state name 0x0004 value-length 0x0003 pending value 0x03 end-of-attributes end-of-attributes-tag Herriot, Butler, [Page 27] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 11.5 Print-URI Request The following is an example of Print-URI request with copies and job- name parameters: Octets Symbolic Value Protocol field 0x0101 1.1 version-number 0x0003 Print-URI operation-id 0x00000001 1 request-id 0x01 start operation-attributes operation-attributes-tag 0x47 charset type value-tag 0x0012 name-length attributes- attributes-charset name charset 0x0008 value-length us-ascii US-ASCII value 0x48 natural-language type value-tag 0x001B name-length attributes- attributes-natural-language name natural- language 0x0005 value-length en-us en-US value 0x45 uri type value-tag 0x000B name-length printer-uri printer-uri name 0x0015 value-length ipp://forest/ printer pinetree value pinetree 0x45 uri type value-tag 0x000C name-length document-uri document-uri name 0x0011 value-length ftp://foo.com ftp://foo.com/foo value /foo 0x42 nameWithoutLanguage type value-tag 0x0008 name-length job-name job-name name 0x0006 value-length foobar foobar value 0x02 start job-attributes job-attributes-tag 0x21 integer type value-tag 0x0006 name-length copies copies name 0x0004 value-length 0x00000001 1 value 0x03 end-of-attributes end-of-attributes-tag Herriot, Butler, [Page 28] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 11.6 Create-Job Request The following is an example of Create-Job request with no parameters and no attributes: Octets Symbolic Value Protocol field 0x0101 1.1 version-number 0x0005 Create-Job operation-id 0x00000001 1 request-id 0x01 start operation-attributes operation-attributes-tag 0x47 charset type value-tag 0x0012 name-length attributes- attributes-charset name charset 0x0008 value-length us-ascii US-ASCII value 0x48 natural-language type value-tag 0x001B name-length attributes- attributes-natural-language name natural- language 0x0005 value-length en-us en-US value 0x45 uri type value-tag 0x000B name-length printer-uri printer-uri name 0x0015 value-length ipp://forest/p printer pinetree value inetree 0x03 end-of-attributes end-of-attributes-tag 11.7 Get-Jobs Request The following is an example of Get-Jobs request with parameters but no attributes: Octets Symbolic Value Protocol field 0x0101 1.1 version-number 0x000A Get-Jobs operation-id 0x00000123 0x123 request-id 0x01 start operation-attributes operation-attributes-tag 0x47 charset type value-tag 0x0012 name-length attributes- attributes-charset name charset 0x0008 value-length us-ascii US-ASCII value 0x48 natural-language type value-tag 0x001B name-length attributes- attributes-natural-language name natural- language 0x0005 value-length en-us en-US value Herriot, Butler, [Page 29] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 Octets Symbolic Value Protocol field 0x45 uri type value-tag 0x000B name-length printer-uri printer-uri name 0x0015 value-length ipp://forest/pi printer pinetree value netree 0x21 integer type value-tag 0x0005 name-length limit limit name 0x0004 value-length 0x00000032 50 value 0x44 keyword type value-tag 0x0014 name-length requested- requested-attributes name attributes 0x0006 value-length job-id job-id value 0x44 keyword type value-tag 0x0000 additional value name-length 0x0008 value-length job-name job-name value 0x44 keyword type value-tag 0x0000 additional value name-length 0x000F value-length document-format document-format value 0x03 end-of-attributes end-of-attributes-tag 11.8 Get-Jobs Response The following is an of Get-Jobs response from previous request with 3 jobs. The Printer returns no information about the second job (because of security reasons): Octets Symbolic Value Protocol field 0x0101 1.1 version-number 0x0000 successful-ok status-code 0x00000123 0x123 request-id (echoed back) 0x01 start operation-attributes operation-attribute-tag 0x47 charset type value-tag 0x0012 name-length attributes- attributes-charset name charset 0x000A value-length ISO-8859-1 ISO-8859-1 value 0x48 natural-language type value-tag 0x001B name-length attributes- attributes-natural-language name natural- language 0x0005 value-length en-us en-US value 0x41 textWithoutLanguage type value-tag Herriot, Butler, [Page 30] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 Octets Symbolic Value Protocol field 0x000E name-length status-message status-message name 0x000D value-length successful-ok successful-ok value 0x02 start job-attributes (1st job-attributes-tag object) 0x21 integer type value-tag 0x0006 name-length job-id job-id name 0x0004 value-length 147 147 value 0x36 nameWithLanguage value-tag 0x0008 name-length job-name job-name name 0x000C value-length 0x0005 sub-value-length fr-ca fr-CA value 0x0003 sub-value-length fou fou name 0x02 start job-attributes (2nd job-attributes-tag object) 0x02 start job-attributes (3rd job-attributes-tag object) 0x21 integer type value-tag 0x0006 name-length job-id job-id name 0x0004 value-length 148 149 value 0x36 nameWithLanguage value-tag 0x0008 name-length job-name job-name name 0x0012 value-length 0x0005 sub-value-length de-CH de-CH value 0x0009 sub-value-length isch guet isch guet name 0x03 end-of-attributes end-of-attributes-tag 12. Appendix C: Registration of MIME Media Type Information for "application/ipp" This appendix contains the information that IANA requires for registering a MIME media type. The information following this paragraph will be forwarded to IANA to register application/ipp whose contents are defined in Section 3 "Encoding of the Operation Layer" in this document: MIME type name: application MIME subtype name: ipp A Content-Type of "application/ipp" indicates an Internet Printing Protocol message body (request or response). Currently there are two Herriot, Butler, [Page 31] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 versions: IPP/1.0, and IPP/1.1, whose syntax is described in Section 3 "Encoding of the Operation Layer" of [ipp-pro-10] and [ipp-pro], respectively, and whose semantics are described in [ipp-mod-10] and [ipp-mod], respectively. Required parameters: none Optional parameters: none Encoding considerations: IPP/1.1 protocol requests/responses MAY contain long lines and ALWAYS contain binary data (for example attribute value lengths). Security considerations: IPP/1.1 protocol requests/responses do not introduce any security risks not already inherent in the underlying transport protocols. Protocol mixed-version interworking rules in [ipp-mod] as well as protocol encoding rules in [ipp-pro] are complete and unambiguous. Interoperability considerations: IPP/1.1 requests (generated by clients) and responses (generated by servers) MUST comply with all conformance requirements imposed by the normative specifications [ipp-mod] and [ipp-pro]. Protocol encoding rules specified in [ipp-pro] are comprehensive, so that interoperability between conforming implementations is guaranteed (although support for specific optional features is not ensured). Both the "charset" and "natural-language" of all IPP/1.1 attribute values which are a LOCALIZED-STRING are explicit within IPP protocol requests/responses (without recourse to any external information in HTTP, SMTP, or other message transport headers). IPP/1.1 servers MUST support both IPP/1.0 and IPP/1.1. See the section in [ipp-pro] entitled "Compatibility with IPP/1.0 Implementations" for a discussion of compatibility with IPP/1.0. Published specification: [ipp-mod-10] Isaacson, S., deBry, R., Hastings, T., Herriot, R., Powell, P., "Internet Printing Protocol/1.0: Model and Semantics" draft-ietf-ipp-model-11.txt, November, 1998. [ipp-mod] Isaacson, S., deBry, R., Hastings, T., Herriot, R., Powell, P., "Internet Printing Protocol/1.1: Model and Semantics" draft-ietf-ipp-model-v11-00.txt, February, 1999. [ipp-pro] Herriot, R., Butler, S., Moore, P., Turner, R., "Internet Printing Protocol/1.1: Encoding and Transport", draft- ietf-ipp-protocol-v11-00.txt, February, 1999. Applications which use this media type: Herriot, Butler, [Page 32] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 Internet Printing Protocol (IPP) print clients and print servers, communicating using HTTP/1.1 (see [IPP-PRO]), SMTP/ESMTP, FTP, or other transport protocol. Messages of type "application/ipp" are self- contained and transport-independent, including "charset" and "natural- language" context for any LOCALIZED-STRING value. Person & email address to contact for further information: Tom Hastings Xerox Corporation 737 Hawaii St. ESAE-231 El Segundo, CA Phone: 310-333-6413 Fax: 310-333-5514 Email: thastings@cp10.es.xerox.com or Robert Herriot Xerox Corporation 3400 Hillview Ave., Bldg #1 Palo Alto, CA 94304 Phone: 650-813-7696 Fax: 650-813-6860 Email: robert.herriot@pahv.xerox.com Intended usage: COMMON 13. Appendix D: Notices The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards- related documentation can be found in BCP-11[BCP-11]. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. Herriot, Butler, [Page 33] Moore , Turner and Wenn Expires August 17, 1999 INTERNET-DRAFT IPP/1.1: Encoding and Transport February 17, 1999 Copyright (C)The Internet Society (1999). 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. 14. Appendix E: Changes from IPP /1.0 IPP/1.1 is identical to IPP/1.0 with the follow changes: 1.Attributes values that identify a printer or job object use a new 'ipp' scheme. The 'http' and 'https' schemes are supported only for backward compatibility. 2.TLS provides security. SSL3 is supported only for backward compatibility. Herriot, Butler, [Page 34] Moore , Turner and Wenn Expires August 17, 1999