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Applications IPP WG IPP Printer PWG Printer Working Group The Internet Printing Protocol (IPP) is an application-level protocol for distributed printing using Internet tools and technologies. This document defines the rules for encoding IPP operations, attributes, and values into the Internet MIME media type called "application/ipp". It also defines the rules for transporting a message body whose Content-Type is "application/ipp" over HTTP and/or HTTPS. The IPP data model and operation semantics are described in "Internet Printing Protocol/1.1: Model and Semantics" (RFC 8011). This document obsoletes RFCs 2910 and 3382.

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 request and response. All IPP implementations support HTTP/1.1, the relevant parts of which are described in the following RFCs: Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests Hypertext Transfer Protocol (HTTP/1.1): Caching Hypertext Transfer Protocol (HTTP/1.1): Authentication The 'Basic' HTTP Authentication Scheme HTTP Digest Access Authentication IPP implementations can support HTTP/2, which is described in the following RFCs: Hypertext Transfer Protocol Version 2 (HTTP/2) HPACK - Header Compression for HTTP/2 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 "Internet Printing Protocol/1.1: Model and Semantics" document and subsequent extensions (collectively known as the IPP Model) define the semantics of such a message body and the supported values. This document specifies the encoding of an IPP request and response message.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in .

Client: Initiator of outgoing IPP session requests and sender of outgoing IPP operation requests (Hypertext Transfer Protocol -- HTTP/1.1 User Agent). Document: An object created and managed by a Printer that contains description, processing, and status information. A Document object may have attached data and is bound to a single Job. 'ipp' URI: An IPP URI as defined in . 'ipps' URI: An IPPS URI as defined in . Job: An object created and managed by a Printer that contains description, processing, and status information. The Job also contains zero or more Document objects. Logical Device: A print server, software service, or gateway that processes Jobs and either forwards or stores the processed Job or uses one or more Physical Devices to render output. Model: The semantics of operations, attributes, values, and status-codes used in the Internet Printing Protocol as defined in the Internet Printing Protocol/1.1: Model and Semantics document and subsequent extensions. Output Device: A single Logical or Physical Device. Physical Device: A hardware implementation of an endpoint device, e.g., a marking engine, a fax modem, etc. Printer: Listener for incoming IPP session requests and receiver of incoming IPP operation requests (Hypertext Transfer Protocol -- HTTP/1.1 Server) that represents one or more Physical Devices or a Logical Device.

ABNF: Augmented Backus-Naur Form ASCII: American Standard Code for Information Interchange HTTP: Hypertext Transfer Protocol HTTPS: HTTP over TLS IANA: Internet Assigned Numbers Authority IEEE: Institute of Electrical and Electronics Engineers IESG: Internet Engineering Steering Group IPP: Internet Printing Protocol (this document and ) ISTO: IEEE Industry Standards and Technology Organization LPD: Line Printer Daemon Protocol PWG: IEEE-ISTO Printer Working Group RFC: Request for Comments TCP: Transmission Control Protocol TLS: Transport Layer Security URI: Uniform Resource Identifier URL: Uniform Resource Locator UTF-8: Unicode Transformation Format - 8-bit

The operation layer is the message body part of the HTTP request or response and it MUST contain a single IPP operation request or IPP 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 and 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 is henceforth called a LOCALIZED-STRING. An octet string MUST be in "Model order" with the first octet in the value (according to the Model 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. A one-octet integer, henceforth called a SIGNED-BYTE, is used for the version-number and tag fields. A two-byte integer, henceforth called a SIGNED-SHORT, is used for the operation-id, status-code, and length fields. A four-byte integer, henceforth called a SIGNED-INTEGER, is used for value fields and the request-id. The following two sections present the encoding of the operation layer in two ways: informally through pictures and description formally through Augmented Backus-Naur Form (ABNF), as specified by RFC 5234 An operation request or response MUST use the encoding described in these two sections.

An operation request or response is encoded as follows:

----------------------------------------------- | version-number | 2 bytes - required ----------------------------------------------- | operation-id (request) | | or | 2 bytes - required | status-code (response) | ----------------------------------------------- | request-id | 4 bytes - required ----------------------------------------------- | attribute-group | n bytes - 0 or more ----------------------------------------------- | end-of-attributes-tag | 1 byte - required ----------------------------------------------- | data | q bytes - optional -----------------------------------------------

The first three fields in the above diagram contain the value of attributes described in Section 4.1.1 of the Model and Semantics document . The fourth field is the "attribute-group" field, and it occurs 0 or more times. Each "attribute-group" field represents a single group of attributes, such as an Operation Attributes group or a Job Attributes group (see the Model). The Model specifies the required attribute groups and their order for each operation request and response. The "end-of-attributes-tag" field is always present, even when the "data" is not present. The Model specifies whether the "data" field is present for each operation request and response.

Each "attribute-group" field is encoded as follows:

----------------------------------------------- | begin-attribute-group-tag | 1 byte ---------------------------------------------------------- | attribute | p bytes |- 0 or more ----------------------------------------------------------

An "attribute-group" field contains zero or more "attribute" fields. Note that the values of the "begin-attribute-group-tag" field and the "end-of-attributes-tag" field are called "delimiter-tags".

An "attribute" field is encoded as follows:

----------------------------------------------- | attribute-with-one-value | q bytes ---------------------------------------------------------- | additional-value | r bytes |- 0 or more ----------------------------------------------------------

When an attribute is single valued (e.g., "copies" with a value of 10) or multi-valued with one value (e.g., "sides-supported" with just the value 'one-sided'), it is encoded with just an "attribute-with-one-value" field. When an attribute is multi-valued with n values (e.g., "sides-supported" with the values 'one-sided' and 'two-sided-long-edge'), it is encoded with an "attribute-with-one-value" field followed by n-1 "additional-value" fields.

Each "attribute-with-one-value" field is encoded as follows:

----------------------------------------------- | 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 "attribute-with-one-value" field is encoded with five subfields: The "value-tag" field specifies the attribute syntax, e.g., 0x44 for the attribute syntax 'keyword'. The "name-length" field specifies the length of the "name" field in bytes, e.g., u in the above diagram or 15 for the name "sides-supported". The "name" field contains the textual name of the attribute, e.g., "sides-supported". The "value-length" field specifies the length of the "value" field in bytes, e.g., v in the above diagram or 9 for the (keyword) value 'one-sided'. The "value" field contains the value of the attribute, e.g., the textual value 'one-sided'.

Each "additional-value" field is encoded as follows:

----------------------------------------------- | value-tag | 1 byte ----------------------------------------------- | name-length (value is 0x0000) | 2 bytes ----------------------------------------------- | value-length (value is w) | 2 bytes ----------------------------------------------- | value | w bytes -----------------------------------------------

An "additional-value" is encoded with four subfields: The "value-tag" field specifies the attribute syntax, e.g., 0x44 for the attribute syntax 'keyword'. The "name-length" field has the value of 0 in order to signify that it is an "additional-value". The value of the "name-length" field distinguishes an "additional-value" field ("name-length" is 0) from an "attribute-with-one-value" field ("name-length" is not 0). The "value-length" field specifies the length of the "value" field in bytes, e.g., w in the above diagram or 19 for the (keyword) value 'two-sided-long-edge'. The "value" field contains the value of the attribute, e.g., the textual value 'two-sided-long-edge'.

Collection attributes create a named group containing related "member" attributes. The "attribute-with-one-value" field for a collection attribute is encoded as follows:

----------------------------------------------- | value-tag (value is 0x34) | 1 byte ----------------------------------------------- | name-length (value is u) | 2 bytes ----------------------------------------------- | name | u bytes ----------------------------------------------- | value-length (value is 0x0000) | 2 bytes ----------------------------------------------------------- | member-attribute | q bytes |-0 or more ----------------------------------------------------------- | end-value-tag (value is 0x37) | 1 byte ----------------------------------------------- | end-name-length (value is 0x0000) | 2 bytes ----------------------------------------------- | end-value-length (value is 0x0000) | 2 bytes -----------------------------------------------

Collection attribute is encoded with eight subfields: The "value-tag" field specifies the start attribute syntax: 0x34 for the attribute syntax 'begCollection'. The "name-length" field specifies the length of the "name" field in bytes, e.g., u in the above diagram or 9 for the name "media-col". Additional collection attribute values use a name length of 0x0000. The "name" field contains the textual name of the attribute, e.g., "media-col". The "value-length" field specifies a length of 0x0000. The "member-attribute" field contains member attributes encoded as defined in . The "end-value-tag" field specifies the end attribute syntax: 0x37 for the attribute syntax 'endCollection'. The "end-name-length" field specifies a length of 0x0000. The "end-value-length" field specifies a length of 0x0000.

Each "member-attribute" field is encoded as follows:

----------------------------------------------- | value-tag (value is 0x4a) | 1 byte ----------------------------------------------- | name-length (value is 0x0000) | 2 bytes ----------------------------------------------- | value-length (value is w) | 2 bytes ----------------------------------------------- | value (member-name) | w bytes ----------------------------------------------- | member-value-tag | 1 byte ----------------------------------------------- | name-length (value is 0x0000) | 2 bytes ----------------------------------------------- | member-value-length (value is x) | 2 bytes ----------------------------------------------- | member-value | x bytes -----------------------------------------------

A "member-attribute" is encoded with eight subfields: The "value-tag" field specifies 0x4a for the attribute syntax 'memberAttrName'. The "name-length" field has the value of 0 in order to signify that it is a "member-attribute" contained in the collection. The "value-length" field specifies the length of the "value" field in bytes, e.g., w in the above diagram or 10 for the member attribute name 'media-type'. Additional member attribute values are specified using a value length of 0. The "value" field contains the name of the member attribute, e.g., the textual value 'media-type'. The "member-value-tag" field specifies the attribute syntax for the member attribute, e.g., 0x44 for the attribute syntax 'keyword'. The second "name-length" field has the value of 0 in order to signify that it is a "member-attribute" contained in the collection. The "member-value-length" field specifies the length of the member attribute value, e.g., x in the above diagram or 10 for the value 'stationery'. The "member-value" field contains the value of the attribute, e.g., the textual value 'stationery'.

From the standpoint of a parser that performs an action based on a "tag" value, 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 | 1 byte - required ----------------------------------------------- | data | y bytes - optional -----------------------------------------------

The following shows what fields the parser would expect after each type of "tag": "begin-attribute-group-tag": expect zero or more "attribute" fields "value-tag": expect the remainder of an "attribute-with-one-value" or an "additional-value" "end-of-attributes-tag": expect that "attribute" fields are complete and there is optional "data"

The ABNF syntax for an IPP message is shown in .

ipp-message = ipp-request / ipp-response ipp-request = version-number operation-id request-id *attribute-group end-of-attributes-tag data ipp-response = version-number status-code request-id *attribute-group end-of-attributes-tag data version-number = major-version-number minor-version-number major-version-number = SIGNED-BYTE minor-version-number = SIGNED-BYTE operation-id = SIGNED-SHORT ; mapping from model status-code = SIGNED-SHORT ; mapping from model request-id = SIGNED-INTEGER ; whose value is > 0 attribute-group = begin-attribute-group-tag *attribute attribute = attribute-with-one-value *additional-value attribute-with-one-value = value-tag name-length name value-length value additional-value = 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 value-tag = %x10-ff ; see Section 3.5.2 begin-attribute-group-tag = %x00-02 / %x04-0f ; see Section 3.5.1 end-of-attributes-tag = %x03 ; tag of 3 ; see Section 3.5.1 SIGNED-BYTE = BYTE SIGNED-SHORT = 2BYTE SIGNED-INTEGER = 4BYTE DIGIT = %x30-39 ; "0" to "9" LALPHA = %x61-7A ; "a" to "z" BYTE = %x00-ff OCTET-STRING = *BYTE

defines additional terms that are referenced in this document and provides an alternate grouping of the delimiter tags.

delimiter-tag = begin-attribute-group-tag / ; see Section 3.5.1 end-of-attributes-tag begin-attribute-group-tag = %x00 / operation-attributes-tag / job-attributes-tag / printer-attributes-tag / unsupported-attributes-tag / future-group-tags operation-attributes-tag = %x01 ; tag of 1 job-attributes-tag = %x02 ; tag of 2 end-of-attributes-tag = %x03 ; tag of 3 printer-attributes-tag = %x04 ; tag of 4 unsupported-attributes-tag = %x05 ; tag of 5 future-group-tags = %x06-0f ; future extensions

Each "attribute-group" field MUST be encoded with the "begin-attribute-group-tag" field followed by zero or more "attribute" sub-fields. maps the Model group name to value of the "begin-attribute-group-tag" field: Model Document Group"begin-attribute-group-tag" field values Operation Attributes"operations-attributes-tag" Job Template Attributes"job-attributes-tag" Job Object Attributes"job-attributes-tag" Unsupported Attributes"unsupported-attributes-tag" Requested Attributes(Get-Job-Attributes) "job-attributes-tag" Requested Attributes(Get-Printer-Attributes)"printer-attributes-tag" Document Contentin a special position at the end of the message as described in . For each operation request and response, the Model prescribes the required and optional attribute groups, along with their order. Within each attribute group, the Model prescribes the required and optional attributes, along with their order. When the Model requires an attribute group in a request or response and the attribute group contains zero attributes, a request or response SHOULD encode the attribute group with the "begin-attribute-group-tag" field followed by zero "attribute" fields. For example, if the Client requests a single unsupported attribute with the Get-Printer-Attributes operation, the Printer MUST return no "attribute" fields, and it SHOULD return a "begin-attribute-group-tag" field for the Printer Attributes group. The Unsupported Attributes group is not such an example. According to the Model, the Unsupported Attributes group SHOULD be present only if the Unsupported Attributes group contains at least one attribute. A receiver of a request MUST be able to process the following as equivalent empty attribute groups: A "begin-attribute-group-tag" field with zero following "attribute" fields. A missing, but expected, "begin-attribute-group-tag" field. When the Model requires a sequence of an unknown number of attribute groups, each of the same type, the encoding MUST contain one "begin-attribute-group-tag" field for each attribute group, even when an "attribute-group" field contains zero "attribute" sub-fields. For example, the Get-Jobs operation may return zero attributes for some Jobs and not others. The "begin-attribute-group-tag" field followed by zero "attribute" fields tells the recipient that there is a Job in queue for which no information is available except that it is in the queue.

Some operation elements are called parameters in the Model. They MUST be encoded in a special position and they MUST NOT appear as operation attributes. These parameters are described in the subsections below.

The "version-number" field consists of a major and minor version-number, each of which is represented by a SIGNED-BYTE. The major version-number is the first byte of the encoding and the minor version-number is the second byte of the encoding. The protocol described in has a major version-number of 1 (0x01) and a minor version-number of 1 (0x01). The ABNF for these two bytes is %x01.01. Note: See for more information on the "version-number" field and IPP version numbers.

The "operation-id" field contains an operation-id value as defined in the Model. The value is encoded as a SIGNED-SHORT and is located in the third and fourth bytes of the encoding of an operation request.

The "status-code" field contains a status-code value as defined in the Model. The value is encoded as a SIGNED-SHORT and is located in the third and fourth bytes of the encoding of an operation response. If an IPP status-code is returned, then the HTTP status-code MUST be 200 (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.

The "request-id" field contains the request-id value as defined in the Model. The value is encoded as a SIGNED-INTEGER and is located in the fifth through eighth bytes of the encoding.

There are two kinds of tags: delimiter tags: delimit major sections of the protocol, namely attribute groups and data value tags: specify the type of each attribute value Tags are part of the IANA IPP registry

specifies the values for the delimiter tags defined in this document. These tags are registered, along with tags defined in other documents, in the "Attribute Group Tags" registry. Tag Value (Hex)Meaning 0x00Reserved 0x01"operation-attributes-tag" 0x02"job-attributes-tag" 0x03"end-of-attributes-tag" 0x04"printer-attributes-tag" 0x05"unsupported-attributes-tag" When a "begin-attribute-group-tag" field occurs in the protocol, it means that zero or more following attributes up to the next group tag are attributes belonging to the attribute group specified by the value of the "begin-attribute-group-tag". For example, if the value of "begin-attribute-group-tag" is 0x01, the following attributes are members of the Operations Attributes group. The "end-of-attributes-tag" (value 0x03) MUST occur exactly once in an operation and MUST be the last "delimiter-tag". If the operation has a document-data group, the Document data in that group follows the "end-of-attributes-tag". The order and presence of "attribute-group" fields (whose beginning is marked by the "begin-attribute-group-tag" subfield) for each operation request and each operation response MUST be that defined in the Model. A Printer MUST treat a "delimiter-tag" (values from 0x00 through 0x0f) differently from a "value-tag" (values from 0x10 through 0xff) so that the Printer knows there is an entire attribute group as opposed to a single value.

The remaining tables show values for the "value-tag" field, which is the first octet of an attribute. The "value-tag" field specifies the type of the value of the attribute. specifies the "out-of-band" values for the "value-tag" field defined in this document. These tags are registered, along with tags defined in other documents, in the "Out-of-Band Attribute Value Tags" registry. Tag Value (Hex)Meaning 0x10unsupported 0x12unknown 0x13no-value specifies the integer values defined in this document for the "value-tag" field; they are registered in the "Attribute Syntaxes" registry. Tag Value (Hex)Meaning 0x20Unassigned integer data type (see IANA IPP registry) 0x21integer 0x22boolean 0x23enum 0x24-0x2fUnassigned integer data types (see IANA IPP registry) specifies the octetString values defined in this document for the "value-tag" field; they are registered in the "Attribute Syntaxes" registry. Tag Value (Hex)Meaning 0x30octetString with an unspecified format 0x31dateTime 0x32resolution 0x33rangeOfInteger 0x34begCollection 0x35textWithLanguage 0x36nameWithLanguage 0x37endCollection 0x38-0x3fUnassigned octetString data types (see IANA IPP registry) specifies the character-string values defined in this document for the "value-tag" field; they are registered in the "Attribute Syntaxes" registry. Tag Value (Hex)Meaning 0x40Unassigned character-string data type (see IANA IPP registry) 0x41textWithoutLanguage 0x42nameWithoutLanguage 0x43Unassigned character-string data type (see IANA IPP registry) 0x44keyword 0x45uri 0x46uriScheme 0x47charset 0x48naturalLanguage 0x49mimeMediaType 0x4amemberAttrName 0x4b-0x5fUnassigned character-string data types (see IANA IPP registry) 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 type definitions in Standards Track documents. 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 four 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. Values from 0x00000000 to 0x3fffffff are reserved for definition in future Standards Track documents. The values 0x40000000 to 0x7fffffff are reserved for vendor extensions.

The "name-length" field consists of a SIGNED-SHORT and specifies the number of octets in the immediately following "name" field. The value of this field excludes the two bytes of the "name-length" field. For example, if the "name" field contains 'sides', the value of this field is 5. If a "name-length" field has a value of zero, the following "name" field is empty and the following value is treated as an additional value for the attribute encoded in the nearest preceding "attribute-with-one-value" field. Within an attribute group, if two or more attributes have the same name, the attribute group is malformed (see ). The zero-length name is the only mechanism for multi-valued attributes.

The "name" field contains the name of an attribute. The Model specifies such names.

The "value-length" field consists of a SIGNED-SHORT, which specifies the number of octets in the immediately following "value" field. The value of this field excludes the two bytes of the "value-length" field. For example, if the "value" field contains the keyword (string) value 'one-sided', the value of this field is 9. 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 binary signed bytes, e.g., the boolean type, the sender MUST encode the value in exactly one octet. 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. For "out-of-band" values for the "value-tag" field defined in this document, such as 'unsupported', the "value-length" MUST be 0 and the "value" empty; the "value" has no meaning when the "value-tag" has one of these "out-of-band" values. For future "out-of-band" "value-tag" fields, the same rule holds unless the definition explicitly states that the "value-length" MAY be non-zero and the "value" non-empty

The syntax types (specified by the "value-tag" field) and most of the details of the representation of attribute values are defined in the Model. augments the information in the Model and defines the syntax types from the Model in terms of the five basic types defined in . The five types are US-ASCII-STRING, LOCALIZED-STRING, SIGNED-INTEGER, SIGNED-SHORT, SIGNED-BYTE, and OCTET-STRING. Syntax of Attribute ValueEncoding textWithoutLanguage, nameWithoutLanguageLOCALIZED-STRING textWithLanguageOCTET-STRING consisting of four fields: a SIGNED-SHORT, which is the number of octets in the following field; a value of type natural-language; a SIGNED-SHORT, which is the number of octets in the following field; and a value of type textWithoutLanguage. The length of a textWithLanguage value MUST be 4 + the value of field a + the value of field c. nameWithLanguageOCTET-STRING consisting of four fields: a SIGNED-SHORT, which is the number of octets in the following field; a value of type natural-language; a SIGNED-SHORT, which is the number of octets in the following field; and 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, naturalLanguage, mimeMediaType, keyword, uri, and uriSchemeUS-ASCII-STRING booleanSIGNED-BYTE where 0x00 is 'false' and 0x01 is 'true' integer and enuma SIGNED-INTEGER dateTimeOCTET-STRING consisting of eleven octets whose contents are defined by "DateAndTime" in RFC 2579 resolutionOCTET-STRING consisting of nine octets of two 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. rangeOfIntegerEight octets consisting of two SIGNED-INTEGERs. The first SIGNED-INTEGER contains the lower bound and the second SIGNED-INTEGER contains the upper bound. 1setOf XEncoding according to the rules for an attribute with more than one value. Each value X is encoded according to the rules for encoding its type. octetStringOCTET-STRING collectionEncoding as defined in . The attribute syntax type of the value determines its encoding and the value of its "value-tag".

The "data" field MUST include any data required by the operation.

HTTP/1.1 is the REQUIRED transport layer for this protocol. HTTP/2 is an OPTIONAL transport layer for this protocol. The operation layer has been designed with the assumption that the transport layer contains the following information: the target URI for the operation; and 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. Printer implementations MUST support HTTP over the IANA-assigned well-known port 631 (the IPP default port), although a Printer implementation can support HTTP over some other port as well. Each HTTP operation MUST use the POST method where the request-target 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 , "Syntax of Encoding". A Client implementation MUST adhere to the rules for a Client described for HTTP . A Printer (server) implementation MUST adhere to the rules for an origin server described for HTTP . 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, consult the HTTP documents . An HTTP/1.1 server MUST support chunking for IPP requests, and an IPP Client MUST support chunking for IPP responses according to HTTP/1.1 .

All Printer and Job objects are identified by a Uniform Resource Identifier (URI) so that they can be persistently and unambiguously referenced. Jobs can also be identified by a combination of Printer URI and Job ID. Some operation elements are encoded twice, once as the request-target on the HTTP request-line and a second time as a REQUIRED operation attribute in the application/ipp entity. These attributes are the target 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 can be different. For example, the HTTP request-target can be relative while the IPP request URI is absolute. HTTP 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 following statements characterize how URIs are used in the mapping of IPP onto HTTP: 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 URIs are not used as the addressing mechanism in the transport layer. Even though these two URIs might not be literally identical (one being relative and the other being absolute), they MUST both reference the same IPP object. 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. Once the HTTP server resource begins to process the HTTP request, it can get the reference to the appropriate IPP Printer object from either the HTTP URI (using to the context of the HTTP server for relative URIs) or from the URI within the operation request; the choice is up to the implementation. HTTP URIs can be relative or absolute, but the target URI in the IPP operation attribute MUST be an absolute URI.

The IPP URI schemes are 'ipp' and 'ipps' . Clients and Printers MUST support the ipp-URI 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. The ipp-URI and ipps-URI are intended as the value of the attributes in this list. 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 URI with a directory service, the Printer MUST register an ipp-URI or ipps-URI. When a Client sends a request, it MUST convert a target ipp-URI to a target http-URL (or ipps-URI to a target https-URI) for the HTTP layer according to the following steps: change the 'ipp' scheme to 'http' or 'ipps' scheme to 'https'; and add an explicit port 631 if the ipp-URL or ipps-URL does not contain an explicit port. Note that port 631 is the IANA-assigned well-known port for the 'ipp' and 'ipps' schemes. The Client MUST use the target http-URL or https-URL in both the HTTP request-line and HTTP headers, as specified by HTTP . However, the Client MUST use the target ipp-URI or ipps-URI 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-URI or ipps-URI 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-URI "ipp://printer.example.com/ipp/print/myqueue", it opens a TCP connection to port 631 (the IPP implicit port) on the host "printer.example.com" and sends the following data:

POST /ipp/print/myqueue HTTP/1.1 Host: printer.example.com:631 Content-type: application/ipp Transfer-Encoding: chunked ... "printer-uri" 'ipp://printer.example.com/ipp/print/myqueue' (encoded in application/ipp message body) ...

As another example, when an IPP Client sends the same request as above via a proxy "myproxy.example.com", it opens a TCP connection to the proxy port 8080 on the proxy host "myproxy.example.com" and sends the following data:

POST http://printer.example.com:631/ipp/print/myqueue HTTP/1.1 Host: printer.example.com:631 Content-type: application/ipp Transfer-Encoding: chunked ... "printer-uri" 'ipp://printer.example.com/ipp/print/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.

The IANA-PRINTER-MIB [RFC3805] has been updated to reference this document; the current version is available from <http://www.iana.org>. See the IANA Considerations in the document "Internet Printing Protocol/1.1: Model and Semantics" for information on IANA considerations for IPP extensions. IANA has updated the existing 'application/ipp' media type registration (whose contents are defined in "Encoding of the Operation Layer") with the following information. Type name: application Subtype name: ipp Required parameters: N/A Optional parameters: N/A Encoding considerations: IPP requests/responses MAY contain long lines and ALWAYS contain binary data (for example, attribute value lengths). Security considerations: IPP requests/responses do not introduce any security risks not already inherent in the underlying transport protocols. Protocol mixed-version interworking rules in as well as protocol-encoding rules in this document are complete and unambiguous. See also the security considerations in this document and . Interoperability considerations: IPP requests (generated by Clients) and responses (generated by servers) MUST comply with all conformance requirements imposed by the normative specifications and this document. Protocol-encoding rules specified in RFC 8010 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 attribute values that are a LOCALIZED-STRING are explicit within IPP requests/responses (without recourse to any external information in HTTP, SMTP, or other message transport headers). Published specifications: RFCs 8010 and 8011 Applications that use this media type: Internet Printing Protocol (IPP) print clients and print servers that communicate using HTTP/HTTPS or other transport protocols. Messages of type "application/ipp" are self-contained and transport independent, including "charset" and "natural-language" context for any LOCALIZED-STRING value. Fragment identifier considerations: N/A Additional information: Deprecated alias names for this type: N/A Magic number(s): N/A File extension(s): N/A Macintosh file type code(s): N/A Person & email address to contact for further information: ISTO PWG IPP Workgroup <ipp@pwg.org> Intended usage: COMMON Restrictions on usage: N/A Author: ISTO PWG IPP Workgroup <ipp@pwg.org> Change controller: ISTO PWG IPP Workgroup <ipp@pwg.org> Provisional registration? (standards tree only): No

See the section on "Internationalization Considerations" in the document "Internet Printing Protocol/1.1: Model and Semantics" for information on internationalization. This document adds no additional issues.

The IPP Model and Semantics document 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. Message Integrity is addressed in the document "Internet Printing Protocol (IPP) over HTTPS Transport Binding and the 'ipps' URI Scheme" .

This section defines the security requirements for IPP Clients and IPP objects.

IPP Clients and Printers SHOULD support Digest Authentication . Use of the Message Integrity feature (qop="auth-int") is OPTIONAL. Note: Previous versions of this specification required support for the MD5 algorithms; however, makes SHA2-256 mandatory to implement and deprecates MD5, only allowing its use for backwards compatibility reasons. IPP implementations that support Digest Authentication MUST support SHA2-256 and SHOULD support MD5 for backwards compatibility. Note: The reason that IPP Clients and Printers SHOULD (rather than MUST) support Digest Authentication is that there is a certain class of Output Devices where it does not make sense. Specifically, a low-end device with limited ROM space and low paper throughput may not need Client Authentication. This class of device typically requires firmware designers to make trade-offs between protocols and functionality to arrive at the lowest-cost solution possible. Factored into the designer's decisions is not just the size of the code, but also the testing, maintenance, usefulness, and time-to-market impact for each feature delivered to the customer. Forcing such low-end devices to provide security in order to claim IPP/1.1 conformance would not make business sense. Print devices that have high-volume throughput and have available ROM space will typically provide support for Client Authentication that safeguards the device from unauthorized access because these devices are prone to a high loss of consumables and paper if unauthorized access occurs.

IPP Clients and Printers SHOULD support Transport Layer Security (TLS) for Server Authentication and Operation Privacy. IPP Printers MAY also support TLS for Client Authentication. IPP Clients and Printers MAY support Basic Authentication for User Authentication if the channel is secure, e.g., IPP over HTTPS . IPP Clients and Printers SHOULD NOT support Basic Authentication over insecure channels. The IPP Model and Semantics document defines two Printer attributes ("uri-authentication-supported" and "uri-security-supported") that the Client can use to discover the security policy of a Printer. That document also outlines IPP-specific security considerations and is the primary reference for security implications with regard to the IPP itself. Note: Because previous versions of this specification did not require TLS support, this version cannot require it for IPP/1.1. However, since printing often involves a great deal of sensitive or private information (medical reports, performance reviews, banking information, etc.) and network monitoring is pervasive (), implementors are strongly encouraged to include TLS support. Note: Because IPP Printers typically use self-signed X.509 certificates, IPP Clients SHOULD support Trust On First Use (defined in ) in addition to traditional X.509 certificate validation.

IPP uses the "Upgrading to TLS Within HTTP/1.1" mechanism for 'ipp' URIs. The Client requests a secure TLS connection by using the HTTP "Upgrade" header while the server agrees in the HTTP response. 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. IPP uses the "HTTPS: HTTP over TLS" mechanism for 'ipps' URIs. The Client and server negotiate a secure TLS connection immediately and unconditionally.

It is beyond the scope of this specification to mandate conformance with versions of IPP other than 1.1. IPP was deliberately designed, however, to make supporting other versions easy. IPP objects (Printers, Jobs, etc.) SHOULD: understand any valid request whose major "version-number" is greater than 0; and respond appropriately with a response containing the same "version-number" parameter value used by the Client in the request (if the Client-supplied "version-number" is supported) or the highest "version-number" supported by the Printer (if the Client-supplied "version-number" is not supported). IPP Clients SHOULD: understand any valid response whose major "version-number" is greater than 0.

The following are rules regarding the "version-number" parameter (see ): Clients MUST send requests containing a "version-number" parameter with the highest supported value, e.g., '1.1', '2.0', etc., and SHOULD try supplying alternate version numbers if they receive a 'server-error-version-not-supported' error return in a response. For example, if a Client sends an IPP/2.0 request that is rejected with the 'server-error-version-not-supported' error and an IPP/1.1 "version-number", it SHOULD retry by sending an IPP/1.1 request. IPP objects (Printers, Jobs, etc.) MUST accept requests containing a "version-number" parameter with a '1.1' value (or reject the request for reasons other than 'server-error-version-not-supported'). IPP objects SHOULD either accept requests whose major version is greater than 0 or reject such requests with the 'server-error-version-not-supported' status-code. See Section 4.1.8 of . In any case, security MUST NOT be compromised when a Client supplies a lower "version-number" parameter in a request. For example, if an IPP/2.0 conforming Printer accepts version '1.1' requests and is configured to enforce Digest Authentication, it MUST do the same for a version '1.1' request.

The following are rules regarding security, the "version-number" parameter, and the URI scheme supplied in target attributes and responses: When a Client supplies a request, the "printer-uri" or "job-uri" target operation attribute MUST have the same scheme as that indicated in one of the values of the "printer-uri-supported" Printer attribute. When the Printer returns the "job-printer-uri" or "job-uri" Job Description attributes, it SHOULD return the same scheme ('ipp', 'ipps', etc.) that the Client supplied in the "printer-uri" or "job-uri" target operation attributes in the Get-Job-Attributes or Get-Jobs request, rather than the scheme used when the Job was created. However, when a Client requests Job attributes using the Get-Job-Attributes or Get-Jobs operations, the Jobs and Job attributes that the Printer returns depends on: (1) the security in effect when the Job was created, (2) the security in effect in the query request, and (3) the security policy in force. The Printer MUST enforce its security and privacy policies based on the owner of the IPP object and the URI scheme and/or credentials supplied by the Client in the current request.

The following changes have been made since the publication of RFC 2910: Added references to current IPP extension specifications. Added optional support for HTTP/2. Added collection attribute syntax from RFC 3382. Fixed typographical errors. Now reference TLS/1.2 and no longer mandate the TLS/1.0 MTI ciphersuites. Updated all references. Updated document organization to follow current style. Updated example ipp: URIs to follow guidelines in RFC 7472. Updated version compatibility for all versions of IPP. Updated HTTP Digest Authentication to optional for Clients. Removed references to (Experimental) IPP/1.0 and usage of http:/https: URLs.

Apple Inc. High North, Inc.

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 is not supported or their values are not supported. OctetsSymbolic ValueProtocol field 0x01011.1version-number 0x0002Print-Joboperation-id 0x000000011request-id 0x01start operation-attributesoperation-attributes-tag 0x47charset typevalue-tag 0x0012name-length attributes-charsetattributes-charsetname 0x0005value-length utf-8UTF-8value 0x48natural-language typevalue-tag 0x001bname-length attributes-natural-languageattributes-natural-languagename 0x0005value-length en-usen-USvalue 0x45uri typevalue-tag 0x000bname-length printer-uriprinter-uriname 0x002cvalue-length ipp://printer.example.com/ipp/print/pinetreeprinter pinetreevalue 0x42nameWithoutLanguage typevalue-tag 0x0008name-length job-namejob-namename 0x0006value-length foobarfoobarvalue 0x22boolean typevalue-tag 0x0016name-length ipp-attribute-fidelityipp-attribute-fidelityname 0x0001value-length 0x01truevalue 0x02start job-attributesjob-attributes-tag 0x21integer typevalue-tag 0x0006name-length copiescopiesname 0x0004value-length 0x0000001420value 0x44keyword typevalue-tag 0x0005name-length sidessidesname 0x0013value-length two-sided-long-edgetwo-sided-long-edgevalue 0x03end-of-attributesend-of-attributes-tag %!PDF...<PDF Document>data

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'. OctetsSymbolic ValueProtocol field 0x01011.1version-number 0x0000successful-okstatus-code 0x000000011request-id 0x01start operation-attributesoperation-attributes-tag 0x47charset typevalue-tag 0x0012name-length attributes-charsetattributes-charsetname 0x0005value-length utf-8UTF-8value 0x48natural-language typevalue-tag 0x001bname-length attributes-natural-languageattributes-natural-languagename 0x0005value-length en-usen-USvalue 0x41textWithoutLanguage typevalue-tag 0x000ename-length status-messagestatus-messagename 0x000dvalue-length successful-oksuccessful-okvalue 0x02start job-attributesjob-attributes-tag 0x21integervalue-tag 0x0006name-length job-idjob-idname 0x0004value-length 147147value 0x45uri typevalue-tag 0x0007name-length job-urijob-uriname 0x0030value-length ipp://printer.example.com/ipp/print/pinetree/147job 147 on pinetreevalue 0x23enum typevalue-tag 0x0009name-length job-statejob-statename 0x0004value-length 0x0003pendingvalue 0x03end-of-attributesend-of-attributes-tag

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). OctetsSymbolic ValueProtocol field 0x01011.1version-number 0x040bclient-error-attributes-or-values-not-supportedstatus-code 0x000000011request-id 0x01start operation-attributesoperation-attributes tag 0x47charset typevalue-tag 0x0012name-length attributes-charsetattributes-charsetname 0x0005value-length utf-8UTF-8value 0x48natural-language typevalue-tag 0x001bname-length attributes-natural-languageattributes-natural-languagename 0x0005value-length en-usen-USvalue 0x41textWithoutLanguage typevalue-tag 0x000ename-length status-messagestatus-messagename 0x002fvalue-length client-error-attributes-or-values-not-supportedclient-error-attributes-or-values-not-supportedvalue 0x05start unsupported-attributesunsupported-attributes tag 0x21integer typevalue-tag 0x0006name-length copiescopiesname 0x0004value-length 0x0000001420value 0x10unsupported (type)value-tag 0x0005name-length sidessidesname 0x0000value-length 0x03end-of-attributesend-of-attributes-tag

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). OctetsSymbolic ValueProtocol field 0x01011.1version-number 0x0001successful-ok-ignored-or-substituted-attributesstatus-code 0x000000011request-id 0x01start operation-attributesoperation-attributes-tag 0x47charset typevalue-tag 0x0012name-length attributes-charsetattributes-charsetname 0x0005value-length utf-8UTF-8value 0x48natural-language typevalue-tag 0x001bname-length attributes-natural-languageattributes-natural-languagename 0x0005value-length en-usen-USvalue 0x41textWithoutLanguage typevalue-tag 0x000ename-length status-messagestatus-messagename 0x002fvalue-length successful-ok-ignored-or-substituted-attributessuccessful-ok-ignored-or-substituted-attributesvalue 0x05start unsupported-attributesunsupported-attributes tag 0x21integer typevalue-tag 0x0006name-length copiescopiesname 0x0004value-length 0x0000001420value 0x10unsupported (type)value-tag 0x0005name-length sidessidesname 0x0000value-length 0x02start job-attributesjob-attributes-tag 0x21integervalue-tag 0x0006name-length job-idjob-idname 0x0004value-length 147147value 0x45uri typevalue-tag 0x0007name-length job-urijob-uriname 0x0030value-length ipp://printer.example.com/ipp/print/pinetree/147job 147 on pinetreevalue 0x23enum typevalue-tag 0x0009name-length job-statejob-statename 0x0004value-length 0x0003pendingvalue 0x03end-of-attributesend-of-attributes-tag

The following is an example of Print-URI request with "copies" and "job-name" parameters: OctetsSymbolic ValueProtocol field 0x01011.1version-number 0x0003Print-URIoperation-id 0x000000011request-id 0x01start operation-attributesoperation-attributes-tag 0x47charset typevalue-tag 0x0012name-length attributes-charsetattributes-charsetname 0x0005value-length utf-8UTF-8value 0x48natural-language typevalue-tag 0x001bname-length attributes-natural-languageattributes-natural-languagename 0x0005value-length en-usen-USvalue 0x45uri typevalue-tag 0x000bname-length printer-uriprinter-uriname 0x002cvalue-length ipp://printer.example.com/ipp/print/pinetreeprinter pinetreevalue 0x45uri typevalue-tag 0x000cname-length document-uridocument-uriname 0x0019value-length ftp://foo.example.com/fooftp://foo.example.com/foovalue 0x42nameWithoutLanguage typevalue-tag 0x0008name-length job-namejob-namename 0x0006value-length foobarfoobarvalue 0x02start job-attributesjob-attributes-tag 0x21integer typevalue-tag 0x0006name-length copiescopiesname 0x0004value-length 0x000000011value 0x03end-of-attributesend-of-attributes-tag

The following is an example of Create-Job request with no parameters and no attributes: OctetsSymbolic ValueProtocol field 0x01011.1version-number 0x0005Create-Joboperation-id 0x000000011request-id 0x01start operation-attributesoperation-attributes-tag 0x47charset typevalue-tag 0x0012name-length attributes-charsetattributes-charsetname 0x0005value-length utf-8UTF-8value 0x48natural-language typevalue-tag 0x001bname-length attributes-natural-languageattributes-natural-languagename 0x0005value-length en-usen-USvalue 0x45uri typevalue-tag 0x000bname-length printer-uriprinter-uriname 0x002cvalue-length ipp://printer.example.com/ipp/print/pinetreeprinter pinetreevalue 0x03end-of-attributesend-of-attributes-tag

The following is an example of Create-Job request with the "media-col" collection attribute with the value "media-size={x-dimension=21000 y-dimension=29700} media-type='stationery'": OctetsSymbolic ValueProtocol field 0x01011.1version-number 0x0005Create-Joboperation-id 0x000000011request-id 0x01start operation-attributesoperation-attributes-tag 0x47charset typevalue-tag 0x0012name-length attributes-charsetattributes-charsetname 0x0005value-length utf-8UTF-8value 0x48natural-language typevalue-tag 0x001bname-length attributes-natural-languageattributes-natural-languagename 0x0005value-length en-usen-USvalue 0x45uri typevalue-tag 0x000bname-length printer-uriprinter-uriname 0x002cvalue-length ipp://printer.example.com/ipp/print/pinetreeprinter pinetreevalue 0x34begCollectionvalue-tag 0x00099name-length media-colmedia-colname 0x00000value-length 0x4amemberAttrNamevalue-tag 0x00000name-length 0x000a10value-length media-sizemedia-sizevalue (member-name) 0x34begCollectionmember-value-tag 0x00000name-length 0x00000member-value-length 0x4amemberAttrNamevalue-tag 0x00000name-length 0x000b11value-length x-dimensionx-dimensionvalue (member-name) 0x21integermember-value-tag 0x00000name-length 0x00044member-value-length 0x0000520821000member-value 0x4amemberAttrNamevalue-tag 0x00000name-length 0x000b11value-length y-dimensiony-dimensionvalue (member-name) 0x21integermember-value-tag 0x00000name-length 0x00044member-value-length 0x0000740429700member-value 0x37endCollectionend-value-tag 0x00000end-name-length 0x00000end-value-length 0x4amemberAttrNamevalue-tag 0x00000name-length 0x000a10value-length media-typemedia-typevalue (member-name) 0x44keywordmember-value-tag 0x00000name-length 0x000a10member-value-length stationerystationerymember-value 0x37endCollectionend-value-tag 0x00000end-name-length 0x00000end-value-length 0x03end-of-attributesend-of-attributes-tag

The following is an example of Get-Jobs request with parameters but no attributes: OctetsSymbolic ValueProtocol field 0x01011.1version-number 0x000aGet-Jobsoperation-id 0x0000007b123request-id 0x01start operation-attributesoperation-attributes-tag 0x47charset typevalue-tag 0x0012name-length attributes-charsetattributes-charsetname 0x0005value-length utf-8UTF-8value 0x48natural-language typevalue-tag 0x001bname-length attributes-natural-languageattributes-natural-languagename 0x0005value-length en-usen-USvalue 0x45uri typevalue-tag 0x000bname-length printer-uriprinter-uriname 0x002cvalue-length ipp://printer.example.com/ipp/print/pinetreeprinter pinetreevalue 0x21integer typevalue-tag 0x0005name-length limitlimitname 0x0004value-length 0x0000003250value 0x44keyword typevalue-tag 0x0014name-length requested-attributesrequested-attributesname 0x0006value-length job-idjob-idvalue 0x44keyword typevalue-tag 0x0000additional valuename-length 0x0008value-length job-namejob-namevalue 0x44keyword typevalue-tag 0x0000additional valuename-length 0x000fvalue-length document-formatdocument-formatvalue 0x03end-of-attributesend-of-attributes-tag

The following is an example of a Get-Jobs response from a previous request with three Jobs. The Printer returns no information about the second Job (because of security reasons): OctetsSymbolic ValueProtocol field 0x01011.1version-number 0x0000successful-okstatus-code 0x0000007b123request-id (echoed back) 0x01start operation-attributesoperation-attributes-tag 0x47charset typevalue-tag 0x0012name-length attributes-charsetattributes-charsetname 0x0005value-length utf-8UTF-8value 0x48natural-language typevalue-tag 0x001bname-length attributes-natural-languageattributes-natural-languagename 0x0005value-length en-usen-USvalue 0x41textWithoutLanguage typevalue-tag 0x000ename-length status-messagestatus-messagename 0x000dvalue-length successful-oksuccessful-okvalue 0x02start job-attributes (1st object)job-attributes-tag 0x21integer typevalue-tag 0x0006name-length job-idjob-idname 0x0004value-length 147147value 0x36nameWithLanguagevalue-tag 0x0008name-length job-namejob-namename 0x000cvalue-length 0x0005sub-value-length fr-cafr-CAvalue 0x0003sub-value-length foufouname 0x02start job-attributes (2nd object)job-attributes-tag 0x02start job-attributes (3rd object)job-attributes-tag 0x21integer typevalue-tag 0x0006name-length job-idjob-idname 0x0004value-length 148149value 0x36nameWithLanguagevalue-tag 0x0008name-length job-namejob-namename 0x0012value-length 0x0005sub-value-length de-CHde-CHvalue 0x0009sub-value-length isch guetisch guetname 0x03end-of-attributesend-of-attributes-tag

The authors would like to acknowledge the following individuals for their contributions to the original IPP/1.1 specifications: Sylvan Butler, Roger deBry, Tom Hastings, Robert Herriot (the original editor of RFC 2910), Paul Moore, Kirk Ocke, Randy Turner, John Wenn, and Peter Zehler.