Internet Printing Protocol (IPP) Scott Isaacson Corporate Architect Novell, Inc. WWW7 Developer Day April 18, 1998 4/18/98 IPP - WWW7

Agenda Background Requirements Model Encoding HTTP Mapping Summary Objects Operations Encoding HTTP Mapping Summary 4/18/98 IPP - WWW7

Internet Printing Protocol (IPP) Background Fall of 1996 Printer Working Group (PWG) meeting on Internet and web printing PWG is a loose, unincorporated alliance among printer vendors, OS vendors, and developers IEEE 1284, Printer MIB, Job Monitoring MIB Presentations Lightweight Document Printing Application (LDPA) HyperText Printing Protocol (HTPP) Simple Web Printing (SWP) 4/18/98 IPP - WWW7

IPP Background (cont.) PWG chartered a working group IETF 12/96: IETF BOF 3/97: IETF WG charter 4-11/97: Various Internet-Drafts 2/98: WG final call Major Contributors System vendors, OS vendors, device vendors, driver vendors, application vendors 4/18/98 IPP - WWW7

Online References Mailing List: Sites: Internet-Drafts (www.ietf.org) ipp@pwg.org (ipp-request@pwg.org) Sites: www.pwg.org/ipp AND ftp.pwg.org/pub/pwg/ipp/ Internet-Drafts (www.ietf.org) Requirements: draft-ietf-ipp-req-02.txt Model: draft-ietf-ipp-model-09.txt Encoding and Transport: draft-ietf-ipp-protocol-04.txt Rationale: draft-ietf-ipp-rat-01.txt LPD Mapping: draft-ietf-ipp-lpd-ipp-map-01.txt 4/18/98 IPP - WWW7

IPP WG Schedule Proposed Standard by end of April 98 Prototyping now being done “Interoperability bake-off” 1998 Use the Internet 4 Vendors have shown interoperability Test suites Conference Demos BrainShare, Xplore, Seybold, etc. 4/18/98 IPP - WWW7

Why IPP? Evolution of network printing Multiple solutions client attached server attached network attached Multiple solutions SPX/IPX LPR/LPD (TCP) Appletalk Netbeui (SMBs) No interoperability High administrative overhead and complexity 4/18/98 IPP - WWW7

IPP Mission Statement Web tools, applications, and technologies working together to support printing on the Internet Web browsers URLs MIME HTTP LDAP SLP SLP LDAP Directory MIME HTTP 4/18/98 IPP - WWW7

Scope for IPP/1.0 End User features: Query, Submit, Cancel Out of scope: Driver download (URL to installation information) Notification (current WG discussions) Presentation and UI Only hooks for HTML page, no standard No Operator features As allowed by local authorization policy No Administrator features Assume product specific administrative solution 4/18/98 IPP - WWW7

Vision: Inter-Enterprise Examples Print from an Application Any application via IPP client pushes document data to printer Print from a Document Repository IPP aware application (Web Browser) pushes document data to printer Print using a Reference Printer pulls document data using reference 4/18/98 IPP - WWW7

Example 1: Application Printing Enterprise A Enterprise B Firewall Firewall Internet IPP Printer Application IPP any Print Data 4/18/98 IPP - WWW7

Example 2: Existing File Printing Enterprise A Enterprise B Firewall Firewall Internet IPP Printer Browser IPP any Print Data Repository 4/18/98 IPP - WWW7

Example 3: Print by Reference Enterprise A Enterprise B Firewall Firewall Internet IPP Printer Browser IPP Print Data any URI Reference Repository 4/18/98 IPP - WWW7

Architecture and Layering Application Spooler Print Driver End User File Browser Notification Directory Naming IPP Client Secure Transport IPP Server IPP Printer Print Service Output Device 4/18/98 IPP - WWW7

IPP Objects Printer Job 4/18/98 IPP - WWW7

IPP Printer Implements IPP Logical or physical device Multiple configurations server embedded Job processing Options for spooling and scheduling Provide job status 4/18/98 IPP - WWW7

IPP Printer Configurations any IPP Printer IPP any 4/18/98 IPP - WWW7

Printer Attributes (Mandatory) Uniform Resource Identifier (URI) Name State Accepting jobs Localization Natural Language (RFC 1766: “en-US”) Default, Supported Charset (RFC 2046: “utf-8”, “utf-16”) 4/18/98 IPP - WWW7

Job Attributes (Mandatory) Job Identifier Job Owner’s Identity Job State 4/18/98 IPP - WWW7

Document Format Use MIME Internet Media Types Types for traditional Page Description Languages (PDLs) “application/postscript” (PostScript) and others (PJL/PCL, IPDS, Interpress, etc.) Types for emerging document formats “text/html” “application/pdf” Etc. 4/18/98 IPP - WWW7

Printer Operations (Mandatory) Print-Job Submits a Job, “pushes” job data to the Printer Validate-Job Validates client supplied attributes (no job data) Get-Jobs Lists jobs at the Printer Get-Printer-Attributes Responds with Printer attributes 4/18/98 IPP - WWW7

Example: Get-Printer-Attributes IPP Printer Get-Printer-Attributes Request requested-attributes: all Get-Printer-Attributes Response printer-name: John’s Printer printer-location: Bldg. A, Room 5 printer-state: processing document-format-supported: ps, pcl media-supported: iso-a4, na-letter sides-supported: two-sided queued-job-count: 45 error-code: ok 4/18/98 IPP - WWW7

Example: Get-Printer-Attributes (Printer Stopped) IPP Printer Get-Printer-Attributes Request requested-attributes:printer-description Get-Printer-Attributes Response printer-name: HR Color Printer printer-state: stopped printer-state-reasons: media-jam-error printer-state-message: Feed Tray 1 queued-job-count:5 error-code: ok 4/18/98 IPP - WWW7

Example: Print-Job Print-Job Request Print-Job Response IPP Printer Print-Job Request job-name: file1.doc copies: 5 print-quality: draft finishing: staple-top-left job-sheet: none data: <octet string> Print-Job Response job-id: 1234 job-state: pending error-code: ok 4/18/98 IPP - WWW7

Example: Print-Job (error) IPP Printer Print-Job Request job-name: file2.doc priority: 100 media: na-letter-transparent finishing: punch number-up: two data: <octet string> Print-Job Response finishing: punch (unsupported) number-up: attribute-unsupported error-code: unsupported-attributes 4/18/98 IPP - WWW7

Job Operations (Mandatory) Cancel-Job End User initiated abort Get-Job-Attributes Responds with current attribute values 4/18/98 IPP - WWW7

Example: Cancel-Job Cancel-Job Request Cancel-Job Response IPP Printer Cancel-Job Request job-id: 1234 message: “Please discard any printed pages.” Cancel-Job Response error-code: ok 4/18/98 IPP - WWW7

Multiple Document Jobs (Optional) “Create-Job” Creates a Job object Validates attributes Followed by multiple “Send-Document” Last Document Flag Existing practice 4/18/98 IPP - WWW7

Example: Create-Job Create-Job Request Create-Job Response IPP Printer Create-Job Request <attributes only, no data> Create-Job Response job-id: 5678 error-code: ok Send-Document Request last-document: false; document data; response: ok last-document: true; document data; response: ok 4/18/98 IPP - WWW7

Print by Reference (Optional) “Print-URI” operation Client supplies attributes Client supplies URI reference to data Printer retrieves document data Multiple document with references “Send-URI” 4/18/98 IPP - WWW7

Example: Print-URI Print-URI Request Print-URI Response IPP Printer Print-URI Request job-name: Acme’s Web Page copies: 1 document-format: text/html document-uri: http://www.acme.com/home.html Print-URI Response job-id: 25 job-state: processing error-code: ok 4/18/98 IPP - WWW7

Job Template Attributes 1) Printer supports some values 2) Printer has a default value 3) Client requests a certain value Example: “finishings” Printer supports: staple, cover, bind Printer default: staple Client requests: cover, bind Printer Supports: a, b, d Printer Default: b Client Requests: a 4/18/98 IPP - WWW7

Job Template (cont.) Cover Events Priority Hold Media Number UP Sides Copies Resolution Quality Document Format (PDLs) Compression 4/18/98 IPP - WWW7

Fidelity Printing Semantics Client supplied “fidelity” attribute “I expect the job exactly as specified - don’t print it if you can’t do it” “Just print the job the best you can - ignore or make substitutions as needed” Client supplied “fidelity” attribute boolean 4/18/98 IPP - WWW7

IPP Override of PDL Client supplies Job Template attributes Affect rendering, production, and finishing Conflicting instructions Embedded PDL instructions Example: Request “a4” media for a job that is “letter” Printer’s “PDL Override” attribute Values: attempted, not-attempted 4/18/98 IPP - WWW7

Printer Attributes (Optional) Location More Info HTML page Site contact info Description Make and Model Driver Installer Color Printing Supported PDL Override State Reasons Job Count Privacy Supported Security Supported 4/18/98 IPP - WWW7

Job Attributes (Optional) More Info HTML page Language State reasons Output device assigned Size Octets, impressions Time submitted Time since Pending Processing Completed Number of intervening jobs 4/18/98 IPP - WWW7

Extensibility Defined mechanisms Well defined space for Type1: Requires an update to the specification Type2: Requires approval of the PWG Type3: Requires IANA registration Type4: Allows for site-by-site additions Well defined space for Private Experimental 4/18/98 IPP - WWW7

Security Does not reinvent the wheel Look to HTTP Look to Transport basic, digest, and beyond Look to Transport Transport Layer Security (TLS) 4/18/98 IPP - WWW7

Encoding and Transport Encoding: application/ipp Simple, regular, binary Embedded solutions “application/ipp” Proposal: XML for protocol data Transport: HTTP/1.1 Ubiquitous (HTTP/1.0 still possible although not optimal) Leverage features (URI naming, chunking, etc.) Printing has already embraced HTTP servers (administration) Focus on simplicity (complexity relates to proxy servers) Security 4/18/98 IPP - WWW7

Transport Mapping Use HTTP/1.1 Each IPP operation is an HTTP POST “Request URI” is the IPP object “Content Type” is “application/ipp” Authentication/authorization checks Leverage HTTP negotiation: Cache and proxy control Proposal: Add new PRINT operations to HTTP 4/18/98 IPP - WWW7

Encoding Diagram: “application/ipp” POST http://www.pwg.org/printer1 HTTP/1.1 Content-Type: application/ipp VERSION 2 bytes - required REQUEST ID 2 bytes - required OPERATION / STATUS CODE 2 bytes - required ATTRIBUTE TAG 1 byte 0 or more ATTRIBUTE SEQUENCE n bytes DATA TAG 1 byte - required DATA m bytes 4/18/98 IPP - WWW7

Conclusion IPP is close to ratification as a set of IETF Proposed Standard RFCs Several interoperable prototypes Ongoing discussions for new features and standard extensions All are invited to participate “application/ipp” operations over HTTP Flexible, Scalable Diverse implementations Diverse configurations 4/18/98 IPP - WWW7