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RFC1486 - An Experiment in Remote Printing

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2008-05-31 18:52:41

Network Working Group M. Rose

Request for Comments: 1486 Dover Beach Consulting, Inc.

C. Malamud

Internet Multicasting Service

July 1993

An EXPeriment in Remote Printing

Status of this Memo

This memo defines an Experimental Protocol for the Internet

community. It does not specify an Internet standard. Discussion and

suggestions for improvement are requested. Please refer to the

current edition of the "IAB Official Protocol Standards" for the

standardization state and status of this protocol. Distribution of

this memo is unlimited.

Table of Contents

1. IntrodUCtion .......................................... 1

1.1 The Advantage of a General-Purpose Infrastructure..... 2

2. Procedure ............................................. 2

2.1 Naming, Addressing, and Routing ...................... 3

2.2 The application/remote-printing Content-Type ......... 4

2.3 Usage Example ........................................ 5

2.4 Remote Printing without MIME ......................... 6

3. The Experiment ........................................ 7

3.1 Infrastructure ....................................... 8

3.1.1 Zones .............................................. 8

3.1.2 MX records ......................................... 8

3.2 Accounting and Privacy ............................... 9

3.3 Mailing list ......................................... 9

3.4 Prototype Implementation ............................. 10

4. Future Issues ......................................... 11

5. Security Considerations ............................... 11

6. Acknowledgements ...................................... 11

7. References ............................................ 11

8. Authors' Addresses..................................... 12

A. The image/tiff Content-Type .......................... 13

B. Uniform Addressing ................................... 13

1. Introduction

Although electronic mail is preferable as a means of third-party

communication, in some cases it may be necessary to print

information, in hard-copy form, at a remote location. The remote

output device may consist of a standard line printer, a printer with

multiple fonts and faces, a printer that can reproduce graphics, or a

facsimile device. Remote output may be accompanied by information

that identifies the intended recipient. This memo describes a

technique for "remote printing" using the Internet mail

infrastructure. In particular, this memo focuses on the case in

which remote printers are connected to the international telephone

network. Furthermore, it describes an experiment in remote printing.

1.1. The Advantage of a General-Purpose Infrastructure

The experiment in remote printing is about "outreach"; specifically,

integrating the e-mail and facsimile communities. By providing easy

Access to remote printing recipients, enterprise-wide access is

enhanced, regardless of kind of institution (e.g., commercial,

educational, or government), or the size of institution (e.g.,

global, regional, or local). This approach at outreach allows an

organization to make it easier for the "outside world" to communicate

with the personnel in the organization who are users of facsimile but

not e-mail; e.g., the sales person, the university registrar, or the

(elected) official. The ease in which the Internet mail

infrastructure can be used to provide this facility is (yet) another

example of the power of a general-purpose infrastructure.

2. Procedure

When information is to be remotely printed, the user application

constructs an RFC822 [1] message, containing a "Message-ID" field

along with a "multipart/mixed" content [2] having two parts, the

first being a "application/remote-printing" content-type, and the

second being an arbitrary content-type corresponding to the

information to be printed. The message is then sent to the remote

printer server's electronic mail address.

It should be noted that not all content-types have a natural printing

representation, e.g., an "audio" or "video" content. For this

reason, the second part of the "multipart/mixed" content should be

one of the following:

text/plain, message/rfc822, application/postscript image/tiff

(defined in Appendix A), any multipart

Note that:

(1) With the "text/plain" content-type, not all character sets may

be available for printing.

(2) With the "message" content-type, the subordinate content will be

processed recursively.

(3) With the "application/postscript" content-type, the remote

printer server should evaluate the contents in a safe execution

environment.

(4) With the "multipart" content-type the subordinate contents will

be processed recursively: for a "multipart/mixed" or

"multipart/digest" content, each subordinate content will start

on a new page, whilst for a "multipart/parallel" content, all

subordinate contents will, if possible, start on the same page.

Naturally, when processing a "multipart/alternative" content,

only one subordinate content will be printed.

When the remote printer server finishes its processing, a message is

returned to the originator, indicating either success or failure.

2.1. Naming, Addressing, and Routing

A printer is identified by a telephone number which corresponds to a

G3-facsimile device connected to the international telephone network,

e.g.,

+1 415 968 2510

where "+1" indicates the IDDD country code, and the remaining string

is a telephone number within that country. This number is used to

construct the address of a remote printer server, which forms the

recipient address for the message, e.g.,

remote-printer@0.1.5.2.8.6.9.5.1.4.1.tpc.int

That is, the local-part of the remote printer server's address is

ALWAYS "remote-printer", and the domain-part is constructed by

reversing the telephone number, converting each digit to a domain-

label, and being placed under "tpc.int."

The message is routed in exactly the same fashion as all other

electronic mail, i.e., using the MX algorithm [3]. Since a remote

printer server might be able to access many printers, the wildcarding

facilities of the DNS [4,5] are used accordingly. For example, if a

remote printer server residing at "dbc.mtview.ca.us" was willing to

access any printer with a telephone number prefix of

+1 415 968

then this resource record might be present

*.8.6.9.5.1.4.1.tpc.int. IN MX 10 dbc.mtview.ca.us.

Naturally, if several remote printer servers were willing to access

any printer in that prefix, multiple MX resource records would be

present.

It should be noted that the presence of a wildcard RR which matches a

remote printer server's address does not imply that the corresponding

telephone number is valid, or, if valid, that a G3-facsimile device

is connected at the phone number.

2.2. The application/remote-printing Content-Type

(1) MIME type name: application

(2) MIME suBType name: remote-printing

(3) Required parameters: none

(4) Optional parameters: none

(5) Encoding considerations: 7bit preferred

(6) Security considerations: none

The "application/remote-printing" content-type contains originator

and recipient information used when generating a cover sheet. Using

the ABNF notation of RFC822, the syntax for this content is:

<content> ::= <recipient-info> CRLF

<originator-info>

[CRLF <cover-info>]

<recipient-info> ::= "Recipient" ":" <value> CRLF

<address-info>

<originator-info> ::= "Originator" ":" <value> CRLF

<address-info>

<address-info> ::= ["Title" ":" <value> CRLF]

["Department" ":" <value> CRLF]

["Organization" ":" <value> CRLF]

["Mailstop" ":" <value> CRLF]

["Address" ":" <value> CRLF]

["Telephone" ":" <value> CRLF]

"Facsimile" ":" <value> CRLF

["Email" ":" <value> CRLF]

<value> ::= *text

[CRLF LWSP-char <value> ]

<cover-info> ::= *(*text CRLF)

Note that the value of the "Email" field is an RFC822 mailbox

address.

2.3. Usage Example

Suppose someone wished to send the author some comments on this memo

using this facility. The message constructed might look like this:

To: remote-printer@0.1.5.2.8.6.9.5.1.4.1.tpc.int

From: "John Q. Public" <jpublic@tpd.org>

Date: Sun, 11 Apr 1993 20:34:13 -0800

Subject: Comments on "An Experiment in Remote Printing"

Message-ID: <19930411203413000.456@tpd.org>

MIME-Version: 1.0

Content-Type: multipart/mixed;

boundary="----- =_aaaaaaaaaa0"

------- =_aaaaaaaaaa0

Content-Type: application/remote-printing

Recipient: Marshall Rose

Title: Principal

Organization: Dover Beach Consulting, Inc.

Address: 420 Whisman Court

Mountain View, CA 94043-2186

US

Telephone: +1 415 968 1052

Facsimile: +1 415 968 2510

Originator: John Q. Public

Organization: The Public Domain

Telephone: +1 801 555 1234

Facsimile: +1 801 555 6789

EMail: "John Q. Public" <jpublic@tpd.org>

Any text appearing here would go on the cover-sheet.

------- =_aaaaaaaaaa0

Content-Type: text/plain; charset="us-ascii"

Here are my comments on your draft.

...

------- =_aaaaaaaaaa0--

2.4. Remote Printing without MIME

If the originator's user agent doesn't support MIME, (e.g., the

originator accesses the Internet mail infrastructure via a gateway in

another mail dominion), then it is still possible for remote printing

to occur, albeit in a more limited fashion. Specifically, because a

"application/remote-printing" content is not present, cover sheet

information must be derived from some other source; and, the message

body will be treated as a "text/plain" content.

Typically, a cover sheet consists of three sections:

o information identifying the originator;

o information identifying the recipient; and,

o additional information supplied by the remote printer server.

To identify the originator, the remote printer server will use the

message headers, usually by stripping any trace headers (i.e.,

"Received" and "Return-Path") and then re-ordering the remaining

headers starting with the "From" header.

To identify the recipient, an alternative syntax is used for

recipient addressing, in which the local-part of the remote printer

server's address consists of "remote-printer" followed by an RFC822

atom, e.g.,

remote-printer.Arlington_Hewes/Room_403@0.1.5.2.8.6.9.5.1.4.1.tpc.int

This mailbox syntax is purposefully restricted in the interests of

pragmatism.

The atom following "remote-printer" is considered an opaque string

for use in recipient identification when generating a cover sheet.

To paraphrase RFC822, an atom is defined as:

atom = 1*atomchar

atomchar= <any upper or lowercase alphabetic character (A-Z a-z)>

/ <any digit (0-9)>

/ "!" / "#" / "$" / "%" / "&" / "'" / "*" / "+"

/ "-" / "/" / "=" / "?" / "^" / "_" / "`" / "{"

/ "" / "}" / "~"

When generating a cover sheet using this opaque string, the remote

printer server will interpret an underscore character ("_") as a

space, and a solidus character ("/") as an end-of-line sequence. A

remote printer server will interpret two consecutive underscore

characters in the opaque string as a single underscore, and two

consecutive solidus characters as a single solidus. So, the opaque

string,

Arlington_Hewes/Room_403

used in the example above might appear on the cover sheet as

To: Arlington Hewes

Room 403

Note that some Internet mail software (especially gateways from

outside the Internet) impose stringent limitations on the size of a

mailbox-string. Thus, originating user agents should take care in

limiting the local-part to no more than 70 or so characters.

Note that by using the alternative syntax for recipient addressing,

it is completely legal to send non- textual messages in which the

cover sheet information is automatically derived -- simply by

including "MIME-Version:" and "Content-Type:" headers in the message,

but omitting the initial "application/remote-printing" content, e.g.,

To: remote-printer.Arlington_Hewes/Room_403@0.1.5.2.8.6.9.5.1.4.1.tpc.int

cc: Marshall Rose <mrose@dbc.mtview.ca.us>

From: Carl Malamud <carl@malamud.com>

Date: Sun, 18 Jul 1993 09:14:13 -0500

Subject: proposal for enhancement

Message-ID: <19930718141413000.123@malamud.com>

MIME-Version: 1.0

Content-Type: application/postcript

%!

Note that by using the alternative syntax for recipient addressing,

remote printing and e-mail recipients can be identified in the same

message.

3. The Experiment

In order to gain experience with this style of remote printing, an

experiment is underway.

3.1. Infrastructure

The domain "tpc.int." is being populated in order to provide the MX-

based infrastructure for routing to a remote printer server. In

order to facilitate distributed operations, this domain is divided

into a zone for each IDDD country code. Sites participating in the

experiment contact the appropriate zone administrator in order to be

listed, by examining the SOA resource record associated with the

zone. For example, a site in the Netherlands (IDDD country code 31)

would contact the zone administrator for the domain "1.3.tpc.int." in

order to be listed, e.g.,

% dig 1.3.tpc.int. soa

Each zone administrator has a simple set of procedures for listing a

participant. For example, in the US (IDDD country code 1),

participating sites send an "exchange file" to the administrator,

which indicates the prefixes that the site wishes to list. The zone

administrator for the domain "1.tpc.int." merges the exchange files

from all participating sites to create a zone for each area code.

These zones are then replicated using the normal DNS zone transfer

procedures.

3.1.1. Zones

It should be noted that zones under "tpc.int" are created on the

basis of IDDD country codes and area codes; they are not created for

each subdomain. For example, in the US and Canada (IDDD country code

1), no more than one zone is allocated for each area code. In

contrast, for countries with a smaller numbering plan, only a single

zone, for the whole country would be allocated. For example, if Fiji

(IDDD country code 679), were to join the experiment, then it is

likely that a single zone would be added to the DNS, i.e.,

"9.7.6.tpc.int."

3.1.2. MX records

The MX records present in a zone can have an arbitrary level of

precision. For example, the North American Numbering Plan (IDDD

country code 1) is structured by a 3-digit area code, followed by a

3-digit exchange prefix, followed by a 4-digit station number. As

such, one might expect that MX records in this zone would be similar

to

*.5.1.4.1.tpc.int. IN MX 10 dbc.mtview.ca.us.

which accessed any printer with a telephone number prefix of

+1 415

(i.e., allowing access to any printer in area code 415), or might be

similar to

*.8.6.9.5.1.4.1.tpc.int. IN MX 10 dbc.mtview.ca.us.

(i.e., allowing access to any printer in area code 415, exchange

prefix 968).

However, the level of precision is arbitrary. For example, if all of

the printers in an organization had a telephone number prefix of

+1 415 96

then an MX record such as

*.6.9.5.1.4.1.tpc.int. IN MX 10 dbc.mtview.ca.us.

could be used.

3.2. Accounting and Privacy

There is no accounting nor settlement in the experiment; however,

participating sites may implement access control to prevent abuse.

Records may be kept for auditing purposes; however, the privacy of a

participant's printing should be honored. As such, any auditing

should contain at most this information:

o the date the message was received;

o the "From" and "Message-ID" fields;

o the size of the body;

o the identity (telephone number) of the printer;

o any telephony-related information, such as call duration;

and,

o any G3-related information, such recipient ID.

3.3. Mailing list

There is a mailing list for the experiment. Interested readers

should send a note to:

tpc-rp-request@aarnet.edu.au

and ask to subscribe to the

tpc-rp@aarnet.edu.au

list.

3.4. Prototype Implementation

A prototype implementation is openly available. The MIME

instructions for retrieval are:

MIME-Version: 1.0

Content-Type: multipart/alternative;

boundary="----- =_aaaaaaaaaa0"

Content-Description: pointers to FTP and e-mail access

------- =_aaaaaaaaaa0

Content-Type: message/external-body;

access-type="mail-server";

server="archive-server@ftp.ics.uci.edu"

Content-Type: application/octet-stream; type="tar";

x-conversions="x-compress"

Content-ID: <4599.735726126.1@dbc.mtview.ca.us>

mimesend mrose/tpc/rp.tar.Z

------- =_aaaaaaaaaa0

Content-Type: message/external-body;

access-type="anon-ftp"; name="rp.tar.Z";

Directory="mrose/tpc"; site="ftp.ics.uci.edu"

Content-Type: application/octet-stream; type="tar";

x-conversions="x-compress"

Content-ID: <4599.735726126.2@dbc.mtview.ca.us>

------- =_aaaaaaaaaa0--

This package contains software for UNIX-based systems, and was

developed and tested under SunOS, with an openly-available facsimile

package (Sam Leffler's FlexFAX package), and contains information for

sites acting as either client or server participants, and zone

administrators.

4. Future Issues

The experiment in remote printing described herein does not address

several issues, e.g.,

o determining which content-types and character sets are

supported by a remote printer server;

o introduction of authentication, integrity, privacy,

authorization, and accounting services;

o preferential selection of a remote printer server; and,

o aggregation of multiple print recipients in a single

message.

Initially, the experiment will not address these issues. However,

subsequent work might consider these issues in detail.

5. Security Considerations

Internet mail may be subject to monitoring by third parties, and in

particular, message relays.

6. Acknowledgements

Carl Malamud of the Internet Multicasting Service provided

substantive comments on the design of the experiment. Douglas Comer

of Purdue, Daniel Karrenberg of RIPE, Sam Leffler of SGI, Paul

Mockapetris of ARPA, also provided comments.

7. References

[1] Crocker, D., "Standard for the Format of ARPA Internet Text

Messages", STD 11, RFC822, UDEL, August, 1982.

[2] Borenstein, N., and N. Freed, "MIME: Mechanisms for Specifying

and Describing the Format of Internet Message Bodies", RFC1341,

Bellcore, Innosoft, June 1992.

[3] Partridge, C., "Mail Routing and the Domain System", RFC974,

CSNET CIC BBN, August 1982.

[4] Mockapetris, P., "Domain Names -- Concepts and Facilities", STD

13, RFC1034, USC/Information Sciences Institute, November 1987.

[5] Mockapetris, P., "Domain Names -- Implementation and

Specification", STD 13, RFC1035, USC/Information Sciences

Institute, November 1987.

8. Authors' Addresses

Marshall T. Rose

Dover Beach Consulting, Inc.

420 Whisman Court

Mountain View, CA 94043-2186

US

Phone: +1 415 968 1052

Fax: +1 415 968 2510

EMail: mrose@dbc.mtview.ca.us

Carl Malamud

Internet Multicasting Service

Suite 1155, The National Press Building

Washington, DC 20045

US

Phone: +1 202 628-2044

Fax: +1 202 628 2042

EMail: carl@malamud.com

Appendix A. The image/tiff Content-Type

(1) MIME type name: image

(2) MIME subtype name: tiff

(3) Required parameters: none

(4) Optional parameters: none

(5) Encoding considerations: base64

(6) Security considerations: none

(7) Published specification: TIFF class F, as defined in:

Tag Image File Format (TIFF) revision 6.0

Developer's Desk Aldus Corporation 411 First Ave. South Suite

200 Seattle, WA 98104 206-622-5500

Appendix B. Uniform Addressing

A user may choose to include several recipients in a message, one or

more of which may be recipients reached via remote printing.

However, the message format accepted by a remote printer server

contains only a single recipient.

There are three solutions to this problem: first, during composition,

a "smart" user agent can determine that one or more remote printing

recipients are present, and submit the appropriate messages. This

has the disadvantage that the submission for the e-mail recipients

does not contain any information about the remote-printing

recipients.

A second solution is to use the alternative syntax for recipient

addressing described in Section 2.4 -- however, this minimizes useful

information available when constructing the cover sheet.

A third solution is for a site participating as a client to offer a

remote printing recipient exploder server to its users. Each remote

printing recipient is assigned a mailbox relative to the exploder,

and, as such, appears as an "ordinary" e-mail address. Using this

strategy, the user agent has no knowledge of which recipients are

accessible via e-mail or remote-printing -- the user simply specifies

a collection of mailbox recipients. Those recipients which are

accessible via remote-printing are automatically routed to the

exploder. For each recipient in the envelope, a local database is

consulted to retrieve addressing information for the recipient, and a

message is submitted to the appropriate remote printer server.

For example, if the original message submitted was:

To: mrose@rpexplode.tpd.org

cc: Arlington Hewes <tpcadmin@dbc.mtview.ca.us>

From: "John Q. Public" <jpublic@tpd.org>

Date: Sun, 11 Apr 1993 20:34:12 -0800

Subject: Comments on "An Experiment in Remote Printing"

Message-ID: <19930411203412000.123@tpd.org>

MIME-Version: 1.0

Content-Type: text/plain; charset=us-ascii

Here are my comments on your draft.

...

then the first recipient, "mrose@rpexplode.tpd.org", would be routed

to an remote printing exploder, which would submit the message shown

in the example in Section 2.3. The second recipient,

"tpcadmin@dbc.mtview.ca.us", would receive the message shown here.

Note that a reply by this recipient could include the remote printing

recipient.

 
  Network Working Group M. Rose Request for Comments: 1486 Dover Beach Consulting, Inc. C. Malamud Internet Multicasting Service July 1993 An EXPeriment in Remote Printing Status of this Memo This memo defines an Experimental Protocol for the Internet community. It does not specify an Internet standard. Discussion and suggestions for improvement are requested. Please refer to the current edition of the "IAB Official Protocol Standards" for the standardization state and status of this protocol. Distribution of this memo is unlimited. Table of Contents 1. IntrodUCtion .......................................... 1 1.1 The Advantage of a General-Purpose Infrastructure..... 2 2. Procedure ............................................. 2 2.1 Naming, Addressing, and Routing ...................... 3 2.2 The application/remote-printing Content-Type ......... 4 2.3 Usage Example ........................................ 5 2.4 Remote Printing without MIME ......................... 6 3. The Experiment ........................................ 7 3.1 Infrastructure ....................................... 8 3.1.1 Zones .............................................. 8 3.1.2 MX records ......................................... 8 3.2 Accounting and Privacy ............................... 9 3.3 Mailing list ......................................... 9 3.4 Prototype Implementation ............................. 10 4. Future Issues ......................................... 11 5. Security Considerations ............................... 11 6. Acknowledgements ...................................... 11 7. References ............................................ 11 8. Authors' Addresses..................................... 12 A. The image/tiff Content-Type .......................... 13 B. Uniform Addressing ................................... 13 1. Introduction Although electronic mail is preferable as a means of third-party communication, in some cases it may be necessary to print information, in hard-copy form, at a remote location. The remote output device may consist of a standard line printer, a printer with multiple fonts and faces, a printer that can reproduce graphics, or a facsimile device. Remote output may be accompanied by information that identifies the intended recipient. This memo describes a technique for "remote printing" using the Internet mail infrastructure. In particular, this memo focuses on the case in which remote printers are connected to the international telephone network. Furthermore, it describes an experiment in remote printing. 1.1. The Advantage of a General-Purpose Infrastructure The experiment in remote printing is about "outreach"; specifically, integrating the e-mail and facsimile communities. By providing easy Access to remote printing recipients, enterprise-wide access is enhanced, regardless of kind of institution (e.g., commercial, educational, or government), or the size of institution (e.g., global, regional, or local). This approach at outreach allows an organization to make it easier for the "outside world" to communicate with the personnel in the organization who are users of facsimile but not e-mail; e.g., the sales person, the university registrar, or the (elected) official. The ease in which the Internet mail infrastructure can be used to provide this facility is (yet) another example of the power of a general-purpose infrastructure. 2. Procedure When information is to be remotely printed, the user application constructs an RFC822 [1] message, containing a "Message-ID" field along with a "multipart/mixed" content [2] having two parts, the first being a "application/remote-printing" content-type, and the second being an arbitrary content-type corresponding to the information to be printed. The message is then sent to the remote printer server's electronic mail address. It should be noted that not all content-types have a natural printing representation, e.g., an "audio" or "video" content. For this reason, the second part of the "multipart/mixed" content should be one of the following: text/plain, message/rfc822, application/postscript image/tiff (defined in Appendix A), any multipart Note that: (1) With the "text/plain" content-type, not all character sets may be available for printing. (2) With the "message" content-type, the subordinate content will be processed recursively. (3) With the "application/postscript" content-type, the remote printer server should evaluate the contents in a safe execution environment. (4) With the "multipart" content-type the subordinate contents will be processed recursively: for a "multipart/mixed" or "multipart/digest" content, each subordinate content will start on a new page, whilst for a "multipart/parallel" content, all subordinate contents will, if possible, start on the same page. Naturally, when processing a "multipart/alternative" content, only one subordinate content will be printed. When the remote printer server finishes its processing, a message is returned to the originator, indicating either success or failure. 2.1. Naming, Addressing, and Routing A printer is identified by a telephone number which corresponds to a G3-facsimile device connected to the international telephone network, e.g., +1 415 968 2510 where "+1" indicates the IDDD country code, and the remaining string is a telephone number within that country. This number is used to construct the address of a remote printer server, which forms the recipient address for the message, e.g., remote-printer@0.1.5.2.8.6.9.5.1.4.1.tpc.int That is, the local-part of the remote printer server's address is ALWAYS "remote-printer", and the domain-part is constructed by reversing the telephone number, converting each digit to a domain- label, and being placed under "tpc.int." The message is routed in exactly the same fashion as all other electronic mail, i.e., using the MX algorithm [3]. Since a remote printer server might be able to access many printers, the wildcarding facilities of the DNS [4,5] are used accordingly. For example, if a remote printer server residing at "dbc.mtview.ca.us" was willing to access any printer with a telephone number prefix of +1 415 968 then this resource record might be present *.8.6.9.5.1.4.1.tpc.int. IN MX 10 dbc.mtview.ca.us. Naturally, if several remote printer servers were willing to access any printer in that prefix, multiple MX resource records would be present. It should be noted that the presence of a wildcard RR which matches a remote printer server's address does not imply that the corresponding telephone number is valid, or, if valid, that a G3-facsimile device is connected at the phone number. 2.2. The application/remote-printing Content-Type (1) MIME type name: application (2) MIME suBType name: remote-printing (3) Required parameters: none (4) Optional parameters: none (5) Encoding considerations: 7bit preferred (6) Security considerations: none The "application/remote-printing" content-type contains originator and recipient information used when generating a cover sheet. Using the ABNF notation of RFC822, the syntax for this content is: <content> ::= <recipient-info> CRLF <originator-info> [CRLF <cover-info>] <recipient-info> ::= "Recipient" ":" <value> CRLF <address-info> <originator-info> ::= "Originator" ":" <value> CRLF <address-info> <address-info> ::= ["Title" ":" <value> CRLF] ["Department" ":" <value> CRLF] ["Organization" ":" <value> CRLF] ["Mailstop" ":" <value> CRLF] ["Address" ":" <value> CRLF] ["Telephone" ":" <value> CRLF] "Facsimile" ":" <value> CRLF ["Email" ":" <value> CRLF] <value> ::= *text [CRLF LWSP-char <value> ] <cover-info> ::= *(*text CRLF) Note that the value of the "Email" field is an RFC822 mailbox address. 2.3. Usage Example Suppose someone wished to send the author some comments on this memo using this facility. The message constructed might look like this: To: remote-printer@0.1.5.2.8.6.9.5.1.4.1.tpc.int From: "John Q. Public" <jpublic@tpd.org> Date: Sun, 11 Apr 1993 20:34:13 -0800 Subject: Comments on "An Experiment in Remote Printing" Message-ID: <19930411203413000.456@tpd.org> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----- =_aaaaaaaaaa0" ------- =_aaaaaaaaaa0 Content-Type: application/remote-printing Recipient: Marshall Rose Title: Principal Organization: Dover Beach Consulting, Inc. Address: 420 Whisman Court Mountain View, CA 94043-2186 US Telephone: +1 415 968 1052 Facsimile: +1 415 968 2510 Originator: John Q. Public Organization: The Public Domain Telephone: +1 801 555 1234 Facsimile: +1 801 555 6789 EMail: "John Q. Public" <jpublic@tpd.org> Any text appearing here would go on the cover-sheet. ------- =_aaaaaaaaaa0 Content-Type: text/plain; charset="us-ascii" Here are my comments on your draft. ... ------- =_aaaaaaaaaa0-- 2.4. Remote Printing without MIME If the originator's user agent doesn't support MIME, (e.g., the originator accesses the Internet mail infrastructure via a gateway in another mail dominion), then it is still possible for remote printing to occur, albeit in a more limited fashion. Specifically, because a "application/remote-printing" content is not present, cover sheet information must be derived from some other source; and, the message body will be treated as a "text/plain" content. Typically, a cover sheet consists of three sections: o information identifying the originator; o information identifying the recipient; and, o additional information supplied by the remote printer server. To identify the originator, the remote printer server will use the message headers, usually by stripping any trace headers (i.e., "Received" and "Return-Path") and then re-ordering the remaining headers starting with the "From" header. To identify the recipient, an alternative syntax is used for recipient addressing, in which the local-part of the remote printer server's address consists of "remote-printer" followed by an RFC822 atom, e.g., remote-printer.Arlington_Hewes/Room_403@0.1.5.2.8.6.9.5.1.4.1.tpc.int This mailbox syntax is purposefully restricted in the interests of pragmatism. The atom following "remote-printer" is considered an opaque string for use in recipient identification when generating a cover sheet. To paraphrase RFC822, an atom is defined as: atom = 1*atomchar atomchar= <any upper or lowercase alphabetic character (A-Z a-z)> / <any digit (0-9)> / "!" / "#" / "$" / "%" / "&" / "'" / "*" / "+" / "-" / "/" / "=" / "?" / "^" / "_" / "`" / "{" / "" / "}" / "~" When generating a cover sheet using this opaque string, the remote printer server will interpret an underscore character ("_") as a space, and a solidus character ("/") as an end-of-line sequence. A remote printer server will interpret two consecutive underscore characters in the opaque string as a single underscore, and two consecutive solidus characters as a single solidus. So, the opaque string, Arlington_Hewes/Room_403 used in the example above might appear on the cover sheet as To: Arlington Hewes Room 403 Note that some Internet mail software (especially gateways from outside the Internet) impose stringent limitations on the size of a mailbox-string. Thus, originating user agents should take care in limiting the local-part to no more than 70 or so characters. Note that by using the alternative syntax for recipient addressing, it is completely legal to send non- textual messages in which the cover sheet information is automatically derived -- simply by including "MIME-Version:" and "Content-Type:" headers in the message, but omitting the initial "application/remote-printing" content, e.g., To: remote-printer.Arlington_Hewes/Room_403@0.1.5.2.8.6.9.5.1.4.1.tpc.int cc: Marshall Rose <mrose@dbc.mtview.ca.us> From: Carl Malamud <carl@malamud.com> Date: Sun, 18 Jul 1993 09:14:13 -0500 Subject: proposal for enhancement Message-ID: <19930718141413000.123@malamud.com> MIME-Version: 1.0 Content-Type: application/postcript %! Note that by using the alternative syntax for recipient addressing, remote printing and e-mail recipients can be identified in the same message. 3. The Experiment In order to gain experience with this style of remote printing, an experiment is underway. 3.1. Infrastructure The domain "tpc.int." is being populated in order to provide the MX- based infrastructure for routing to a remote printer server. In order to facilitate distributed operations, this domain is divided into a zone for each IDDD country code. Sites participating in the experiment contact the appropriate zone administrator in order to be listed, by examining the SOA resource record associated with the zone. For example, a site in the Netherlands (IDDD country code 31) would contact the zone administrator for the domain "1.3.tpc.int." in order to be listed, e.g., % dig 1.3.tpc.int. soa Each zone administrator has a simple set of procedures for listing a participant. For example, in the US (IDDD country code 1), participating sites send an "exchange file" to the administrator, which indicates the prefixes that the site wishes to list. The zone administrator for the domain "1.tpc.int." merges the exchange files from all participating sites to create a zone for each area code. These zones are then replicated using the normal DNS zone transfer procedures. 3.1.1. Zones It should be noted that zones under "tpc.int" are created on the basis of IDDD country codes and area codes; they are not created for each subdomain. For example, in the US and Canada (IDDD country code 1), no more than one zone is allocated for each area code. In contrast, for countries with a smaller numbering plan, only a single zone, for the whole country would be allocated. For example, if Fiji (IDDD country code 679), were to join the experiment, then it is likely that a single zone would be added to the DNS, i.e., "9.7.6.tpc.int." 3.1.2. MX records The MX records present in a zone can have an arbitrary level of precision. For example, the North American Numbering Plan (IDDD country code 1) is structured by a 3-digit area code, followed by a 3-digit exchange prefix, followed by a 4-digit station number. As such, one might expect that MX records in this zone would be similar to *.5.1.4.1.tpc.int. IN MX 10 dbc.mtview.ca.us. which accessed any printer with a telephone number prefix of +1 415 (i.e., allowing access to any printer in area code 415), or might be similar to *.8.6.9.5.1.4.1.tpc.int. IN MX 10 dbc.mtview.ca.us. (i.e., allowing access to any printer in area code 415, exchange prefix 968). However, the level of precision is arbitrary. For example, if all of the printers in an organization had a telephone number prefix of +1 415 96 then an MX record such as *.6.9.5.1.4.1.tpc.int. IN MX 10 dbc.mtview.ca.us. could be used. 3.2. Accounting and Privacy There is no accounting nor settlement in the experiment; however, participating sites may implement access control to prevent abuse. Records may be kept for auditing purposes; however, the privacy of a participant's printing should be honored. As such, any auditing should contain at most this information: o the date the message was received; o the "From" and "Message-ID" fields; o the size of the body; o the identity (telephone number) of the printer; o any telephony-related information, such as call duration; and, o any G3-related information, such recipient ID. 3.3. Mailing list There is a mailing list for the experiment. Interested readers should send a note to: tpc-rp-request@aarnet.edu.au and ask to subscribe to the tpc-rp@aarnet.edu.au list. 3.4. Prototype Implementation A prototype implementation is openly available. The MIME instructions for retrieval are: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----- =_aaaaaaaaaa0" Content-Description: pointers to FTP and e-mail access ------- =_aaaaaaaaaa0 Content-Type: message/external-body; access-type="mail-server"; server="archive-server@ftp.ics.uci.edu" Content-Type: application/octet-stream; type="tar"; x-conversions="x-compress" Content-ID: <4599.735726126.1@dbc.mtview.ca.us> mimesend mrose/tpc/rp.tar.Z ------- =_aaaaaaaaaa0 Content-Type: message/external-body; access-type="anon-ftp"; name="rp.tar.Z"; Directory="mrose/tpc"; site="ftp.ics.uci.edu" Content-Type: application/octet-stream; type="tar"; x-conversions="x-compress" Content-ID: <4599.735726126.2@dbc.mtview.ca.us> ------- =_aaaaaaaaaa0-- This package contains software for UNIX-based systems, and was developed and tested under SunOS, with an openly-available facsimile package (Sam Leffler's FlexFAX package), and contains information for sites acting as either client or server participants, and zone administrators. 4. Future Issues The experiment in remote printing described herein does not address several issues, e.g., o determining which content-types and character sets are supported by a remote printer server; o introduction of authentication, integrity, privacy, authorization, and accounting services; o preferential selection of a remote printer server; and, o aggregation of multiple print recipients in a single message. Initially, the experiment will not address these issues. However, subsequent work might consider these issues in detail. 5. Security Considerations Internet mail may be subject to monitoring by third parties, and in particular, message relays. 6. Acknowledgements Carl Malamud of the Internet Multicasting Service provided substantive comments on the design of the experiment. Douglas Comer of Purdue, Daniel Karrenberg of RIPE, Sam Leffler of SGI, Paul Mockapetris of ARPA, also provided comments. 7. References [1] Crocker, D., "Standard for the Format of ARPA Internet Text Messages", STD 11, RFC822, UDEL, August, 1982. [2] Borenstein, N., and N. Freed, "MIME: Mechanisms for Specifying and Describing the Format of Internet Message Bodies", RFC1341, Bellcore, Innosoft, June 1992. [3] Partridge, C., "Mail Routing and the Domain System", RFC974, CSNET CIC BBN, August 1982. [4] Mockapetris, P., "Domain Names -- Concepts and Facilities", STD 13, RFC1034, USC/Information Sciences Institute, November 1987. [5] Mockapetris, P., "Domain Names -- Implementation and Specification", STD 13, RFC1035, USC/Information Sciences Institute, November 1987. 8. Authors' Addresses Marshall T. Rose Dover Beach Consulting, Inc. 420 Whisman Court Mountain View, CA 94043-2186 US Phone: +1 415 968 1052 Fax: +1 415 968 2510 EMail: mrose@dbc.mtview.ca.us Carl Malamud Internet Multicasting Service Suite 1155, The National Press Building Washington, DC 20045 US Phone: +1 202 628-2044 Fax: +1 202 628 2042 EMail: carl@malamud.com Appendix A. The image/tiff Content-Type (1) MIME type name: image (2) MIME subtype name: tiff (3) Required parameters: none (4) Optional parameters: none (5) Encoding considerations: base64 (6) Security considerations: none (7) Published specification: TIFF class F, as defined in: Tag Image File Format (TIFF) revision 6.0 Developer's Desk Aldus Corporation 411 First Ave. South Suite 200 Seattle, WA 98104 206-622-5500 Appendix B. Uniform Addressing A user may choose to include several recipients in a message, one or more of which may be recipients reached via remote printing. However, the message format accepted by a remote printer server contains only a single recipient. There are three solutions to this problem: first, during composition, a "smart" user agent can determine that one or more remote printing recipients are present, and submit the appropriate messages. This has the disadvantage that the submission for the e-mail recipients does not contain any information about the remote-printing recipients. A second solution is to use the alternative syntax for recipient addressing described in Section 2.4 -- however, this minimizes useful information available when constructing the cover sheet. A third solution is for a site participating as a client to offer a remote printing recipient exploder server to its users. Each remote printing recipient is assigned a mailbox relative to the exploder, and, as such, appears as an "ordinary" e-mail address. Using this strategy, the user agent has no knowledge of which recipients are accessible via e-mail or remote-printing -- the user simply specifies a collection of mailbox recipients. Those recipients which are accessible via remote-printing are automatically routed to the exploder. For each recipient in the envelope, a local database is consulted to retrieve addressing information for the recipient, and a message is submitted to the appropriate remote printer server. For example, if the original message submitted was: To: mrose@rpexplode.tpd.org cc: Arlington Hewes <tpcadmin@dbc.mtview.ca.us> From: "John Q. Public" <jpublic@tpd.org> Date: Sun, 11 Apr 1993 20:34:12 -0800 Subject: Comments on "An Experiment in Remote Printing" Message-ID: <19930411203412000.123@tpd.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Here are my comments on your draft. ... then the first recipient, "mrose@rpexplode.tpd.org", would be routed to an remote printing exploder, which would submit the message shown in the example in Section 2.3. The second recipient, "tpcadmin@dbc.mtview.ca.us", would receive the message shown here. Note that a reply by this recipient could include the remote printing recipient.
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