< draft-ietf-fax-goals-03.txt   draft-ietf-fax-goals-04.txt >
Internet Fax Working Group Larry Masinter Internet Fax Working Group Larry Masinter
INTERNET-DRAFT Xerox Corporation INTERNET-DRAFT Xerox Corporation
August 27, 1998 Expires in 6 months September 23, 1998 Expires in 6 months
draft-ietf-fax-goals-03.txt draft-ietf-fax-goals-04.txt
Terminology and Goals for Internet Fax Terminology and Goals for Internet Fax
Status of this memo Status of this memo
This document is an Internet-Draft. Internet-Drafts are working This document is an Internet-Draft. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute and its working groups. Note that other groups may also distribute
working documents as Internet Drafts. working documents as Internet Drafts.
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5.2 Goals for transmission 5.2 Goals for transmission
5.3 Goals for addressing 5.3 Goals for addressing
5.4 Goals for security 5.4 Goals for security
5.5 Goals for capability exchange 5.5 Goals for capability exchange
6. Security Considerations 6. Security Considerations
7. Acknowledgements 7. Acknowledgements
8. Copyright 8. Copyright
9. Author's address 9. Author's address
10. References 10. References
Abstract
This document defines a number of terms useful for the discussion of
Internet Fax. In addition, it describes the goals of the Internet Fax
working group and establishes a baseline of desired functionality
against which protocols for Internet Fax can be judged. It encompasses
the goals for all modes of facsimile delivery, including 'real-time',
'session', and 'store and forward'. Different levels of desirability
are indicated throughout the document.
1. Introduction 1. Introduction
Facsimile (Fax) has a long tradition as a telephony application for Facsimile (Fax) has a long tradition as a telephony application for
sending a document from one terminal device to another. sending a document from one terminal device to another.
Many mechanisms for sending fax documents over the Internet have been Many mechanisms for sending fax documents over the Internet have been
demonstrated and deployed and are currently in use. The general demonstrated and deployed and are currently in use. The general
application of using the Internet for facsimile is called "Internet application of using the Internet for facsimile is called "Internet
Fax". Fax".
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{3} there is general belief that this is a useful feature {3} there is general belief that this is a useful feature
of Internet Fax, but that other factors might override; of Internet Fax, but that other factors might override;
a definition that does not provide this element is a definition that does not provide this element is
acceptable. acceptable.
In addition, the following terms are used: In addition, the following terms are used:
"service" An operational service offered by a service provider. "service" An operational service offered by a service provider.
"application" A use of systems to perform a particular function. "application" A use of systems to perform a particular function.
"terminal" The endpoint of a communication application. "terminal" The endpoint of a communication application.
"goal" An objective of the standarization "goal" An objective of the standarization process.
2. Definitions and Operation Modes 2. Definitions and Operation Modes
This section defines some of the basic terms for Internet Fax. This section defines some of the basic terms for Internet Fax.
2.1 User model of fax and basic operations 2.1 User model of fax and basic operations
The phrase "traditional facsimile" or "G3Fax" is used to denote The phrase "traditional facsimile" or "G3Fax" is used to denote
implementations of [T.30]. Facsimile (fax) is a telephony application implementations of [T.30]. Facsimile (fax) is a telephony application
for sending a document from one terminal device to another. for sending a document from one terminal device to another.
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5) the sending device scans the paper and transmits the image 5) the sending device scans the paper and transmits the image
of the paper of the paper
6) simultaneously, the remote device receives the transmission 6) simultaneously, the remote device receives the transmission
and prints the image on paper and prints the image on paper
7) upon completion of transmission and successful processing 7) upon completion of transmission and successful processing
by the recipient, the sending user is notified of success by the recipient, the sending user is notified of success
Although not usually visible to the user, the operation (5) of Although not usually visible to the user, the operation (5) of
transmission consists of transmission consists of
5a) negotiation: the capabilities of the sender and recipient 5a) negotiation: the capabilities of the recipient are obtained,
are exchanged, and suitable mutually acceptable parameters and suitable mutually available parameters for the communication
for the communication are selected are selected
5b) scanning: creating digitized images of pages of a document 5b) scanning: creating digitized images of pages of a document
5c) compression: the image data is encoded using a data compression 5c) compression: the image data is encoded using a data compression
method method
5d) transmission: the data is sent from one terminal to the other 5d) transmission: the data is sent from one terminal to the other
In addition, the terminiation of operations (5d) and (6) may be In addition, the terminiation of operations (5d) and (6) may be
characterized as consisting of: characterized as consisting of:
6a) completed delivery: the message has completed transmission 6a) completed delivery: the message has completed transmission
6b) completed receipt: the message has been accepted by the recipient 6b) completed receipt: the message has been accepted by the recipient
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>From a protocol perspective, the information conveyed in the >From a protocol perspective, the information conveyed in the
transmission consists of both "protocol" (control information, transmission consists of both "protocol" (control information,
capabilities, identification) and also "document content". capabilities, identification) and also "document content".
The document content consists primarily of the "document image" plus The document content consists primarily of the "document image" plus
additional metadata accompanying the image. The means by which an additional metadata accompanying the image. The means by which an
image of a document is encoded within the fax content is the "image image of a document is encoded within the fax content is the "image
data representation". data representation".
When the fax has been sucessfully transmitted, the sender receives a When the fax has been successfully transmitted, the sender receives a
"confirmation": an indication that the fax content was delivered, "confirmation": an indication that the fax content was delivered.
received, and processed. This "confirmation" is an internal signal This "confirmation" is an internal signal and is not normally visible
and is not normally visible to the sending user, although some error to the sending user, although some error messages are visible, to
messages are visible, to allow a page to be retransmitted. allow a page to be retransmitted.
2.2 Definition of Internet Fax 2.2 Definition of Internet Fax
The phrase "Internet Fax" is used to denote an application which The phrase "Internet Fax" is used to denote an application which
supports an approximation to the user model of fax (Section 2.1), but supports an approximation to the user model of fax (Section 2.1), but
where Internet protocols are used instead of the telephone network for where Internet protocols are used instead of the telephone network for
(some portion of) the transmission. The exact modes and operations of (some portion of) the transmission. The exact modes and operations of
traditional facsimile need not be duplicated exactly. traditional facsimile need not be duplicated exactly.
2.3 Internet Fax Roles 2.3 Internet Fax Roles
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In addition, other traditional Internet applications might also In addition, other traditional Internet applications might also
participate in Internet Fax, including Internet mail users, Web participate in Internet Fax, including Internet mail users, Web
browsers, Internet printing hosts. browsers, Internet printing hosts.
2.4 Internet Fax Devices 2.4 Internet Fax Devices
The Internet Fax roles may be embedded in a variety of combinations The Internet Fax roles may be embedded in a variety of combinations
and configurations within devices and larger applications. They may and configurations within devices and larger applications. They may
be combined with other elements, e.g., a traditional T.30 fax be combined with other elements, e.g., a traditional T.30 fax
device. Many different configurations of applications should {2} be device. Many different configurations of applications and systems
able to participate in Internet Fax; the specification should not should {2} be able to participate in Internet Fax; the specification
unnecessarily restrict the range of devices, applications and services should not unnecessarily restrict the range of devices, applications
that can participate. and services that can participate.
The phrase "IFax device" is used to indicate a device which supports A device that supports Internet Fax might support any combination of
any combination of the roles defined in 2.3, as embodied in a single the roles defined in 2.3.
device which is engaged in an Internet Fax application.
2.4.1 Gateway devices 2.4.1 Gateway devices
A traditional fax terminal has a telephone line connection (PSTN) with A traditional fax terminal has a telephone line connection (GSTN) with
a fax modem used to connect over the telephone network. To connect a a fax modem used to connect over the telephone network. To connect a
fax terminal to the Internet requires a service which offers fax terminal to the Internet requires a service which offers
connections on one side to the PSTN using standard fax signals, and on connections on one side to the GSTN using standard fax signals, and on
the other side to the Internet. This role might be performed by a the other side to the Internet. This role might be performed by a
"relay" (e.g., transmitting T.30 signals over real-time controlled TCP "relay" (e.g., transmitting T.30 signals over real-time controlled TCP
connections) or a "gateway" (e.g., translating T.30 to TIFF/email). connections) or a "gateway" (e.g., translating T.30 to TIFF/email).
With these applications, the role of Internet Fax is to transport the With these applications, the role of Internet Fax is to transport the
fax content across the Internet, e.g., with fax content across the Internet, e.g., with
[fax-term]-PSTNfax->[onramp]-Internet Fax->[recipient] [fax-term]-GSTNfax->[onramp]-Internet Fax->[recipient]
[sender]-Internet Fax->[offramp]-PSTNFax->[fax-term] [sender]-Internet Fax->[offramp]-GSTNFax->[fax-term]
A onramp and/or offramp application may be local to a single fax A onramp and/or offramp application may be local to a single fax
terminal. For example, the gateway application might exist within a small terminal. For example, the gateway application might exist within a small
device which has a telephone interface on one side and a network device which has a telephone interface on one side and a network
connection on the other. To the fax machine, it looks like a telephone connection on the other. To the fax machine, it looks like a telephone
connection, although it might shunt some or all connections to connection, although it might shunt some or all connections to
Internet Fax instead (Such devices are called "Bump-in-cord.") Internet Fax instead (Such devices are called "Bump-in-cord.")
An onramp or offramp application may be a local facility serving many fax An onramp or offramp application may be a local facility serving many fax
terminals. For example, outgoing telephone fax calls through a company terminals. For example, outgoing telephone fax calls through a company
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Onramps and offramps may serve a wider area or broader collection of Onramps and offramps may serve a wider area or broader collection of
users, e.g., services run by service bureaus, offering subscription users, e.g., services run by service bureaus, offering subscription
services; the telephone sender or the recipient might subscribe to the services; the telephone sender or the recipient might subscribe to the
service. service.
The target of an offramp may be a "hunt group": a set of telephone The target of an offramp may be a "hunt group": a set of telephone
numbers, each of which have a possibly different fax terminal numbers, each of which have a possibly different fax terminal
attached. attached.
2.4.2 New "IFax" terminals 2.4.2 New "Internet Fax" devices
Manufacturers of traditional facsimile devices may offer new devices Manufacturers may offer new devices which support any combination of
built out of similar components (scanner, processor, and printer), the roles defined in setion 2.3. In particular, a device resembling a
which offer a similar functionality to a fax device, but which traditional fax terminal, built out of similar components (scanner,
connects to the Internet. These devices might also offer a traditional processor, and printer), could offer a similar functionality to a
fax modem capability, or might send documents exclusively through the traditional facsimile terminal, but be designed to connect to the
Internet. Such devices might have a permanent Internet connection Internet rather than, or in addition to, a telephone line connection.
(through a LAN connection) or might have occasional connectivity
through a (data) modem to an Internet Service Provider. Such devices might have a permanent Internet connection (through a LAN
connection) or might have occasional connectivity through a (data)
modem to an Internet Service Provider.
2.4.3 Internet hosts 2.4.3 Internet hosts
Internet users using Internet hosts with standard application suites Internet users using Internet hosts with standard application suites
must {1} be able to exchange faxes with other participants in Internet must {1} be able to exchange faxes with other participants in Internet
Fax, with minimum required enhancements to their operating Fax, with minimum required enhancements to their operating
environment. environment.
Interoperability with Internet mail users, either as Internet Fax Interoperability with Internet mail users, either as Internet Fax
senders or recipients, is highly desirable {2}. senders or recipients, is highly desirable {2}.
Internet users might receive faxes over the Internet and display them Internet users might receive faxes over the Internet and display them
on their screens, or have them automatically printed when received. on their screens, or have them automatically printed when received.
Similarly, the Internet Fax messages originating from the user might Similarly, the Internet Fax messages originating from the user might
be the output of a software application which would normally print, or be the output of a software application which would normally print, or
specially constructed fax-sending software, or may be input directly specially constructed fax-sending software, or may be input directly
from a scanner attached to the user's terminal. from a scanner attached to the user's terminal.
The Internet Fax capability might be integrated into existing The Internet Fax capability might be integrated into existing
fax/network fax software or email software, e.g., by the addition of fax/network fax software or email software, e.g., by the addition of
"Ifax Printer Drivers" that would render the document to the printer drivers that would render the document to the
appropriate content-type and cause it to be delivered using an appropriate content-type and cause it to be delivered using an
Internet Fax protocol. Internet Fax protocol.
In some cases, the user might have a multi-function peripheral which In some cases, the user might have a multi-function peripheral which
integrated a scanner and printer and which gave operability similar to integrated a scanner and printer and which gave operability similar to
that of the stand-alone fax terminal. that of the stand-alone fax terminal.
2.4.4 Internet messaging 2.4.4 Internet messaging
In Internet mail, there are a number of components that operate in the In Internet mail, there are a number of components that operate in the
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of agents in the communication. of agents in the communication.
"Session" Internet Fax is defined such that delivery notification is "Session" Internet Fax is defined such that delivery notification is
provided to the transmitting terminal prior to disconnection. Unlike provided to the transmitting terminal prior to disconnection. Unlike
"store and forward", there is an expection that direct communication, "store and forward", there is an expection that direct communication,
negotiation, and retransmission can take place between the two negotiation, and retransmission can take place between the two
endpoints. endpoints.
"Real-time" Internet Fax allows for two [T.30] standard facsimile "Real-time" Internet Fax allows for two [T.30] standard facsimile
terminals to engage in a document transmission in a way that all of terminals to engage in a document transmission in a way that all of
the [T.30] communication protocol is preserved. the essential elements of the [T.30] communication protocol are
preserved and there is minimal elongation of the session as compared
to Group 3 fax over the GSTN.
These modes are different in the end-user expectation of immediacy, These modes are different in the end-user expectation of immediacy,
reliability, and in the ease of total compatibility with legacy or reliability, and in the ease of total compatibility with legacy or
traditional facsimile terminals; the modes may have different traditional facsimile terminals; the modes may have different
requirements on operational infrastructure connecting sender and requirements on operational infrastructure connecting sender and
recipient. recipient.
3. Goals for Internet Fax 3. Goals for Internet Fax
Facsimile over the Internet must define the mechanisms by which a Facsimile over the Internet must define the mechanisms by which a
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only for the "store-and-forward" facsimile, although it would be only for the "store-and-forward" facsimile, although it would be
useful {3} for "session" and "real-time" modes of delivery of Internet useful {3} for "session" and "real-time" modes of delivery of Internet
Fax. Fax.
The requirement for interoperability has strong implications for the The requirement for interoperability has strong implications for the
protocol design. Interoperability must not {1} depend on having the protocol design. Interoperability must not {1} depend on having the
same kind of networking equipment at each end. same kind of networking equipment at each end.
As with most Internet application protocols, interoperability must {1} As with most Internet application protocols, interoperability must {1}
be independent of the nature of the networking link, whether a simple be independent of the nature of the networking link, whether a simple
IP-based LAN, an internal private IP networks, or the public IP-based LAN, an internal private IP networks, or the public Internet.
Internet. The standard for Internet Fax must {1} be global and have no The standard for Internet Fax must {1} be "global": that is, a single
special features for local operations. specification which does not have or require special features of
the transport mechanism for local operations.
If Internet Fax is to use the Internet mail transport mechanisms, it If Internet Fax is to use the Internet mail transport mechanisms, it
must {1} interoperate consistently with the current Internet mail must {1} interoperate consistently with the current Internet mail
environment, and, in particular, with the non-terminal devices listed environment, and, in particular, with the non-terminal devices listed
in section 2.4.4. If Internet Fax messages might arrive in user's in section 2.4.4. If Internet Fax messages might arrive in user's
mailboxes, it is required {1} that the protocol interoperate mailboxes, it is required {1} that the protocol interoperate
successfully with common user practices for mail messages: storing successfully with common user practices for mail messages: storing
them in databases, retransmission, forwarding, creation of mail them in databases, retransmission, forwarding, creation of mail
digests, replay of old messages at times long after the original digests, replay of old messages at times long after the original
receipt, and replying to messages using non-fax equipment. receipt, and replying to messages using non-fax equipment.
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important that the user can get an assurance that the transmitted data important that the user can get an assurance that the transmitted data
was received by a terminal at the address dialed by the user. was received by a terminal at the address dialed by the user.
This goal translates to the Internet environment. The 'Internet Fax' This goal translates to the Internet environment. The 'Internet Fax'
application must {1} define the mechanisms by which a sender may application must {1} define the mechanisms by which a sender may
request notification of the completion of transmission of the message, request notification of the completion of transmission of the message,
and receive a determinate response as to whether the message was and receive a determinate response as to whether the message was
delivered, not delivered, or that no confirmation of delivery is delivered, not delivered, or that no confirmation of delivery is
possible. possible.
Originally, fax "confirmation" indicated that the message was recieved Originally, fax "confirmation" implied that the message was received
and processed, e.g., delivered to the output paper tray of the and processed, e.g., delivered to the output paper tray of the
recipient fax device. With the addition of memory buffering and recipient fax device. In reality, this implication was relying upon a
PC-based fax modems, traditional fax confirmation still indicated some signal produced by the receiving terminal that the incoming page had
assurance of processability; e.g., a fax modem would not confirm been inspected and was determined to be of reasonable (or
receipt of an incoming fax if it required compression mechanisms that unacceptable) quality, via an unspecified algorithm.
were not supported.
Still, this is not the same as a confirmation that the message was In later devices which support error correction mode, the ECM method
"read": that a human had confirmed that the message was (per [T.30]) enabled error checking via a specific algorithm,
received. Confirmation that the message was read (above and beyond the providing a more exact indication that the bits within the compressed
notification that the message was delivered) is desirable {3}, but not image were not corrupted during transmission. With the addition of
required. memory buffering, PC-based fax modems and the more common use of error
correction mode, traditional fax confirmation still implies some
assurance of processability; (e.g., a fax modem would not be able to
receive an incoming fax if it required compression mechanisms that
were not supported) without reporting on whether the image has been
printed or viewed.
Consequently, the fax confirmation is not the same as a confirmation
that the message was "read": that a human had confirmed that the
message was received. It is desirable {3}, but not required, that
Internet Fax support confirmation that a message has been read (above
and beyond the confirmation that the message has been delivered).
4.4 Quick Delivery 4.4 Quick Delivery
In many cases, fax transmission is used for delivery of documents In many cases, fax transmission is used for delivery of documents
where there is a strong user requirement for timeliness, with some where there is a strong user requirement for timeliness, with some
guarantees that if transmission begins at all, it will complete guarantees that if transmission begins at all, it will complete
quickly. For example, it is a common practice to fax documents for quickly. For example, it is a common practice to fax documents for
discussion to other participants in a telephone conference call prior discussion to other participants in a telephone conference call prior
to the call. to the call.
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for privacy and integrity that is as good or better than that for privacy and integrity that is as good or better than that
available for telephone-based fax. The Internet Fax standard should available for telephone-based fax. The Internet Fax standard should
{2} specify how secure messages can be sent, in an interoperable {2} specify how secure messages can be sent, in an interoperable
fashion. The Internet Fax protocol should {2} encourage the fashion. The Internet Fax protocol should {2} encourage the
introduction of security features, e.g., by requiring that minimum introduction of security features, e.g., by requiring that minimum
capability devices still accept signed messages (even if ignoring the capability devices still accept signed messages (even if ignoring the
signature.) signature.)
In the case where the sender is responsible for payment for offramp In the case where the sender is responsible for payment for offramp
services in a remote location, it is desirable {3} to provide for services in a remote location, it is desirable {3} to provide for
authentication of the sender and billing information from the offramp authentication and authorization of the sender, as well as enable
to be negotiated securely. billing related information from the offramp to be transferred
securely.
5.5 Goals for capabilities exchange 5.5 Goals for capabilities exchange
Traditional fax supports a wide range of devices, including high Traditional fax supports a wide range of devices, including high
resolution ("Superfine"); recent enhancements include methods for resolution ("Superfine"); recent enhancements include methods for
color and a variety of compression mechanisms. Fax messaging includes color and a variety of compression mechanisms. Fax messaging includes
the capability for "non-standard frames", which allow vendors to the capability for "non-standard frames", which allow vendors to
introduce proprietary data formats. In addition, facsimile supports introduce proprietary data formats. In addition, facsimile supports
"binary file transfer": a method of sending arbitrary binary data in a "binary file transfer": a method of sending arbitrary binary data in a
fax message. fax message.
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Larry Masinter Larry Masinter
Xerox Corporation Xerox Corporation
3333 Coyote Hill Road 3333 Coyote Hill Road
Palo Alto, CA 94304 Palo Alto, CA 94304
masinter@parc.xerox.com masinter@parc.xerox.com
http://www.parc.xerox.com/masinter http://www.parc.xerox.com/masinter
Fax: (650) 812-4333 Fax: (650) 812-4333
10. References 10. References
[T.30] ITU-T (CCITT), "Procedures for Document Facsimile Transmission [T.30] "Procedures for Document Facsimile Transmission in the General
in the General Switched Telephone Network", ITU-T (CCITT), Switched Telephone Network", ITU-T (CCITT), Recommendation
Recommendation T.30, July, 1996. T.30, July, 1996.
[RFC2298] R. Fajman, "An Extensible Message Format for Message Disposition [F.185] "Internet facsimile: Guidelines for the support of the
Notifications", RFC 2298, March 1998. communication of facsimile documents", ITU-T (CCITT),
Recommendation F.185, 1998.
[RFC1123] R. Braden, "Requirements for Internet hosts - application [T.37] "Procedures for the transfer of facsimile data via
pand support", RFC 1123, October 1989. store-and-forward on the Internet", ITU-T (CCITT),
Recommendation T.37, 1998.
[T.38] "Procedures for real time Group 3 facsimile communication
between terminals using IP Networks", ITU-T (CCITT),
Recommendation T.38, 1998.
[RFC2305] K. Toyoda, H.Ohno, J.Murai, D.Wing, "A Simple Mode of
Facsimile Using Internet Mail", RFC 2305, March 1998.
[RFC2298] R. Fajman, "An Extensible Message Format for Message
Disposition Notifications", RFC 2298, March 1998.
[RFC1123] R. Braden, "Requirements for Internet hosts - Application
and Support", RFC 1123, October 1989.
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