GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc767

RFC:767

                                  
                                  
                                  
                                  
                                  
                                  
   A STRUCTURED FORMAT FOR TRANSMISSION OF MULTI-MEDIA DOCUMENTS
                                  
                                  
                                  
                         Jonathan B. Postel
                            August 1980
                                  
                                  
                                  
                                  
                   Information Sciences Institute
                 University of Southern California
                         4676 Admiralty Way
                 Marina del Rey, California  90291
                           (213) 822-1511

< INC-PROJECT, MMMSFS.NLS.21, >, 5-Sep-80 20:19 JBP ;;;;

                                                                Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                         TABLE OF CONTENTS
  PREFACE ........................................................ iii

1. INTRODUCTION …………………………………………….. 1

1.1.  Motivation ................................................... 1
1.2.  Scope ........................................................ 1
1.3.  Terminology .................................................. 1
1.4.  Document Description ......................................... 2
1.5.  Other Work ................................................... 2

2. SPECIFICATION ……………………………………………. 3

2.1.  Document ..................................................... 3
2.2.  Message Objects  ............................................. 5
2.3.  Body Structures ............................................. 13
2.3.1.  Simple Elements ........................................... 13
2.3.2.  Structured Text ........................................... 13
2.3.3.  NLS File Example .......................................... 13
2.3.4.  Multimedia Structures ..................................... 15
2.3.5.  The Media ................................................. 21
2.3.6.  TEXT ...................................................... 22
2.3.7.  VOICE ..................................................... 22
2.3.8.  FACSIMILE ................................................. 23
2.3.9.  GRAPHICS .................................................. 24

3. EXAMPLES & SCENARIOS …………………………………….. 25

Example 1:  Text Example .......................................... 25
Example 2:  Multimedia Example .................................... 28

REFERENCES …………………………………………………. 31

Postel [Page i]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents

[Page ii] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                              PREFACE

This is the first edition of this format specification and should be treated as a request for comments, advice, and suggestions. A great deal of prior work has been done on computer aided message systems and some of this is listed in the reference section. This specification was shaped by many discussions with members of the ARPA research community, and others interested in the development of computer aided message systems. This document was prepared as part of the ARPA sponsored Internetwork Concepts Research Project at ISI.

                                                            Jon Postel

Postel [Page iii]

August 1980

         A Structured Format for Transmission of Multi-Media Documents

Postel [Page iv]

RFC: 767 J. Postel

                                                               USC-ISI
                                                           August 1980
   A STRUCTURED FORMAT FOR TRANSMISSION OF MULTI-MEDIA DOCUMENTS
                          1.  INTRODUCTION

This document describes a format for transmitting structured data representations of multimedia documents. This format is intended to be used with the Internet Message Protocol in an internetwork message delivery system. That system is designed to transmit messages between processes in host computers called Message Processing Modules (MPMs). MPMs are located in several networks and together constitute an internetwork message delivery system. The Internet Message Protocol defines a message as being composed of an Identification, a Command, and a Document. This report is intended to define the format of such Documents. The reader is assumed to be familiar with the Internet Message Protocol [1].

1.1. Motivation

Computer applications are being implemented which interact with users
in a variety of media (text, graphics, facsimile, speech).  As
computer devices become available to process multimedia information it
becomes desirable to use computers to exchange multimedia information
between programs and users via various mechanisms including computer
mail.

1.2. Scope

This format is intended to be used for the transmission of multimedia
documents in the internetwork message delivery system, but it is
thought that it has a wider applicability.

1.3. Terminology

The messages are routed by a process called the Message Processing
Module or MPM.  Messages are created and consumed by User Interface
Programs (UIPs) in conjunction with users.
The basic unit transferred between MPMs is called a message.  A
message is made up of a transaction identifier (which uniquely
identifies the message), a command (which contains the necessary
information for delivery), and document.  The document is a data
structure.
For a personal letter the document body corresponds to the contents of

Postel [Page 1]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents Introduction

the letter; the document header corresponds to the date line,
greeting, and signature.
For an inter-office memo the document body corresponds to the text;
the document header corresponds to the header of the memo.
The commands correspond to the information used by the Post Office or
the mail room to route the letter or memo.  Some of the information in
the command is supplied by the UIP.

1.4. Document Description

The document is composed of fields.  Each field will carry an
identifying name.  Typical fields are DATE, TO, SUBJECT, and BODY.
Most of the fields will be very simple, some will be complex.  The
body field may be quite complex.  For example, the DATE is a very
constrained character string specifying the date and time in ISO
format. A more complex example is the TO field which is a list of
mailboxes, where a mailbox is itself a property list of address
information items.  The BODY may be simply a character string, or a
very structured collection of data representing information in
different media.
The BODY may be structured to indicate a controlled presentation of
multimedia information.  There is provision for the inclusion of text,
graphics, facsimile, and voice information in the body of documents.
The presentation of information units may sequential, independent, or
simultaneous.

1.5. Other Work

This protocol the benefited from the earlier work on message protocols
in the ARPA Network [2,3,4,5,6], and the ideas of others about the
design of computer message systems [7,8,9,10,11,12,13,14,15,16,17,18].

[Page 2] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                         2.  SPECIFICATION

The structured format of a document is built on the basic data elements used in the Internet Message Protocol [1].

2.1. Document

The document is a property list of <name,value> pairs called fields.
A few fields are specifically required and many are optional.  Some of
the field values are simple and a few are quite complicated.  In
particular the body value may be highly structured.
Older message systems have considered the document to be divided into
a header and a body, and have used keywords to indicate specific
header fields (e.g., date, to, subject).  Roughly speaking, this
functionality is provided in this new structured format by considering
the name part of the <name,value> pair to be a keyword.  In addition,
this new structured format eliminates the separate treatment of the
body.
It is impossible to foresee the many forms documents will take so the
standard for a document header must be flexible.  The approach here is
to define a set of basic fields and allow addition of whatever fields
are necessary.  Features added in this fashion may not be understood
by others.
The minimum document is a property list of the following fields:
  Name     Value
  ----     -----
  DATE     date string (name)
  SENDER   a mailbox
  SUBJECT  subject string (text)
  BODY     a data structure
A typical document is a property list containing the following fields:
  Name     Value
  ----     -----
  DATE     date string (name)
  SENDER   a mailbox
  FROM     list of mailboxes
  TO       list of mailboxes
  CC       list of mailboxes
  SUBJECT  subject string (text)
  BODY     a data structure

Postel [Page 3]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents Specification

An elaborate document might contain the following fields:
  Name        Value
  ----        -----
  DATE        date string (name)
  SENDER      a mailbox
  FROM        list of mailboxes
  TO          list of mailboxes
  CC          list of mailboxes
  BCC         list of mailboxes
  REPLY-TO    list of mailboxes
  SUBJECT     subject string (text)
  COMMENTS    comment string (text)
  MESSAGE-ID  message identifier of this message (text)
  IN-REPLY-TO message identifier of previous message (text)
  REFERENCES  message identifiers of other messages (text)
  KEYWORDS    key terms used in this message (text)
  BODY        a data structure
One of the key objects is the mailbox.  It appears in the sender,
from, to, cc, bcc, and reply-to fields.  The mailbox is a property
list of objects that combine to specify a destination recipient for a
message.  Most of the <name,value> pairs that make up a mailbox are
identical to those used in the deliver command in the Internet Message
Protocol [1].  A few additional <name,value> pairs are defined for use
in a mailbox in the document context.  In particular, there is a field
for the real name of a person in contrast to the "user name" which
identifies a computer account.
In addition there is a field to specify a distribution group name.
Such group names are used to indicate that a document is being sent to
a group of recipients.  This essentially presents an alternate form
for a mailbox which consists of the single <name,value> pair for the
group name.  There is no required relationship between a group name
mailbox and other mailboxes in the same list.
For example, all of the following situations are allowed:
  .  a mailbox list consisting of a single mailbox specifying a
     particular user,
  .  a mailbox list consisting of a single mailbox with a group name,
  .  a mailbox list consisting of a mailbox with a group name and a
     mailbox specifying a particular user, with either the user in or
     not in the group,
  .  a mailbox list consisting of a mailbox with a group name and a

[Page 4] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                                                         Specification
     several mailboxes specifying a particular users, with some users
     in the group and some not,
  .  a mailbox list consisting of several mailboxes specifying group
     names and a several mailboxes specifying a particular users, with
     some users in the groups and some not.

2.2. Message Objects

In the documents of messages, we use a set of objects such as mailbox
or date.  These objects are encoded in basic data elements.  Some
objects are simple things like integers or character strings, other
objects are more complex things like lists or property lists.  The
following is a list of the objects used in messages.  The object
descriptions are in alphabetical order.
Account
  The account information.  Represented by a name element.
Address
  Address is intended to contain the minimum information necessary to
  identify a user, and no more (compare with mailbox).
  An address is a property list which contains the following
  <name,value> pairs:
    name    description
    ----    -----------
    NET     network name
    HOST    host name
    USER    user name
  or:
    name    description
    ----    -----------
    MPM     mpm-identifier
    USER    user name
Answer
  A yes (true) or no (false) answer to a question.  Represented by a
  boolean element.

Postel [Page 5]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents Specification

BCC
  A list of mailboxes.  The addresses of those who receive "blind
  carbon copies" of the message.
Body
  A data structure.  This may be as simple as a character string
  (represented by a name or text element), or complex structure of
  lists.  It may be encrypted in part or in whole.  Section 3.3
  describes some possible structured bodies.
C
  A character.  Represented by a name element.
CC
  A list of mailboxes.  When copies of a message are sent to others in
  addition to the addresses in the To object, those to whom the copies
  are sent will have their addresses recorded here.
City
  A city.  Represented by a name element.
Comments
  A comment string.  Represented by a text element.
Count
  A count of items of some sort.  Represented by a integer element.
Country
  A country.  Represented by a name element.

[Page 6] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                                                         Specification
Date
  The date and time are represented according to the International
  Standards Organization (ISO) recommendations [19,20,21].  Taken
  together the ISO recommendations 2014, 3307, and 4031 result in the
  following representation of the date and time:
    yyyy-mm-dd-hh:mm:ss,fff+hh:mm
  Where yyyy is the four-digit year, mm is the two-digit month, dd is
  the two-digit day, hh is the two-digit hour in 24 hour time, mm is
  the two-digit minute, ss is the two-digit second, and fff is the
  decimal fraction of the second.  To this basic date and time is
  appended the offset from Greenwich as plus or minus hh hours and mm
  minutes.
  The time is local time and the offset is the difference between
  local time and Coordinated Universal Time (UTC).  To convert from
  local time to UTC algebraically subtract the offset from the local
  time.
  For example, when the time in
            Los Angeles is  14:25:00-08:00
            the UTC is      22:25:00
  or when the time in
            Paris is        11:43:00+01:00
            the UTC is      10:43:00
Device
  A device name.  Represented by a name element.
Document
  A property list of fields.
Distribution Group
  An distribution group is a property list which contains the
  following <name,value> pair:
    name    description
    ----    -----------
    GROUP   document distribution group name
  This construct is used so that a distribution group will be a
  special case of a mailbox.

Postel [Page 7]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents Specification

Facsimile Structure
  A facsimile data structure.  Represented by a property list.
File
  A file name.  Represented by a name element.
Format
  A format indicator.  Represented by a name element.
From
  A list of mailboxes.  The From is the name of the author of a
  document.
Graphics Structure
  A graphics data structure.  Represented by a property list.
Group
  A document distribution group name.  Represented by a name element.
Host
  A host name.  Represented by a name element.
Ident
  The identifier of a person, usually their initials.  Represented by
  a name element.
In-Reply-To
  The message identifier of previous message.  Represented by a text
  element.
Internet Address
  This identifies a host in the ARPA internetwork environment.  The
  internet address is a 32 bit number, the higher order 8 bits
  identify the network, and the lower order 24 bits identify the host
  on that network [22].  For use in this format the internet address
  is divided into eight bit fields and the value of each field is
  represented in decimal digits.  For example, the ARPANET address of
  ISIE is 167837748 and is represented as 10,1,0,52.  Further, this

[Page 8] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                                                         Specification
  representation may be extended to include an address within a host,
  such as the TCP port of an MPM, for example, 10,1,0,52,0,45.
Keywords
  The key terms used in this message.  Represented by a text element.
Mailbox
  This is the destination address of a user of the internetwork mail
  system.  Mailbox contains information such as network, host,
  location, and local user identifier of the recipient of the message.
  The mailbox may contain information in addition to the minimum
  required for delivery.
  As an example, when one sends a message to someone for the first
  time, he may include many items to aid in identifying the correct
  recipient.  However, once he gets a reply to this message, the reply
  will contain an Address (as opposed to Mailbox) which may be used
  from then on.
    A mailbox is a property list.  A mailbox might contain the
    following <name,value> pairs:
      name    description
      ----    -----------
      MPM     mpm-identifier
      NET     network name
      HOST    host name
      PORT    address of MPM within the host
      USER    user name (computer account name)
      PERSON  the real name of a person
      GROUP   document distribution group
      ORG     organization name
      CITY    city
      STATE   state
      COUNTRY country
      ZIP     zip code
      PHONE   phone number
  The minimum mail box is an Address or a Distribution Group.
Message-ID
  The message identifier of this message.  This is not related to the
  MPM message identification, but is a UIP long term document
  identifier.  Represented by a text element.

Postel [Page 9]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents Specification

MPM-Identifier
  The internetwork address of an MPM.  This may be the ARPA Internet
  Address or an X.121 Public Data Network Address [23].  The
  mpm-identifier is a property list which has one <name,value> pair.
  This unusual structure is used so that it will be easy to determine
  the type of address used.
Net
  A network name.  Represented by a name element.
NLS Block
  The information in an NLS node.  Represented by a property list.
NLS Node
  An NLS block and substructure.  Represented by a property list.
NLS Substructure
  A list of NLS nodes.  Represented by a list.
Org
  An organization name.  Represented by a name element.
Paragraph
  A paragraph of text.  Represented by a text element.
Parcel
  The basic unit of voice data.  Represented by a bitstr element.
Person
  The real name of a person.  Represented by a name element.
Password
  A password.  Represented by a name element.
Phone
  A phone number.  Represented by a name element.

[Page 10] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                                                         Specification
Pointer
  A pointer to information stored outside this data structure.  A
  property list containing the information necessary to locate the
  external data, the information necessary to gain access to the
  external data, and the information necessary to apply the correct
  interpretation to the external data.  For example, this might
  include:
    name       description
    ----       -----------
    NET        network name
    HOST       host name
    FILE       file name
    USER       user name (computer account name)
    PASSWORD   password
    ACCOUNT    account
    FORMAT     format
Port
  The address of MPM within the host.  Represented by a name element.
Presentation Descriptor
  A property list of <name,value> pairs, where the name is an order
  indicator, and the value is a presentation element.  The order
  indicators are SEQUENTIAL, SIMULTANEOUS, and INDEPENDENT.
Presentation Element
  A property list of media structures.
Protocol
  The name of the coding scheme used for a medium.  Represented by a
  name element.
References
  The message identifiers of other messages.  Represented by a list of
  text elements.
Reply-To
  A list of mailboxes.  Sometimes it will be desired to direct the
  replies of a message to some address other than the from or the
  sender.  In such a case the reply-to object can be used.

Postel [Page 11]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents Specification

R 450 Block
  The unit of Rapicom 450 data (585 bits).  Represented by a bitstr
  element.
Sender
  A mailbox.  The sender will contain the address of the individual
  who sent the message.  In some cases this is NOT the same as the
  author of the message.  Under such a condition, the author should be
  specified in the from object.
SID
  An NLS statement indetifier.  Represented by a integer element.
State
  A state name.  Represented by a name element.
Subject
  The subject of the message.  Represented by a text element.
Text Structure
  A text data structure.  Represented by a property list.
To
  A list of mailboxes.  To identifies the addressees of the message.
User
  A user name (computer account name).  Represented by a name element.
Version
  A version number.  Represented by a index element.
Vocoder
  A vocoder name.  Represented by a name element.
Voice Structure
  A voice data structure.  Represented by a property list.

[Page 12] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                                                         Specification
X121 Address
  This identifies a host in the Public Data Network environment.  When
  used as a part of identifier, it identifies the originating host of
  a message.  The X121 address is a sequence of up to 14 digits [23].
  For use in this format the X121 address is represented in decimal
  digits.
ZIP
  A zip code.  Represented by a name element.

2.3. Body Structures

2.3.1.  Simple Elements
  The body could simply be a single data element.  For example a
  single text element can represent a lengthy character string.
    <body> := TEXT
    or
    text:"this is the actual text of the body"
2.3.2.  Structured Text
  The body could be thought of as paragraphs, where each paragraph is
  represented by a text element.  The paragraphs are then the elements
  of a list.
    <body> := LIST (<paragraph>, <paragraph>, ...)
      <paragraph> := TEXT
    or
    list:(text:"paragraph one", text:"paragraph two", ...)
2.3.3.  NLS File Example
  It is possible to represent the data from NLS files in this format.
  NLS is a large multipurpose system which operates on structured data
  files.  The files are tree structured, and there is data associated
  with each node of the tree.  There are several fields associated
  with each node as well.

Postel [Page 13]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents Specification

  An NLS file is:
    proplist(                                                     file
      name:"FILENAME", name:<file>                        name of file
      name:"CREATION-DATE", name:<date>         creation date and time
      name:"VERSION", index:<version>              file version number
      name:"SID-COUNT", integer<count>               current SID count
      name:"LAST-WRITER", name:<ident>             last writer of file
      name:"OWNER", name:<ident>                         owner of file
      name:"LAST-WRITE-TIME", name:<date>     last write date and time
      name:"LEFT-NAME-DELIM-DEFAULT", name:<c>            default name
      name:"RIGHT-NAME-DELIM-DEFAULT", name:<c>             delimiters
      name:"SUBSTRUCTURE", <nls-substructure>             substructure
    )endlist
  An NLS substructure is:
    list:(                                                substructure
      <nls-node>                                 node is defined below
        .
        .
        .
    )endlist
  An NLS node is:
    proplist:(                                                    node
      name:"BLOCK", <nls-block>                    block defined below
      name:"SUBSTRUCTURE", <nls-substructure>             substructure
    )endlist
  An NLS block is:
    proplist:(                                                   block
      name:"LEFT-NAME-DELIM", name:<c>             left name delimiter
      name:"RIGHT-NAME-DELIM", name:<c>           right name delimiter
      name:"SID", integer:<sid>                             SID number
      name:"CREATOR", name:<ident>                   statement creator
      name:"CREATION-TIME", name:<date>         creation date and time
      name:"DATA", <data>                           data defined below
    )endlist

[Page 14] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                                                         Specification
  NLS data is:
    proplist:(                                                    data
      name:"<a data name>", <type depends on data name>
                  .           .
                  .           .
                  .           .
    )endlist
  For text, data is:
    proplist:(                                                    data
      name:"TEXT", text:"text of statement"                       text
    )endlist
2.3.4.  Multimedia Structures
  One can conceive of graphical information being displayed along with
  a running commentary, much as seminars use slides.  A slide and its
  description are tied together.  The coordination of such a
  presentation is central to its understanding.  This synchronization
  should be captured within the document structure.
  There are three fundamentally different types of time ordered
  control which are needed within the document structure.  These are:
    Simultaneous
    Sequential
    Independent
  Simultaneous data is intended for synchronous presentation.  The
  implication is that this data is presented in parallel.
  Sequential data items will be presented one at a time, in the order
  listed.  The ordering is strictly left to right.
  Independent data can be presented in any time order.  It is not
  ordered in any manner.
  The data is broken into small information units called presentation
  elements or PEs.  The PEs can be combined in structures to control
  the presentation order.  A PE is a property list of elements
  representing information of various media.  For example:
    <pe> := proplist(
              name:"VOICE", <voice-structure>,
              name:"GRAPHICS", <graphics-structure>
            )endlist

Postel [Page 15]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents Specification

  PEs are combined into larger controled presentations by
  presentation-descriptors or PDs.  A PD is a property list which
  specifies the type of time ordering of the PEs in its list.
    <pd> := <<seq>> | <<sim>> | <<ind>>
    <<seq>> := name:"SEQUENTIAL", <pe>
    <<sim>> := name:"SIMULTANEOUS", <pe>
    <<ind>> := name:"INDEPENDENT", <pe>
  A PE is a property list of the media <name,value> pairs, or PDs.
    <pe> := <<text>> | <<voice>> | <<facsimile>>
          | <<graphics>> | <pd>
    <<text>> := name:"TEXT", <text structure>
    <<voice>> := name:"VOICE", <voice structure>
    <<facsimile>> := name:"FACSIMILE", <facsimile structure>
    <<graphics>> := name:"GRAPHICS", <graphics structure>
  If more than one <name,value> pair is present within a PE the media
  are presented on different output devices in the order specified by
  the PE's parent PD.  The order of appearance within the proplist is
  important only in the event that the parent PD specified sequential
  ordering.
  The structure of multimedia messages which use this scheme will be
  demonstrated by a few simple examples chosen to illustrate a basic
  text document and the different ordering options.  The last example
  will suggest some more exotic uses.

[Page 16] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                                                         Specification
  Plain Text Message
    A simple text body could be represented in a single text data
    structure.  To give the simplest example of a structured body we
    show a simple text body represented in the multimedia structure.
      <body> := <pd>
        <pd> := <<seq>>
          <<seq>> :=  name:"SEQUENTIAL", <pe>
            <pe> := name:"TEXT", <text structure>
      or
      proplist: (name:"SEQUENTIAL",
                proplist:(
                  name:"TEXT", <text structure>
                )endlist
      )endlist
  Simultaneous Ordering
    This ordering option is used to indicate when separate streams are
    to be presented in parallel.  For example, assume GRAPHICS and
    VOICE data were to be presented using simultaneously.
      <body> := <pd>
        <pd> := <<sim>>
          <<sim>> :=  name:"SIMULTANEOUS", <pe>
            <pe> := name:"VOICE", <voice structure>
                    name:"GRAPHICS", <graphics structure>
      or
      proplist:(
        name:"SIMULTANEOUS",
          proplist:(
            name:"VOICE", <voice structure>
            name:"GRAPHICS", <graphics structure>
          )endlist
      )endlist

Postel [Page 17]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents Specification

  Sequential Ordering
    This option is used to indicate sequential time ordering.  The
    media in the sub-tree below this PD are not separate streams.
    Using again the example above, assume GRAPHICS and VOICE data were
    to be presented using sequential ordering.
      <body> := <pd>
        <pd> := <<seq>>
          <<seq>> :=  name:"SEQUENTIAL", <pe>
            <pe> := name:"VOICE", <voice structure>
                    name:"GRAPHICS", <graphics structure>
      or
      proplist:(
        name:"SEQUENTIAL",
          proplist:(
            name:"VOICE", <voice structure>
            name:"GRAPHICS", <graphics structure>
          )endlist
      )endlist
  Independent Ordering
    It is apparent that some output devices are very slow in
    comparison to others.  An example which demonstrates this is
    facsimile.  The majority of facsimile devices are slow.  A
    detailed picture transmitted at 9600 baud takes minutes to print.
    It is inconvenient for the user to wait on such a device when the
    voice or text information which accompanies it is short.
    For example, if the document a facsimile image and the text
    "Hello Frank, here's a copy of that picture you requested."  The
    user need not wait for the picture.  The facsimile machine might
    be spooled, in which case he would pick up the picture later.  In
    a sense the picture was time independent of the text.

[Page 18] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                                                         Specification
      <body> := <pd>
        <pd> := <<ind>>
          <<ind>> :=  name:"INDEPENDENT", <pe>
            <pe> := name:"FACSIMILE", <facsimile structure>
                    name:"TEXT", <text structure>
      or
      proplist:(
        name:"INDEPENDENT",
          proplist:(
            name:"FACSIMILE", <facsimile structure>
            name:"TEXT", <text structure>
          )endlist
      )endlist
  A Stream Example
    By making use of the structure and the sequential ordering option
    it is possible to initiate a stream.  The stream will proceed at
    its own pace until concluded.
      <body> := <pd>
        <pd> := <<seq>>
          <<seq>> :=  name:"SEQUENTIAL", <pe>
            <pe> := <pd>
              <pd> := <<sim>>
                <<sim>> :=  name:"SIMULTANEOUS", <pe>
                  <pe> := name:"VOICE", <voice structure>
                          name:"GRAPHICS", <graphics structure>

Postel [Page 19]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents Specification

      or
      proplist:(
        name:"SEQUENTIAL",
          proplist:(
            name:"SIMULTANEOUS",
              proplist:(
                name:"VOICE", <voice structure>
                name:"GRAPHICS", <graphics structure>
              )endlist,
            name:"SIMULTANEOUS",
              proplist:(
                name:"VOICE", <voice structure>
                name:"GRAPHICS", <graphics structure>
              )endlist,
            .
            .
            .
          )endlist
      )endlist
    Such a document structure suggests a slide presentation.
  Multiple Active Stream Example
    This example is exotic but illustrates what is possible. By making
    use of the structure and the simultaneous ordering it is possible
    to start in parallel two or more separate streams. Each stream
    will proceed at its own pace until all are concluded.
      <body> := <pd>
        <pd> := name:"SIMULTANEOUS", <pe>
          <pe> = <pd>
            <pd> := name:"SEQUENTIAL", <pe>
              <pe> = <pd>
                <pd> := name:"SIMULTANEOUS", <pe>
                  <pe> := name:"VOICE",
                                                     <voice structure>
                          name:"GRAPHICS",
                                                  <graphics structure>

[Page 20] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                                                         Specification
      or
      proplist:(
       name:"SIMULTANEOUS",
         proplist:(
           name:"SEQUENTIAL",
             proplist:(
               name:"SIMULTANEOUS",
                 proplist:(
                   name:"VOICE", <voice structure>
                   name:"GRAPHICS", <graphics structure>
                 )endlist,
               name:"SIMULTANEOUS",
                  proplist:(
                    name:"VOICE", <voice structure>
                    name:"GRAPHICS", <graphics structure>
                  )endlist,
               .
               .
               .
             )endlist
           name:"SEQUENTIAL",
             proplist:(
               name:"SIMULTANEOUS",
                 proplist:(
                   name:"VOICE", <voice structure>
                   name:"GRAPHICS", <graphics structure>
                 )endlist,
               .
               .
               .
             )endlist
         )endlist
      )endlist
2.3.5.  The Media
  So far no explicit description has been given for the media classes
  which fit into a PE.  It is not known what types of media will be
  supported in the various document stations in the future. Those for
  which support is in part already available are:
    TEXT
    VOICE
    FACSIMILE
    GRAPHICS
  Standard formats for data in each of these media must be defined.

Postel [Page 21]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents Specification

2.3.6.  TEXT
  The text data may be structured according to a variety of protocols
  (yet to be defined).  The top level of the data structure is a
  property list which identifies the protocol, and the version of that
  protocol.
    name:"TEXT", proplist:(
                    name:"PROTOCOL", <protocol>,
                    name:"VERSION", <version>,
                    name:"DATA", <data>
                  )endlist
  The first protocol is called PARAGRAPH, and the data is a list of
  paragraphs, where each paragraph is a text element.
    name:"DATA", list:(
                   text: <paragraph>
                   text: <paragraph>
                   .
                   .
                   .
                 )endlist
2.3.7.  VOICE
  Since a good deal of research has been done towards implementing the
  transmission of voice data on the ARPANET, the Network Voice
  Protocol (NVP) provides the basis for the standard for voice data
  [24].
  Voice data a property list which specifies the vocoder being used,
  the transmission protocol and the parcel data.  The parcel data form
  is specific to the protocol used and is grouped in lists.
    name:"VOICE", proplist:(
                    name:"VOCODER", <vocoder>,
                    name:"PROTOCOL", <protocol>,
                    name:"VERSION", <version>,
                    name:"DATA", <data>
                  )endlist
  The NVP protocol has a number of parameters, the version number
  specifies a certain set of the parameters used by the vocoder
  hardware and software to set up timing and define the type of coding
  used.  It is not expected that within a document the version number
  will change.

[Page 22] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                                                         Specification
  NVP itself supports negotiation of these parameters to insure both
  ends of a network speech connection 'understand' one another.  Since
  no such interactive negotiation is possible in a document system,
  negotiation capabilities have been excluded.  As differing hardware
  becomes available new versions may be defined.
  For the NVP protocol the data list will take the following form:
    name:"DATA", list:(
                   bitstr: <parcel>
                   bitstr: <parcel>
                   .
                   .
                   .
                 )endlist
  The items in the list are parcels.  The individual parcels  are bit
  string data elements whose contents and length are predefined by the
  version number.  The number of parcels in a parcel group is
  available from the item count in the enclosing list header.
2.3.8.  FACSIMILE
  There are a number of facsimile devices in use.  While standards are
  being established by CCITT [25], of the devices available today many
  are incompatible due to proprietary compression algorithms.  The
  description of fax data will allow for the possibility of several
  protocols.
    name:"FACSIMILE", proplist:(
                        name:"DEVICE", <device>,
                        name:"PROTOCOL", <protocol>,
                        name:"DATA", <data>
                      )endlist
  There are few facsimile devices interfaced to computers though, and
  the existing experiments in the ARPANET all use the RAPICOM 450.  A
  first facsimile standard format will be based on the data structure
  used for this machine [26].  That is, for device RAPICOM450 and
  protocol BLOCK, the data will be:
    name:"DATA", list:(
                   bitstr:<r450-block>,
                   bitstr:<r450-block>,
                   .
                   .
                   .
                 )endlist

Postel [Page 23]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents Specification

  Where an r450-block is a 585 bit unit.
2.3.9.  GRAPHICS
  The situation for graphics bears much similarity to facsimile.
  Devices on the market today have a variety of user interfaces and
  options. A similar structure is defined.
    name:"GRAPHICS", proplist:(
                        name:"DEVICE", <device>,
                        name:"PROTOCOL", <protocol>,
                        name:"DATA", <data>
                      )endlist
  There are several candidate protocols for use in describing graphics
  data in documents.  One is the Network Graphics Protocol [27],
  another is the Graphics Language [28,29], and a third is the
  SIGGRAPH Core System [30].

[Page 24] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                      3.  EXAMPLES & SCENARIOS

Example 1: Text Example

Suppose we want to send the following message:
  Date: 1979-03-29-11:46-08:00
  From: Jon Postel <Postel@ISIF>
  Subject: Meeting Thursday
  To: Danny Cohen <Cohen@ISIB>
  CC: Linda
   
  Danny:
   
  Please mark your calendar for our meeting Thursday at 3 pm.
   
  --jon.
It will be encoded in the structured format.  The following will
present successive steps in the top down generation of this message.
The identification and command portions of the messages will not be
expanded here (see [1]).
1.  message
2.  (identification, command, document)
3.  (ID:<<identification>>,
     CMD:<<command>>,
     DOC:( date, from, subject, to, cc, body))
4.  (ID:<<identification>>,
     CMD:<<command>>,
     DOC:(DATE:date,
          FROM:from
          SUBJECT:subject,
          TO:to,
          CC:cc,
          BODY:body))
5.  (ID:<<identification>>,
     CMD:<<command>>,
     DOC:(DATE: 1979-03-29-11:46-08:00,
          FROM: (NET:ARPANET,HOST:ISIF,USER:Postel,PERSON:Jon Postel),
          SUBJECT: Meeting Thursday,
          TO: (NET:ARPANET,HOST:ISIB,USER:Cohen,PERSON:Danny Cohen),
          CC: (NET:ARPANET,HOST:ISIF,USER:Linda),
          BODY:
            Danny:

Postel [Page 25]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents Examples & Scenarios

             
            Please mark your calendar for our meeting
            Thursday at 3 pm.
             
            --jon.))
6.  PROPLIST:
     (ID:<<identification>>,
      CMD:<<command>>,
      DOC:
        PROPLIST:(
          DATE: 1979-03-29-11:46-08:00,
          FROM:
            LIST:(
              PROPLIST:(
                NET:ARPANET,
                HOST:ISIF,
                USER:Postel,
                PERSON:Jon Postel,
              )ENDLIST,
            )ENDLIST,
          SUBJECT: Meeting Thursday,
          TO:
            LIST:(
              PROPLIST:(
                NET:ARPANET,
                HOST:ISIB,
                USER:Cohen,
                PERSON:Danny Cohen,
              )ENDLIST,
            )ENDLIST,
          CC:
            LIST:(
              PROPLIST:(
                NET:ARPANET,
                HOST:ISIF,
                USER:Linda,
              )ENDLIST,
            )ENDLIST,
          BODY:
            Danny:
             
            Please mark your calendar for our meeting
            Thursday at 3 pm.
             
            --jon.
        )ENDLIST
      )ENDLIST

[Page 26] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                                                  Examples & Scenarios
7.  proplist:(
      name:"ID", <<identification>>,
      name:"CMD", <<command>>,
      name:"DOC",
        proplist:(
          name:"DATE", name:"1979-03-29-11:46-08:00",
          name:"FROM",
            list:(
              proplist:(
                name:"NET", name:"ARPANET",
                name:"HOST", name:"ISIF",
                name:"USER", name:"Postel",
                name:"PERSON", name:"Jon Postel",
              )endlist,
            )endlist,
          name:"SUBJECT", text:"Meeting Thursday",
          name:"TO",
            list:(
              proplist:(
                name:"NET", name:"ARPANET",
                name:"HOST", name:"ISIB",
                name:"USER", name:"Cohen",
                name:"PERSON", name:"Danny Cohen",
              )endlist,
            )endlist,
          name:"CC",
            list:(
              proplist:(
                name:"NET", name:"ARPANET",
                name:"HOST", name:"ISIF",
                name:"USER", name:"Linda",
              )endlist,
            )endlist,
          name:"BODY",
            text:"Danny:
                   
                  Please mark your calendar for our
                  meeting Thursday at 3 pm.
                   
                  --jon."
        )endlist
      )endlist

Postel [Page 27]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents Examples & Scenarios

Example 2: Multimedia Example

    proplist:(
      name:"ID", <<identification>>,
      name:"CMD", <<command>>,
      name:"DOC",
        proplist:(
          name:"DATE", name:"1980-08-06-11:46-08:00",
          name:"FROM",
            list:(
              proplist:(
                name:"NET", name:"ARPANET",
                name:"HOST", name:"ISIF",
                name:"USER", name:"Postel",
                name:"PERSON", name:"Jon Postel",
              )endlist,
            )endlist,
          name:"SUBJECT", text:"Multimedia Test Message",
          name:"TO",
            list:(
              proplist:(
                name:"GROUP", name:"Multimedia Experiment List",
              )endlist,
            )endlist,
          name:"CC",
            list:(
              proplist:(
                name:"NET", name:"ARPANET",
                name:"HOST", name:"ISIF",
                name:"USER", name:"Linda",
              )endlist,
            )endlist,
          name:"BODY",
            proplist:(
              name:"SEQUENTIAL",
                proplist:(
                  name:"TEXT",
                    proplist:(
                      name:"PROTOCOL", name:"PARAGRAPH",
                      name:"VERSION", index:"1",
                      name:"DATA",
                        list:(
                          text:"This is a test of multimedia mail."
                          text:"I hope you like it."
                        )endlist
                    )endlist

[Page 28] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                                                  Examples & Scenarios
                  name:"SIMULTANEOUS",
                    proplist:(
                      name:"VOICE",
                        proplist:(
                          name:"VOCODER", name:<vocoder>,
                          name:"PROTOCOL", name:"NVP",
                          name:"VERSION", index:"1",
                          name:"DATA",
                            list:(
                              bitstr:<parcel>
                              bitstr:<parcel>
                            )endlist
                        )endlist
                      name:"GRAPHICS",
                        proplist:(
                          name:"DEVICE", name:<device>,
                          name:"PROTOCOL", name:<protocol>,
                          name:"VERSION", index:<version>,
                          name:"DATA",<data>
                            )endlist
                        )endlist
                    )endlist
              name:"SEQUENTIAL",
                proplist:(
                  name:"TEXT,
                    proplist:(
                      name:"PROTOCOL", name:"PARAGRAPH",
                      name:"VERSION", index:"1",
                      name:"DATA",
                        list:(
                          text:"That was supposed to be some voice
                                and graphics in parallel."
                          text:"--jon."
                        )endlist
                    )endlist
                )endlist
              )endlist
            )endlist
       )endlist

Postel [Page 29]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents

[Page 30] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                             REFERENCES

[1] Postel, J., "Internet Message Protocol," RFC 759, 113,

    USC/Information Sciences Institute, August 1980.

[2] Bhushan, A., K. Pogran, R. Tomlinson, and J. White, "Standardizing

    Network Mail Headers," RFC 561, NIC 18516, September 1973.

[3] Myer, T., and D. Henderson, "Message Transmission Protocol,"

    RFC 680, NIC 32116, 30 April 1975.

[4] Crocker, D., J. Vittal, K. Pogran, and D. Henderson, "Standard for

    the Format of ARPA Network Text Messages," RFC 733, NIC 41952,
    21 November 1977.

[5] Barber, D., and J. Laws, "A Basic Mail Scheme for EIN," INWG 192,

    February 1979.

[6] Braaten, O., "Introduction to a Mail Protocol," Norwegian

    Computing Center, INWG 180, August 1978.

[7] Crocker, D., E. Szurkowski, and D. Farber, "An Internetwork Memo

    Distribution Capability - MMDF," Sixth Data Communications
    Symposium, ACM/IEEE, November 1979.

[8] Haverty, J., D. Henderson, and D. Oestreicher, "Proposed

    Specification of an Inter-site Message Protocol," 8 July 1975.

[9] Thomas, R., "Providing Mail Services for NSW Users," BBN NSW

    Working Note 24, Bolt Beranek and Newman, October 1978.

[10] White, J., "A Proposed Mail Protocol," RFC 524, NIC 17140, SRI

    International, 13 June 1973.

[11] White, J., "Description of a Multi-Host Journal," NIC 23144, SRI

    International, 30 May 1974.

[12] White, J., "Journal Subscription Service," NIC 23143, SRI

    International, 28 May 1974.

[13] Levin, R., and M. Schroeder, "Transport of Electronic Messages

    Through a Network," Teleinformatics 79, Boutmy & Danthine (eds.)
    North Holland Publishing Co., 1979.

[14] Earnest, L., and J. McCarthy, "DIALNET: A Computer Communications

    Study," Computer Science Department, Stanford University, August
    1978.

Postel [Page 31]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents References

[15] Crispin M., "DIALNET: A Telephone Network Data Communications

    Protocol," DECUS Proceedings, Fall 1979.

[16] Caulkins, D., "The Personal Computer Network (PCNET) Project: A

    Status Report," Dr. Dobbs Journal of Computer Calisthenics and
    Orthodontia,  v.5, n.6, June 1980.

[17] Postel, J., "NSW Transaction Protocol (NSWTP)," USC/Information

    Sciences Institute, IEN 38, May 1978.

[18] Haverty, J., "MSDTP – Message Services Data Transmission

    Protocol," RFC 713, NIC 34739, April 1976.

[19] ISO-2014, "Writing of calendar dates in all-numeric form,"

    Recommendation 2014, International Organization for
    Standardization, 1975.

[20] ISO-3307, "Information Interchange – Representations of time of

    the day," Recommendation 3307, International Organization for
    Standardization, 1975.

[21] ISO-4031, "Information Interchange – Representation of local time

    differentials," Recommendation 4031, International Organization
    for Standardization, 1978.

[22] Postel, J., "DOD Standard Internet Protocol," USC/Information

    Sciences Institute, IEN 128, NTIS number AD A079730, January 1980.

[23] CCITT-X.121, "International Numbering Plan for Public Data

    Networks," Recommendation X.121, CCITT, Geneva, 1978.

[24] Cohen, D., "Specifications for the Network Voice Protocol (NVP),"

    NIC 42444, RFC 741, NSC 68, RR-75-39, USC/Information Sciences
    Institute, January 1976.

[25] CCITT-T.30, "Procedures for Document Facsimile Transmission in the

    General Switched Telephone Network," Recommendation T.30, Orange
    Book, V. 7, The International Telephone and Telegraph Consulative
    Committee,  International Telecommunication Union, Geneva, 1977.

[26] Treadwell, S., "FAX File Format," ARPANET Message, 14 November

    1979.

[27] Sproull, R., and E. Thomas, "A Network Graphics Protocol,"

    NIC 24308, Xerox Palo Alto Research Center, August 1974.

[Page 32] Postel

August 1980

         A Structured Format for Transmission of Multi-Media Documents
                                                            References

[28] Bisbey, R., and D. Hollingworth, "A Distributable,

    Display-Device-Independent Vector Graphics System for Command and
    Control," RR-80-87, USC/Information Sciences Institute, July 1980.

[29] Bisbey, R., D. Hollingworth, and B. Britt, "Graphics Language,"

    TM-80-18, USC/Information Sciences Institute, July 1980.

[30] Graphics Standard Planning Committee, "Core System," Computer

    Graphics, V. 13, N. 3, SIGGRAPH, ACM, August 1979.

Postel [Page 33]

                                                           August 1980

A Structured Format for Transmission of Multi-Media Documents

[Page 34] Postel

/data/webs/external/dokuwiki/data/pages/rfc/rfc767.txt · Last modified: 1992/10/15 21:56 by 127.0.0.1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki