📄 rfc2204.txt
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Network Working Group D. Nash
Request for Comments: 2204 ODETTE
Category: Informational September 1997
ODETTE File Transfer Protocol
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Abstract
This memo describes a file transfer protocol to facilitate electronic
data interchange between trading partners.
The protocol, denoted the ODETTE File Transfer Protocol, supports
both direct communication between installations and indirect
communication via a third party clearing centre. It was developed by
the Organisation for Data Exchange by Tele Transmission in Europe to
facilitate communication within the European motor industry and is
presented here to allow for wider use within the Internet community.
Table of Contents
1. Introduction 3
1.1 - Background 3
1.2 - Relationship to the original ODETTE Standard 3
1.3 - General Principles 3
1.4 - Structure 4
1.5 - Virtual Files 4
1.6 - Service Description 7
2. Network Service (TCP Transport Service) 7
2.1 - Introduction 7
2.2 - Service Primitives 7
2.3 - Port Assignment 9
3. File Transfer Service 9
3.1 - Model 10
3.2 - Session Setup 11
3.3 - File Transfer 13
3.4 - Session Take Down 16
3.5 - Service State Automata 19
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RFC 2204 ODETTE File Transfer Protocol September 1997
4. Protocol Specification 22
4.1 - Overview 22
4.2 - Start Session Phase 22
4.3 - Start File Phase 23
4.4 - Data Transfer Phase 26
4.5 - End File Phase 27
4.6 - End Session Phase 27
4.7 - Problem Handling 28
5. Commands and Formats 28
5.1 - Conventions 28
5.2 - Commands 29
5.3 - Command Formats 29
5.4 - Identification Code 45
6. ODETTE-FTP Data Exchange Buffer 46
6.1 - Overview 46
6.2 - Data Exchange Buffer Format 46
6.3 - Buffer Filling Rules 47
7. Stream Transmission Buffer (TCP only) 47
7.1 - Introduction 47
7.2 - Stream Transmission Header Format 49
8. Protocol State Machine 50
8.1 - ODETTE-FTP State Machine 50
8.2 - Error Handling 50
8.3 - States 51
8.4 - Input Events 53
8.5 - Output Events 54
8.6 - Local Variables 55
8.7 - Local Constants 55
8.8 - Session Connection State Table 56
8.9 - Error and Abort State Table 58
8.10 - Speaker State Table 1 59
8.11 - Speaker State Table 2 63
8.12 - Listener State Table 65
8.13 - Example 68
9. Security Considerations 68
Appendix A Virtual File Mapping Example 69
Appendix B ISO 646 Character Subset 72
Acknowledgements 73
References 73
ODETTE Address 74
Author's Address 74
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RFC 2204 ODETTE File Transfer Protocol September 1997
1. Introduction
1.1 Background
The ODETTE File Transfer Protocol (ODETTE-FTP) was defined in 1986 by
working group four of the Organisation for Data Exchange by Tele
Transmission in Europe (ODETTE) to address the electronic data
interchange (EDI) requirements of the European automotive industry.
It was designed in the spirit of the Open System Interconnection
(OSI) model utilising the Network Service provided by the CCITT X25
recommendation.
Over the last ten years ODETTE-FTP has been widely deployed on
systems of all sizes from personal computers to large mainframes. As
a result of the wide scale deployment of internet technology and the
trend towards global business practices, ODETTE has decided to extend
the scope of it's file transfer protocol to allow the use of TCP/IP
and to make the protocol available to the Internet community.
This memo describes the ODETTE-FTP protocol using the Transmission
Control Protocol for it's network service.
1.2 Relationship to the original ODETTE Standard
This memo is an interpretation of version 1.3 of the ODETTE File
Transfer Protocol [OFTP]. In the event of any ambiguity between this
document and the original ODETTE-FTP, the original shall take
precedence.
For ODETTE-FTP on TCP/IP the following sections have been added with
respect to the original document.
Section 2 - Network Service
Section 7 - Stream Transmission Buffer
Appendix A - Virtual File mapping example
1.3 General Principles
The aim of the ODETTE-FTP is to facilitate the transmission of a file
between one or more locations in a way that is independent of the
data communication network, system hardware and software environment.
In designing and specifying the protocol, the following factors were
considered.
1. The possible differences of size and sophistication (file storage,
small and large systems).
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RFC 2204 ODETTE File Transfer Protocol September 1997
2. The necessity to work with existing systems (reduce changes to
existing products and allow easy implementation).
3. Systems of different ages.
4. Systems of different manufactures.
5. The potential for growth in sophistication (limit impact and avoid
changes at other locations).
1.4 Structure
ODETTE-FTP is modelled on the OSI reference model. It is designed to
use the Network Service provided by level 3 of the model and provide
a File Service to the users. Thus the protocol spans levels 4 to 7
of model.
The description of the ODETTE-FTP contained in this memo is closely
related to the original 'X.25' specification of the protocol and in
the spirit of the OSI model describes:
1. A File Service provided to a user monitor.
2. A protocol for the exchange of information between peer
ODETTE-FTP entities.
A major consideration in adapting the protocol to use the
Transmission Control Protocol (TCP) was the desire to make no changes
to the existing protocol by adding the functionality required to
allow implementors to support internet communication with only minor
changes to existing ODETTE-FTP engines. To this end an additional
header has been added to the start of each exchange buffer to allow
the TCP byte stream to be broken up into the discrete exchange
buffers expected by the ODETTE-FTP protocol.
1.5 Virtual Files
Information is always exchanged between ODETTE-FTP entities in a
standard representation called a Virtual File. This allows data
transfer without regard for the nature of the communicating systems.
The mapping of a file between a local and virtual representation will
vary from system to system and is not defined here.
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RFC 2204 ODETTE File Transfer Protocol September 1997
o---------o
Site | Local |
A | File A |
o---------o
|
o----------------------- Mapping A ------------------------o
| | |
| o---------o |
| | Virtual | |
| | File | |
| o---------o |
| o------------------------------------------------o |
| | | |
| | ODETTE-FTP | |
| | | |
| o------------------------------------------------o |
| o---------o o---------o |
| | Virtual | | Virtual | |
| | File | | File | |
| o---------o o----+----o |
| | | |
o------ Mapping B ------------------------ Mapping C ------o
| |
o---------o o----+----o
| Local | Site Site | Local |
| File B | B C | File C |
o---------o o---------o
A Virtual File is described by a set of attributes identifying and
defining the data to be transferred. The main attributes are:
1.5.1 Organisation:
Sequential
Logical records are presented one after another. The ODETTE-FTP
must be aware of the record boundaries.
1.5.2 Identification
Dataset Name
Dataset name of the Virtual File being transfered, assigned by
bilateral agreement.
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RFC 2204 ODETTE File Transfer Protocol September 1997
Time stamp (HHMMSS)
A file qualifier indicating the time the Virtual File was made
available for transmission.
Date stamp (YYMMDD)
A file qualifier indicating the date the Virtual File was made
available for transmission.
The Dataset Name, Date and Time attributes are assigned by a Virtual
File's Originator and are used to uniquely identify the file. They
must not be changed by intermediate locations.
The Date attribute represents the decade and year in a two digit
field. Since the ODETTE-FTP only uses this information to identify a
particular Virtual File it will continue to operate correctly in the
year 2000 and beyond.
The User Monitor may use the Virtual File Date attribute in local
processes involving date comparisons and calculations. Any such use
falls outside the scope of this protocol and year 2000 handling is a
local implementation issue.
1.5.3 Record Format
Four record formats are defined.
Fixed (F)
Each record in the file has the same length.
Variable (V)
The records in the file can have different lengths.
Unstructured (U)
The file contains a stream of data. No structure is defined.
Text File (T)
A Text File is defined as a sequence of ASCII characters,
containing no control characters except CR/LF which delimits
lines. A line will not have more than 2048 characters.
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RFC 2204 ODETTE File Transfer Protocol September 1997
1.5.4 Restart
ODETTE-FTP can negotiate the restart of an interrupted Virtual File
transmission. Fixed and Variable format files are restarted on
record boundaries. For Unstructured and Text files the restart
position is expressed as a file offset in 1K (1024 octet) blocks.
The restart position is always calculated relative to the Virtual
File.
1.6 Service Description
ODETTE-FTP provides a file transfer service to a user monitor and in
turn uses the Internet transport layer stream service to communicate
between peers.
These services are specified in this memo using service primitives
grouped into four classes as follows:
Request (RQ) An entity asks the service to do some work.
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