Net2/usr/src/contrib/isode/others/X/X-STANDARDS
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Replied: John Dyer <NJIN04@uk.ac.rutherford.gec-b>
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From: John Dyer <NJIN04@uk.ac.rutherford.gec-b>
To: ISO-XWINDOWS@uk.ac.rutherford,
"x3h3.6" <x3h3.6%edu.mit.lcs.expo@uk.ac.nsfnet-relay>
Date: Thu, 23 Nov 89 10:58 GMT
Subject: Proposed Transport Annex to X DSE
Message-Id: <23 NOV 1989 10:58:09 NJIN04@UK.AC.RUTHERFORD.GEC-B>
Here is the revised Appendix to the X Window System DSE. This version is a
re write of the previuos version, but has been changed to accommodate the
use of any Transport Class (ie TP0 through to TP4).
The major changes involve the NON use of user data fields in T-CONNECT
and T-DISCONNECT.
John Dyer
Joint Network Team
--------------------------------------------------------------------------------
DRAFT (v2.0) PROPOSED APPENDIX xx
X Windows Mapping to OSI
This appendix should be treated as an integral part of (the ANSI
standard X3H3.6/yy-nnnn).
This appendix defines the mapping of the X Windows protocol defined
in (the ANSI standard X3H3.6/yy-nnnn) onto the communication
services provided by the Open Systems Interconnection (OSI)
standards. (The OSI reference model is described in ISO 7498). It
shows not only the mappings onto the OSI communication primitives,
but also how the registration and addressing requirements of the X
Windows protocol are handled for OSI.
This appendix consists of two sections, section A.1 for the mapping
of X Windows functions onto OSI service primitives and section A.2
for the X Windows registration requirements.
This appendix references ISO 8072 (Transport Service Definition) and
uses the notation and conventions which are contained in sections 3,
4 and 5 of that document.
A.1 Mapping X Windows Functions to OSI Service primitives
This section specifies the OSI service primitives used to support
the X Windows functions.
The X Windows requirements on the communication mechanism which have
been considered in choosing this OSI service are :
a) the asynchronous nature of the way X Windows uses the
communication mechanism,
b) connection oriented communication,
c) reliable communication service,
d) full duplex communication,
e) process addressing, i.e. ability to select a particular X Windows
server,
f) the supporting OSI functionality that most closely matches that
for which X Windows was written,
g) efficiency,
h) interworking with existing implementations.
These requirements are met using a connection oriented TWS (two way
simultaneous, i.e. full duplex) OSI Transport Layer connection
providing a service direct to client and server.
A.1.1 Transport Connection Establishment and Termination
A.1.1.1 Connection Establishment
| The X Window function OPEN DISPLAY (see Part 1, section 7.6.1 of the
| ANSI standard X3H3.6/yy-nnnn) establishes a connection between the
| client and server. For operation over OSI, the transport service
| connection is made by T-CONNECT, however the X Windows OPEN DISPLAY
| function is not carried in the T-CONNECT User-Data parameter, but in
| the User-Data of the subsequent T-DATA.
The COTS T-CONNECT service is defined in section 12 and the
T-CONNECT parameters are listed in table 5 of ISO 8072.
A.1.1.1.1 COTS T-CONNECT parameters and OPEN DISPLAY
| The T-CONNECT parameter values for support of OPEN DISPLAY are as
| specified in table 1. An explanation of the use of each parameter
| follows the table.
| Table 1 -- T-CONNECT Parameter Values to support OPEN DISPLAY
+-------------------------------------+-----+-----+-----+-----+
| T-CONNECT Parameter Name | Req | Ind | Rsp | Cnf |
| +-------------------------------------+-----+-----+-----+-----+
| | Called Address | X | X(=)| | |
| +-------------------------------------+-----+-----+-----+-----+
| | Calling Address | X | X(=)| | |
| +-------------------------------------+-----+-----+-----+-----+
| | Responding Address | | | X | X(=)|
| +-------------------------------------+-----+-----+-----+-----+
| | Expedited Data Option | N | N | N | N |
| +-------------------------------------+-----+-----+-----+-----+
| | Quality of Service | N | N | N | N |
| +-------------------------------------+-----+-----+-----+-----+
| | User-Data | N | N | N | N |
+-------------------------------------+-----+-----+-----+-----+
| Key: X: Mandatory Parameter
(=): The value of this parameter is indentical to the value
of the corresponding parameter of the preceding primitive.
| N: Not used by X Windows - where the parameter needs a value
| as a mandatory requirement of the transport service it may
| take a default value.
| Addresses: The paramaters which take address values all refer to
| TSAPs. These addresses are unique within the scope of TSAP
| addresses.
Called Address: This mandatory parameter identifies the application
process which is the X Windows server to which the T-CONNECT is
being sent. It conveys the address of the TSAP to which the
transport connection is to be established.
Calling Address: This mandatory parameter identifies the application
process which is the X Windows client. It conveys the address of
the TSAP from which the transport connection has been requested.
Responding Address: This mandatory parameter conveys the address of
the TSAP to which the transport connection has been established
and is identical to the Called Address parameter.
Expedited Data Option: X Windows deals with all communication
requests serially and does not have the notion of urgent data.
The Expedited Data Option therefore always takes the value 'not
selected'.
Quality of Service: This mandatory parameter consists of a list of
parameters specifying the quality of service for the transport
connection. The parameters are defined in section 10 of ISO
8072.
Note: This parameter is currently not widely used by OSI
applications and is not used by X Windows.
| TS User-Data: This mandatory parameter is not used by X Windows OPEN
| DISPLAY.
A.1.1.2 Connection Release
| A.1.1.2.1 COTS T-DISCONNECT and CLOSE DISPLAY
The X Window function CLOSE DISPLAY is used to terminate the
| connection from the client in an orderly fashion. The X Windows
| function CLOSE DISPLAY is mapped to T-DATA User-Data and the
| transport connection terminated by a subsequent T-DISCONNECT.
| Table 2 T-DISCONNECT Parameter Values to support CLOSE DISPLAY
+----------------------------------+-----+-----+
| T-DISCONNECT Parameter Name | Req | Ind |
+----------------------------------+-----+-----+
| | Disconnect Reason | | X |
+----------------------------------+-----+-----+
| | User Data | N | N |
+----------------------------------+-----+-----+
| Key: X: Mandatory Parameter
| N: Not used by X Windows - where the parameter needs a value
| as a mandatory requirement of the transport service it may
| take a default value.
Reason: The disconnection reason parameter gives information
indicating the cause of the transport connection release. The
reason will be one of those listed in section 14.2.1 of ISO
8072.
| User data: This mandatory parameter is not used by X Windows CLOSE
| DISPLAY.
| A.1.1.2.2 COTS T-DISCONNECT and KILL CLIENT
| The X Window function KILL CLIENT request from the server to
| terminate the client immediately is mapped to T-DATA User-Data. The
| transport service connection being terminated by a subsequent
| T-DISCONNECT. The T-DISCONNECT parameter values for support of KILL
| CLIENT are as specified in table 3.
| Table 3 T-DISCONNECT Parameter Values to support KILL CLIENT
+----------------------------------+-----+-----+
| T-DISCONNECT Parameter Name | Req | Ind |
+----------------------------------+-----+-----+
| | Disconnect Reason | | X |
+----------------------------------+-----+-----+
| | User Data | N | N |
+----------------------------------+-----+-----+
| Key: X: Mandatory Parameter
| N: Not used by X Windows - where the parameter needs a value
| as a mandatory requirement of the transport service it may
| take a default value.
Reason: The disconnection reason parameter gives information
indicating the cause of the transport connection release. The
reason will be one of those listed in section 14.2.1 of ISO
8072.
| User data: This mandatory parameter is not used by the X Windows
| KILL CLIENT function.
A.1.2 Data Transmission
| All of the X Windows functions datstream is to be carried in the
| transport service T-DATA User-Data. This includes the functions OPEN
| DISPLAY, CLOSE DISPLAY and KILL CLIENT specifically mentioned above.
T-DATA has only one parameter as shown in table 4. An explanation of
the use of this parameter follows the table.
Table 4 T-DATA Parameter Values
+-------------------------------------+-----+-----+
| T-DATA Parameter Name | Req | Ind |
+-------------------------------------+-----+-----+
| | User data | X | X(=)|
+-------------------------------------+-----+-----+
| Key: X: Mandatory Parameter
(=): The value of this parameter is indentical to the value
of the corresponding parameter of the preceding primitive.
User data: This mandatory parameter passes all X Windows functions
and datastreams between X Windows clients and servers. For
support of X Windows, the ASN.1 type of this data is EXTERNAL
where the encoding is as specified in Part 2 of (the ANSI
standard X3H3.6/yy-nnnn).
A.1.3 Lower Layer Requirements
| Layers 1 to 3 may be any coordinated set of protocols, either
| connection oriented or connectionless, capable of supporting the
| Connection Oriented Transport Service.
| This appendix defines a mapping onto a Transport service which is
| capable of supporting all of the five protocol classes specified in
| sections 7 to 12 of ISO 8073 (Connection Oriented Transport Protocol
| Specification). It is recommended that for a Connection Oriented
| Network the appropriate Transport Protocol Class is class 0, as
| specified in section 8 of ISO 8073.
A.2 Registration, Names and Addresses
A.2.1 Registration
The registration requirements for X Windows consist of registering
the names of X Windows servers.
The resolution of names to addresses may be handled using local
(e.g. non-standardized) mechanisms or by the use of the OSI
Directory service, see ISO 9594.
| ***END OF PROPOSED TEXT (JD v2.0 24/10/89)***