

















		 The Input Method Protocol

			Version 1.0

		   X Consortium Standard

		 X Version 11, Release 6.8




		      Masahiko Narita
		      FUJITSU Limited.

			Hideki Hiura
		       SunSoft, Inc.





			  ABSTRACT

     This specifies a protocol between IM library and
     IM (Input Method) Server for internationalized
     text input, which is independent from any specific
     language, any specific input method and the trans-
     port layer used in communication between the IM
     library and the IM Server, and uses a client-
     server model.  This protocol allows user to use
     his/her favorite input method for all applications
     within the stand-alone distributed environment.

































    X Window System is a trademark of X Consortium, Inc.

       Copyright (C) 1993, 1994 by X Consortium, Inc.




Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documenta-
tion files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or
sell copies of the Software, and to permit persons to whom
the Software is furnished to do so, subject to the following
conditions:

The above copyright notice and this permission notice shall
be included in all copies or substantial portions of the
Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PUR-
POSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE X CONSOR-
TIUM BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
OR OTHER DEALINGS IN THE SOFTWARE.

Except as contained in this notice, the name of the X Con-
sortium shall not be used in advertising or otherwise to
promote the sale, use or other dealings in this Software
without prior written authorization from the X Consortium.




	Copyright (C) 1993, 1994 by FUJITSU LIMITED

     Copyright (C) 1993, 1994 by Sun Microsystems, Inc.















Permission to use, copy, modify, and distribute this docu-
mentation for any purpose and without fee is hereby granted,
provided that the above copyright notice and this permission
notice appear in all copies.  Fujitsu and Sun Microsystems
make no representations about the suitability for any pur-
pose of the information in this document.  This documenta-
tion is provided as is without express or implied warranty.



























































1.  Introduction

1.1.  Scope

The internationalization in the X Window System Version 11,
Release 5 (X11R5) provides a common API which application
developers can use to create portable internationalized pro-
grams and to adapt them to the requirements of different
native languages, local customs, and character string encod-
ings (this is called ``localization'').  As one of its
internationalization mechanisms X11R5 has defined a func-
tional interface for internationalized text input, called
XIM (X Input Method).

When a client-server model is used with an IM (Input Method)
implementation, a protocol must be established between the
client and the server.	However, the protocol used to inter-
face Input Method Servers (IM Servers) with the Input Method
libraries (IM libraries) to which applications are linked
was not addressed in X11R5.  This led application developers
to depend on vendor-specific input methods, decreased the
user's choice of available input methods, and made it more
difficult for developers to create portable applications.
This paper describes the Input Method Protocol developed for
X11R6 to resolve the above problems and to address the
requirements of existing and future input methods.

The Input Method Protocol is independent from the transport
layer used in communication between the IM library and the
IM Server.  Thus, the input method protocol can be built on
any inter-process communication mechanism, such as TCP/IP or
the X protocol.

In addition, the protocol provides for future extensions
such as differing input model types.


1.2.  Background

Text input is much more simple for some languages than oth-
ers.  English, for instance, uses an alphabet of a manage-
able size, and input consists of pressing the corresponding
key on a keyboard, perhaps in combination with a shift key
for capital letters or special characters.

Some languages have larger alphabets, or modifiers such as
accents, which require the addition of special key combina-
tions in order to enter text.  These input methods may
require ``dead-keys'' or ``compose-keys'' which, when fol-
lowed by different combinations of key strokes, generate
different characters.

Text input for ideographic languages is much less simple.
In these languages, characters represent actual objects



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X Input Method Protocol 		    X11, Release 6.8


rather than phonetic sounds used in pronouncing a word, and
the number of characters in these languages may continue to
grow.  In Japanese, for instance, most text input methods
involve entering characters in a phonetic alphabet, after
which the input method searches a dictionary for possible
ideographic equivalents (of which there may be many).  The
input method then presents the candidate characters for the
user to choose from.

In Japanese, either Kana (phonetic symbols) or Roman letters
are typed and then a region is selected for conversion to
Kanji. Several Kanji characters may have the same phonetic
representation. If that is the case with the string entered,
a menu of characters is presented and the user must choose
the appropriate one. If no choice is necessary or a prefer-
ence has been established, the input method does the substi-
tution directly.

These complicated input methods must present state informa-
tion (Status Area), text entry and edit space (Preedit
Area), and menu/choice presentations (Auxiliary Area).	Much
of the protocol between the IM library and the IM Server
involves managing these IM areas.  Because of the size and
complexity of these input methods, and because of how widely
they vary from one language or locale to another, they are
usually implemented as separate processes which can serve
many client processes on the same computer or network.


1.3.  Input Method Styles

X11 internationalization support includes the following four
types of input method:

     - on-the-spot:	 The client application is directed
			 by the IM Server to display all
			 pre-edit data at the site of text
			 insertion.  The client registers
			 callbacks invoked by the input
			 method during pre-editing.

     - off-the-spot:	 The client application provides
			 display windows for the pre-edit
			 data to the input method which dis-
			 plays into them directly.

     - over-the-spot:	 The input method displays pre-edit
			 data in a window which it brings up
			 directly over the text insertion
			 position.

     - root-window:	 The input method displays all pre-
			 edit data in a separate area of the
			 screen in a window specific to the



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X Input Method Protocol 		    X11, Release 6.8


			 input method.

Client applications must choose from the available input
methods supported by the IM Server and provide the display
areas and callbacks required by the input method.


2.  Architecture

2.1.  Implementation Model

Within the X Window System environment, the following two
typical architectural models can be used as an input
method's implementation model.

     - Client/Server model:
			 A separate process, the IM Server,
			 processes input and handles preed-
			 iting, converting, and committing.
			 The IM library within the applica-
			 tion, acting as client to the IM
			 Server, simply receives the commit-
			 ted string from the IM Server.

     - Library model:	 All input is handled by the IM
			 library within the application.
			 The event process is closed within
			 the IM library and a separate IM
			 Server process may not be required.

Most languages which need complex preediting, such as Asian
languages, are implemented using the Client/Server IM model.
Other languages which need only dead key or compose key pro-
cessing, such as European languages, are implemented using
the Library model.

In this paper, we discuss mainly the Client/Server IM model
and the protocol used in communication between the IM
library (client) and the IM Server.


2.2.  Structure of IM

When the client connects or disconnects to the IM Server, an
open or close operation occurs between the client and the IM
Server.

The IM can be specified at the time of XOpenIM() by setting
the locale of the client and a locale modifier. Since the IM
remembers the locale at the time of creation XOpenIM() can
be called multiple times (with the setting for the locale
and the locale modifier changed) to support multiple lan-
guages.




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X Input Method Protocol 		    X11, Release 6.8


In addition, the supported IM type can be obtained using
XGetIMValues().

The client usually holds multiple input (text) fields. Xlib
provides a value type called the ``Input Context'' (IC) to
manage each individual input field.  An IC can be created by
specifying XIM using XCreateIC(), and it can be destroyed
using XDestroyIC().

The IC can specify the type of IM which is supported by XIM
for each input field, so each input field can handle a dif-
ferent type of IM.

Most importantly information such as the committed string
sent from the IM Server to the client, is exchanged based on
each IC.

Since each IC corresponds to an input field, the focused
input field should be announced to the IM Server using XSet-
ICFocus(). (XUnsetICFocus() can also be used to change the
focus.)


2.3.  Event Handling Model

Existing input methods support either the FrontEnd method,
the BackEnd method, or both.  This protocol specifically
supports the BackEnd method as the default method, but also
supports the FrontEnd method as an optional IM Server exten-
sion.

The difference between the FrontEnd and BackEnd methods is
in how events are delivered to the IM Server.  (Fig. 1)


2.3.1.	BackEnd Method

In the BackEnd method, client window input events are always
delivered to the IM library, which then passes them to the
IM Server.  Events are handled serially in the order deliv-
ered, and therefore there is no synchronization problem
between the IM library and the IM Server.

Using this method, the IM library forwards all KeyPress and
KeyRelease events to the IM Server (as required by the Event
Flow Control model described in section 2.4. ``Event Flow
Control''), and synchronizes with the IM Server (as
described in section 4.16.  ``Filtering Events'').


2.3.2.	FrontEnd Method

In the FrontEnd method, client window input events are
delivered by the X server directly to both the IM Server and



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X Input Method Protocol 		    X11, Release 6.8


the IM library.  Therefore this method provides much better
interactive performance while preediting (particularly in
cases such as when the IM Server is running locally on the
user's workstation and the client application is running on
another workstation over a relatively slow network).

However, the FrontEnd model may have synchronization prob-
lems between the key events handled in the IM Server and
other events handled in the client, and these problems could
possibly cause the loss or duplication of key events.  For
this reason, the BackEnd method is the core method sup-
ported, and the FrontEnd method is made available as an
extension for performance purposes. (Refer to Appendix A for
more information.)











































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X Input Method Protocol 		    X11, Release 6.8


... 0.05 6.513 4.737 10.45 ... 0.000i 3.937i 4.687i 0.000i

       +


			  ____________________
			  |		      |
			  |  Application      |
			  |		      |
			  |  _______	      |
			  |	    |	      |
			  |  |	 |____________|
			  |  |	 |  | Library |
			  |  |	 |____________|
			  |___________________|
			     |	    |
			     |	    |
			     |	 _____________________
			     |	 |		      |
			     |	 |    IM Server       |
			     |	 |____________________|
	       BackEnd Method|(Core)	    |FrontEnd Method (Extension)
			     |		    |
			  ____________________
			  |		      |
			  |	 X Server     |
			  |___________________|


		  Fig.1 The Flow of Events


2.4.  Event Flow Control

This protocol supports two event flow models for communica-
tion between the IM library and the IM Server (Static and
Dynamic).

Static Event Flow requires that input events always be sent
to the IM Server from the client.

Dynamic Event Flow, however, requires only that those input
events which need to be processed (converted) be sent to the
IM Server from the client.

For instance, in the case of inputing a combination of ASCII
characters and Chinese characters, ASCII characters do not
need to be processed in the IM Server, so their key events
do not have to be sent to the IM Server.  On the other hand,
key events necessary for composing Chinese characters must
be sent to the IM Server.

Thus, by adopting the Dynamic Event Flow, the number of
requests among the X Server, the client, and the IM Server



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X Input Method Protocol 		    X11, Release 6.8


is significantly reduced, and the number of context switches
is also reduced, resulting in improved performance.  The IM
Server can send XIM_REGISTER_TRIGGERKEYS message in order to
switch the event flow in the Dynamic Event Flow.

The protocol for this process is described in section 4.5.
``Event Flow Control''.


3.  Default Preconnection Convention

IM Servers are strongly encouraged to register their sym-
bolic names as the ATOM names into the IM Server directory
property, XIM_SERVERS, on the root window of the screen_num-
ber 0.	This property can contain a list of ATOMs, and the
each ATOM represents each possible IM Server.  IM Server
names are restricted to POSIX Portable Filename Character
Set.  To discover if the IM Server is active, see if there
is an owner for the selection with that atom name.  To learn
the address of that IM Server, convert the selection target
TRANSPORT, which will return a string form of the transport
address(es).  To learn the supported locales of that IM
Server, convert the selection target LOCALES, which will
return a set of names of the supported locales in the syntax
X/Open defines.

The basic semantics to determine the IM Server if there are
multiple ATOMs are found in XIM_SERVERS property, is first
fit if the IM Server name is not given as a X modifier's
category im.

The address information retrievable from the TRANSPORT tar-
get is a transport-specific name.  The preregistered formats
for transport-specific names are listed in Appendix B.
Additional transport-specific names may be registered with X
Consortium.

For environments that lack X connections, or for IM Servers
which do not use the X Window System, the preconnection con-
vention with IM Server may be given outside the X Window
system (e.g. using a Name Service).


4.  Protocol

The protocol described below uses the bi-directional syn-
chronous/asynchronous request/reply/error model and is spec-
ified using the same conventions outlined in Section 2 of
the core X Window System protocol [1]:








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X Input Method Protocol 		    X11, Release 6.8


4.1.  Basic Requests Packet Format

This section describes the requests that may be exchanged
between the client and the IM Server.

The basic request packet header format is as follows.

	       major-opcode:		CARD8
	       minor-opcode:		CARD8
	       length:			CARD16

The MAJOR-OPCODE specifies which core request or extension
package this packet represents.  If the MAJOR-OPCODE corre-
sponds to a core request, the MINOR-OPCODE contains 8 bits
of request-specific data.  (If the MINOR-OPCODE is not used,
it is 0.)  Otherwise, the MAJOR-OPCODE and the MINOR-OPCODE
are specified by XIM_QUERY_EXTENSION message.  (Refer to
4.7. Query the supported extension protocol list.)  The
LENGTH field specifies the number of 4 bytes elements fol-
lowing the header.  If no additional data is followed by the
header, the LENGTH field will be 0.


4.2.  Data Types

The following data types are used in the core X IM Server
protocol:

BITMASK16
  CARD16

BITMASK32
  CARD32

PADDING FORMAT
  Where N is some expression, and Pad(N) is the number of bytes needed to round N up to a
  multiple of four.
     Pad(N) = (4 - (N mod 4)) mod 4

LPCE
  1		    A character from the4 X Portable Character Set in Latin Portable
		    Character Encoding















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X Input Method Protocol 		    X11, Release 6.8


STRING
  2  n		    length of string in bytes
  n  LISTofLPCE     string
  p		    unused, p=Pad(2+n)

STR
  1  n		    length of name in bytes
  n  STRING8	    name

XIMATTR
  2  CARD16	    attribute ID (*1)
  2  CARD16	    type of the value (*2)
  2  n		    length of im-attribute
  n  STRING8	    im-attribute
  p		    unused, p = Pad(2+n)

The im-attribute argument specifies XIM values such as XNQueryInputStyle.

XICATTR
  2  CARD16	    attribute ID (*1)
  2  CARD16	    type of the value (*2)
  2  n		    length of ic-attribute
  n  STRING8	    ic-attribute
  p		    unused, p = Pad(2+n)


(*1) XIMATTR and XICATTR are used during the setup stage and
     XIMATTRIBUTE and XICATTRIBUTE are used after each
     attribute ID has been recognized by the IM Server and
     the IM library.


(*2) The value types are defined as follows:

     ------------------------------------------------------------------------------------------
     values   data			format
     ------------------------------------------------------------------------------------------
     #0       Separator of NestedList	----- (*3)
     #1       byte data 		CARD8
     #2       word data 		CARD16
     #3       long data 		CARD32
     #4       char data 		STRING8
     #5       Window			CARD32
     #10      XIMStyles 		2	     n		      number of XIMStyle list
					2			      unused
					n	     CARD32	      XIMStyle list
     #11      XRectangle		2	     INT16	      X
					2	     INT16	      Y
					2	     CARD16	      width
					2	     CARD16	      height
     #12      XPoint			2	     INT16	      X
					2	     INT16	      Y
     #13      XFontSet			2	     n		      length of Base font name




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X Input Method Protocol 		    X11, Release 6.8


     ------------------------------------------------------------------------------------------
     values   data			format
     ------------------------------------------------------------------------------------------
					n	     STRING8	      Base font name list
					p			      unused, p = Pad(2+n)
     #15      XIMHotKeyTriggers 	4	     n		      number of XIMTRIGGERKEY
								      list (*4)
					n	     XIMTRIGGERKEY    XIMHotkeyTrigger list
     #16      XIMHotKeyState			     XIMHOTKEYSTATE   HotKey processing state
     #17      XIMStringConversion	XIMSTRCONVTEXT
     #18      XIMPreeditState		XIMPREEDITSTATE
     #19      XIMResetState		XIMRESETSTATE
     #x7fff   NestedList		-----
     ------------------------------------------------------------------------------------------



(*3) The IC value for the separator of NestedList is defined
     as follows,
	  #define   XNSeparatorofNestedList   ``separato-
     rofNestedList''
     , which is registered in X Consortium and cannot be
     used for any other purpose.


(*4) LISTofFOO
	  A Type name of the form LISTof FOO means a counted
	  list of elements of type FOO.  The size of the
	  length field may vary (it is not necessarily the
	  same size as a FOO), and in some cases, it may be
	  implicit.


XIMTRIGGERKEY
  4  CARD32	    keysym
  4  CARD32	    modifier
  4  CARD32	    modifier mask

ENCODINGINFO
  2  n		    length of encoding info
  n  STRING8	    encoding info
  p		    unused, p=Pad(2+n)

EXT
  1  CARD8	    extension major-opcode
  1  CARD8	    extension minor-opcode
  2  n		    length of extension name
  n  STRING8	    extension name
  p		    unused, p = Pad(n)

XIMATTRIBUTE
  2  CARD16	    attribute ID
  2  n		    value length
  n		    value



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X Input Method Protocol 		    X11, Release 6.8


  p		    unused, p = Pad(n)

XICATTRIBUTE
  2  CARD16	    attribute ID
  2  n		    value length
  n		    value
  p		    unused, p = Pad(n)


















































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X Input Method Protocol 		    X11, Release 6.8


XIMSTRCONVTEXT
  2  CARD16		      XIMStringConversionFeedback
     #x0000001		      XIMStringConversionLeftEdge
     #x0000002		      XIMStringConversionRightEdge
     #x0000004		      XIMStringConversionTopEdge
     #x0000008		      XIMStringConversionBottomEdge
     #x0000010		      XIMStringConversionConvealed
     #x0000020		      XIMStringConversionWrapped
  2  n			      byte length of the retrieved string
  n  STRING8		      retrieved string
  p			      unused, p = Pad(n)
  2  m			      byte length of feedback array
  2			      unused
  m  LISTofXIMSTRCONVFEEDBACK feedback array(*1)

(*1) This field is reserved for future use.


XIMFEEDBACK
  4  CARD32	    XIMFeedback
     #x000001	    XIMReverse
     #x000002	    XIMUnderline
     #x000004	    XIMHighlight
     #x000008	    XIMPrimary
     #x000010	    XIMSecondary
     #x000020	    XIMTertiary
     #x000040	    XIMVisibleToForward
     #x000080	    XIMVisibleToBackward
     #x000100	    XIMVisibleCenter

XIMHOTKEYSTATE
  4  CARD32	    XIMHotKeyState
     #x0000001	    XIMHotKeyStateON
     #x0000002	    XIMHotKeyStateOFF

XIMPREEDITSTATE
  4  CARD32	    XIMPreeditState
     #x0000001	    XIMPreeditEnable
     #x0000002	    XIMPreeditDisable

XIMRESETSTATE
  4  CARD32	    XIMResetState
     #x0000001	    XIMInitialState
     #x0000002	    XIMPreserveState


4.3.  Error Notification

Both the IM Server and the IM library return XIM_ERROR mes-
sages instead of the corresponding reply messages if any
errors occur during data processing.

At most one error is generated per request. If more than one
error condition is encountered in processing a request, the



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X Input Method Protocol 		    X11, Release 6.8


choice of which error is returned is implementation-depen-
dent.


     XIM_ERROR (IM Server <--> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  2	BITMASK16	    flag (*1)
		#0000		    Both Input-Method-ID and Input-Context-ID are invalid
		#0001		    Input-Method-ID is valid
		#0002		    Input-Context-ID is valid
	  2	CARD16		    Error Code
		#1		    BadAlloc
		#2		    BadStyle
		#3		    BadClientWindow
		#4		    BadFocusWindow
		#5		    BadArea
		#6		    BadSpotLocation
		#7		    BadColormap
		#8		    BadAtom
		#9		    BadPixel
		#10		    BadPixmap
		#11		    BadName
		#12		    BadCursor
		#13		    BadProtocol
		#14		    BadForeground
		#15		    BadBackground
		#16		    LocaleNotSupported
		#999		    BadSomething (*2)
	  2	n		    byte length of error detail.
	  2	CARD16		    type of error detail (*3)
	  n	STRING8 	    error detail (*4)
	  p			    unused, p = Pad(n)



     (*1) Before an IM is created, both Input-Method-ID and
	  Input-Context-ID are invalid.  Before an IC is
	  created, only Input-Method-ID is valid.  After
	  that, both of Input-Method-ID and Input-Context-ID
	  are valid.

     (*2) Unspecific error, for example ``language engine
	  died''

     (*3) This field is reserved for future use.

     (*4) Vendor defined detail error message


4.4.  Connection Establishment

XIM_CONNECT message requests to establish a connection over
a mutually-understood virtual stream.



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X Input Method Protocol 		    X11, Release 6.8


     XIM_CONNECT (IM library -> IM Server)
	  1			    byte order
		#x42 MSB first
		#x6c LSB first
	  1			    unused
	  2	CARD16		    client-major-protocol-version (*1)
	  2	CARD16		    client-minor-protocol-version (*1)
	  2	CARD16		    number of client-auth-protocol-names
	  n	LISTofSTRING	    client-auth-protocol-names



     (*1) Specify the version of IM Protocol that the client
	  supports.


A client must send XIM_CONNECT message as the first message
on the connection.  The list specifies the names of authen-
tication protocols the sending IM Server is willing to per-
form.  (If the client need not authenticate, the list may be
omited.)

XIM_AUTH_REQUIRED message is used to send the authentication
protocol name and protocol-specific data.

     XIM_AUTH_REQUIRED (IM library <--> IM Server)
	  1	CARD8		    auth-protocol-index
	  3			    unused
	  2	n		    length of authentication data
	  2			    unused
	  n	<varies>	    data
	  p			    unused, p = Pad(n)


The auth-protocol is specified by an index into the list of
names given in the XIM_CONNECT or XIM_AUTH_SETUP message.
Any protocol-specific data that might be required is also
sent.

The IM library sends XIM_AUTH_REPLY message as the reply to
XIM_AUTH_REQUIRED message, if the IM Server is authenti-
cated.

     XIM_AUTH_REPLY (IM library -> IM Server)
	  2	n		    length of authentication data
	  2			    unused
	  2	n		    length of authentication data
	  2			    unused
	  n	<varies>	    data
	  p			    unused, p = Pad(n)


The auth data is specific to the authentication protocol in
use.



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XIM_AUTH_NEXT message requests to send more auth data.

     XIM_AUTH_NEXT (IM library <--> IM Server)
	  2	n		    length of authentication data
	  2			    unused
	  n	<varies>	    data
	  p			    unused, p = Pad(n)


The auth data is specific to the authentication protocol in
use.

The IM Server sends XIM_AUTH_SETUP message to authenticate
the client.

     XIM_AUTH_SETUP (IM Server -> IM library)
	  2	CARD16		    number of client-auth-protocol-names
	  2			    unused
	  n	LISTofSTRING	    server-auth-protocol-names


The list specifies the names of authentication protocols the
client is willing to perform.

XIM_AUTH_NG message requests to give up the connection.

     XIM_AUTH_NG (IM library <--> IM Server)


The IM Server sends XIM_CONNECT_REPLY message as the reply
to XIM_CONNECT or XIM_AUTH_REQUIRED message.

     XIM_CONNECT_REPLY (IM Server -> IM library)
	  2	CARD16		    server-major-protocol-version (*1)
	  2	CARD16		    server-minor-protocol-version (*1)



     (*1) Specify the version of IM Protocol that the IM
	  Server supports.  This document specifies major
	  version one, minor version zero.


Here are the state diagrams for the client and the IM
Server.

State transitions for the client

     init_status:
	  Use authorization function -> client_ask
	  Not use authorization function -> client_no_check






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X Input Method Protocol 		    X11, Release 6.8


     start:
	  Send XIM_CONNECT
	       If client_ask -> client_wait1
	       If client_no_check, client-auth-protocol-
	       names may be omited -> client_wait2


     client_wait1:
	  Receive XIM_AUTH_REQUIRED -> client_check
	  Receive <other> -> client_NG


     client_check:
	  If no more auth needed, send XIM_AUTH_REPLY ->
	  client_wait2
	  If good auth data, send XIM_AUTH_NEXT ->
	  client_wait1
	  If bad auth data, send XIM_AUTH_NG -> give up on
	  this protocol


     client_wait2:
	  Receive XIM_CONNECT_REPLY -> connect
	  Receive XIM_AUTH_SETUP -> client_more
	  Receive XIM_AUTH_NEXT -> client_more
	  Receive XIM_AUTH_NG -> give up on this protocol
	  Receive <other> -> client_NG


     client_more:
	  Send XIM_AUTH_REQUIRED -> client_wait2


     client_NG:
	  Send XIM_AUTH_NG -> give up on this protocol


State transitions for the IM Server

     init-status:
	  Use authorization function -> server_ask
	  Not use authorization function -> server_no_check


     start:
	  Receive XIM_CONNECT -> start2
	  Receive <other> -> server_NG


     start2:
	  If client_ask, send XIM_AUTH_REQUIRED ->
	  server_wait1
	  If client_no_check and server_ask, send
	  XIM_AUTH_SETUP -> server_wait2



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X Input Method Protocol 		    X11, Release 6.8


	  If client_no_check and server_no_check, send
	  XIM_CONNECT_REPLY -> connect


     server_wait1:
	  Receive XIM_AUTH_REPLY -> server2
	  Receive XIM_AUTH_NEXT -> server_more
	  Receive <other> -> server_NG


     server_more
	  Send XIM_AUTH_REQUIRED -> server_wait1


     server2
	  If server_ask, send XIM_AUTH_SETUP -> server_wait2
	  If server_no_check, send XIM_CONNECT_REPLY -> con-
	  nect


     server_wait2
	  Receive XIM_AUTH_REQUIRED -> server_check
	  Receive <other> -> server_NG


     server_check
	  If no more auth data, send XIM_CONNECT_REPLY ->
	  connect
	  If bad auth data, send XIM_AUTH_NG -> give up on
	  this protocol
	  If good auth data, send XIM_AUTH_NEXT ->
	  server_wait2


     server_NG
	  Send XIM_AUTH_NG -> give up on this protocol


XIM_DISCONNECT message requests to shutdown the connection
over a mutually-understood virtual stream.

     XIM_DISCONNECT (IM library -> IM Server)


XIM_DISCONNECT is a synchronous request.  The IM library
should wait until it receives either an XIM_DISCONNECT_REPLY
packet or an XIM_ERROR packet.


     XIM_DISCONNECT_REPLY (IM Server -> IM library)


XIM_OPEN requests to establish a logical connection between
the IM library and the IM Server.



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X Input Method Protocol 		    X11, Release 6.8


     XIM_OPEN (IM library -> IM Server)
	  n	STR		    locale name
	  p			    unused, p = Pad(n)


XIM_OPEN is a synchronous request.  The IM library should
wait until receiving either an XIM_OPEN_REPLY packet or an
XIM_ERROR packet.


     XIM_OPEN_REPLY (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	n		    byte length of IM attributes supported
	  n	LISTofXIMATTR	    IM attributes supported
	  2	m		    byte length of IC attributes supported
	  2	CARD16		    unused
	  m	LISTofXICATTR	     IC attributes supported


XIM_OPEN_REPLY message returns all supported IM and IC
attributes in LISTofXIMATTR and LISTofXICATTR.	These IM and
IC attribute IDs are used to reduce the amount of data which
must be transferred via the network. In addition, this indi-
cates to the IM library what kinds of IM/IC attributes can
be used in this session, and what types of data will be
exchanged. This allows the IM Server provider and applica-
tion writer to support IM system enhancements with new IM/IC
attributes, without modifying Xlib.  The IC value for the
separator of NestedList must be included in the LISTofXI-
CATTR.

XIM_CLOSE message requests to shutdown the logical connec-
tion between the IM library and the IM Server.

     XIM_CLOSE (IM library -> IM Server)
	  2	CARD16		    input-method-ID
	  2			    unused


XIM_CLOSE is a synchronous request.  The IM library should
wait until receiving either an XIM_CLOSE_REPLY packet or an
XIM_ERROR packet.


     XIM_CLOSE_REPLY (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2			    unused



4.5.  Event Flow Control

An IM Server must send XIM_SET_EVENT_MASK message to the IM
library in order for events to be forwarded to the IM



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X Input Method Protocol 		    X11, Release 6.8


Server, since the IM library initially doesn't forward any
events to the IM Server. In the protocol, the IM Server will
specify masks of X events to be forwarded and which need to
be synchronized by the IM library.


     XIM_SET_EVENT_MASK (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  4	EVENTMASK	    forward-event-mask (*1)
	  4	EVENTMASK	    synchronous-event-mask (*2)



     (*1) Specify all the events to be forwarded to the IM
	  Server by the IM library.

     (*2) Specify the events to be forwarded with synchro-
	  nous flag on by the IM library.


XIM_SET_EVENT_MASK is an asynchronous request.	The event
masks are valid immediately after they are set until changed
by another XIM_SET_EVENT_MASK message.	If input-context-ID
is set to zero, the default value of the input-method-ID
will be changed to the event masks specified in the request.
That value will be used for the IC's which have no individ-
ual values.

Using the Dynamic Event Flow model, an IM Server sends
XIM_REGISTER_TRIGGERKEYS message to the IM library before
sending XIM_OPEN_REPLY message.  Or the IM library may sup-
pose that the IM Server uses the Static Event Flow model.

     XIM_REGISTER_TRIGGERKEYS (IM Server -> IM library)
	  2	CARD16		      input-method-ID
	  2			      unused
	  4	n		      byte length of on-keys
	  n	LISTofXIMTRIGGERKEY   on-keys list
	  4	m		      byte length of off-keys
	  m	LISTofXIMTRIGGERKEY   off-keys list


XIM_REGISTER_TRIGGERKEYS is an asynchronous request.  The IM
Server notifys the IM library of on-keys and off-keys lists
with this message.

The IM library notifys the IM Server with XIM_TRIGGER_NOTIFY
message that a key event matching either on-keys or off-keys
has been occurred.


     XIM_TRIGGER_NOTIFY (IM library -> IM Server)




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X Input Method Protocol 		    X11, Release 6.8


	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  4	CARD32		    flag
		#0		    on-keys list
		#1		    off-keys list
	  4	CARD32		    index of keys list
	  4	EVENTMASK	    client-select-event-mask (*1)



     (*1) Specify the events currently selected by the IM
	  library with XSelectInput.


XIM_TRIGGER_NOTIFY is a synchronous request.  The IM library
should wait until receiving either an XIM_TRIG-
GER_NOTIFY_REPLY packet or an XIM_ERROR packet.


     XIM_TRIGGER_NOTIFY_REPLY (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID



4.6.  Encoding Negotiation

XIM_ENCODING_NEGOTIATION message requests to decide which
encoding to be sent across the wire.  When the negotiation
fails, the fallback default encoding is Portable Character
Encoding.

     XIM_ENCODING_NEGOTIATION (IM library -> IM Server).sp 6p
	  2	CARD16		     input-method-ID
	  2	n		     byte length of encodings listed by name
	  n	LISTofSTR	     list of encodings supported in the IM library.
	  p			     unused, p = Pad(n)
	  2	m		     byte length of encodings listed by detailed data
	  2			     unused
	  m	LISTofENCODINGINFO   list of encordings supported in the IM library


The IM Server must choose one encoding from the list sent by
the IM library.  If index of the encording determined is -1
to indicate that the negotiation is failed, the fallback
default encoding is used.  The message must be issued after
sending XIM_OPEN message via XOpenIM().  The name of encod-
ing may be registered with X Consortium.

XIM_ENCODING_NEGOTIATION is a synchronous request.  The IM
library should wait until receiving either an XIM_ENCOD-
ING_NEGOTIATION_REPLY packet or an XIM_ERROR packet.





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X Input Method Protocol 		    X11, Release 6.8


     XIM_ENCODING_NEGOTIATION_REPLY (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    category of the encoding determined.
		#0		    name
		#1		    detailed data
	  2	INT16		    index of the encoding determinated.
	  2			    unused



4.7.  Query the supported extension protocol list

XIM_QUERY_EXTENSION message requests to query the IM exten-
sions supported by the IM Server to which the client is
being connected.

     XIM_QUERY_EXTENSION (IM library -> IM Server)
	  2	CARD16		    input-method-ID
	  2	n		    byte length of extensions supported by
				    the IM library
	  n	LISTofSTR	    extensions supported by the IM library
	  p			    unused, p = Pad(n)


An example of a supported extension is FrontEnd.  The mes-
sage must be issued after sending XIM_OPEN message via
XOpenIM().

If n is 0, the IM library queries the IM Server for all
extensions.

If n is not 0, the IM library queries whether the IM Server
supports the contents specified in the list.

If a client uses an extension request without previously
having issued a XIM_QUERY_EXTENSION message for that exten-
sion, the IM Server responds with a BadProtocol error.	If
the IM Server encounters a request with an unknown MAJOR-
OPCODE or MINOR-OPCODE, it responds with a BadProtocol
error.

XIM_QUERY_EXTENSION is a synchronous request.  The IM
library should wait until receiving either an
XIM_QUERY_EXTENSION_REPLY packet or an XIM_ERROR packet.


     XIM_QUERY_EXTENSION_REPLY (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	n		    byte length of extensions supported
				    by both the IM library and the IM
				    Server






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X Input Method Protocol 		    X11, Release 6.8


	  n	LISTofEXT	    list of extensions supported by
				    both the IM library and the IM
				    Server


XIM_QUERY_EXTENSION_REPLY message returns the list of exten-
sions supported by both the IM library and the IM Server. If
the list passed in XIM_QUERY_EXTENSION message is NULL, the
IM Server returns the full list of extensions supported by
the IM Server.	If the list is not NULL, the IM Server
returns the extensions in the list that are supported by the
IM Server.

A zero-length string is not a valid extension name.  The IM
library should disregard any zero-length strings that are
returned in the extension list.  The IM library does not use
the requests which are not supported by the IM Server.


4.8.  Setting IM Values

XIM_SET_IM_VALUES requests to set attributes to the IM.

     XIM_SET_IM_VALUES (IM library -> IM Server)
	  2	CARD16		     input-method-ID
	  2	n		     byte length of im-attribute
	  n	LISTofXIMATTRIBUTE   im-attributes


The im-attributes in XIM_SET_IM_VALUES message are specified
as a LISTofXIMATTRIBUTE, specifying the attributes to be
set. Attributes other than the ones returned by
XIM_OPEN_REPLY message should not be specified.

XIM_SET_IM_VALUES is a synchronous request. The IM library
should wait until receiving either an XIM_SET_IM_VAL-
UES_REPLY packet or an XIM_ERROR packet, because it must
receive the error attribute if XIM_ERROR message is
returned.

     XIM_SET_IM_VALUES_REPLY (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2			    unused


XIM_SET_IM_VALUES_REPLY message returns the input-method-ID
to distinguish replies from multiple IMs.


4.9.  Getting IM Values

XIM_GET_IM_VALUES requests to query IM values supported by
the IM Server currently being connected.




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X Input Method Protocol 		    X11, Release 6.8


     XIM_GET_IM_VALUES (IM library -> IM Server)
	  2	CARD16		    input-method-ID
	  2	n		    byte length of im-attribute-id
	  n	LISTofCARD16	    im-attribute-id
	  p			    unused, p=Pad(n)


XIM_GET_IM_VALUES is a synchronous request.  The IM library
should wait until it receives either an XIM_GET_IM_VAL-
UES_REPLY packet or an XIM_ERROR packet.

     XIM_GET_IM_VALUES_REPLY (IM Server -> IM library)
	  2	CARD16		     input-method-ID
	  2	n		     byte length of im-attributes returned
	  n	LISTofXIMATTRIBUTE   im-attributes returned


The IM Server returns IM values with XIM_GET_IM_VALUES_REPLY
message.  The order of the returned im-attribute values cor-
responds directly to that of the list passed with the
XIM_GET_IM_VALUES message.


4.10.  Creating an IC

XIM_CREATE_IC message requests to create an IC.


     XIM_CREATE_IC (IM library -> IM Server)
	  2	CARD16		     input-method-ID
	  2	n		     byte length of ic-attributes
	  n	LISTofXICATTRIBUTE   ic-attributes


The input-context-id is specified by the IM Server to iden-
tify the client (IC).  (It is not specified by the client in
XIM_CREATE_IC message.), and it should not be set to zero.

XIM_CREATE_IC is a synchronous request which returns the
input-context-ID.  The IM library should wait until it
receives either an XIM_CREATE_IC_REPLY packet or an
XIM_ERROR packet.

     XIM_CREATE_IC_REPLY (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID



4.11.  Destroying the IC

XIM_DESTROY_IC message requests to destroy the IC.





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X Input Method Protocol 		    X11, Release 6.8


     XIM_DESTROY_IC (IM library -> IM Server)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID


XIM_DESTROY_IC is a synchronous request. The IM library
should not free its resources until it receives an
XIM_DESTROY_IC_REPLY message because XIM_DESTROY_IC message
may result in Callback packets such as XIM_PREEDIT_DRAW and
XIM_PREEDIT_DONE.


     XIM_DESTROY_IC_REPLY (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID



4.12.  Setting IC Values

XIM_SET_IC_VALUES messages requests to set attributes to the
IC.

     XIM_SET_IC_VALUES (IM library -> IM Server)
	  2	CARD16		     input-method-ID
	  2	CARD16		     input-context-ID
	  2	n		     byte length of ic-attributes
	  2			     unused
	  n	LISTofXICATTRIBUTE   ic-attributes


The ic-attributes in XIM_SET_IC_VALUES message are specified
as a LISTofXICATTRIBUTE, specifying the attributes to be
set. Attributes other than the ones returned by
XIM_OPEN_REPLY message should not be specified.

XIM_SET_IC_VALUES is a synchronous request. The IM library
should wait until receiving either an XIM_SET_IC_VAL-
UES_REPLY packet or an XIM_ERROR packet, because it must
receive the error attribute if XIM_ERROR message is
returned.

     XIM_SET_IC_VALUES_REPLY (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID



4.13.  Getting IC Values

XIM_GET_IC_VALUES message requests to query IC values sup-
ported by the IM Server currently being connected.





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X Input Method Protocol 		    X11, Release 6.8


     XIM_GET_IC_VALUES (IM library -> IM Server)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  2	n		    byte length of ic-attribute-id
	  n	LISTofCARD16	    ic-attribute-id
	  p			    unused, p=Pad(2+n)


In LISTofCARD16, the appearance of the ic-attribute-id for
the separator of NestedList shows the end of the heading
nested list.

XIM_GET_IC_VALUES is a synchronous request and returns each
attribute with its values to show the correspondence.  The
IM library should wait until receiving either an
XIM_GET_IC_VALUES_REPLY packet or an XIM_ERROR packet.

     XIM_GET_IC_VALUES_REPLY (IM Server -> IM library)
	  2	CARD16		     input-method-ID
	  2	CARD16		     input-context-ID
	  2	n		     byte length of ic-attribute
	  2			     unused
	  n	LISTofXICATTRIBUTE   ic-attribute



4.14.  Setting IC Focus

XIM_SET_IC_FOCUS message requests to set the focus to the
IC.

     XIM_SET_IC_FOCUS (IM library -> IM Server)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID


XIM_SET_IC_FOCUS is an asynchronous request.


4.15.  Unsetting IC Focus

XIM_UNSET_IC_FOCUS message requests to unset the focus to
the focused IC.

     XIM_UNSET_IC_FOCUS (IM library -> IM Server)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID


XIM_UNSET_IC_FOCUS is an asynchronous request.







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X Input Method Protocol 		    X11, Release 6.8


4.16.  Filtering Events

Event filtering is mainly provided for BackEnd method to
allow input method to capture X events transparently to
clients.

X Events are forwarded by XIM_FORWARD_EVENT message.  This
message can be operated both synchronously and asyn-
chronously.  If the requester sets the synchronous flag, the
receiver must send XIM_SYNC_REPLY message back to the
requester when all the data processing is done.

Protocol flow of BackEnd model


With BackEnd method, the protocol flow can be classified
into two methods in terms of synchronization, depending on
the synchronous-eventmask of XIM_SET_EVENT_MASK message.
One can be called on-demand-synchronous method and another
can be called as full-synchronous method.

In on-demand-synchronous method, the IM library always
receives XIM_FORWARD_EVENT or XIM_COMMIT message as a syn-
chronous request. Also, the IM Server needs to synchronously
process the correspondent reply from the IM library and the
following XIM_FORWARD_EVENT message sent from the IM library
when any of the event causes the IM Server to send XIM_FOR-
WARD_EVENT or XIM_COMMIT message to the IM library, so that
the input service is consistent.  If the IM library gets the
control back from the application after receiving the syn-
chronous request, the IM library replies for the synchronous
request before processing any of the events. In this time,
the IM Server blocks XIM_FORWARD_EVENT message which is sent
by the IM library, and handles it after receiving the reply.
However, the IM Server handles the other protocols at any
time.

In full-synchronous method, the IM library always sends
XIM_FORWARD_EVENT message to the IM Server as a synchronous
request. Therefore, the reply to it from the IM Server will
be put between the XIM_FORWARD_EVENT message and its
XIM_SYNC_REPLY message.  In case of sending XIM_FOR-
WARD_EVENT or XIM_COMMIT message, the IM Server should set
the synchronous flag off. Because the synchronization can be
done by the following XIM_SYNC_REPLY message.


Sample Protocol flow chart 1

Following chart shows one of the simplest protocol flow
which only deals with keyevents for preediting operation.

... 0.425 6.888 6.3 10.296 ... 0.000i 3.408i 5.875i 0.000i




			     26





X Input Method Protocol 		    X11, Release 6.8


	     Xlib API	 IM library		  IM Server
  Key event_-XNextEvent        |		  |
	     XFilterEvent------|		  |
			      -| XIM_FORWARD_EVENT|
			       |		--|
  Key event_-XNextEvent        | XIM_FORWARD_EVENT|synchronous
	     XFilterEvent      | or XIM_COMMIT	  |request
			      -| (synchronous)	  |
		     ----------|--		--|	 ___
	     XNextEvent        |		--|Pending  |
	     XFilterEvent (returnXIM_FORWARD_EVENT|	    |
       _____ XmbLookupString   |		  |	    |
 Application moves	     --|  XIM_SYNC	--|	    |
 the focus   XSetICFocus_______|__XIM_SYNC_REPLY_-|	    |
			       |_________________ |processed|
			       |  XIM_SET_IC_FOCUS|(The focused
			       |		--|IC is changed)
	     XNextEvent        |XIM_SYNC_REPLY as-apreplysed|
			      -|of the XIM_FORWARD_EVENT    |
			     --|		  |	    |
			       |	       -- |processed|



		 Fig.2 Sample Protocol Flow


Sample Protocol flow chart 2

Following chart shows one of the complex protocol flow,
which deals with multiple focus windows and button press
event as well as keyevent, and the focus is moved by the
application triggered by both of keyevent and button press
event.























			     27





X Input Method Protocol 		    X11, Release 6.8


... 0.425 5.575 6.3 10.296 ... 0.000i 4.721i 5.875i 0.000i

	     Xlib API	 IM library		  IM Server
  Key event_-XNextEvent        |		  |
	     XFilterEvent------|		  |
			      -| XIM_FORWARD_EVENT|
			       |	       -- |
  Key event_-XNextEvent        | XIM_FORWARD_EVENT|synchronous
	     XFilterEvent      | or XIM_COMMIT	  |request
			      -| (synchronous)	  |
  focusnchangXSetICFocus       |		--|Pending__
		      Pending untilM_FORWARD_EVENT|	    |
		      sync cycle-is doneM_SYNC	--|	    |
			       |--		  |	    |
			       |-- XIM_SYNC_REPLY |	    |
	     XNextEvent       -|XIM_SET_IC_FOCUS is	    |
	     XFilterEvent (returpendabecause another sync cycle
       _____ XmbLookupString | |is started by XIM_COMMIT    |
 Application moves	     | |		  |	    |
 the focus   XSetICFocus_______| XIM_SET_IC_FOCUS |	    |
			     | |		--|processed|
			     | |		--|(The focused
			     | |		  |IC is changed)
 Key event_--XNextEvent      | |XIM_SYNC_REPLY as apreplysed|
			     | |of the XIM_FORWARD_EVENT    |
	     XFilterEvent    |-|		  |	    |
			     |+|	       -- |processed|
			     -+|   XIM_SET_IC_FOCUS
			       |	       -- |processed
			       |	       -- |
			       |XIM_FORWARD_EVENT |



	      Fig.3 Sample Protocol Flow chart



     XIM_FORWARD_EVENT (IM library <--> IM Server)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  2	BITMASK16	    flag
		#0001		    synchronous
		#0002		    request filtering (*1)
		#0004		    request lookupstring (*2)
	  2	CARD16		    serial number
		XEVENT		    X event



     (*1) Indicate the receiver should filter events and
	  possible preedit may be invoked.





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X Input Method Protocol 		    X11, Release 6.8


     (*2) Indicate the receiver should only do lookup
	  string. The IM Server is expected to just do a
	  conversion of the key event to the best candidate.
	  This bit may affect the state of the preedit state
	  (e.g. compose of dead key sequences).

XEVENT format is same as the X Protocol event for-
mat(xEvent).  As the value of xEvent's sequenceNumber is the
bottom of 16 bit of XEvent's xany.serial, the top of 16 bit
is sent by serial number(INT16).

XIM_FORWARD_EVENT message is used for forwarding the events
from the IM library to the IM Server in order for IM to be
able to filter the event. On the other hand, this message is
also used for forwarding the events from the IM Server to
the IM library if the event forwarded from the IM library is
not filtered.  The IM Server, which receives XIM_FOR-
WARD_EVENT message without synchronous bit, should set syn-
chronous bit.  If both ``request event filtering'' and
``request lookupstring'' flag are set, then both filtering
and lookup should be done for the same event.


4.17.  Synchronizing with the IM Server

XIM_SYNC message requests to synchronize the IM library and
the IM Server.

     XIM_SYNC (IM library <--> IM Server)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID


This synchronization can be started either on the IM library
side or on the IM Server side.	The side which receives
XIM_SYNC message should process all XIM requests before
replying. The input-context-ID is necessary to distinguish
the IC with which the IM library and the IM Server are syn-
chronized.

     XIM_SYNC_REPLY (IM Server <--> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID


The side which receives XIM_FORWARD_EVENT, XIM_COMMIT or any
other message with synchronous bit, should process all XIM
request before replying, and send XIM_SYNC_REPLY message as
the reply to the previous message.








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X Input Method Protocol 		    X11, Release 6.8


4.18.  Sending a committed string

When the IM Server commits a string, the IM Server sends
either the committed string or list of KeySym, or both, by
XIM_COMMIT message.

     XIM_COMMIT (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  2	BITMASK16	    flag
		#0001		    synchronous
		#0002		    XLookupChars
		#0004		    XLookupKeySym
		#0006		     XLookupBoth = XLookupChars | XLookupKeySym


     If flag is XLookupKeySym, the arguments continue as
     follows:

	  2			    unused
	  4	KEYSYM		    KeySym


     If flag is XLookupChars, the arguments continue as fol-
     lows:

	  2	m		    byte length of committed string
	  m	LISTofBYTE	    committed string
	  p			    unused, p = Pad(m)


     If flag is XLookupBoth, the arguments continue as fol-
     lows:

	  2			    unused
	  4	KEYSYM		    KeySym
	  2	n		    byte length of committed string
	  n	LISTofBYTE	    committed string
	  p			    unused, p = Pad(2+n)


The IM Server which receives XIM_COMMIT message without syn-
chronous bit should set synchronous bit.


4.19.  Reset IC

XIM_RESET_IC message requests to reset the status of IC in
the IM Server.

     XIM_RESET_IC (IM library -> IM Server)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID




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X Input Method Protocol 		    X11, Release 6.8


XIM_RESET_IC is a synchronous request. The IM library should
wait until receiving either an XIM_RESET_IC_REPLY packet or
an XIM_ERROR packet.


     XIM_RESET_IC_REPLY (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  2	n		    byte length of preedit string
	  n	LISTofBYTE	    preedit string
	  p			    unused, p = Pad(2+n)


XIM_RESET_IC_REPLY message returns the input-context-ID to
distinguish replies from multiple ICs.


4.20.  Callbacks

If XIMStyle has XIMPreeditArea or XIMStatusArea set, XIMGe-
ometryCallback may be used, and if XIMPreeditCallback and/or
XIMStatusCallback are set, corresponding callbacks may be
used.

Any callback request may be sent from an IM Server to an IM
client asynchronously in response to any request previously
sent by the IM client to the IM Server.

When an IM Server needs to send a callback request syn-
chronously with the request previously sent by an IM client,
the IM Server sends it before replying to the previous
request.


4.20.1.  Negotiating geometry

The IM Server sends XIM_GEOMETRY message to start geometry
negotiation, if XIMStyle has XIMPreeditArea or XIMStatusArea
set.

     XIM_GEOMETRY (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID


There is always a single Focus Window, even if some input
fields have only one IC.


4.20.2.  Converting a string


     XIM_STR_CONVERSION (IM Server -> IM library)




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X Input Method Protocol 		    X11, Release 6.8


	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  2	CARD16		    XIMStringConversionPosition
	  2			    unused
	  4	CARD32		    XIMCaretDirection
		#0		    XIMForwardChar
		#1		    XIMBackwardChar
		#2		    XIMForwardWord
		#3		    XIMBackwardWord
		#4		    XIMCaretUp
		#5		    XIMCaretDown
		#6		    XIMNextLine
		#7		    XIMCPreviousLine
		#8		    XIMLineStart
		#9		    XIMLineEnd
		#10		    XIMAbsolutePosition
		#11		    XIMDontChange
	  2	CARD16		    factor
	  2	CARD16		    XIMStringConversionOperation
		#0001		    XIMStringConversionSubstitution
		#0002		    XIMStringConversionRetrieval
	  2	INT16		    byte length to multiply the XIM-
				    StringConversionType



XIM_STR_CONVERSION message may be used to start the string
conversion from the IM Server.


     XIM_STR_CONVERSION_REPLY (IM library -> IM Server)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  4	CARD32		    XIMStringConversionFeedback
		XIMSTRCONVTEXT	    XIMStringConversionText



XIM_STR_CONVERSION_REPLY message returns the string to be
converted and the feedback information array.


4.20.3.  Preedit Callbacks

The IM Server sends XIM_PREEDIT_START message to call the
XIMPreeditStartCallback function.

     XIM_PREEDIT_START (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID


The reply to this message must be sent synchronously. The
reply forwards the return value from the callback function



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X Input Method Protocol 		    X11, Release 6.8


to the IM Server.

     XIM_PREEDIT_START_REPLY (IM library -> IM Server)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  4	INT32		    return value


XIM_PREEDIT_START_REPLY message returns the input-context-ID
to distinguish replies from multiple IC's.  The return value
contains the return value of the function XIMPreeditStart-
Callback.

The IM Server sends XIM_PREEDIT_DRAW message to call the
XIMPreeditDrawCallback function.

     XIM_PREEDIT_DRAW (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  4	INT32		    caret
	  4	INT32		    chg_first
	  4	INT32		    chg_length
	  4	BITMASK32	    status
		#x0000001	    no string
		#x0000002	    no feedback
	  2	n		    length of preedit string
	  n	STRING8 	    preedit string
	  p			    unused, p = Pad(2+n)
	  2	m		    byte length of feedback array
	  2			    unused
	  m	LISTofXIMFEEDBACK   feedback array


The fields ``caret'', ``chg_first'' and ``chg_length'' cor-
respond to the fields of XIMPreeditDrawCallbackStruct.	When
the ``no string'' bit of the status field is set, the text
field of XIMPreeditDrawCallbackStruct is NULL.	When the
``no feedback'' bit of the status field is set, the text
feedback field of XIMPreeditDrawCallbackStruct is NULL.
When the above bits are not set, ``preedit string'' contains
the preedit string to be displayed, and the feedback array
contains feedback information.

The IM Server sends XIM_PREEDIT_CARET message to call the
PreeditCaretCallback function.

     XIM_PREEDIT_CARET (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  4	INT32		    position
	  4	CARD32		    direction
		#0		    XIMForwardChar
		#1		    XIMBackwardChar




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X Input Method Protocol 		    X11, Release 6.8


		#2		    XIMForwardWord
		#3		    XIMBackwardWord
		#4		    XIMCaretUp
		#5		    XIMCaretDown
		#6		    XIMNextLine
		#7		    XIMCPreviousLine
		#8		    XIMLineStart
		#9		    XIMLineEnd
		#10		    XIMAbsolutePosition
		#11		    XIMDontChange
	  4	CARD32		    style
		#0		    XIMInvisible
		#1		    XIMCPrimary
		#2		    XIMSecondary


Each entry corresponds to a field of XIMPreeditCaretCall-
backStruct.  Since this callback sets the caret position,
its reply must be sent synchronously.

     XIM_PREEDIT_CARET_REPLY (IM library -> IM Server)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  4	CARD32		    position


The position is the value returned by the callback function
after it has been called.

The IM Server sends XIM_PREEDIT_DONE message to call the
XIMPreeditDoneCallback function.

     XIM_PREEDIT_DONE (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID



4.20.4.  Preedit state notify

     XIM_PREEDITSTATE (IM Server -> IM Library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  4	BITMASK32	    XIMPreeditState
		#x0000000	    XIMPreeditUnknown
		#x0000001	    XIMPreeditEnable
		#x0000002	    XIMPreeditDisable




XIM_PREEDITSTATE message is used to call the XIMPreedit-
StateNotifyCallback function.




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X Input Method Protocol 		    X11, Release 6.8


4.20.5.  Status Callbacks

The IM Server sends XIM_STATUS_START message to call the
XIMStatusStartCallback function.

     XIM_STATUS_START (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID


The IM Server sends XIM_STATUS_DRAW message to call the XIM-
StatusDrawCallback function.

     XIM_STATUS_DRAW (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  4	CARD32		    type
		#0		    XIMTextType
		#1		    XIMBitmapType


     If type is XIMTextType, the arguments continue as fol-
     lows.

	  4	BITMASK32	    status
		#x0000001	    no string
		#x0000002	    no feedback
	  2	n		    length of status string
	  n	STRING8 	    status string
	  p			    unused, p = Pad(2+n)
	  2	m		    byte length of feedback array
	  2			    unused
	  m	LISTofXIMFEEDBACK   feedback array


     If type is XIMBitmapType, the arguments continue as
     follows.

	  4	PIXMAP		    pixmap data


The field ``type'' corresponds to the field in XIMStatus-
DrawCallbackStruct.

The IM Server sends XIM_STATUS_DONE message to call the XIM-
StatusDoneCallback function.

     XIM_STATUS_DONE (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID







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X Input Method Protocol 		    X11, Release 6.8


5.  Acknowledgements

This document represents the culmination of several years of
debate and experiments done under the auspices of the MIT X
Consortium i18n working group.	Although this was a group
effort, the author remains responsible for any errors or
omissions.

We would like to thank to all members of this group.  And we
would like to make special thanks to the following people
(in alphabetical order) for their participation in the IM
Protocol design, Hector Chan, Takashi Fujiwara, Yoshio Hori-
uchi, Makoto Inada, Hiromu Inukai, Mickael Kung, Seiji
Kuwari, Franky Ling, Hiroyuki Machida, Hiroyuki Miyamoto,
Frank Rojas, Bob Scheifler, Makiko Shimamura, Shoji
Sugiyama, Hidetoshi Tajima, Masaki Takeuchi, Makoto Waka-
matsu, Masaki Wakao, Nobuyuki Tanaka, Shigeru Yamada, Kat-
suhisa Yano, Jinsoo Yoon.


6.  References

All of the following documents are X Consortium standards
available from MIT:

[1] Scheifler, Robert W., ``X Window System Protocol Version
11''

[2] Scheifler, Robert W. etc., ``Xlib - C Language X Inter-
face''



























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X Input Method Protocol 		    X11, Release 6.8


			 Appendix A

		     Common Extensions


Extension opcodes and packet names (e.g.
XIM_EXT_SET_EVENT_MASK ) for additional extensions may be
registered with X Consortium.  The following is a commonly
well-known extended packet.



(1)  Extension to manipulate the event handling

XIM_EXT_SET_EVENT_MASK message specifies the set of event
masks that the IM library should manipulate.

     XIM_EXT_SET_EVENT_MASK (IM Server -> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  4	EVENTMASK	    filter-event-mask (*1)
	  4	EVENTMASK	    intercept-event-mask (*2)
	  4	EVENTMASK	    select-event-mask (*3)
	  4	EVENTMASK	    forward-event-mask (*4)
	  4	EVENTMASK	    synchronous-event-mask (*5)


     (*1) Specify the events to be neglected by the IM
	  library via XFilterEvent.

     (*2) Specify the events to be deselected by the IM
	  library with XSelectInput.

     (*3) Specify the events to be selected by the IM
	  library with XSelectInput.

     (*4) Specify all the events to be forwarded to the IM
	  Server by the IM library.

     (*5) Specify the events to be forwarded with synchro-
	  nous flag on by the IM library.

The IM library must reply XIM_SYNC_REPLY message to the IM
Server. This request is valid after the ic is created.



(2)  Extension for improvement of performance

The following requests may be used for improvement of per-
formance.

XIM_EXT_FORWARD_KEYEVENT message may be used instead of
XIM_FORWARD_EVENT message.



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X Input Method Protocol 		    X11, Release 6.8


     XIM_EXT_FORWARD_KEYEVENT (IM Server <--> IM library)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  2	BITMASK16	    flag
		#0001		    synchronous
	  2	CARD16		    sequence number
	  1	BYTE		    xEvent.u.u.type
	  1	BYTE		    keycode
	  2	CARD16		    state
	  4	CARD32		    time
	  4	CARD32		    window














































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X Input Method Protocol 		    X11, Release 6.8


XIM_EXT_MOVE message may be used to change the spot location
instead of  XIM_SET_IC_VALUES message.	It is effective only
if the client specified XIMPreeditPosition.

     XIM_EXT_MOVE (IM library -> IM Server)
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  2	INT16		    X
	  2	INT16		    Y


XIM_EXT_MOVE message is a asynchronous request.













































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X Input Method Protocol 		    X11, Release 6.8


			 Appendix B

The list of transport specific IM Server address format registered


The following format represents the ATOM contained in
XIM_SERVERS property and the string returned from the
request converting selection target LOCALES and TRANSPORT.

	  ``{@category=[value,...]}...''


The following categories are currently registered.

     server	 : IM Server name (used for XIM_SERVERS)
     locale	 : XPG4 locale name (LOCALES)
     transport	 : transport-specific name (TRANSPORT)


The preregistered formats for transport-specific names are
as follows:

     TCP/IP Names

	  The following syntax should be used for system
	  internal domain names:

	       <local name>  ::= ``local/''<hostname>``:''<pathname>


	  Where <pathname> is a path name of socket address.

	  IM Server's name should be set to <pathname> to
	  run multiple IM Server at the same time

	  The following syntax should be used for Internet
	  domain names:

	       <TCP name>  ::=	``tcp/''<hostname>``:''<ipportnumber>

	  where <hostname> is either symbolic (such as
	  expo.lcs.mit.edu) or numeric decimal (such as
	  18.30.0.212).  The <ipportnumber> is the port on
	  which the IM Server is listening for connections.
	  For example:

	       tcp/expo.lcs.mit.edu:8012
	       tcp/18.30.0.212:7890


     DECnet Names

	  The following syntax should be used for DECnet
	  names:



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X Input Method Protocol 		    X11, Release 6.8


	       <DECnet name>  ::=  ``decnet/''<nodename>``::IMSERVER$''<objname>

	  where <nodename> is either symbolic (such as
	  SRVNOD) or the numeric decimal form of the DECnet
	  address (such as 44.70).  The <objname> is normal,
	  case-insensitive DECnet object name. For example:

	       DECNET/SRVNOD::IMSERVER$DEFAULT
	       decnet/44.70::IMSERVER$other


     X Names

	  The following syntax should be used for X names:

	       <X name>  ::=  ``X/''


If a given category has multiple values, the value is evalu-
ated in order of setting.





































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X Input Method Protocol 		    X11, Release 6.8


			 Appendix C

		      Protocol number


Major Protocol number

	 XIM_CONNECT			       #001
	 XIM_CONNECT_REPLY		       #002
	 XIM_DISCONNECT 		       #003
	 XIM_DISCONNECT_REPLY		       #004

	 XIM_AUTH_REQUIRED		       #010
	 XIM_AUTH_REPLY 		       #011
	 XIM_AUTH_NEXT			       #012
	 XIM_AUTH_SETUP 		       #013
	 XIM_AUTH_NG			       #014

	 XIM_ERROR			       #020

	 XIM_OPEN			       #030
	 XIM_OPEN_REPLY 		       #031
	 XIM_CLOSE			       #032
	 XIM_CLOSE_REPLY		       #033
	 XIM_REGISTER_TRIGGERKEYS	       #034
	 XIM_TRIGGER_NOTIFY		       #035
	 XIM_TRIGGER_NOTIFY_REPLY	       #036
	 XIM_SET_EVENT_MASK		       #037
	 XIM_ENCODING_NEGOTIATION	       #038
	 XIM_ENCODING_NEGOTIATION_REPLY        #039
	 XIM_QUERY_EXTENSION		       #040
	 XIM_QUERY_EXTENSION_REPLY	       #041
	 XIM_SET_IM_VALUES		       #042
	 XIM_SET_IM_VALUES_REPLY	       #043
	 XIM_GET_IM_VALUES		       #044
	 XIM_GET_IM_VALUES_REPLY	       #045

	 XIM_CREATE_IC			       #050
	 XIM_CREATE_IC_REPLY		       #051
	 XIM_DESTROY_IC 		       #052
	 XIM_DESTROY_IC_REPLY		       #053
	 XIM_SET_IC_VALUES		       #054
	 XIM_SET_IC_VALUES_REPLY	       #055
	 XIM_GET_IC_VALUES		       #056
	 XIM_GET_IC_VALUES_REPLY	       #057
	 XIM_SET_IC_FOCUS		       #058
	 XIM_UNSET_IC_FOCUS		       #059
	 XIM_FORWARD_EVENT		       #060
	 XIM_SYNC			       #061
	 XIM_SYNC_REPLY 		       #062
	 XIM_COMMIT			       #063
	 XIM_RESET_IC			       #064
	 XIM_RESET_IC_REPLY		       #065




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X Input Method Protocol 		    X11, Release 6.8



	 XIM_GEOMETRY			       #070
	 XIM_STR_CONVERSION		       #071
	 XIM_STR_CONVERSION_REPLY	       #072
	 XIM_PREEDIT_START		       #073
	 XIM_PREEDIT_START_REPLY	       #074
	 XIM_PREEDIT_DRAW		       #075
	 XIM_PREEDIT_CARET		       #076
	 XIM_PREEDIT_CARET_REPLY	       #077
	 XIM_PREEDIT_DONE		       #078
	 XIM_STATUS_START		       #079
	 XIM_STATUS_DRAW		       #080
	 XIM_STATUS_DONE		       #081
	 XIM_PREEDITSTATE		       #082


(*) The IM Server's extension protocol number should be more
than #128.







































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X Input Method Protocol 		    X11, Release 6.8


			 Appendix D

		    Implementation Tips



(1)  FrontEnd Method

FrontEnd method is recognized as a performance acceleration
by the trade off of the variety of the reliability.

In order to use the FrontEnd method, the IM library must
query the IM Server to see if the FrontEnd extension is
available.  The query is made by using the XIM_QUERY_EXTEN-
SION message. The IM Server may send XIM_EXT_SET_EVENT_MASK
message with intercept-event-mask, forward-event-mask, and
synchronous-event-mask values set after replying
XIM_QUERY_EXTENSION_REPLY message.

FrontEnd method can be implemented in a couple of ways
depending on how the IM Server utilize
XIM_EXT_SET_EVENT_MASK message.

One approach is to update both of the input mask and the
filter-event-mask depending on the preeidting state. The
sample protocol sequence using the static event flow is as
follows:


... 1.675 6.888 6.237 10.296 ... 0.000i 3.408i 4.562i 0.000i

		IM library		    IM Server
       Keys in the on-key-list		    |
	     _________-|_XIM_FORWARD_EVENT  |
		       |_________________   |
		       |XIM_EXT_SET_EVENT_MASK
	 event mask is changedrcept-event-maskvistsetsk is changed
	 to deselect the event		    |to select the event
		       |		    |
		       |		    |_______
		       |		    |--
		       |		    | X events directly come
		       |		    | to the IM Server.
		       |		    | when preediting is turning off
		       |_________________   |
	 event mask is changedT_SET_EVENT_MASKevent mask is changed
	 to select the eventlect-event-mask istseteselect the event
		       |		    |
		       |		    |
		       |		    |
		       |		    |
		       |		    |





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X Input Method Protocol 		    X11, Release 6.8


To pursuit a maximum performance regardless of the preedit-
ing mode, the IM Server may use the dynamic event flow with
the following sample protocol sequence.






















































			     45





X Input Method Protocol 		    X11, Release 6.8


... 1.675 6.888 6.237 10.296 ... 0.000i 3.408i 4.562i 0.000i

		IM library		    IM Server
       Keys in the on-key-list		    |
	     _________-|_XIM_TRIGGER_NOTIFY |
		       |_________________   |
		       |XIM_EXT_SET_EVENT_MASK
	 event mask is changedrcept-event-maskvistsetsk is changed
	 to deselect theXeventIGGER_NOTIFY_REPLYselect the event
		       |_________________   |
		       |		    |_______
		       |		    |--
		       |		    | X events directly come
		       |		    | to the IM Server.
		       |		    | when preediting is turning off
		       |_________________   |
	 event mask is changedT_SET_EVENT_MASKevent mask is changed
	 to select the eventlect-event-mask istseteselect the event
		       |		    |
		       |		    |
		       |		    |
		       |		    |
		       |		    |


This method can reduce the XIM protocol traffic dramatically
by updating intercept-event-mask and select-event-mask
accordingly.  The tradeoff of this performance improvement
is that the key events may be lost or disordered in some
particular situation, such as when the user types the key-
board in following sequence really fast:
     <preediting on key>``some strings''<preediting off
     key>``another string''
Since this method requires the input mask updates to the
both the IM Server and Xlib when turning on and off the
preediting, and there is a time lag till the requests take
effect when two client issues the input mask updates simul-
taneously.

Another approach of the FrontEnd method is to update the
filter-event-mask depending on the preediting state and not
to update the input mask.  The IM Server must register both
of the preediting on key list and off key list by XIM_REGIS-
TER_TRIGGERKEYS message.  In this method, Both the IM Server
and the IM client select the same events on the same
client's window, so that the events are delivered to both of
the IM Server and the client. The preediting on and off
states are expressed by whether the key events are filtered
or not.  The sample protocol sequence are as follows:








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X Input Method Protocol 		    X11, Release 6.8


<<Using static event flow>>


... 1.488 7.325 6.487 10.358 ... 0.000i 3.033i 4.999i 0.000i

		IM library		    IM Server

     Keys in the_on-key-lXIM_FORWARD_EVENT  |__Keys_in_the on-key-list
		      | _________________-  |--
		      | XIM_EXT_SET_EVENT_MASK
	   the specified eventsr-event-mask istsetspecified events
	   are being filtered		    | are being processed
		      | 		    |
		      | 		    |
      Keys in the off-key-list		    |  Keys in the off-key-list
	     _________| 		    |__________
		      |  _________________  |
		      | XIfilter-event-maskAis set
		      | 		    |
	   the specified events 	    | the specified events
	   are being processed		    | are being discarded
		      | 		    |
		      | 		    |
		      | 		    |
		      | 		    |

<<Using the dynamic event flow>>

... 1.488 7.325 6.487 10.358 ... 0.000i 3.033i 4.999i 0.000i

		IM library		    IM Server

     Keys in the_on-key-list_TRIGGER_NOTIFY |__Keys_in_the on-key-list
		      | _________________-  |--
		      | XIM_EXT_SET_EVENT_MASK
	   the specified eventsr-event-mask istsetspecified events
	   are being filtered		    | are being processed
		      | XIM_TRIGGER_NOTIFY_REPLY
		      | _________________   |
      Keys in the off-key-list		    |  Keys in the off-key-list
	     _________| 		    |__________
		      |  _________________  |
		      | XIfilter-event-maskAis set
		      | 		    |
	   the specified events 	    | the specified events
	   are being processed		    | are being discarded
		      | 		    |
		      | 		    |
		      | 		    |
		      | 		    |


This method does not have the problem of the time lag when
going across the preediting on and off mode, however, the



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X Input Method Protocol 		    X11, Release 6.8


amount of the performance acceleration is not as good as the
method described above.

In general, the FrontEnd method requires some synchroniza-
tion to some of the X protocols, such as the ChangeWindowAt-
tribute protocol for the event mask change or the GrabKey
protocol, since it relies on the X's principal event dis-
patching mechanism. Any X protocol bindings do not consider
the synchronization might cause some mis-synchronization
between the IM clients and the IM Server.















































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X Input Method Protocol 		    X11, Release 6.8


(2)  Transport Layer

The Xlib XIM implementation is layered into three functions,
a protocol layer, an interface layer and a transport layer.
The purpose of this layering is to make the protocol inde-
pendent of transport implementation.  Each function of these
layers are:

     The protocol layer
	  implements overall function of XIM and calls the
	  interface layer functions when it needs to commu-
	  nicate to IM Server.

     The interface layer
	  separates the implementation of the transport
	  layer from the protocol layer, in other words, it
	  provides implementation independent hook for the
	  transport layer functions.

     The transport layer
	  handles actual data communication with IM Server.
	  It is done by a set of several functions named
	  transporters.

The interface layer and the transport layer make various
communication channels usable such as X Protocol, TCP/IP,
DECnet or STREAM.  The following is a sample implementation
for the transporter using the X connection.  Refer to
"xtrans" for the transporter using Socket Transport.

At the beginning of the X Transport connection for the XIM
transport mechanism, two different windows must be created
either in an Xlib XIM or in an IM Server, with which the
Xlib and the IM Server exchange the XIM transports by using
the ClientMessage events and Window Properties.  In the fol-
lowing, the window created by the Xlib is referred as the
"client communication window", and on the other hand, the
window created by the IM Server is referred as the "IMS com-
munication window".

Connection

     In order to establish a connection, a communication
     window is created.  A ClientMessage in the following
     event's format is sent to the owner window of
     XIM_SERVER selection, which the IM Server has created.

     Refer to "The Input Method Protocol" for the XIM_SERVER
     atom.

      Table D-1; The ClientMessage sent to the IMS window.






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X Input Method Protocol 		    X11, Release 6.8


     -----------------------+------------------------------------------------
     Structure Member	    | Contents
     -----------------------+------------------------------------------------
     int       type	    | ClientMessage
     u_long    serial	    | Set by the X Window System
     Bool      send_event   | Set by the X Window System
     Display   *display     | The display to which connects
     Window    window	    | IMS Window ID
     Atom      message_type | XInternAtom(display, ``_XIM_XCONNECT'', False)
     int       format	    | 32
     long      data.l[0]    | client communication window ID
     long      data.l[1]    | client-major-transport-version (*1)
     long      data.l[2]    | client-major-transport-version (*1)
     -----------------------+------------------------------------------------


     In order to establish the connection (to notify the IM
     Server communication window), the IM Server sends a
     ClientMessage in the following event's format to the
     client communication window.





































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	 Table D-2; The ClientMessage sent by IM Server.

     -----------------------+-------------------------------------------------------
     Structure Member	    | Contents
     -----------------------+-------------------------------------------------------
     int       type	    | ClientMessage
     u_long    serial	    | Set by the X Window System
     Bool      send_event   | Set by the X Window System
     Display   *display     | The display to which connects
     Window    window	    | client communication window ID
     Atom      message_type | XInternAtom(display, ``_XIM_XCONNECT'', False)
     int       format	    | 32
     long      data.l[0]    | IMS communication window ID
     long      data.l[1]    | server-major-transport-version (*1)
     long      data.l[2]    | server-minor-transport-version (*1)
     long      data.l[3]    | dividing size between ClientMessage and Property (*2)
     -----------------------+-------------------------------------------------------



     (*1) major/minor-transport-version
	       The read/write method is decided by the com-
	       bination of major/minor-transport-version, as
	       follows:

	  Table D-3; The read/write method and the major/minor-transport-version

      +------------------+---------------------------------------+
      |Transport-version | read/write				 |
      +--------+---------+---------------------------------------+
      | major  |  minor  |					 |
      +--------+---------+---------------------------------------+
      |   0    |    0	 | only-CM & Property-with-CM		 |
      |        |    1	 | only-CM & multi-CM			 |
      |        |    2	 | only-CM & multi-CM & Property-with-CM |
      +--------+---------+---------------------------------------+
      |   1    |    0	 | PropertyNotify			 |
      +--------+---------+---------------------------------------+
      |   2    |    0	 | only-CM & PropertyNotify		 |
      |        |    1	 | only-CM & multi-CM & PropertyNotify	 |
      +--------+---------+---------------------------------------+



      only-CM		 :   data is sent via a ClientMessage
      multi-CM		 :   data is sent via multiple ClientMessages
      Property-with-CM	 :   data is written in Property, and its Atom
			     is send via ClientMessage
      PropertyNotify	 :   data is written in Property, and its Atom
			     is send via PropertyNotify


	  The method to decide major/minor-transport-version
	  is as follows:



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X Input Method Protocol 		    X11, Release 6.8


	  (1)  The client sends 0 as major/minor-transport-
	       version to the IM Server.  The client must
	       support all methods in Table D-3.  The client
	       may send another number as major/minor-trans-
	       port-version to use other method than the
	       above in the future.

	  (2)  The IM Server sends its major/minor-trans-
	       port-version number to the client. The client
	       sends data using the method specified by the
	       IM Server.

	  (3)  If major/minor-transport-version number is
	       not available, it is regarded as 0.


     (*2) dividing size between ClientMessage and Property
	       If data is sent via both of multi-CM and
	       Property, specify the dividing size between
	       ClientMessage and Property. The data, which
	       is smaller than this size, is sent via multi-
	       CM (or only-CM), and the data, which is lager
	       than this size, is sent via Property.



read/write

     The data is transferred via either ClientMessage or
     Window Property in the X Window System.

     Format for the data from the Client to the IM Server

	  ClientMessage

	  If data is sent via ClientMessage event, the for-
	  mat is as follows:

	  Table D-4; The ClientMessage event's format (first
			      or middle)

	  -----------------------+------------------------------------------------
	  Structure Member	 | Contents
	  -----------------------+------------------------------------------------
	  int	    type	 | ClientMessage
	  u_long    serial	 | Set by the X Window System
	  Bool	    send_event	 | Set by the X Window System
	  Display   *display	 | The display to which connects
	  Window    window	 | IMS communication window ID
	  Atom	    message_type | XInternAtom(display, ``_XIM_MOREDATA'', False)
	  int	    format	 | 8
	  char	    data.b[20]	 | (read/write DATA : 20 byte)
	  -----------------------+------------------------------------------------




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	  Table D-5; The ClientMessage event's format (only
			       or last)

	  -----------------------+------------------------------------------------
	  Structure Member	 | Contents
	  -----------------------+------------------------------------------------
	  int	    type	 | ClientMessage
	  u_long    serial	 | Set by the X Window System
	  Bool	    send_event	 | Set by the X Window System
	  Display   *display	 | The display to which connects
	  Window    window	 | IMS communication window ID
	  Atom	    message_type | XInternAtom(display, ``_XIM_PROTOCOL'', False)
	  int	    format	 | 8
	  char	    data.b[20]	 | (read/write DATA : MAX 20 byte)  (*1)
	  -----------------------+------------------------------------------------


	  (*1) If the data is smaller than 20 byte, all data
	       other than available data must be 0.

	  Property

	  In the case of large data, data will be sent via
	  the Window Property for the efficiency.  There are
	  the following two methods to notify Property, and
	  transport-version is decided which method is used.


	  (1)  The XChangeProperty function is used to store
	       data in the client communication window, and
	       Atom of the stored data is notified to the IM
	       Server via ClientMessage event.

	  (2)  The XChangeProperty function is used to store
	       data in the client communication window, and
	       Atom of the stored data is notified to the IM
	       Server via PropertyNotify event.

	  The arguments of the XChangeProperty are as fol-
	  lows:

















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	    Table D-6; The XChangeProperty event's format

	  --------------------+--------------------------------
	  Argument	      | Contents
	  --------------------+--------------------------------
	  Display   *display  | The display to which connects
	  Window    window    | IMS communication window ID
	  Atom	    property  | read/write property Atom (*1)
	  Atom	    type      | XA_STRING
	  int	    format    | 8
	  int	    mode      | PropModeAppend
	  u_char    *data     | read/write DATA
	  int	    nelements | length of DATA
	  --------------------+--------------------------------



	  (*1) The read/write property ATOM allocates the
	       following strings by XInternAtom.
		    ``_clientXXX''

	  The client changes the property with the mode of
	  PropModeAppend and the IM Server will read it with
	  the delete mode i.e. (delete = True).

	  If Atom is notified via ClientMessage event, the
	  format of the ClientMessage is as follows:

	  Table D-7; The ClientMessage event's format to
			send Atom of property

	  -----------------------+------------------------------------------------
	  Structure Member	 | Contents
	  -----------------------+------------------------------------------------
	  int	    type	 | ClientMessage
	  u_long    serial	 | Set by the X Window System
	  Bool	    send_event	 | Set by the X Window System
	  Display   *display	 | The display to which connects
	  Window    window	 | IMS communication window ID
	  Atom	    message_type | XInternAtom(display, ``_XIM_PROTOCOL'', False)
	  int	    format	 | 32
	  long	    data.l[0]	 | length of read/write property Atom
	  long	    data.l[1]	 | read/write property Atom
	  -----------------------+------------------------------------------------


     Format for the data from the IM Server to the Client

	  ClientMessage

	  The format of the ClientMessage is as follows:

	  Table D-8; The ClientMessage event's format (first
			      or middle)



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	  -----------------------+------------------------------------------------
	  Structure Member	 | Contents
	  -----------------------+------------------------------------------------
	  int	    type	 | ClientMessage
	  u_long    serial	 | Set by the X Window System
	  Bool	    send_event	 | Set by the X Window System
	  Display   *display	 | The display to which connects
	  Window    window	 | client communication window ID
	  Atom	    message_type | XInternAtom(display, ``_XIM_MOREDATA'', False)
	  int	    format	 | 8
	  char	    data.b[20]	 | (read/write DATA : 20 byte)
	  -----------------------+------------------------------------------------













































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	  Table D-9; The ClientMessage event's format (only
			       or last)

	  -----------------------+------------------------------------------------
	  Structure Member	 | Contents
	  -----------------------+------------------------------------------------
	  int	    type	 | ClientMessage
	  u_long    serial	 | Set by the X Window System
	  Bool	    send_event	 | Set by the X Window System
	  Display   *display	 | The display to which connects
	  Window    window	 | client communication window ID
	  Atom	    message_type | XInternAtom(display, ``_XIM_PROTOCOL'', False)
	  int	    format	 | 8
	  char	    data.b[20]	 | (read/write DATA : MAX 20 byte) (*1)
	  -----------------------+------------------------------------------------



	  (*1) If the data size is smaller than 20 bytes,
	       all data other than available data must be 0.

	  Property

	  In the case of large data, data will be sent via
	  the Window Property for the efficiency. There are
	  the following two methods to notify Property, and
	  transport-version is decided which method is used.


	  (1)  The XChangeProperty function is used to store
	       data in the IMS communication window, and
	       Atom of the property is sent via the
	       ClientMessage event.

	  (2)  The XChangeProperty function is used to store
	       data in the IMS communication window, and
	       Atom of the property is sent via PropertyNo-
	       tify event.

	  The arguments of the XChangeProperty are as fol-
	  lows:

	    Table D-10; The XChangeProperty event's format

	  --------------------+----------------------------------
	  Argument	      | Contents
	  --------------------+----------------------------------
	  Display   *display  | The display which to connects
	  Window    window    | client communication window ID
	  Atom	    property  | read/write property Atom (*1)
	  Atom	    type      | XA_STRING
	  int	    format    | 8
	  int	    mode      | PropModeAppend




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X Input Method Protocol 		    X11, Release 6.8


	  --------------------+----------------------------------
	  Argument	      | Contents
	  --------------------+----------------------------------
	  u_char    *data     | read/write DATA
	  int	    nelements | length of DATA
	  --------------------+----------------------------------



	  (*1) The read/write property ATOM allocates some
	       strings, which are not allocated by the
	       client, by XInternAtom.

	  The IM Server changes the property with the mode
	  of PropModeAppend and the client reads it with the
	  delete mode, i.e. (delete = True).

	  If Atom is notified via ClientMessage event, the
	  format of the ClientMessage is as follows:






































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X Input Method Protocol 		    X11, Release 6.8


	  Table D-11; The ClientMessage event's format to
			send Atom of property

	  -----------------------+------------------------------------------------
	  Structure Member	 | Contents
	  -----------------------+------------------------------------------------
	  int	    type	 | ClientMessage
	  u_long    serial	 | Set by the X Window System
	  Bool	    send_event	 | Set by the X Window System
	  Display   *display	 | The display to which connects
	  Window    window	 | client communication window ID
	  Atom	    message_type | XInternAtom(display, ``_XIM_PROTOCOL'', False)
	  int	    format	 | 32
	  long	    data.l[0]	 | length of read/write property ATOM
	  long	    data.l[1]	 | read/write property ATOM
	  -----------------------+------------------------------------------------


Closing Connection

     If the client disconnect with the IM Server, shutdown
     function should free the communication window proper-
     ties and etc..


































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X Input Method Protocol 		    X11, Release 6.8


		     Table of Contents


1. Introduction  . . . . . . . . . . . . . . . . . . . .   1
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . .   1
1.2. Background  . . . . . . . . . . . . . . . . . . . .   1
1.3. Input Method Styles . . . . . . . . . . . . . . . .   2
2. Architecture  . . . . . . . . . . . . . . . . . . . .   3
2.1. Implementation Model  . . . . . . . . . . . . . . .   3
2.2. Structure of IM . . . . . . . . . . . . . . . . . .   3
2.3. Event Handling Model  . . . . . . . . . . . . . . .   4
2.3.1. BackEnd Method  . . . . . . . . . . . . . . . . .   4
2.3.2. FrontEnd Method . . . . . . . . . . . . . . . . .   4
2.4. Event Flow Control  . . . . . . . . . . . . . . . .   6
3. Default Preconnection Convention  . . . . . . . . . .   7
4. Protocol  . . . . . . . . . . . . . . . . . . . . . .   7
4.1. Basic Requests Packet Format  . . . . . . . . . . .   8
4.2. Data Types  . . . . . . . . . . . . . . . . . . . .   8
4.3. Error Notification  . . . . . . . . . . . . . . . .  12
4.4. Connection Establishment  . . . . . . . . . . . . .  13
4.5. Event Flow Control  . . . . . . . . . . . . . . . .  18
4.6. Encoding Negotiation  . . . . . . . . . . . . . . .  20
4.7. Query the supported extension protocol list . . . .  21
4.8. Setting IM Values . . . . . . . . . . . . . . . . .  22
4.9. getting IM Values . . . . . . . . . . . . . . . . .  22
4.10. Creating an IC . . . . . . . . . . . . . . . . . .  23
4.11. Destroying the IC  . . . . . . . . . . . . . . . .  23
4.12. Setting IC Values  . . . . . . . . . . . . . . . .  24
4.13. Getting IC Values  . . . . . . . . . . . . . . . .  24
4.14. Setting IC Focus . . . . . . . . . . . . . . . . .  25
4.15. Unsetting IC Focus . . . . . . . . . . . . . . . .  25
4.16. Filtering Events . . . . . . . . . . . . . . . . .  26
4.17. Synchronizing with the IM Server . . . . . . . . .  29
4.18. Sending a committed string . . . . . . . . . . . .  30
4.19. Reset IC . . . . . . . . . . . . . . . . . . . . .  30
4.20. Callbacks  . . . . . . . . . . . . . . . . . . . .  31
4.20.1. Negotiating geometry . . . . . . . . . . . . . .  31
4.20.2. Converting a string  . . . . . . . . . . . . . .  31
4.20.3. Preedit Callbacks  . . . . . . . . . . . . . . .  32
4.20.4. Preedit state notify . . . . . . . . . . . . . .  34
4.20.5. Status Callbacks . . . . . . . . . . . . . . . .  35
5. Acknowledgements  . . . . . . . . . . . . . . . . . .  36
6. References  . . . . . . . . . . . . . . . . . . . . .  36
Appendix A - Common Extensions . . . . . . . . . . . . .  37
Appendix B - The list of transport specific IM
Server names registered  . . . . . . . . . . . . . . . .  40
Appendix C - Protocol number . . . . . . . . . . . . . .  42
Appendix D - Implementation Tips . . . . . . . . . . . .  44












