1mThe Input Method Protocol0m

			1mVersion 1.00m

		   1mX Consortium Standard0m

		 1mX Version 11, Release 6.40m





		      4mMasahiko24m 4mNarita0m
		      FUJITSU Limited.

			4mHideki24m 4mHiura0m
		       SunSoft, Inc.





			  4mABSTRACT0m

     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 © 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 © 1993, 1994 by FUJITSU LIMITED

      Copyright © 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.



























































1m1.  Introduction0m

1m1.1.	Scope0m

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.


1m1.2.	Background0m

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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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.


1m1.3.	Input Method Styles0m

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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			 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.


1m2.  Architecture0m

1m2.1.	Implementation Model0m

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.


1m2.2.	Structure of IM0m

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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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.)


1m2.3.	Event Handling Model0m

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)


1m2.3.1.  BackEnd Method0m

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'').


1m2.3.2.  FrontEnd Method0m

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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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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... 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


1m2.4.	Event Flow Control0m

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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is significantly reduced, and the number of context switches
is also reduced, resulting in improved performance.  The IM
Server can send 4mXIM_REGISTER_TRIGGERKEYS24m 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''.


1m3.  Default Preconnection Convention0m

IM Servers are strongly encouraged to register their sym-
bolic names as the ATOM names into the IM Server directory
property, 4mXIM_SERVERS,24m 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
4mTRANSPORT,24m which will return a string form of the transport
address(es).  To learn the supported locales of that IM
Server, convert the selection target 4mLOCALES,24m 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 4mXIM_SERVERS24m property, is first
fit if the IM Server name is not given as a X modifier's
category 4mim.0m

The address information retrievable from the 4mTRANSPORT24m 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).


1m4.  Protocol0m

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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1m4.1.	Basic Requests Packet Format0m

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 4mXIM_QUERY_EXTENSION24m 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.


1m4.2.	Data Types0m

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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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:

     ------------------------------------------------------------------------------------------
     1mvalues	data			  format0m
     ------------------------------------------------------------------------------------------
     #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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     ------------------------------------------------------------------------------------------
     1mvalues	data			  format0m
     ------------------------------------------------------------------------------------------
					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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  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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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


1m4.3.	Error Notification0m

Both the IM Server and the IM library return 4mXIM_ERROR24m 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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choice of which error is returned is implementation-depen-
dent.


     1mXIM_ERROR (IM Server <--> IM library)0m
	  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


1m4.4.	Connection Establishment0m

4mXIM_CONNECT24m message requests to establish a connection over
a mutually-understood virtual stream.



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     1mXIM_CONNECT (IM library -> IM Server)0m
	  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 4mXIM_CONNECT24m 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.)

4mXIM_AUTH_REQUIRED24m message is used to send the authentication
protocol name and protocol-specific data.

     1mXIM_AUTH_REQUIRED (IM library <--> IM Server)0m
	  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 4mXIM_CONNECT24m or 4mXIM_AUTH_SETUP24m message.
Any protocol-specific data that might be required is also
sent.

The IM library sends 4mXIM_AUTH_REPLY24m message as the reply to
4mXIM_AUTH_REQUIRED24m message, if the IM Server is authenti-
cated.

     1mXIM_AUTH_REPLY (IM library -> IM Server)0m
	  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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4mXIM_AUTH_NEXT24m message requests to send more auth data.

     1mXIM_AUTH_NEXT (IM library <--> IM Server)0m
	  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 4mXIM_AUTH_SETUP24m message to authenticate
the client.

     1mXIM_AUTH_SETUP (IM Server -> IM library)0m
	  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.

4mXIM_AUTH_NG24m message requests to give up the connection.

     1mXIM_AUTH_NG (IM library <--> IM Server)0m


The IM Server sends 4mXIM_CONNECT_REPLY24m message as the reply
to 4mXIM_CONNECT24m or 4mXIM_AUTH_REQUIRED24m message.

     1mXIM_CONNECT_REPLY (IM Server -> IM library)0m
	  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.

1mState transitions for the client0m

     4minit_status24m:
	  Use authorization function -> 4mclient_ask0m
	  Not use authorization function -> 4mclient_no_check0m






			     1m150m





1mX Input Method Protocol		      X11, Release 6.10m


     4mstart24m:
	  Send 4mXIM_CONNECT0m
	       If 4mclient_ask24m -> 4mclient_wait10m
	       If 4mclient_no_check24m, client-auth-protocol-
	       names may be omited -> 4mclient_wait20m


     4mclient_wait124m:
	  Receive 4mXIM_AUTH_REQUIRED24m -> 4mclient_check0m
	  Receive <other> -> 4mclient_NG0m


     4mclient_check24m:
	  If no more auth needed, send 4mXIM_AUTH_REPLY24m ->
	  4mclient_wait20m
	  If good auth data, send 4mXIM_AUTH_NEXT24m ->
	  4mclient_wait10m
	  If bad auth data, send 4mXIM_AUTH_NG24m -> give up on
	  this protocol


     4mclient_wait224m:
	  Receive 4mXIM_CONNECT_REPLY24m -> connect
	  Receive 4mXIM_AUTH_SETUP24m -> 4mclient_more0m
	  Receive 4mXIM_AUTH_NEXT24m -> 4mclient_more0m
	  Receive 4mXIM_AUTH_NG24m -> give up on this protocol
	  Receive <other> -> 4mclient_NG0m


     4mclient_more24m:
	  Send 4mXIM_AUTH_REQUIRED24m -> 4mclient_wait20m


     4mclient_NG24m:
	  Send 4mXIM_AUTH_NG24m -> give up on this protocol


1mState transitions for the IM Server0m

     4minit-status24m:
	  Use authorization function -> 4mserver_ask0m
	  Not use authorization function -> 4mserver_no_check0m


     4mstart24m:
	  Receive 4mXIM_CONNECT24m -> 4mstart20m
	  Receive <other> -> 4mserver_NG0m


     4mstart224m:
	  If 4mclient_ask24m, send 4mXIM_AUTH_REQUIRED24m ->
	  4mserver_wait10m
	  If 4mclient_no_check24m and 4mserver_ask24m, send
	  4mXIM_AUTH_SETUP24m -> 4mserver_wait20m



			     1m160m





1mX Input Method Protocol		      X11, Release 6.10m


	  If 4mclient_no_check24m and 4mserver_no_check24m, send
	  4mXIM_CONNECT_REPLY24m -> connect


     4mserver_wait124m:
	  Receive 4mXIM_AUTH_REPLY24m -> 4mserver20m
	  Receive 4mXIM_AUTH_NEXT24m -> 4mserver_more0m
	  Receive <other> -> 4mserver_NG0m


     4mserver_more0m
	  Send 4mXIM_AUTH_REQUIRED24m -> 4mserver_wait10m


     4mserver20m
	  If 4mserver_ask24m, send 4mXIM_AUTH_SETUP24m -> 4mserver_wait20m
	  If 4mserver_no_check24m, send 4mXIM_CONNECT_REPLY24m -> con-
	  nect


     4mserver_wait20m
	  Receive 4mXIM_AUTH_REQUIRED24m -> 4mserver_check0m
	  Receive <other> -> 4mserver_NG0m


     4mserver_check0m
	  If no more auth data, send 4mXIM_CONNECT_REPLY24m ->
	  connect
	  If bad auth data, send 4mXIM_AUTH_NG24m -> give up on
	  this protocol
	  If good auth data, send 4mXIM_AUTH_NEXT24m ->
	  4mserver_wait20m


     4mserver_NG0m
	  Send 4mXIM_AUTH_NG24m -> give up on this protocol


4mXIM_DISCONNECT24m message requests to shutdown the connection
over a mutually-understood virtual stream.

     1mXIM_DISCONNECT (IM library -> IM Server)0m


4mXIM_DISCONNECT24m is a synchronous request.  The IM library
should wait until it receives either an 4mXIM_DISCONNECT_REPLY0m
packet or an 4mXIM_ERROR24m packet.


     1mXIM_DISCONNECT_REPLY (IM Server -> IM library)0m


4mXIM_OPEN24m requests to establish a logical connection between
the IM library and the IM Server.



			     1m170m





1mX Input Method Protocol		      X11, Release 6.10m


     1mXIM_OPEN (IM library -> IM Server)0m
	  n	STR		    locale name
	  p			    unused, p = Pad(n)


4mXIM_OPEN24m is a synchronous request.	 The IM library should
wait until receiving either an 4mXIM_OPEN_REPLY24m packet or an
4mXIM_ERROR24m packet.


     1mXIM_OPEN_REPLY (IM Server -> IM library)0m
	  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


4mXIM_OPEN_REPLY24m 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.

4mXIM_CLOSE24m message requests to shutdown the logical connec-
tion between the IM library and the IM Server.

     1mXIM_CLOSE (IM library -> IM Server)0m
	  2	CARD16		    input-method-ID
	  2			    unused


4mXIM_CLOSE24m is a synchronous request.  The IM library should
wait until receiving either an 4mXIM_CLOSE_REPLY24m packet or an
4mXIM_ERROR24m packet.


     1mXIM_CLOSE_REPLY (IM Server -> IM library)0m
	  2	CARD16		    input-method-ID
	  2			    unused



1m4.5.	Event Flow Control0m

An IM Server must send 4mXIM_SET_EVENT_MASK24m message to the IM
library in order for events to be forwarded to the IM



			     1m180m





1mX Input Method Protocol		      X11, Release 6.10m


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.


     1mXIM_SET_EVENT_MASK (IM Server -> IM library)0m
	  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.


4mXIM_SET_EVENT_MASK24m is an asynchronous request.  The event
masks are valid immediately after they are set until changed
by another 4mXIM_SET_EVENT_MASK24m 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
4mXIM_REGISTER_TRIGGERKEYS24m message to the IM library before
sending 4mXIM_OPEN_REPLY24m message.  Or the IM library may sup-
pose that the IM Server uses the Static Event Flow model.

     1mXIM_REGISTER_TRIGGERKEYS (IM Server -> IM library)0m
	  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


4mXIM_REGISTER_TRIGGERKEYS24m 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 4mXIM_TRIGGER_NOTIFY0m
message that a key event matching either on-keys or off-keys
has been occurred.


     1mXIM_TRIGGER_NOTIFY (IM library -> IM Server)0m




			     1m190m





1mX Input Method Protocol		      X11, Release 6.10m


	  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.


4mXIM_TRIGGER_NOTIFY24m is a synchronous request.  The IM library
should wait until receiving either an 4mXIM_TRIG-0m
4mGER_NOTIFY_REPLY24m packet or an 4mXIM_ERROR24m packet.


     1mXIM_TRIGGER_NOTIFY_REPLY (IM Server -> IM library)0m
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID



1m4.6.	Encoding Negotiation0m

4mXIM_ENCODING_NEGOTIATION24m message requests to decide which
encoding to be sent across the wire.  When the negotiation
fails, the fallback default encoding is Portable Character
Encoding.

     1mXIM_ENCODING_NEGOTIATION (IM library -> IM Server).sp 6p0m
	  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 4mXIM_OPEN24m message via XOpenIM().  The name of encod-
ing may be registered with X Consortium.

4mXIM_ENCODING_NEGOTIATION24m is a synchronous request.	 The IM
library should wait until receiving either an 4mXIM_ENCOD-0m
4mING_NEGOTIATION_REPLY24m packet or an 4mXIM_ERROR24m packet.





			     1m200m





1mX Input Method Protocol		      X11, Release 6.10m


     1mXIM_ENCODING_NEGOTIATION_REPLY (IM Server -> IM library)0m
	  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



1m4.7.	Query the supported extension protocol list0m

4mXIM_QUERY_EXTENSION24m message requests to query the IM exten-
sions supported by the IM Server to which the client is
being connected.

     1mXIM_QUERY_EXTENSION (IM library -> IM Server)0m
	  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 4mXIM_OPEN24m 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 4mXIM_QUERY_EXTENSION24m message for that exten-
sion, the IM Server responds with a 4mBadProtocol24m error.  If
the IM Server encounters a request with an unknown MAJOR-
OPCODE or MINOR-OPCODE, it responds with a 4mBadProtocol0m
error.

4mXIM_QUERY_EXTENSION24m is a synchronous request.  The IM
library should wait until receiving either an
4mXIM_QUERY_EXTENSION_REPLY24m packet or an 4mXIM_ERROR24m packet.


     1mXIM_QUERY_EXTENSION_REPLY (IM Server -> IM library)0m
	  2	CARD16		    input-method-ID
	  2	n		    byte length of extensions supported
				    by both the IM library and the IM
				    Server






			     1m210m





1mX Input Method Protocol		      X11, Release 6.10m


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


4mXIM_QUERY_EXTENSION_REPLY24m message returns the list of exten-
sions supported by both the IM library and the IM Server. If
the list passed in 4mXIM_QUERY_EXTENSION24m 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.


1m4.8.	Setting IM Values0m

4mXIM_SET_IM_VALUES24m requests to set attributes to the IM.

     1mXIM_SET_IM_VALUES (IM library -> IM Server)0m
	  2	CARD16		     input-method-ID
	  2	n		     byte length of im-attribute
	  n	LISTofXIMATTRIBUTE   im-attributes


The im-attributes in 4mXIM_SET_IM_VALUES24m message are specified
as a LISTofXIMATTRIBUTE, specifying the attributes to be
set. Attributes other than the ones returned by
4mXIM_OPEN_REPLY24m message should not be specified.

4mXIM_SET_IM_VALUES24m is a synchronous request. The IM library
should wait until receiving either an 4mXIM_SET_IM_VAL-0m
4mUES_REPLY24m packet or an 4mXIM_ERROR24m packet, because it must
receive the error attribute if 4mXIM_ERROR24m message is
returned.

     1mXIM_SET_IM_VALUES_REPLY (IM Server -> IM library)0m
	  2	CARD16		    input-method-ID
	  2			    unused


4mXIM_SET_IM_VALUES_REPLY24m message returns the input-method-ID
to distinguish replies from multiple IMs.


1m4.9.	Getting IM Values0m

4mXIM_GET_IM_VALUES24m requests to query IM values supported by
the IM Server currently being connected.




			     1m220m





1mX Input Method Protocol		      X11, Release 6.10m


     1mXIM_GET_IM_VALUES (IM library -> IM Server)0m
	  2	CARD16		    input-method-ID
	  2	n		    byte length of im-attribute-id
	  n	LISTofCARD16	    im-attribute-id
	  p			    unused, p=Pad(n)


4mXIM_GET_IM_VALUES24m is a synchronous request.  The IM library
should wait until it receives either an 4mXIM_GET_IM_VAL-0m
4mUES_REPLY24m packet or an 4mXIM_ERROR24m packet.

     1mXIM_GET_IM_VALUES_REPLY (IM Server -> IM library)0m
	  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 4mXIM_GET_IM_VALUES_REPLY0m
message.  The order of the returned im-attribute values cor-
responds directly to that of the list passed with the
4mXIM_GET_IM_VALUES24m message.


1m4.10.	 Creating an IC0m

4mXIM_CREATE_IC24m message requests to create an IC.


     1mXIM_CREATE_IC (IM library -> IM Server)0m
	  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
4mXIM_CREATE_IC24m message.), and it should not be set to zero.

4mXIM_CREATE_IC24m is a synchronous request which returns the
input-context-ID.  The IM library should wait until it
receives either an 4mXIM_CREATE_IC_REPLY24m packet or an
4mXIM_ERROR24m packet.

     1mXIM_CREATE_IC_REPLY (IM Server -> IM library)0m
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID



1m4.11.	 Destroying the IC0m

4mXIM_DESTROY_IC24m message requests to destroy the IC.





			     1m230m





1mX Input Method Protocol		      X11, Release 6.10m


     1mXIM_DESTROY_IC (IM library -> IM Server)0m
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID


4mXIM_DESTROY_IC24m is a synchronous request. The IM library
should not free its resources until it receives an
4mXIM_DESTROY_IC_REPLY24m message because 4mXIM_DESTROY_IC24m message
may result in Callback packets such as 4mXIM_PREEDIT_DRAW24m and
4mXIM_PREEDIT_DONE.0m


     1mXIM_DESTROY_IC_REPLY (IM Server -> IM library)0m
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID



1m4.12.	 Setting IC Values0m

4mXIM_SET_IC_VALUES24m messages requests to set attributes to the
IC.

     1mXIM_SET_IC_VALUES (IM library -> IM Server)0m
	  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 4mXIM_SET_IC_VALUES24m message are specified
as a LISTofXICATTRIBUTE, specifying the attributes to be
set. Attributes other than the ones returned by
4mXIM_OPEN_REPLY24m message should not be specified.

4mXIM_SET_IC_VALUES24m is a synchronous request. The IM library
should wait until receiving either an 4mXIM_SET_IC_VAL-0m
4mUES_REPLY24m packet or an 4mXIM_ERROR24m packet, because it must
receive the error attribute if 4mXIM_ERROR24m message is
returned.

     1mXIM_SET_IC_VALUES_REPLY (IM Server -> IM library)0m
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID



1m4.13.	 Getting IC Values0m

4mXIM_GET_IC_VALUES24m message requests to query IC values sup-
ported by the IM Server currently being connected.





			     1m240m





1mX Input Method Protocol		      X11, Release 6.10m


     1mXIM_GET_IC_VALUES (IM library -> IM Server)0m
	  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.

4mXIM_GET_IC_VALUES24m is a synchronous request and returns each
attribute with its values to show the correspondence.  The
IM library should wait until receiving either an
4mXIM_GET_IC_VALUES_REPLY24m packet or an 4mXIM_ERROR24m packet.

     1mXIM_GET_IC_VALUES_REPLY (IM Server -> IM library)0m
	  2	CARD16		     input-method-ID
	  2	CARD16		     input-context-ID
	  2	n		     byte length of ic-attribute
	  2			     unused
	  n	LISTofXICATTRIBUTE   ic-attribute



1m4.14.	 Setting IC Focus0m

4mXIM_SET_IC_FOCUS24m message requests to set the focus to the
IC.

     1mXIM_SET_IC_FOCUS (IM library -> IM Server)0m
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID


4mXIM_SET_IC_FOCUS24m is an asynchronous request.


1m4.15.	 Unsetting IC Focus0m

4mXIM_UNSET_IC_FOCUS24m message requests to unset the focus to
the focused IC.

     1mXIM_UNSET_IC_FOCUS (IM library -> IM Server)0m
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID


4mXIM_UNSET_IC_FOCUS24m is an asynchronous request.







			     1m250m





1mX Input Method Protocol		      X11, Release 6.10m


1m4.16.	 Filtering Events0m

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

X Events are forwarded by 4mXIM_FORWARD_EVENT24m message.  This
message can be operated both synchronously and asyn-
chronously.  If the requester sets the synchronous flag, the
receiver must send 4mXIM_SYNC_REPLY24m message back to the
requester when all the data processing is done.

1mProtocol flow of BackEnd model0m


With BackEnd method, the protocol flow can be classified
into two methods in terms of synchronization, depending on
the synchronous-eventmask of 4mXIM_SET_EVENT_MASK24m 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 4mXIM_FORWARD_EVENT24m or 4mXIM_COMMIT24m message as a syn-
chronous request. Also, the IM Server needs to synchronously
process the correspondent reply from the IM library and the
following 4mXIM_FORWARD_EVENT24m message sent from the IM library
when any of the event causes the IM Server to send 4mXIM_FOR-0m
4mWARD_EVENT24m or 4mXIM_COMMIT24m 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 4mXIM_FORWARD_EVENT24m 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
4mXIM_FORWARD_EVENT24m message to the IM Server as a synchronous
request. Therefore, the reply to it from the IM Server will
be put between the 4mXIM_FORWARD_EVENT24m message and its
4mXIM_SYNC_REPLY24m message.  In case of sending 4mXIM_FOR-0m
4mWARD_EVENT24m or 4mXIM_COMMIT24m message, the IM Server should set
the synchronous flag off. Because the synchronization can be
done by the following 4mXIM_SYNC_REPLY24m message.


1mSample Protocol flow chart 10m

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




			     1m260m





1mX Input Method Protocol		      X11, Release 6.10m


	     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


1mSample Protocol flow chart 20m

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.























			     1m270m





1mX Input Method Protocol		      X11, Release 6.10m


... 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



     1mXIM_FORWARD_EVENT (IM library <--> IM Server)0m
	  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.





			     1m280m





1mX Input Method Protocol		      X11, Release 6.10m


     (*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).

4mXIM_FORWARD_EVENT24m 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 4mXIM_FOR-0m
4mWARD_EVENT24m 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.


1m4.17.	 Synchronizing with the IM Server0m

4mXIM_SYNC24m message requests to synchronize the IM library and
the IM Server.

     1mXIM_SYNC (IM library <--> IM Server)0m
	  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
4mXIM_SYNC24m 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.

     1mXIM_SYNC_REPLY (IM Server <--> IM library)0m
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID


The side which receives 4mXIM_FORWARD_EVENT,24m 4mXIM_COMMIT24m or any
other message with synchronous bit, should process all XIM
request before replying, and send 4mXIM_SYNC_REPLY24m message as
the reply to the previous message.








			     1m290m





1mX Input Method Protocol		      X11, Release 6.10m


1m4.18.	 Sending a committed string0m

When the IM Server commits a string, the IM Server sends
either the committed string or list of KeySym, or both, by
4mXIM_COMMIT24m message.

     1mXIM_COMMIT (IM Server -> IM library)0m
	  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 4mXIM_COMMIT24m message without syn-
chronous bit should set synchronous bit.


1m4.19.	 Reset IC0m

4mXIM_RESET_IC24m message requests to reset the status of IC in
the IM Server.

     1mXIM_RESET_IC (IM library -> IM Server)0m
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID




			     1m300m





1mX Input Method Protocol		      X11, Release 6.10m


4mXIM_RESET_IC24m is a synchronous request. The IM library should
wait until receiving either an 4mXIM_RESET_IC_REPLY24m packet or
an 4mXIM_ERROR24m packet.


     1mXIM_RESET_IC_REPLY (IM Server -> IM library)0m
	  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)


4mXIM_RESET_IC_REPLY24m message returns the input-context-ID to
distinguish replies from multiple ICs.


1m4.20.	 Callbacks0m

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.


1m4.20.1.  Negotiating geometry0m

The IM Server sends 4mXIM_GEOMETRY24m message to start geometry
negotiation, if XIMStyle has XIMPreeditArea or XIMStatusArea
set.

     1mXIM_GEOMETRY (IM Server -> IM library)0m
	  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.


1m4.20.2.  Converting a string0m


     1mXIM_STR_CONVERSION (IM Server -> IM library)0m




			     1m310m





1mX Input Method Protocol		      X11, Release 6.10m


	  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



4mXIM_STR_CONVERSION24m message may be used to start the string
conversion from the IM Server.


     1mXIM_STR_CONVERSION_REPLY (IM library -> IM Server)0m
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  4	CARD32		    XIMStringConversionFeedback
		XIMSTRCONVTEXT	    XIMStringConversionText



4mXIM_STR_CONVERSION_REPLY24m message returns the string to be
converted and the feedback information array.


1m4.20.3.  Preedit Callbacks0m

The IM Server sends 4mXIM_PREEDIT_START24m message to call the
XIMPreeditStartCallback function.

     1mXIM_PREEDIT_START (IM Server -> IM library)0m
	  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



			     1m320m





1mX Input Method Protocol		      X11, Release 6.10m


to the IM Server.

     1mXIM_PREEDIT_START_REPLY (IM library -> IM Server)0m
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  4	INT32		    return value


4mXIM_PREEDIT_START_REPLY24m 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 4mXIM_PREEDIT_DRAW24m message to call the
XIMPreeditDrawCallback function.

     1mXIM_PREEDIT_DRAW (IM Server -> IM library)0m
	  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 4mXIM_PREEDIT_CARET24m message to call the
PreeditCaretCallback function.

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




			     1m330m





1mX Input Method Protocol		      X11, Release 6.10m


		#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.

     1mXIM_PREEDIT_CARET_REPLY (IM library -> IM Server)0m
	  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 4mXIM_PREEDIT_DONE24m message to call the
XIMPreeditDoneCallback function.

     1mXIM_PREEDIT_DONE (IM Server -> IM library)0m
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID



1m4.20.4.  Preedit state notify0m

     1mXIM_PREEDITSTATE (IM Server -> IM Library)0m
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  4	BITMASK32	    XIMPreeditState
		#x0000000	    XIMPreeditUnknown
		#x0000001	    XIMPreeditEnable
		#x0000002	    XIMPreeditDisable




4mXIM_PREEDITSTATE24m message is used to call the XIMPreedit-
StateNotifyCallback function.




			     1m340m





1mX Input Method Protocol		      X11, Release 6.10m


1m4.20.5.  Status Callbacks0m

The IM Server sends 4mXIM_STATUS_START24m message to call the
XIMStatusStartCallback function.

     1mXIM_STATUS_START (IM Server -> IM library)0m
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID


The IM Server sends 4mXIM_STATUS_DRAW24m message to call the XIM-
StatusDrawCallback function.

     1mXIM_STATUS_DRAW (IM Server -> IM library)0m
	  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 4mXIM_STATUS_DONE24m message to call the XIM-
StatusDoneCallback function.

     1mXIM_STATUS_DONE (IM Server -> IM library)0m
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID







			     1m350m





1mX Input Method Protocol		      X11, Release 6.10m


1m5.  Acknowledgements0m

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.


1m6.  References0m

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

[1] Scheifler, Robert W., 4m``X24m 4mWindow24m 4mSystem24m 4mProtocol24m 4mVersion0m
4m11''0m

[2] Scheifler, Robert W. etc., 4m``Xlib24m 4m-24m 4mC24m 4mLanguage24m 4mX24m 4mInter-0m
4mface''0m



























			     1m360m





1mX Input Method Protocol		      X11, Release 6.10m


			 1mAppendix A0m

		     1mCommon Extensions0m


Extension opcodes and packet names (e.g.
4mXIM_EXT_SET_EVENT_MASK24m ) for additional extensions may be
registered with X Consortium.  The following is a commonly
well-known extended packet.



1m(1)  22mExtension to manipulate the event handling

4mXIM_EXT_SET_EVENT_MASK24m message specifies the set of event
masks that the IM library should manipulate.

     1mXIM_EXT_SET_EVENT_MASK (IM Server -> IM library)0m
	  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 4mXIM_SYNC_REPLY24m message to the IM
Server. This request is valid after the ic is created.



1m(2)  22mExtension for improvement of performance

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

4mXIM_EXT_FORWARD_KEYEVENT24m message may be used instead of
4mXIM_FORWARD_EVENT24m message.



			     1m370m





1mX Input Method Protocol		      X11, Release 6.10m


     1mXIM_EXT_FORWARD_KEYEVENT (IM Server <--> IM library)0m
	  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














































			     1m380m





1mX Input Method Protocol		      X11, Release 6.10m


4mXIM_EXT_MOVE24m 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.

     1mXIM_EXT_MOVE (IM library -> IM Server)0m
	  2	CARD16		    input-method-ID
	  2	CARD16		    input-context-ID
	  2	INT16		    X
	  2	INT16		    Y


4mXIM_EXT_MOVE24m message is a asynchronous request.













































			     1m390m





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			 1mAppendix B0m

1mThe list of transport specific IM Server address format registered0m


The following format represents the ATOM contained in
4mXIM_SERVERS24m property and the string returned from the
request converting selection target LOCALES and TRANSPORT.

	  ``{@4mcategory24m=[4mvalue24m,...]}...''


The following categories are currently registered.

     1mserver	   22m: IM Server name (used for XIM_SERVERS)
     1mlocale	   22m: XPG4 locale name (LOCALES)
     1mtransport   22m: transport-specific name (TRANSPORT)


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

     1mTCP/IP Names0m

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

	       <4mlocal24m 4mname24m>  ::= ``local/''<4mhostname24m>``:''<4mpathname24m>


	  Where <4mpathname24m> is a path name of socket address.

	  IM Server's name should be set to <4mpathname24m> to
	  run multiple IM Server at the same time

	  The following syntax should be used for Internet
	  domain names:

	       <4mTCP24m 4mname24m>  ::=  ``tcp/''<4mhostname24m>``:''<4mipportnumber24m>

	  where <4mhostname24m> is either symbolic (such as
	  expo.lcs.mit.edu) or numeric decimal (such as
	  18.30.0.212).	 The <4mipportnumber24m> 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


     1mDECnet Names0m

	  The following syntax should be used for DECnet
	  names:



			     1m400m





1mX Input Method Protocol		      X11, Release 6.10m


	       <4mDECnet24m 4mname24m>	::=  ``decnet/''<4mnodename24m>``::IMSERVER$''<4mobjname24m>

	  where <4mnodename24m> is either symbolic (such as
	  SRVNOD) or the numeric decimal form of the DECnet
	  address (such as 44.70).  The <4mobjname24m> is normal,
	  case-insensitive DECnet object name. For example:

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


     1mX Names0m

	  The following syntax should be used for X names:

	       <4mX24m 4mname24m>  ::=	``X/''


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





































			     1m410m





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			 1mAppendix C0m

		      1mProtocol number0m


1mMajor Protocol number0m

	 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




			     1m420m





1mX Input Method Protocol		      X11, Release 6.10m



	 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.







































			     1m430m





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			 1mAppendix D0m

		    1mImplementation Tips0m



1m(1)  22mFrontEnd 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 4mXIM_QUERY_EXTEN-0m
4mSION24m message. The IM Server may send 4mXIM_EXT_SET_EVENT_MASK0m
message with intercept-event-mask, forward-event-mask, and
synchronous-event-mask values set after replying
4mXIM_QUERY_EXTENSION_REPLY24m message.

FrontEnd method can be implemented in a couple of ways
depending on how the IM Server utilize
4mXIM_EXT_SET_EVENT_MASK24m 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
		       |		    |
		       |		    |
		       |		    |
		       |		    |
		       |		    |





			     1m440m





1mX Input Method Protocol		      X11, Release 6.10m


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.






















































			     1m450m





1mX Input Method Protocol		      X11, Release 6.10m


... 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 4mXIM_REGIS-0m
4mTER_TRIGGERKEYS24m 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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<<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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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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1m(2)  22mTransport 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:

     4mThe24m 4mprotocol24m 4mlayer0m
	  implements overall function of XIM and calls the
	  interface layer functions when it needs to commu-
	  nicate to IM Server.

     4mThe24m 4minterface24m 4mlayer0m
	  separates the implementation of the transport
	  layer from the protocol layer, in other words, it
	  provides implementation independent hook for the
	  transport layer functions.

     4mThe24m 4mtransport24m 4mlayer0m
	  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".

1mConnection0m

     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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     -----------------------+------------------------------------------------
     1mStructure Member	      22m| 1mContents0m
     -----------------------+------------------------------------------------
     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.

     -----------------------+-------------------------------------------------------
     1mStructure Member	      22m| 1mContents0m
     -----------------------+-------------------------------------------------------
     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

      +------------------+---------------------------------------+
      |1mTransport-version 22m| 1mread/write				22m|
      +--------+---------+---------------------------------------+
      | 1mmajor	 22m|  1mminor	22m|					   |
      +--------+---------+---------------------------------------+
      |	  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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	  (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.



1mread/write0m

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

     1mFormat for the data from the Client to the IM Server0m

	  1mClientMessage0m

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

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

	  -----------------------+------------------------------------------------
	  1mStructure Member	   22m| 1mContents0m
	  -----------------------+------------------------------------------------
	  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)

	  -----------------------+------------------------------------------------
	  1mStructure Member	   22m| 1mContents0m
	  -----------------------+------------------------------------------------
	  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.

	  1mProperty0m

	  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

	  --------------------+--------------------------------
	  1mArgument		22m| 1mContents0m
	  --------------------+--------------------------------
	  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 1mXInternAtom22m.
		    ``_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

	  -----------------------+------------------------------------------------
	  1mStructure Member	   22m| 1mContents0m
	  -----------------------+------------------------------------------------
	  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
	  -----------------------+------------------------------------------------


     1mFormat for the data from the IM Server to the Client0m

	  1mClientMessage0m

	  The format of the ClientMessage is as follows:

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



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1mX Input Method Protocol		      X11, Release 6.10m


	  -----------------------+------------------------------------------------
	  1mStructure Member	   22m| 1mContents0m
	  -----------------------+------------------------------------------------
	  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)

	  -----------------------+------------------------------------------------
	  1mStructure Member	   22m| 1mContents0m
	  -----------------------+------------------------------------------------
	  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.

	  1mProperty0m

	  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

	  --------------------+----------------------------------
	  1mArgument		22m| 1mContents0m
	  --------------------+----------------------------------
	  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




			     1m560m





1mX Input Method Protocol		      X11, Release 6.10m


	  --------------------+----------------------------------
	  1mArgument		22m| 1mContents0m
	  --------------------+----------------------------------
	  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 1mXInternAtom22m.

	  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:






































			     1m570m





1mX Input Method Protocol		      X11, Release 6.10m


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

	  -----------------------+------------------------------------------------
	  1mStructure Member	   22m| 1mContents0m
	  -----------------------+------------------------------------------------
	  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
	  -----------------------+------------------------------------------------


1mClosing Connection0m

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


































			     1m580m





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		     1mTable of Contents0m


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