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<book id="trans">

<bookinfo>
   <title>The XIM Transport Specification</title>
   <subtitle>Revision 0.1</subtitle>
   <releaseinfo>X Version 11, Release &fullrelvers;</releaseinfo>
   <authorgroup>
      <author>
         <firstname>Takashi</firstname><surname>Fujiwara</surname>
         <affiliation><orgname>FUJITSU LIMITED</orgname></affiliation>
      </author>
   </authorgroup>
   <copyright><year>1994</year><holder>FUJITSU LIMITED</holder></copyright>

<abstract>
<title>Abstract</title>
<para>
This specification describes the transport layer interfaces between Xlib and IM Server,
which makes various channels usable such as X protocol or TCP/IP, DECnet and etc.
</para>
</abstract>

<legalnotice>

<para>
Permission to use, copy, modify, and distribute this documentation for any purpose 
and without fee is hereby granted, provided that the above copyright notice and
this permission notice appear in all copies.
Fujitsu makes no representations about the suitability for any purpose of the
information in this document. This documentation is provided as is
without express or implied warranty.
</para>

<para role="multiLicensing">Copyright © 1994 X Consortium</para>
<para>
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files
(the &ldquo;Software&rdquo;), 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:
</para>

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

<para>
THE SOFTWARE IS PROVIDED &ldquo;AS IS&rdquo;, WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN
NO EVENT SHALL THE X CONSORTIUM 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.
</para>

<para>
Except as contained in this notice, the name of the X Consortium 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.
</para>

<para>X Window System is a trademark of The Open Group.</para>

</legalnotice>
</bookinfo>

<chapter id='X_Transport_Specification'>
<title>X Transport Specification</title>

<sect1 id="Introduction">
<title>Introduction</title>
<!-- .XS -->
<!-- (SN Introduction -->
<!-- .XE -->
<para>
<!-- .LP -->
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 independent of transport implementation.
Each function of these layers are:
<!-- .RS 3 -->
</para>
<variablelist>
  <varlistentry>
    <term><emphasis>The protocol layer</emphasis></term>
    <listitem>
      <para>
implements overall function of XIM and calls the interface layer
functions when it needs to communicate to IM Server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><emphasis>The interface layer</emphasis></term>
    <listitem>
      <para>
separates the implementation of the transport layer from the protocol
layer, in other words, it provides implementation independent hook for
the transport layer functions.
      </para>
    </listitem>
  </varlistentry>

  <varlistentry>
    <term><emphasis>The transport layer</emphasis></term>
    <listitem>
      <para>
handles actual data communication with IM Server. It is done by a set
of several functions named transporters.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

<para>
This specification describes the interface layer and the transport
layer, which makes various communication channels usable such as
X protocol or, TCP/IP, DECnet, STREAM, etc., and provides
the information needed for adding another new transport layer.
In addition, sample implementations for the transporter using the
X connection is described in section 4. <!-- xref -->
</para>
</sect1>

<sect1 id="Initialization">
<title>Initialization</title>

<sect2 id="Registering_structure_to_initialize">
<title>Registering structure to initialize</title>

<para>
The structure typed as TransportSW contains the list of the transport
layer the specific implementations supports.
</para>

<literallayout class="monospaced">
typedef struct {
      char *transport_name;
      Bool (*config);
} TransportSW;
</literallayout>

<informaltable frame="none">
  <?dbfo keep-together="always" ?>
  <tgroup cols="2" align='left' colsep='0' rowsep='0'>
  <colspec colname="col1" colwidth='1.0*'/>
  <colspec colname="col2" colwidth='1.0*'/>
  <tbody>
    <row>
      <entry><emphasis>transport_name</emphasis></entry>
      <entry>name of transport<footnote><para>Refer to "The Input Method Protocol: Appendix B</para></footnote></entry>
    </row>
    <row>
      <entry><emphasis>config</emphasis></entry>
      <entry>initial configuration function</entry>
    </row>
  </tbody>
  </tgroup>
</informaltable>

<para>
A sample entry for the Xlib supporting transporters is shown below:
</para>

<literallayout class="monospaced">
TransportSW _XimTransportRec[] = {
/*     char <emphasis remap='I'>*</emphasis>:
 *     transport_name,     Bool <emphasis remap='I'>(*config)()</emphasis>
 */
      "X",             _XimXConf,
      "tcp",           _XimTransConf,
      "local",         _XimTransConf,
      "decnet",        _XimTransConf,
      "streams",       _XimTransConf,
      (char *)NULL,    (Bool (*)())NULL,
};
</literallayout>

</sect2>
<sect2 id="Initialization_function">
<title>Initialization function</title>
<!-- .XS -->
<!-- (SN Initialization function -->
<!-- .XE -->
<para>
The following function will be called once when Xlib configures the
transporter functions.
</para>

<funcsynopsis>
<funcprototype>
  <funcdef>Bool <function>(*config)</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
  <paramdef>char<parameter> *transport_data</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>im</emphasis>
    </term>
    <listitem>
      <para>
Specifies XIM structure address.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>transport_data</emphasis>
    </term>
    <listitem>
      <para>
Specifies the data specific to the transporter, in IM Server address.<footnote><para>Refer to "The Input Method Protocol: Appendix B</para></footnote>
    </para>
  </listitem>
  </varlistentry>
</variablelist>

<para>
This function must setup the transporter function pointers.
</para>

<para>
<!-- .LP -->
The actual <emphasis remap='I'>config</emphasis> function will be chosen by IM Server at the
pre-connection time, matching by the <emphasis remap='I'>transport_name</emphasis> specified
in the <function>_XimTransportRec</function> array; The specific members of XimProto
structure listed below must be initialized so that point they
appropriate transporter functions.
</para>

<para>
If the specified transporter has been configured successfully, this
function returns True. There is no Alternative Entry for config
function itself.
</para>

<para>
The structure XimProto contains the following function pointers:
</para>

<literallayout class="monospaced">
Bool (*connect)();               /* Open connection */
Bool (*shutdown)();              /* Close connection */
Bool (*write)();                 /* Write data */
Bool (*read)();                  /* Read data */
Bool (*flush)();                 /* Flush data buffer */
Bool (*register_dispatcher)();   /* Register asynchronous data handler */
Bool (*call_dispatcher)();       /* Call dispatcher */
</literallayout>

<para>
These functions are called when Xlib needs to communicate the
IM Server. These functions must process the appropriate procedure
described below.
</para>

</sect2>
</sect1>
<sect1 id='The_interfacetransport_layer_functions'>
<title>The interface/transport layer functions</title>
<para>
Following functions are used for the transport interface.
</para>

<table frame="all" id="transport_layer_functions_2">
  <?dbfo keep-together="always" ?>
  <title>The Transport Layer Functions</title>
  <tgroup cols="3" align='left' colsep='1' rowsep='1'>
  <colspec colname="col1" colwidth="3.0*"/>
  <colspec colname="col2" colwidth="3.0*"/>
  <colspec colname="col3" colwidth='1.0*'/>
  <thead>
    <row>
      <entry align='center'>Alternate Entry (Interface Layer)</entry>
      <entry align='center'>XimProto member (Transport Layer)</entry>
      <entry align='center'>Section</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>_XimConnect</entry>
      <entry>connect</entry>
      <entry>3.1</entry>
    </row>
    <row>
      <entry>_XimShutdown</entry>
      <entry>shutdown</entry>
      <entry>3.2</entry>
    </row>
    <row>
      <entry>_XimWrite</entry>
      <entry>write</entry>
      <entry>3.3</entry>
    </row>
    <row>
      <entry>_XimRead</entry>
      <entry>read</entry>
      <entry>3.4</entry>
    </row>
    <row>
      <entry>_XimFlush</entry>
      <entry>flush</entry>
      <entry>3.5</entry>
    </row>
    <row>
      <entry>_XimRegisterDispatcher</entry>
      <entry>register_dispatcher</entry>
      <entry>3.6</entry>
    </row>
    <row>
      <entry>_XimCallDispatcher</entry>
      <entry>call_dispatcher</entry>
      <entry>3.7</entry>
    </row>
  </tbody>
  </tgroup>
</table>

<para>
The Protocol layer calls the above functions using the Alternative
Entry in the left column. The transport implementation defines
XimProto member function in the right column. The Alternative Entry is
provided so as to make easier to implement the Protocol Layer.
</para>

<sect2 id="Opening_connection">
<title>Opening connection</title>
<para>
<!-- .LP -->
When <function>XOpenIM</function> is called, the following function is called to connect
with the IM Server.
</para>

<funcsynopsis>
<funcprototype>
  <funcdef>Bool <function>(*connect)</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>im</emphasis>
    </term>
    <listitem>
      <para>
Specifies XIM structure address.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

<para>
This function must establishes the connection to the IM Server. If the
connection is established successfully, this function returns True.
The Alternative Entry for this function is:
</para>

<funcsynopsis id='_XimConnect'>
<funcprototype>
  <funcdef>Bool <function> _XimConnect</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>im</emphasis>
    </term>
    <listitem>
      <para>
Specifies XIM structure address.
      </para>
    </listitem>
  </varlistentry>
</variablelist>
</sect2>

<sect2 id="Closing_connection">
<title>Closing connection</title>
<!-- .XS -->
<!-- (SN Closing connection -->
<!-- .XE -->
<para>
<!-- .LP -->
When <function>XCloseIM</function> is called, the following function is called to
disconnect the connection with the IM Server. The Alternative Entry
for this function is:
</para>

<funcsynopsis>
<funcprototype>
  <funcdef>Bool <function> (*shutdown)</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>im</emphasis>
    </term>
    <listitem>
      <para>
Specifies XIM structure address.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

<para>
<!-- .LP -->
This function must close connection with the IM Server. If the
connection is closed successfully, this function returns True. The
Alternative Entry for this function is:
</para>

<funcsynopsis id='_XimShutdown'>
<funcprototype>
  <funcdef>Bool <function>_XimShutdown</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>im</emphasis>
    </term>
    <listitem>
      <para>
Specifies XIM structure address.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

</sect2>

<sect2 id="Writing_data">
<title>Writing data</title>
<para>
The following function is called, when Xlib needs to write data to the
IM Server.
</para>

<funcsynopsis id='_XimWrite'>
<funcprototype>
  <funcdef>Bool <function> _XimWrite</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
  <paramdef>INT16<parameter> len</parameter></paramdef>
  <paramdef>XPointer<parameter> data</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>im</emphasis>
    </term>
    <listitem>
      <para>
Specifies XIM structure address.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>len</emphasis>
    </term>
    <listitem>
      <para>
Specifies the length of writing data.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>data</emphasis>
    </term>
    <listitem>
      <para>
Specifies the writing data.
    </para>
  </listitem>
  </varlistentry>
</variablelist>

<para>
This function writes the <emphasis remap='I'>data</emphasis> to the IM Server, regardless
of the contents.  The number of bytes is passed to <emphasis remap='I'>len</emphasis>. The
writing data is passed to <emphasis remap='I'>data</emphasis>. If data is sent successfully,
the function returns True. Refer to "The Input Method Protocol" for
the contents of the writing data. The Alternative Entry for this
function is:
</para>

<funcsynopsis>
<funcprototype>
  <funcdef>Bool <function>_XimWrite</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
  <paramdef>INT16<parameter> len</parameter></paramdef>
  <paramdef>XPointer<parameter> data</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>im</emphasis>
    </term>
    <listitem>
      <para>
Specifies XIM structure address.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>len</emphasis>
    </term>
    <listitem>
      <para>
Specifies the length of writing data.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>data</emphasis>
    </term>
    <listitem>
      <para>
Specifies the writing data.
    </para>
  </listitem>
  </varlistentry>
</variablelist>

</sect2>
<sect2 id="Reading_data">
<title>Reading data</title>
<para>
The following function is called when Xlib waits for response from IM
server synchronously.
</para>

<funcsynopsis id='_XimRead'>
<funcprototype>
  <funcdef>Bool <function> _XimRead</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
  <paramdef>XPointer<parameter> read_buf</parameter></paramdef>
  <paramdef>int<parameter> buf_len</parameter></paramdef>
  <paramdef>int<parameter> *ret_len</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>im</emphasis>
    </term>
    <listitem>
      <para>
Specifies XIM structure address.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>read_buf</emphasis>
    </term>
    <listitem>
      <para>
Specifies the buffer to store data.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>buf_len</emphasis>
    </term>
    <listitem>
      <para>
Specifies the size of the <emphasis remap='I'>buffer</emphasis>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>ret_len</emphasis>
    </term>
    <listitem>
      <para>
Specifies the length of stored data.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

<para>
This function stores the read data in <emphasis remap='I'>read_buf</emphasis>, which size is
specified as <emphasis remap='I'>buf_len</emphasis>. The size of data is set to <emphasis remap='I'>ret_len</emphasis>.
This function return True, if the data is read normally or reading
data is completed.
</para>
<para>
The Alternative Entry for this function is:
</para>

<funcsynopsis>
<funcprototype>
  <funcdef>Bool <function> _XimRead</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
  <paramdef>INT16<parameter> *ret_len</parameter></paramdef>
  <paramdef>XPointer<parameter> buf</parameter></paramdef>
  <paramdef>int<parameter> buf_len</parameter></paramdef>
  <paramdef>Bool<parameter> (*predicate)()</parameter></paramdef>
  <paramdef>XPointer<parameter> predicate_arg</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>im</emphasis>
    </term>
    <listitem>
      <para>
Specifies XIM structure address.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>ret_len</emphasis>
    </term>
    <listitem>
      <para>
Specifies the size of the <emphasis remap='I'>data</emphasis> buffer.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>buf</emphasis>
    </term>
    <listitem>
      <para>
Specifies the buffer to store data.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>buf_len</emphasis>
    </term>
    <listitem>
      <para>
Specifies the length of <emphasis remap='I'>buffer</emphasis>.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>predicate</emphasis>
    </term>
    <listitem>
      <para>
Specifies the predicate for the XIM data.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>predicate_arg</emphasis>
    </term>
    <listitem>
      <para>
Specifies the predicate specific data.
<!-- .sp 6p -->
    </para>
  </listitem>
  </varlistentry>
</variablelist>

<para>
The predicate procedure indicates whether the <emphasis remap='I'>data</emphasis> is for the
XIM or not. <emphasis remap='I'>len</emphasis>
This function stores the read data in <emphasis remap='I'>buf</emphasis>, which size
is specified as <emphasis remap='I'>buf_len</emphasis>. The size of data is set to
<emphasis remap='I'>ret_len</emphasis>.  If <emphasis remap='I'>preedicate()</emphasis>
returns True, this function returns True.  If not, it calls the registered callback function.
</para>

<para>
The procedure and its arguments are:
</para>


<funcsynopsis>
<funcprototype>
  <funcdef>void <function>(*predicate)</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
  <paramdef>INT16<parameter> len</parameter></paramdef>
  <paramdef>XPointer<parameter> data</parameter></paramdef>
  <paramdef>XPointer<parameter> predicate_arg</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>im</emphasis>
    </term>
    <listitem>
      <para>
Specifies XIM structure address.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>len</emphasis>
    </term>
    <listitem>
      <para>
Specifies the size of the <emphasis remap='I'>data</emphasis> buffer.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>data</emphasis>
    </term>
    <listitem>
      <para>
Specifies the buffer to store data.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>predicate_arg</emphasis>
    </term>
    <listitem>
      <para>
Specifies the predicate specific data.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

</sect2>
<sect2 id="Flushing_buffer">
<title>Flushing buffer</title>
<para>
The following function is called when Xlib needs to flush the data.
</para>

<funcsynopsis>
<funcprototype>
  <funcdef>void <function>(*flush)</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>im</emphasis>
    </term>
    <listitem>
      <para>
Specifies XIM structure address.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

<para>
This function must flush the data stored in internal buffer on the
transport layer. If data transfer is completed, the function returns
True.  The Alternative Entry for this function is:
</para>

<funcsynopsis id='_XimFlush'>
<funcprototype>
  <funcdef>void <function> _XimFlush</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>im</emphasis>
    </term>
    <listitem>
      <para>
Specifies XIM structure address.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

</sect2>
<sect2 id="Registering_asynchronous_data_handler">
<title>Registering asynchronous data handler</title>
<para>
Xlib needs to handle asynchronous response from IM Server. This is
because some of the XIM data occur asynchronously to X events.
</para>

<para>
Those data will be handled in the <emphasis remap='I'>Filter</emphasis>,
and the <emphasis remap='I'>Filter</emphasis>
will call asynchronous data handler in the protocol layer. Then it
calls dispatchers in the transport layer. The dispatchers are
implemented by the protocol layer. This function must store the
information and prepare for later call of the dispatchers using
<xref linkend='_XimCallDispatcher' xrefstyle='select: title'/>.
</para>

<para>
When multiple dispatchers are registered, they will be called
sequentially in order of registration, on arrival of asynchronous
data. The register_dispatcher is declared as following:
</para>

<funcsynopsis>
<funcprototype>
  <funcdef>Bool <function>(*register_dispatcher)</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
  <paramdef>Bool<parameter> (*dispatcher)()</parameter></paramdef>
  <paramdef>XPointer<parameter> call_data</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>im</emphasis>
    </term>
    <listitem>
      <para>
Specifies XIM structure address.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>dispatcher</emphasis>
    </term>
    <listitem>
      <para>
Specifies the dispatcher function to register.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>call_data</emphasis>
    </term>
    <listitem>
      <para>
Specifies a parameter for the <emphasis remap='I'>dispatcher</emphasis>.
    </para>
  </listitem>
  </varlistentry>
</variablelist>

<para>
The dispatcher is a function of the following type:
</para>

<funcsynopsis>
<funcprototype>
  <funcdef>Bool <function>(*dispatcher)</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
  <paramdef>INT16<parameter> len</parameter></paramdef>
  <paramdef>XPointer<parameter> data</parameter></paramdef>
  <paramdef>XPointer<parameter> call_data</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>im</emphasis>
    </term>
    <listitem>
      <para>
Specifies XIM structure address.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>len</emphasis>
    </term>
    <listitem>
      <para>
Specifies the size of the <emphasis remap='I'>data</emphasis> buffer.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>data</emphasis>
    </term>
    <listitem>
      <para>
Specifies the buffer to store data.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>call_data</emphasis>
    </term>
    <listitem>
      <para>
Specifies a parameter passed to the register_dispatcher.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

<para>
The dispatcher is provided by the protocol layer. They are called once
for every asynchronous data, in order of registration. If the data is
used, it must return True. otherwise, it must return False.
</para>

<para>
If the dispatcher function returns True, the Transport Layer assume
that the data has been processed by the upper layer.  The Alternative
Entry for this function is:
</para>

<funcsynopsis id='_XimRegisterDispatcher'>
<funcprototype>
  <funcdef>Bool <function> _XimRegisterDispatcher</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
  <paramdef>Bool<parameter> (*dispatcher)()</parameter></paramdef>
  <paramdef>XPointer<parameter> call_data</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>im</emphasis>
    </term>
    <listitem>
      <para>
Specifies XIM structure address.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>dispatcher</emphasis>
    </term>
    <listitem>
      <para>
Specifies the dispatcher function to register.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>call_data</emphasis>
    </term>
    <listitem>
      <para>
Specifies a parameter for the <emphasis remap='I'>dispatcher</emphasis>.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

</sect2>
<sect2 id="Calling_dispatcher">
<title>Calling dispatcher</title>
<para>
The following function is used to call the registered dispatcher
function, when the asynchronous response from IM Server has arrived.
</para>

<funcsynopsis>
<funcprototype>
  <funcdef>Bool <function>(*call_dispatcher)</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
  <paramdef>INT16<parameter> len</parameter></paramdef>
  <paramdef>XPointer<parameter> data</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>im</emphasis>
    </term>
    <listitem>
      <para>
Specifies XIM structure address.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>len</emphasis>
    </term>
    <listitem>
      <para>
Specifies the size of <emphasis remap='I'>data</emphasis> buffer.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>data</emphasis>
    </term>
    <listitem>
      <para>
Specifies the buffer to store data.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

<para>
The call_dispatcher must call the dispatcher function, in order of
their registration. <emphasis remap='I'>len</emphasis> and <emphasis remap='I'>data</emphasis> are the data passed to
register_dispatcher.
</para>

<para>
The return values are checked at each invocation, and if it finds
True, it immediately return with true for its return value.
</para>

<para>
It is depend on the upper layer whether the read data is XIM
Protocol packet unit or not.
The Alternative Entry for this function is:
</para>

<funcsynopsis id='_XimCallDispatcher'>
<funcprototype>
  <funcdef>Bool <function> _XimCallDispatcher</function></funcdef>
  <paramdef>XIM<parameter> im</parameter></paramdef>
  <paramdef>INT16<parameter> len</parameter></paramdef>
  <paramdef>XPointer<parameter> call_data</parameter></paramdef>
</funcprototype>
</funcsynopsis>

</sect2>
</sect1>
<sect1 id="Sample_implementations_for_the_Transport_Layer">
<title>Sample implementations for the Transport Layer</title>
<para>
Sample implementations for the transporter using the X connection is
described here.
</para>

<sect2 id="X_Transport">
<title>X Transport</title>
<para>
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 following, 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 communication window".
</para>

<sect3 id="Connection">
<title>Connection</title>
<para>
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.
</para>

<para>
<!-- .LP -->
Refer to "The Input Method Protocol" for the XIM_SERVER atom.
</para>

<table frame="topbot" id="transport_layer_functions">
  <?dbfo keep-together="always" ?>
  <title>The ClientMessage sent to the IMS window.</title>
  <tgroup cols="3" align='left' colsep='0' rowsep='0'>
  <colspec colname="col1" colwidth='1.0*'/>
  <colspec colname="col2" colwidth='1.0*' colsep='1'/>
  <colspec colname="col3" colwidth="3.5*"/>
  <spanspec namest="col1" nameend="col2" spanname="span-horiz"/>
  <thead>
    <row rowsep='1'>
      <entry spanname="span-horiz" colsep='1'>Structure Member</entry>
      <entry>Contents</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>int</entry>
      <entry>type</entry>
      <entry>ClientMessage</entry>
    </row>
    <row>
      <entry>u_long</entry>
      <entry>serial</entry>
      <entry>Set by the X Window System</entry>
    </row>
    <row>
      <entry>Bool</entry>
      <entry>send_event</entry>
      <entry>Set by the X Window System</entry>
    </row>
    <row>
      <entry>Display</entry>
      <entry>*display</entry>
      <entry>The display to which connects</entry>
    </row>
    <row>
      <entry>Window</entry>
      <entry>window</entry>
      <entry>IMS Window ID</entry>
    </row>
    <row>
      <entry>Atom</entry>
      <entry>message_type</entry>
      <entry>XInternAtom(display, "_XIM_CONNECT", false)</entry>
    </row>
    <row>
      <entry>int</entry>
      <entry>format</entry>
      <entry>32</entry>
    </row>
    <row>
      <entry>long</entry>
      <entry>data.1[0]</entry>
      <entry>client communication window ID</entry>
    </row>
    <row>
      <entry>long</entry>
      <entry>data.1[1]</entry>
      <entry>client-major-transport-version(*1)</entry>
    </row>
    <row>
      <entry>long</entry>
      <entry>data.1[2]</entry>
      <entry>client-major-transport-version(*1)</entry>
    </row>
  </tbody>
  </tgroup>
</table>

<para>
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.
</para>

<table frame="topbot" id="clientmessage_sent_by_im_server">
  <?dbfo keep-together="always" ?>
  <title>The ClientMessage sent by IM Server.</title>
  <tgroup cols="3" colsep='0' rowsep='0'>
  <colspec colname="col1" colwidth='1.0*'/>
  <colspec colname="col2" colwidth='1.0*' colsep="1"/>
  <colspec colname="col3" colwidth="3.5*"/>
  <spanspec namest="col1" nameend="col2" spanname="span-horiz"/>
  <thead>
    <row rowsep='1'>
      <entry spanname="span-horiz" colsep='1'>Structure Member</entry>
      <entry>Contents</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>int</entry>
      <entry>type</entry>
      <entry>ClientMessage</entry>
    </row>
    <row>
      <entry>u_long</entry>
      <entry>serial</entry>
      <entry>Set by the X Window System</entry>
    </row>
    <row>
      <entry>Bool</entry>
      <entry>send_event</entry>
      <entry>Set by the X Window System</entry>
    </row>
    <row>
      <entry>Display</entry>
      <entry>*display</entry>
      <entry>The display to which connects</entry>
    </row>
    <row>
      <entry>Window</entry>
      <entry>window</entry>
      <entry>IMS Window ID</entry>
    </row>
    <row>
      <entry>Atom</entry>
      <entry>message_type</entry>
      <entry>XInternAtom(display, "_XIM_CONNECT", false)</entry>
    </row>
    <row>
      <entry>int</entry>
      <entry>format</entry>
      <entry>32</entry>
    </row>
    <row>
      <entry>long</entry>
      <entry>data.1[0]</entry>
      <entry>client communication window ID</entry>
    </row>
    <row>
      <entry>long</entry>
      <entry>data.1[1]</entry>
      <entry>client-major-transport-version(*1)</entry>
    </row>
    <row>
      <entry>long</entry>
      <entry>data.1[2]</entry>
      <entry>client-major-transport-version(*1)</entry>
    </row>
    <row>
      <entry>long</entry>
      <entry>data.1[3]</entry>
      <entry>dividing size between ClientMessage and Property(*2)</entry>
    </row>
  </tbody>
  </tgroup>
</table>

<para>
(*1) major/minor-transport-version
</para>

<para>
The read/write method is decided by the combination of
major/minor-transport-version, as follows:
</para>

<table frame="all" id="readwrite_method_and_the_majorminor_transport_version">
  <?dbfo keep-together="always" ?>
  <title>The read/write method and the major/minor-transport-version</title>
  <tgroup cols="3" colsep='1' rowsep='1'>
  <colspec colname="col1" colwidth='1.0*'/>
  <colspec colname="col2" colwidth='1.0*'/>
  <colspec colname="col3" colwidth="3.0*"/>
  <spanspec namest="col1" nameend="col2" spanname="span-horiz" align="center"/>
  <thead>
    <row>
      <entry spanname="span-horiz">Transport-version</entry>
      <entry>read/write</entry>
    </row>
    <row>
      <entry>major</entry>
      <entry>minor</entry>
      <entry></entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry morerows="2">0</entry>
      <entry>0</entry>
      <entry>only-CM &amp; Property-with-CM</entry>
    </row>
    <row>
      <entry>1</entry>
      <entry>only-CM &amp; multi-CM</entry>
    </row>
    <row>
      <entry>2</entry>
      <entry>only-CM &amp; multi-CM &amp; Property-with-CM</entry>
    </row>
    <row>
      <entry>1</entry>
      <entry>0</entry>
      <entry>PropertyNotify</entry>
    </row>
    <row>
      <entry morerows="1">2</entry>
      <entry>0</entry>
      <entry>only-CM &amp; PropertyNotify</entry>
    </row>
    <row>
      <entry>1</entry>
      <entry>only-CM &amp; multi-CM &amp; PropertyNotify</entry>
    </row>
  </tbody>
  </tgroup>
</table>

<literallayout class="monospaced">
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

</literallayout>


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

<itemizedlist>
  <listitem>
    <para>
The client sends 0 as major/minor-transport-version to the IM Server.
The client must support all methods in Table 4-3. <!-- xref -->
The client may send another number as major/minor-transport-version to
use other method than the above in the future.
    </para>
  </listitem>
  <listitem>
    <para>
The IM Server sends its major/minor-transport-version number to
the client. The client sends data using the method specified by the
IM Server.
    </para>
  </listitem>
  <listitem>
    <para>
If major/minor-transport-version number is not available, it is regarded
as 0.
    </para>
  </listitem>
</itemizedlist>

<para>
(*2) dividing size between ClientMessage and Property
</para>

<para>
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.
</para>

</sect3>

<sect3 id='readwrite'>
<title>read/write</title>
<para>
The data is transferred via either ClientMessage or Window Property in
the X Window System.
</para>

<sect4 id="Format_for_the_data_from_the_Client_to_the_IM_Server">
<title>Format for the data from the Client to the IM Server</title>
<para>
<emphasis role="bold">ClientMessage</emphasis>
</para>

<para>
If data is sent via ClientMessage event, the format is as follows:
</para>

<table frame="topbot" id="clientmessage_events_format_first_or_middle">
  <?dbfo keep-together="always" ?>
  <title>The ClientMessage event's format (first or middle)</title>
  <tgroup cols="3" align='left' colsep='0' rowsep='0'>
  <colspec colname="col1" colwidth='1.0*'/>
  <colspec colname="col2" colwidth='1.0*' colsep="1"/>
  <colspec colname="col3" colwidth="3.5*"/>
  <spanspec namest="col1" nameend="col2" spanname="span-horiz"/>
  <thead>
    <row rowsep='1'>
      <entry spanname="span-horiz" colsep='1'>Structure Member</entry>
      <entry>Contents</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>int</entry>
      <entry>type</entry>
      <entry>ClientMessage</entry>
    </row>
    <row>
      <entry>u_long</entry>
      <entry>serial</entry>
      <entry>Set by the X Window System</entry>
    </row>
    <row>
      <entry>Bool</entry>
      <entry>send_event</entry>
      <entry>Set by the X Window System</entry>
    </row>
    <row>
      <entry>Display</entry>
      <entry>*display</entry>
      <entry>The display to which connects</entry>
    </row>
    <row>
      <entry>Window</entry>
      <entry>window</entry>
      <entry>IMS Window ID</entry>
    </row>
    <row>
      <entry>Atom</entry>
      <entry>message_type</entry>
      <entry>XInternAtom(display, "_XIM_MOREDATA", False)</entry>
    </row>
    <row>
      <entry>int</entry>
      <entry>format</entry>
      <entry>8</entry>
    </row>
    <row>
      <entry>char</entry>
      <entry>data.b[20]</entry>
      <entry>(read/write DATA : 20 byte)</entry>
    </row>
  </tbody>
  </tgroup>
</table>



<table frame="topbot" id="clientmessage_events_format_only_or_last">
  <?dbfo keep-together="always" ?>
  <title>The ClientMessage event's format (only or last)</title>
  <tgroup cols="3" align='left' colsep='0' rowsep='0'>
  <colspec colname="col1" colwidth='1.0*'/>
  <colspec colname="col2" colwidth='1.0*' colsep="1"/>
  <colspec colname="col3" colwidth="3.5*"/>
  <spanspec namest="col1" nameend="col2" spanname="span-horiz"/>
  <thead>
    <row rowsep='1'>
      <entry spanname="span-horiz" colsep='1'>Structure Member</entry>
      <entry>Contents</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>int</entry>
      <entry>type</entry>
      <entry>ClientMessage</entry>
    </row>
    <row>
      <entry>u_long</entry>
      <entry>serial</entry>
      <entry>Set by the X Window System</entry>
    </row>
    <row>
      <entry>Bool</entry>
      <entry>send_event</entry>
      <entry>Set by the X Window System</entry>
    </row>
    <row>
      <entry>Display</entry>
      <entry>*display</entry>
      <entry>The display to which connects</entry>
    </row>
    <row>
      <entry>Window</entry>
      <entry>window</entry>
      <entry>IMS Window ID</entry>
    </row>
    <row>
      <entry>Atom</entry>
      <entry>message_type</entry>
      <entry>XInternAtom(display, "_XIM_PROTOCOL", False)</entry>
    </row>
    <row>
      <entry>int</entry>
      <entry>format</entry>
      <entry>8</entry>
    </row>
    <row>
      <entry>char</entry>
      <entry>data.b[20]</entry>
      <entry>(read/write DATA : MAX 20 byte)
<footnote><para>If the data is smaller
than 20 bytes, all data other than available data must be 0.
</para></footnote>
      </entry>
    </row>
  </tbody>
  </tgroup>
</table>

<para>
<emphasis role="bold">Property</emphasis>
</para>

<para>
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.
</para>

<itemizedlist>
  <listitem>
    <para>
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.
    </para>
  </listitem>
  <listitem>
    <para>
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.
    </para>
  </listitem>
</itemizedlist>

<para>
The arguments of the XChangeProperty are as follows:
</para>


<table frame="topbot" id="xchangeproperty_events_format">
  <?dbfo keep-together="always" ?>
  <title>The XChangeProperty event's format</title>
  <tgroup cols="3" align='left' colsep='0' rowsep='0'>
  <colspec colname="col1" colwidth='1.0*'/>
  <colspec colname="col2" colwidth='1.0*' colsep="1"/>
  <colspec colname="col3" colwidth="3.5*"/>
  <spanspec namest="col1" nameend="col2" spanname="span-horiz" align="left"/>
  <thead>
    <row rowsep='1'>
      <entry spanname="span-horiz" colsep='1'>Argument</entry>
      <entry>Contents</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>Display</entry>
      <entry>*display</entry>
      <entry>The display to which connects</entry>
    </row>
    <row>
      <entry>Window</entry>
      <entry>window</entry>
      <entry>IMS communication window ID</entry>
    </row>
    <row>
      <entry>Atom</entry>
      <entry>property</entry>
      <entry>read/write property Atom (*1)</entry>
    </row>
    <row>
      <entry>int</entry>
      <entry>format</entry>
      <entry>8</entry>
    </row>
    <row>
      <entry>int</entry>
      <entry>mode</entry>
      <entry>PropModeAppend</entry>
    </row>
    <row>
      <entry>u_char</entry>
      <entry>*data</entry>
      <entry>read/write DATA</entry>
    </row>
    <row>
      <entry>int</entry>
      <entry>nelements</entry>
      <entry>length of DATA</entry>
    </row>
  </tbody>
  </tgroup>
</table>

<para>
(*1) The read/write property ATOM allocates the following strings by
<function>XInternAtom</function>.
"_clientXXX"
</para>

<para>
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).
</para>

<para>
If Atom is notified via ClientMessage event, the format of the ClientMessage
is as follows:
</para>

<table frame="topbot" id="clientmessage_events_format_to_send_atom_of_property">
  <?dbfo keep-together="always" ?>
  <title>The ClientMessage event's format to send Atom of property</title>
  <tgroup cols="3" align='left' colsep='0' rowsep='0'>
  <colspec colname="col1" colwidth='1.0*'/>
  <colspec colname="col2" colwidth='1.0*' colsep="1"/>
  <colspec colname="col3" colwidth="3.5*"/>
  <spanspec namest="col1" nameend="col2" spanname="span-horiz"/>
  <thead>
    <row rowsep='1'>
      <entry spanname="span-horiz" colsep='1'>Structure Member</entry>
      <entry>Contents</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>int</entry>
      <entry>type</entry>
      <entry>ClientMessage</entry>
    </row>
    <row>
      <entry>u_long</entry>
      <entry>serial</entry>
      <entry>Set by the X Window System</entry>
    </row>
    <row>
      <entry>Bool</entry>
      <entry>send_event</entry>
      <entry>Set by the X Window System</entry>
    </row>
    <row>
      <entry>Display</entry>
      <entry>*display</entry>
      <entry>The display to which connects</entry>
    </row>
    <row>
      <entry>Window</entry>
      <entry>window</entry>
      <entry>IMS Window ID</entry>
    </row>
    <row>
      <entry>Atom</entry>
      <entry>message_type</entry>
      <entry>XInternAtom(display, "_XIM_PROTOCOL", False)</entry>
    </row>
    <row>
      <entry>int</entry>
      <entry>format</entry>
      <entry>8</entry>
    </row>
    <row>
      <entry>long</entry>
      <entry>data.1[0]</entry>
      <entry>length of read/write property Atom</entry>
    </row>
    <row>
      <entry>long</entry>
      <entry>data.1[1]</entry>
      <entry>read/write property Atom</entry>
    </row>
  </tbody>
  </tgroup>
</table>
</sect4>

<sect4 id="Format_for_the_data_from_the_IM_Server_to_the_Client">
<title>Format for the data from the IM Server to the Client</title>
<para>
<emphasis role="bold">ClientMessage</emphasis>
</para>

<para>
The format of the ClientMessage is as follows:
</para>

<table frame="topbot" id="clientmessage_events_format_first_or_middle_2">
  <?dbfo keep-together="always" ?>
  <title>The ClientMessage event's format (first or middle)</title>
  <tgroup cols="3" align='left' colsep='0' rowsep='0'>
  <colspec colname="col1" colwidth='1.0*'/>
  <colspec colname="col2" colwidth='1.0*' colsep="1"/>
  <colspec colname="col3" colwidth="3.5*"/>
  <spanspec namest="col1" nameend="col2" spanname="span-horiz"/>
  <thead>
    <row rowsep='1'>
      <entry spanname="span-horiz" colsep='1'>Structure Member</entry>
      <entry>Contents</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>int</entry>
      <entry>type</entry>
      <entry>ClientMessage</entry>
    </row>
    <row>
      <entry>u_long</entry>
      <entry>serial</entry>
      <entry>Set by the X Window System</entry>
    </row>
    <row>
      <entry>Bool</entry>
      <entry>send_event</entry>
      <entry>Set by the X Window System</entry>
    </row>
    <row>
      <entry>Display</entry>
      <entry>*display</entry>
      <entry>The display to which connects</entry>
    </row>
    <row>
      <entry>Window</entry>
      <entry>window</entry>
      <entry>IMS Window ID</entry>
    </row>
    <row>
      <entry>Atom</entry>
      <entry>message_type</entry>
      <entry>XInternAtom(display, "_XIM_MOREDATA", False)</entry>
    </row>
    <row>
      <entry>int</entry>
      <entry>format</entry>
      <entry>8</entry>
    </row>
    <row>
      <entry>char</entry>
      <entry>data.b[20]</entry>
      <entry>(read/write DATA : 20 byte)</entry>
    </row>
  </tbody>
  </tgroup>
</table>





<table frame="topbot" id="clientmessage_events_format_only_or_last_2">
  <?dbfo keep-together="always" ?>
  <title>The ClientMessage event's format (only or last)</title>
  <tgroup cols="3" align='left' colsep='0' rowsep='0'>
  <colspec colname="col1" colwidth='1.0*'/>
  <colspec colname="col2" colwidth='1.0*' colsep="1"/>
  <colspec colname="col3" colwidth="3.5*"/>
  <spanspec namest="col1" nameend="col2" spanname="span-horiz"/>
  <thead>
    <row rowsep='1'>
      <entry spanname="span-horiz" colsep='1'>Structure Member</entry>
      <entry>Contents</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>int</entry>
      <entry>type</entry>
      <entry>ClientMessage</entry>
    </row>
    <row>
      <entry>u_long</entry>
      <entry>serial</entry>
      <entry>Set by the X Window System</entry>
    </row>
    <row>
      <entry>Bool</entry>
      <entry>send_event</entry>
      <entry>Set by the X Window System</entry>
    </row>
    <row>
      <entry>Display</entry>
      <entry>*display</entry>
      <entry>The display to which connects</entry>
    </row>
    <row>
      <entry>Window</entry>
      <entry>window</entry>
      <entry>IMS Window ID</entry>
    </row>
    <row>
      <entry>Atom</entry>
      <entry>message_type</entry>
      <entry>XInternAtom(display, "_XIM_PROTOCOL", False)</entry>
    </row>
    <row>
      <entry>int</entry>
      <entry>format</entry>
      <entry>8</entry>
    </row>
    <row>
      <entry>char</entry>
      <entry>data.b[20]</entry>
      <entry>(read/write DATA : MAX 20 byte) (*1)</entry>
    </row>
  </tbody>
  </tgroup>
</table>

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

<para>
<emphasis role="bold">Property</emphasis>
</para>

<para>
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.
</para>

<itemizedlist>
  <listitem>
    <para>
The XChangeProperty function is used to store data in the IMS
communication window, and Atom of the property is sent via the
ClientMessage event.
    </para>
  </listitem>
  <listitem>
    <para>
The XChangeProperty function is used to store data in the IMS
communication window, and Atom of the property is sent via
PropertyNotify event.
    </para>
  </listitem>
</itemizedlist>

<para>
The arguments of the XChangeProperty are as follows:
</para>

<table frame="topbot" id="xchangeproperty_events_format_b">
  <?dbfo keep-together="always" ?>
  <title>The XChangeProperty event's format</title>
  <tgroup cols="3" align='left' colsep='0' rowsep='0'>
  <colspec colname="col1" colwidth='1.0*'/>
  <colspec colname="col2" colwidth='1.0*' colsep="1"/>
  <colspec colname="col3" colwidth="3.5*"/>
  <spanspec namest="col1" nameend="col2" spanname="span-horiz" align="left"/>
  <thead>
    <row rowsep='1'>
      <entry spanname="span-horiz" colsep='1'>Argument</entry>
      <entry>Contents</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>Display</entry>
      <entry>*display</entry>
      <entry>The display to which connects</entry>
    </row>
    <row>
      <entry>Window</entry>
      <entry>window</entry>
      <entry>IMS communication window ID</entry>
    </row>
    <row>
      <entry>Atom</entry>
      <entry>property</entry>
      <entry>read/write property Atom (*1)</entry>
    </row>
    <row>
      <entry>int</entry>
      <entry>format</entry>
      <entry>8</entry>
    </row>
    <row>
      <entry>int</entry>
      <entry>mode</entry>
      <entry>PropModeAppend</entry>
    </row>
    <row>
      <entry>u_char</entry>
      <entry>*data</entry>
      <entry>read/write DATA</entry>
    </row>
    <row>
      <entry>int</entry>
      <entry>nelements</entry>
      <entry>length of DATA</entry>
    </row>
  </tbody>
  </tgroup>
</table>

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

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

<para>
If Atom is notified via ClientMessage event, the format of the ClientMessage
is as follows:
</para>

<table frame="topbot" id="clientmessage_events_format_to_send_atom_of_property_2">
  <?dbfo keep-together="always" ?>
  <title>The ClientMessage event's format to send Atom of property</title>
  <tgroup cols="3" align='left' colsep='0' rowsep='0'>
  <colspec colname="col1" colwidth='1.0*'/>
  <colspec colname="col2" colwidth='1.0*' colsep="1"/>
  <colspec colname="col3" colwidth="3.5*"/>
  <spanspec namest="col1" nameend="col2" spanname="span-horiz"/>
  <thead>
    <row rowsep='1'>
      <entry spanname="span-horiz" colsep='1'>Structure Member</entry>
      <entry>Contents</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>int</entry>
      <entry>type</entry>
      <entry>ClientMessage</entry>
    </row>
    <row>
      <entry>u_long</entry>
      <entry>serial</entry>
      <entry>Set by the X Window System</entry>
    </row>
    <row>
      <entry>Bool</entry>
      <entry>send_event</entry>
      <entry>Set by the X Window System</entry>
    </row>
    <row>
      <entry>Display</entry>
      <entry>*display</entry>
      <entry>The display to which connects</entry>
    </row>
    <row>
      <entry>Window</entry>
      <entry>window</entry>
      <entry>IMS Window ID</entry>
    </row>
    <row>
      <entry>Atom</entry>
      <entry>message_type</entry>
      <entry>XInternAtom(display, "_XIM_PROTOCOL", False)</entry>
    </row>
    <row>
      <entry>int</entry>
      <entry>format</entry>
      <entry>8</entry>
    </row>
    <row>
      <entry>long</entry>
      <entry>data.1[0]</entry>
      <entry>length of read/write property Atom</entry>
    </row>
    <row>
      <entry>long</entry>
      <entry>data.1[1]</entry>
      <entry>read/write property Atom</entry>
    </row>
  </tbody>
  </tgroup>
</table>

</sect4>
</sect3>
<sect3 id="Closing_Connection">
<title>Closing Connection</title>

<para>
If the client disconnect with the IM Server, shutdown function should
free the communication window properties and etc..
</para>

</sect3>
</sect2>
</sect1>

<sect1 id="References">
<title>References</title>
<para>
[1] Masahiko Narita and Hideki Hiura, <emphasis remap='I'>"The Input Method Protocol"</emphasis>
</para>
</sect1>

</chapter>
</book>
