prelude-msg.sgml

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<!-- ##### SECTION Title ##### -->
prelude-msg

<!-- ##### SECTION Short_Description ##### -->
Prelude Messaging API

<!-- ##### SECTION Long_Description ##### -->
<para>
This Mesaging API is used for differents Prelude program to communicate
together. It feature compatibility between version, and use a way to describe
data similar to XML.
</para>

<para>
The Message header contain the protocol version, which is only to be used
in case the main protocol structure change (compatibility break), The tag 
describe the kind of message, The fragment field may be used if a message 
is sent in several time, The priority may be used by the receiving end 
to priorityze task, The datalen contain the size of the whole message in 
network byte order

<programlisting>

   8bits    8bits   8bits     8bits                32bits
+--------+--------+--------+----------+------------------------------+
|version |   tag  |priority| fragment |            datalen           |
+--------+--------+--------+----------+------------------------------+

</programlisting>
</para>


<para>
Then the message itself contain submessage composed of :

A tag describing the kind of payload, the len of the payload (in network byte order),
the payload itself, and an end of message byte (0xff) in order to resynchronize in 
case of problem.

<programlisting>

  8bits              32bits                                   8bits
+--------+--------------------------------+-----------------+--------+
|  tag   |             len                |     payload     |  0xff  |                     
+--------+--------------------------------+-----------------+--------+

</programlisting>
</para>

<!-- ##### SECTION See_Also ##### -->
<para>
prelude-msgbuf
</para>

<!-- ##### SECTION Stability_Level ##### -->


<!-- ##### TYPEDEF prelude_msg_t ##### -->
<para>

</para>


<!-- ##### ENUM prelude_msg_priority_t ##### -->
<para>

</para>

@PRELUDE_MSG_PRIORITY_NONE: 
@PRELUDE_MSG_PRIORITY_LOW: 
@PRELUDE_MSG_PRIORITY_MID: 
@PRELUDE_MSG_PRIORITY_HIGH: 

<!-- ##### FUNCTION prelude_msg_read ##### -->
<para>

</para>

@msg: 
@pio: 
@Returns: 


<!-- ##### FUNCTION prelude_msg_forward ##### -->
<para>

</para>

@msg: 
@dst: 
@src: 
@Returns: 


<!-- ##### FUNCTION prelude_msg_get ##### -->
<para>

</para>

@msg: 
@tag: 
@len: 
@buf: 
@Returns: 


<!-- ##### FUNCTION prelude_msg_recycle ##### -->
<para>

</para>

@msg: 


<!-- ##### FUNCTION prelude_msg_mark_end ##### -->
<para>

</para>

@msg: 


<!-- ##### FUNCTION prelude_msg_dynamic_new ##### -->
<para>

</para>

@ret: 
@flush_msg_cb: 
@data: 
@Returns: 


<!-- ##### FUNCTION prelude_msg_new ##### -->
<para>

</para>

@ret: 
@msgcount: 
@msglen: 
@tag: 
@priority: 
@Returns: 


<!-- ##### FUNCTION prelude_msg_set ##### -->
<para>

</para>

@msg: 
@tag: 
@len: 
@data: 
@Returns: 


<!-- ##### FUNCTION prelude_msg_write ##### -->
<para>

</para>

@msg: 
@dst: 
@Returns: 


<!-- ##### FUNCTION prelude_msg_set_tag ##### -->
<para>

</para>

@msg: 
@tag: 


<!-- ##### FUNCTION prelude_msg_set_priority ##### -->
<para>

</para>

@msg: 
@priority: 


<!-- ##### FUNCTION prelude_msg_get_tag ##### -->
<para>

</para>

@msg: 
@Returns: 


<!-- ##### FUNCTION prelude_msg_get_priority ##### -->
<para>

</para>

@msg: 
@Returns: 


<!-- ##### FUNCTION prelude_msg_get_len ##### -->
<para>

</para>

@msg: 
@Returns: 


<!-- ##### FUNCTION prelude_msg_get_datalen ##### -->
<para>

</para>

@msg: 
@Returns: