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</blockquote><h4>ASYNCHRONOUS COMMUNICATION</h4><blockquote><p>
<p>
The shipped version of <b><i>snmpQueMonitor</i>(&nbsp;)</b> uses <b><i><a href="./subagentLib.html#snmpMasterHandlerWR">snmpMasterHandlerWR</a></i>(&nbsp;)</b> and
thus processes messages asynchronously.  However, if necessary, you can
rewrite <b><i>snmpQueMonitor</i>(&nbsp;)</b> to call <b><i><a href="./subagentLib.html#snmpMasterHandlerAsync">snmpMasterHandlerAsync</a></i>(&nbsp;)</b> instead.  For
more information on <b><i><a href="./subagentLib.html#snmpMasterHandlerAsync">snmpMasterHandlerAsync</a></i>(&nbsp;)</b>, see its reference entry.
<p>
</blockquote><h4>RETURNS</h4><blockquote><p>
N/A
</blockquote><h4>SEE ALSO</h4><blockquote><p>
<b><a href="./masterIoLib.html#top">masterIoLib</a></b>

<hr>
<a name="masterIpcComp"></a>
<p align=right>
<a href="rtnIndex.html"><i>Libraries :  Routines</i></a></p>

</blockquote><h1><i>masterIpcComp</i>(&nbsp;)</h1> <blockquote></a></blockquote><h4>NAME</h4><blockquote>  
<p><strong><i>masterIpcComp</i>(&nbsp;)</strong> - transmit a completion of transmission message</p>

</blockquote><h4>SYNOPSIS</h4><blockquote><p>
<pre>void masterIpcComp
    (
    OCTET_T     opcode,   /* this specifies what needs to be done */
    EBUFFER_T * ebuf,     /* reply message to be sent */
    VBL_T *     vblist,   /* list of varbinds that the message contained */
    PTR_T       ipchandle /* subagent address */
    )</pre>

</blockquote><h4>DESCRIPTION</h4><blockquote><p>
If the SNMP master agent uses <b><i><a href="./subagentLib.html#snmpMasterHandlerAsync">snmpMasterHandlerAsync</a></i>(&nbsp;)</b> to process
a subagent's unsolicited control message (such as a registration request),
it uses <b><i><a href="./masterIoLib.html#masterIpcComp">masterIpcComp</a></i>(&nbsp;)</b> to complete processing for the message.  In the
current implementation, this means telling the subagent the completion
status of a registration or deregistration request.  However, you can
rewrite this function to implement a broader range of responses (such
as forwarding traps to the SNMP manager).
<p>
When the master agent calls this routine, it uses <i>opcode</i> to indicate
the processing status of the message.  If the status indicates an error,
<b><i><a href="./masterIoLib.html#masterIpcComp">masterIpcComp</a></i>(&nbsp;)</b> drops the packet.  If the status indicates success, the
master agent uses the <i>ebuf</i> parameter to pass in a message for the subagent
at <i>ipchandle</i>.  Internally, <b><i><a href="./masterIoLib.html#masterIpcComp">masterIpcComp</a></i>(&nbsp;)</b> calls <b><i><a href="./masterIoLib.html#masterIoWrite">masterIoWrite</a></i>(&nbsp;)</b> to
forward the message to the specified subagent.  If this message is the
response to a successful registration request, it contains the group ID
for the MIB variables just added to the master agent's MIB tree.  The
subagent needs this group ID for any deregistration request it might
send later.  It also uses this ID to register instances of the object
just registered.
<p>
If the <i>opcode</i> is a value of 1 or greater (up to and including 127),
the master agent uses the <i>vblist</i> parameter to pass in a varbind list
that it extracted from the control message.  In the current implementation,
the <b><i><a href="./masterIoLib.html#masterIpcComp">masterIpcComp</a></i>(&nbsp;)</b> routine does nothing with the message and returns.
However, you could modify <b><i><a href="./masterIoLib.html#masterIpcComp">masterIpcComp</a></i>(&nbsp;)</b> to process the message according
to the value specified by <i>opcode</i>.  For example, if <i>opcode</i> indicates
a trap, you could forward the information at <i>vblist</i> to the SNMP manager.
<p>
Currently, <b>subagent.h</b> defines symbolic constants for opcodes 1 through 12
(with opcode 11, <b>SA_TRAP_REQUEST</b>, reserved for trap requests).  You are
free to use the remaining opcodes for message types specific to your
implementation.
<p>
</blockquote><h4>RETURNS</h4><blockquote><p>
N/A
</blockquote><h4>SEE ALSO</h4><blockquote><p>
<b><a href="./masterIoLib.html#top">masterIoLib</a></b>

<hr>
<a name="masterIoWrite"></a>
<p align=right>
<a href="rtnIndex.html"><i>Libraries :  Routines</i></a></p>

</blockquote><h1><i>masterIoWrite</i>(&nbsp;)</h1> <blockquote></a></blockquote><h4>NAME</h4><blockquote>  
<p><strong><i>masterIoWrite</i>(&nbsp;)</strong> - send the encoded buffer to the subagent</p>

</blockquote><h4>SYNOPSIS</h4><blockquote><p>
<pre>STATUS masterIoWrite
    (
    EBUFFER_T * pBuf, /* reply message to be sent */
    PTR_T       saId, /* subagent address */
    INT_32_T    flg   /* type of message */
    )</pre>

</blockquote><h4>DESCRIPTION</h4><blockquote><p>
This routine transmits the byte array at <i>pBuf</i> to the subagent at <i>saId</i>.
This routine is called from a wide variety of functions in the master
agent.  For example, <b><i><a href="./masterIoLib.html#masterIpcSend">masterIpcSend</a></i>(&nbsp;)</b> calls this routine when it needs
to query the subagent about one of the MIB variables it manages.  Likewise,
the <b><i><a href="./masterIoLib.html#masterIpcAyt">masterIpcAyt</a></i>(&nbsp;)</b> function calls this routine when needs to check the IPC
link status.  Similarly, <b><i>snmpQueMonitor</i>(&nbsp;)</b> calls this routine to tell the
agent the results of a registration or deregistration request.
<p>
The master agent uses the value <i>flg</i> to specify the general nature of
the message it is writing to the subagent, which partially determines how
the subagent responds.  For example, when the master agent is responding
to the subagent after successfully handling its registration request, the
master agent uses a <i>flg</i> value of <b>REG_COMPLETE</b>.  When the master agent
does an "are you there" check, it specifies a <i>flg</i> value of <b>IPC_AYT</b>.
<b>REG_COMPLETE</b> and <b>IPC_AYT</b> are the only currently valid <i>flg</i> values.
<p>
</blockquote><h4>RETURNS</h4><blockquote><p>
OK or ERROR.
</blockquote><h4>SEE ALSO</h4><blockquote><p>
<b><a href="./masterIoLib.html#top">masterIoLib</a></b>

<hr>
<a name="masterIpcSend"></a>
<p align=right>
<a href="rtnIndex.html"><i>Libraries :  Routines</i></a></p>

</blockquote><h1><i>masterIpcSend</i>(&nbsp;)</h1> <blockquote></a></blockquote><h4>NAME</h4><blockquote>  
<p><strong><i>masterIpcSend</i>(&nbsp;)</strong> - send a message to a subagent</p>

</blockquote><h4>SYNOPSIS</h4><blockquote><p>
<pre>INT_32_T masterIpcSend
    (
    EBUFFER_T * pBuf,     /* message to be sent */
    PTR_T       ipchandle /* address of subagent */
    )</pre>

</blockquote><h4>DESCRIPTION</h4><blockquote><p>
The SNMP master agent calls when it needs to send a query in <i>buf</i> to
the subagent at the <i>ipchandle</i> address. If this routine is used with
<b><i><a href="./subagentLib.html#snmpMasterHandlerAsync">snmpMasterHandlerAsync</a></i>(&nbsp;)</b>, you must rewrite the function according to the
prototype of <b>IPCSEND_AS_T</b> (see <b>subagent.h</b>). The additional
parameter <i>reqid</i> in this prototype is the request ID of the message
being sent. Use <i>reqid</i> to call <b><i><a href="./subagentLib.html#snmpMasterCleanup">snmpMasterCleanup</a></i>(&nbsp;)</b> if the IPC layer
times out.
<p>
Internally, this function calls <b><i><a href="./masterIoLib.html#masterIoWrite">masterIoWrite</a></i>(&nbsp;)</b> to put a message on the
subagent's message queue.  If you have rewritten <b><i><a href="./masterIoLib.html#masterIoWrite">masterIoWrite</a></i>(&nbsp;)</b> to use
different IPC mechanism, such as sockets, you should take care that your
rewrite of <b><i><a href="./masterIoLib.html#masterIoWrite">masterIoWrite</a></i>(&nbsp;)</b> is compatible with its use in <b><i><a href="./masterIoLib.html#masterIpcSend">masterIpcSend</a></i>(&nbsp;)</b>.
<p>
</blockquote><h4>RETURNS</h4><blockquote><p>
0, if the packet has been sent successfully; 1, if and error has<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;been&nbsp;detected&nbsp;that&nbsp;caused&nbsp;the&nbsp;objects&nbsp;to&nbsp;be&nbsp;marked&nbsp;inactive&nbsp;and<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;possibly&nbsp;removed;&nbsp;2,&nbsp;if&nbsp;the&nbsp;processing&nbsp;of&nbsp;the&nbsp;current&nbsp;packet&nbsp;is<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;allowed&nbsp;to&nbsp;continue&nbsp;without&nbsp;freeing&nbsp;up&nbsp;objects.
</blockquote><h4>SEE ALSO</h4><blockquote><p>
<b><a href="./masterIoLib.html#top">masterIoLib</a></b>

<hr>
<a name="masterIpcRcv"></a>
<p align=right>
<a href="rtnIndex.html"><i>Libraries :  Routines</i></a></p>

</blockquote><h1><i>masterIpcRcv</i>(&nbsp;)</h1> <blockquote></a></blockquote><h4>NAME</h4><blockquote>  
<p><strong><i>masterIpcRcv</i>(&nbsp;)</strong> - wait for a reply from the subagent</p>

</blockquote><h4>SYNOPSIS</h4><blockquote><p>
<pre>INT_32_T masterIpcRcv
    (
    EBUFFER_T * pBuf,     /* buffer to be filled */
    PTR_T       ipchandle /* pointer to the IPC handle */
    )</pre>

</blockquote><h4>DESCRIPTION</h4><blockquote><p>
This routine waits for a response after query has been sent to the
subagent.  In the shipped implementation of the WindNet SNMP master agent,
this function waits on a message queue that is local to the master agent.
This message queue is used to facilitate communication between <b>tSnmpd</b>,
the task that manages communication with the SNMP manager, and <b>tMonQue</b>,
the task that manages communication between the SNMP master agent and
its subagents.
<p>
In the shipped master agent code, subagents communicate with the master
agent by putting messages on the message queue monitored by <b>tMonQue</b>.
If the message is a control message, it is processed by <b><i><a href="./subagentLib.html#snmpMasterHandlerWR">snmpMasterHandlerWR</a></i>(&nbsp;)</b>.
If the message is a query response, it is transferred to the local message
queue on which <b><i><a href="./masterIoLib.html#masterIpcRcv">masterIpcRcv</a></i>(&nbsp;)</b> is waiting.  All of this is handled
synchronously.  Thus, while the master agent is waiting for a response
from the subagent, it is blocked.  Normally, the amount of time spent
blocked is quite short and is not a problem.
<p>
However, it is an imperfect world, so it is possible that a response
for a query never makes it back to the subagent.  To handle this
possibility, the shipped version of the WindNet SNMP master agent puts
a timeout on its wait for a query response.  If you should rewrite the
SNMP master agent for any reason, make sure that you preserve this timeout.
<p>
</blockquote><h4>RETURNS</h4><blockquote><p>
0, if the packet was received successfully; 1, if an error or a<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;timeout&nbsp;has&nbsp;caused&nbsp;the&nbsp;objects&nbsp;to&nbsp;be&nbsp;marked&nbsp;inactive&nbsp;and<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;subsequently&nbsp;removed;&nbsp;2,&nbsp;if&nbsp;the&nbsp;master&nbsp;agent&nbsp;will&nbsp;allow&nbsp;the&nbsp;<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;current&nbsp;packet&nbsp;to&nbsp;be&nbsp;processed&nbsp;without&nbsp;freeing&nbsp;objects.
</blockquote><h4>SEE ALSO</h4><blockquote><p>
<b><a href="./masterIoLib.html#top">masterIoLib</a></b>

<hr>
<a name="masterIpcAyt"></a>
<p align=right>
<a href="rtnIndex.html"><i>Libraries :  Routines</i></a></p>

</blockquote><h1><i>masterIpcAyt</i>(&nbsp;)</h1> <blockquote></a></blockquote><h4>NAME</h4><blockquote>  
<p><strong><i>masterIpcAyt</i>(&nbsp;)</strong> - check the status of the IPC link</p>

</blockquote><h4>SYNOPSIS</h4><blockquote><p>
<pre>INT_32_T masterIpcAyt
    (
    PTR_T ipchandle /* pointer to IPC handle */
    )</pre>

</blockquote><h4>DESCRIPTION</h4><blockquote><p>
This is an "are you there" routine.  The SNMP master agent calls this
routine whenever it needs to do a status check on the IPC link to the 
address <i>ipchandle</i>.  This routine puts a null-buffer message of type 
<b>IPC_AYT</b> on the subagent's message queue. If the subagent replies with 
a message of the same type, the link is considered active.
<p>
</blockquote><h4>RETURNS</h4><blockquote><p>
0, if the link is inactive; 1, if the link is inactive
</blockquote><h4>SEE ALSO</h4><blockquote><p>
<b><a href="./masterIoLib.html#top">masterIoLib</a></b>

<hr>
<a name="masterIpcFree"></a>
<p align=right>
<a href="rtnIndex.html"><i>Libraries :  Routines</i></a></p>

</blockquote><h1><i>masterIpcFree</i>(&nbsp;)</h1> <blockquote></a></blockquote><h4>NAME</h4><blockquote>  
<p><strong><i>masterIpcFree</i>(&nbsp;)</strong> - free the IPC resources allocated by the SNMP master agent</p>

</blockquote><h4>SYNOPSIS</h4><blockquote><p>
<pre>void masterIpcFree
    (
    PTR_T ipchandle /* pointer to IPC handle */
    )</pre>

</blockquote><h4>DESCRIPTION</h4><blockquote><p>
The SNMP master agent calls this routine to free a pointer to an IPC handle.
This is part of the deregistration process for an SNMP agent.
<p>
</blockquote><h4>RETURNS</h4><blockquote><p>
N/A
</blockquote><h4>SEE ALSO</h4><blockquote><p>
<b><a href="./masterIoLib.html#top">masterIoLib</a></b>

<hr>
<a name="masterQueCleanup"></a>
<p align=right>
<a href="rtnIndex.html"><i>Libraries :  Routines</i></a></p>

</blockquote><h1><i>masterQueCleanup</i>(&nbsp;)</h1> <blockquote></a></blockquote><h4>NAME</h4><blockquote>  
<p><strong><i>masterQueCleanup</i>(&nbsp;)</strong> - free resources allocated for SNMP master agent</p>

</blockquote><h4>SYNOPSIS</h4><blockquote><p>
<pre>

void masterQueCleanup (void)</pre>

</blockquote><h4>DESCRIPTION</h4><blockquote><p>
This routine is called from the cleanup routine in <b><a href="./snmpIoLib.html#top">snmpIoLib</a></b> if the
agent fails to allocate resources.  This routine deletes the message queue
and all other resources that have been allocated for the master agent.
<p>
</blockquote><h4>RETURNS</h4><blockquote><p>
N/A
</blockquote><h4>SEE ALSO</h4><blockquote><p>
<b><a href="./masterIoLib.html#top">masterIoLib</a></b>

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