SNMPAGENTAPI(3) Net-SNMP SNMPAGENTAPI(3)

NAME
       snmpagentapi - embedding an agent into a external application

SYNOPSIS
       #include 
       #include 
       #include 

       int
       main (int argc, char *argv[])
       {
         int agentxsubagent = 1;  /* Change this if you're a master agent.  */

         snmpenablestderrlog();

         /*  If we're an AgentX subagent...  */
         if (agentxsubagent) {
             /* ...make us an AgentX client.  */
             netsnmpdssetboolean(NETSNMPDSAPPLICATIONID,
                                    NETSNMPDSAGENTROLE, 1);
         }

         initagent("yourappname");

         /*  Initialize your MIB code here.  */
         initmymibcode();

         /*  `yourappname' will be used to read yourappname.conf files.  */
         initsnmp("yourappname");

         /*  If we're going to be a SNMP master agent...  */
         if (!agentxsubagent)
             initmasteragent();  /*  Listen on default port (161).  */

         /*  Your main loop here...  */
         while (whatever) {
             /* if you use select(), see snmpapi(3) */
             /*     -- OR --  */
             agentcheckandprocess(0); /* 0 == don't block */
         }

         /*  At shutdown time:  */
         snmpshutdown("yourappname");
       }

       Then:
       $(CC) ... `net-snmp-config -agent-libs`


DESCRIPTION
       Our  goal  is to create a easy to use interface to the Net-SNMP package
       such that you can take  code  that  you  have  written  that  has  been
       designed  to  be  a  Net-SNMP  MIB module and embed it into an external
       application where you can either chose to be a SNMP master agent or  an
       AgentX  sub-agent  using  the  same MIB module code.  Our suggestion is
       that you use our (or another) SNMP agent as the AgentX master agent and
       chose to become an AgentX subagent which then attaches to the master.

       The  Net-SNMP  package  provides  a pair of libraries that enables easy
       embedding of an SNMP or AgentX agent into an external software package.
       AgentX  is  an extensible protocol designed to allow multiple SNMP sub-
       agents all run on one machine under a single SNMP master agent.  It  is
       defined in RFC 2741.

       You will need to perform a few tasks in order to accomplish this. First
       off, you will need to initialize both the SNMP  library  and  the  SNMP
       agent  library.  As  indicated above, this is done slightly differently
       depending on whether or not you are going to perform as a master  agent
       or an AgentX sub-agent.

CCOONNFFIIGGUURRAATTIIOONN
       If  you intend to operate as an AgentX sub-agent, you will have to con-
       figured the Net-SNMP package with agentx support (which is turned on by
       default, so just don't turn it off)

       Additionally, you will need to link against the net-snmp libraries (use
       the output of "net-snmp-config -agent-libs" to get a library list) and
       call subagentpreinit() as indicated above.

CCOOMMPPIILLIINNGG
       In  order  to  make  use of any of the above API, you will need to link
       against at least the four libraries listed above.

FFUUNNCCTTIIOONNSS
       where to find out more information on them.  It is certainly not a com-
       plete list of what is available within all the net-snmp libraries.

       snmpenablestderrlog()
              Logs  error  output  from  the  SNMP agent to the standard error
              stream.

       netsnmpdssetboolean()
              Please see the defaultstore(3) manual page for more information
              about this API.

       initagent(char *name)
              Initializes  the  embedded  agent.  This should be called before
              the iinniittssnnmmpp(()) call.  name is used to dictate what  .conf  file
              to read when iinniittssnnmmpp(()) is called later.

       initsnmp(char *name)
              Initializes  the SNMP library.  Note that one of the things this
              will do will be to read configuration files in an effort to con-
              figure  your application. It will attempt to read the configura-
              tion files named by the name string that you passed in.  It  can
              be  used to configure access control, for instance.   Please see
              the readconfig(3),  snmpconfig(5),  and  snmpd.conf(5)  manual
              pages for further details on this subject.

       initmasteragent(void)
              Initializes  the  master  agent and causes it to listen for SNMP
              requests on its default UDP port of 161.

       agentcheckandprocess(int block)
              This checks for packets arriving on the SNMP port and  processes
              them if some are found.  If block is non-zero, the function call
              will block until a packet arrives or an alarm must be  run  (see
              snmpalarm(3)).   The return value from this function is a posi-
              tive integer  if  packets  were  processed,  zero  if  an  alarm
              occurred and -1 if an error occured.

       snmpshutdown(char *name);
              This shuts down the agent, saving any needed persistent storage,
              etc.

SEE ALSO
       http://www.net-snmp.org/tutorial-5/toolkit/,  select(2),   snmpapi(3),
       defaultstore(3),    snmpalarm(3),   readconfig(3),   snmpconfig(5),
       snmpd.conf(5)



4.2 Berkeley Distribution         02 Apr 2001                SNMPAGENTAPI(3)