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.\" ========================================================================
.\"
.IX Title "SNMP::Extension::PassPersist 3pm"
.TH SNMP::Extension::PassPersist 3pm "2015-05-29" "perl v5.20.2" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
SNMP::Extension::PassPersist \- Generic pass/pass_persist extension framework
for Net\-SNMP
.SH "VERSION"
.IX Header "VERSION"
This is the documentation of \f(CW\*(C`SNMP::Extension::PassPersist\*(C'\fR version 0.07
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
Typical setup for a \f(CW\*(C`pass\*(C'\fR program:
.PP
.Vb 2
\&    use strict;
\&    use SNMP::Extension::PassPersist;
\&
\&    # create the object
\&    my $extsnmp = SNMP::Extension::PassPersist\->new;
\&
\&    # add a few OID entries
\&    $extsnmp\->add_oid_entry($oid, $type, $value);
\&    $extsnmp\->add_oid_entry($oid, $type, $value);
\&
\&    # run the program
\&    $extsnmp\->run;
.Ve
.PP
Typical setup for a \f(CW\*(C`pass_persist\*(C'\fR program:
.PP
.Vb 2
\&    use strict;
\&    use SNMP::Extension::PassPersist;
\&
\&    my $extsnmp = SNMP::Extension::PassPersist\->new(
\&        backend_collect => \e&update_tree
\&    );
\&    $extsnmp\->run;
\&
\&
\&    sub update_tree {
\&        my ($self) = @_;
\&
\&        # add a serie of OID entries
\&        $self\->add_oid_entry($oid, $type, $value);
\&        ...
\&
\&        # or directly add a whole OID tree
\&        $self\->add_oid_tree(\e%oid_tree);
\&    }
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This module is a framework for writing Net-SNMP extensions using the
\&\f(CW\*(C`pass\*(C'\fR or \f(CW\*(C`pass_persist\*(C'\fR mechanisms.
.PP
When in \f(CW\*(C`pass_persist\*(C'\fR mode, it provides a mechanism to spare
resources by quitting from the main loop after a given number of
idle cycles.
.PP
This module can use \f(CW\*(C`Sort::Key::OID\*(C'\fR when it is available, for sorting
OIDs faster than with the internal pure Perl function.
.SH "METHODS"
.IX Header "METHODS"
.SS "\fInew()\fP"
.IX Subsection "new()"
Creates a new object. Can be given any attributes as a hash or hashref.
See \*(L"\s-1ATTRIBUTES\*(R"\s0 for the list of available attributes.
.PP
\&\fBExamples:\fR
.PP
For a \f(CW\*(C`pass\*(C'\fR command, most attributes are useless:
.PP
.Vb 1
\&    my $extsnmp = SNMP::Extension::PassPersist\->new;
.Ve
.PP
For a \f(CW\*(C`pass_persist\*(C'\fR command, you'll usually want to at least set the
\&\f(CW\*(C`backend_collect\*(C'\fR callback:
.PP
.Vb 5
\&    my $extsnmp = SNMP::Extension::PassPersist\->new(
\&        backend_collect => \e&update_tree,
\&        idle_count      => 10,      # no more than 10 idle cycles
\&        refresh         => 10,      # refresh every 10 sec
\&    );
.Ve
.SS "\fIrun()\fP"
.IX Subsection "run()"
This method does the following things:
.IP "\(bu" 4
process the command line arguments in order to decide in which mode
the program has to be executed
.IP "\(bu" 4
call the backend init callback
.IP "\(bu" 4
call the backend collect callback a first time
.PP
Then, when in \f(CW\*(C`pass\*(C'\fR mode, the corresponding \s-1SNMP\s0 command is executed,
its result is printed on the output filehandle, and \f(CW\*(C`run()\*(C'\fR returns.
.PP
When in \f(CW\*(C`pass_persist\*(C'\fR mode, \f(CW\*(C`run()\*(C'\fR enters a loop, reading Net-SNMP
queries on its input filehandle, processing them, and printing result
on its output filehandle. The backend collect callback is called every
\&\f(CW\*(C`refresh\*(C'\fR seconds. If no query is read from the input after \f(CW\*(C`idle_count\*(C'\fR
cycles, \f(CW\*(C`run()\*(C'\fR returns.
.SS "add_oid_entry(\s-1FUNC_OID, FUNC_TYPE, FUNC_VALUE\s0)"
.IX Subsection "add_oid_entry(FUNC_OID, FUNC_TYPE, FUNC_VALUE)"
Add an entry to the \s-1OID\s0 tree.
.SS "add_oid_tree(\s-1HASH\s0)"
.IX Subsection "add_oid_tree(HASH)"
Merge an \s-1OID\s0 tree to the main \s-1OID\s0 tree, using the same structure as
the one of the \s-1OID\s0 tree itself.
.SS "\fIdump_oid_tree()\fP"
.IX Subsection "dump_oid_tree()"
Print a complete listing of the \s-1OID\s0 tree on the output file handle.
.SH "ATTRIBUTES"
.IX Header "ATTRIBUTES"
This module's attributes are generated by \f(CW\*(C`Class::Accessor\*(C'\fR, and can
therefore be passed as arguments to \f(CW\*(C`new()\*(C'\fR or called as object methods.
.SS "backend_collect"
.IX Subsection "backend_collect"
Set the code reference for the \fIcollect\fR callback. See also \*(L"\s-1CALLBACKS\*(R"\s0.
.SS "backend_fork"
.IX Subsection "backend_fork"
When set to true, the backend callbacks will be executed in a separate
process. Default value is false.
.SS "backend_init"
.IX Subsection "backend_init"
Set the code reference for the \fIinit\fR callback. See also \*(L"\s-1CALLBACKS\*(R"\s0.
.SS "backend_pipe"
.IX Subsection "backend_pipe"
Contains the pipe used to communicate with the backend child, when executed
in a separate process.
.SS "dispatch"
.IX Subsection "dispatch"
Gives access to the internal dispatch table, stored as a hash with the
following structure:
.PP
.Vb 4
\&    dispatch => {
\&        SNMP_CMD  =>  { nargs => NUMBER_ARGS,  code => CODEREF },
\&        ...
\&    }
.Ve
.PP
where the \s-1SNMP\s0 command is always in lowercase, \f(CW\*(C`nargs\*(C'\fR gives the number
of arguments expected by the command and \f(CW\*(C`code\*(C'\fR the callback reference.
.PP
You should not modify this table unless you really know what you're doing.
.SS "heap"
.IX Subsection "heap"
Give access to the heap.
.SS "idle_count"
.IX Subsection "idle_count"
Get/set the number of idle cycles before ending the run loop.
.SS "input"
.IX Subsection "input"
Get/set the input filehandle.
.SS "oid_tree"
.IX Subsection "oid_tree"
Gives access to the internal \s-1OID\s0 tree, stored as a hash with the
following structure:
.PP
.Vb 4
\&    oid_tree => {
\&        FUNC_OID  =>  [ FUNC_TYPE, FUNC_VALUE ],
\&        ...
\&    }
.Ve
.PP
where \f(CW\*(C`FUNC_OID\*(C'\fR is the absolute \s-1OID\s0 of the \s-1SNMP\s0 function, \f(CW\*(C`FUNC_TYPE\*(C'\fR
the function type (\f(CW"integer"\fR, \f(CW"counter"\fR, \f(CW"gauge"\fR, etc), and
\&\f(CW\*(C`FUNC_VALUE\*(C'\fR the function value.
.PP
You should not directly modify this hash but instead use the appropriate
methods for adding \s-1OID\s0 entries.
.SS "output"
.IX Subsection "output"
Get/set the output filehandle.
.SS "refresh"
.IX Subsection "refresh"
Get/set the refresh delay before calling the backend collect callback
to update the \s-1OID\s0 tree.
.SH "CALLBACKS"
.IX Header "CALLBACKS"
The callbacks are invoked with the corresponding object as first argument,
as for a normal method. A heap is available for storing user-defined data.
.PP
In the specific case of a program running in \f(CW\*(C`pass_persist\*(C'\fR mode with
a forked backend, the callbacks are only executed in the child process
(the forked backend).
.PP
The currently implemented callbacks are:
.IP "\(bu" 4
init
.Sp
This callback is called once, before the first \fIcollect\fR invocation
and before the main loop. It can be accessed and modified through the
\&\f(CW\*(C`backend_init\*(C'\fR attribute.
.IP "\(bu" 4
collect
.Sp
This callback is called every \f(CW\*(C`refresh\*(C'\fR seconds so the user can update
the \s-1OID\s0 tree using the \f(CW\*(C`add_oid_entry()\*(C'\fR and \f(CW\*(C`add_oid_tree()\*(C'\fR methods.
.SS "Examples"
.IX Subsection "Examples"
For simple needs, only the \fIcollect\fR callback needs to be defined:
.PP
.Vb 3
\&    my $extsnmp = SNMP::Extension::PassPersist\->new(
\&        backend_collect => \e&update_tree,
\&    );
\&
\&    sub update_tree {
\&        my ($self) = @_;
\&
\&        # fetch the number of running processes
\&        my $nb_proc = @{ Proc::ProcessTable\->new\->table };
\&
\&        $self\->add_oid_entry(".1.3.6.1.4.1.32272.10", gauge", $nb_proc);
\&    }
.Ve
.PP
A more advanced example is when there is a need to connect to a database,
in which case both the \fIinit\fR and \fIcollect\fR callback need to be defined:
.PP
.Vb 4
\&    my $extsnmp = SNMP::Extension::PassPersist\->new(
\&        backend_init    => \e&connect_db,
\&        backend_collect => \e&update_tree,
\&    );
\&
\&    sub connect_db {
\&        my ($self) = @_;
\&        my $heap = $self\->heap;
\&
\&        # connect to a database
\&        my $dbh = DBI\->connect($dsn, $user, $password);
\&        $heap\->{dbh} = $dbh;
\&    }
\&
\&    sub update_tree {
\&        my ($self) = @_;
\&        my $heap = $self\->heap;
\&
\&        # fetch the number of records from a given table
\&        my $dbh = $heap\->{dbh};
\&        my $sth = $dbh\->prepare_cached("SELECT count(*) FROM whatever");
\&        $sth\->execute;
\&        my ($count) = $sth\->fetchrow_array;
\&
\&        $self\->add_oid_entry(".1.3.6.1.4.1.32272.20", "gauge", $count);
\&    }
.Ve
.SH "SEE ALSO"
.IX Header "SEE ALSO"
SNMP::Persist is another pass_persist backend for writing Net-SNMP 
extensions, but relies on threads.
.PP
The documentation of Net-SNMP, especially the part on how to configure
a \f(CW\*(C`pass\*(C'\fR or \f(CW\*(C`pass_persist\*(C'\fR extension:
.IP "\(bu" 4
main site: <http://www.net\-snmp.org/>
.IP "\(bu" 4
configuring a pass or pass_persist extension:
<http://www.net\-snmp.org/docs/man/snmpd.conf.html#lbBB>
.SH "BUGS"
.IX Header "BUGS"
Please report any bugs or feature requests to 
\&\f(CW\*(C`bug\-snmp\-extension\-passpersist at rt.cpan.org\*(C'\fR, 
or through the web interface at 
<http://rt.cpan.org/Public/Dist/Display.html?Name=SNMP\-Extension\-PassPersist>.
I will be notified, and then you'll automatically be notified of 
progress on your bug as I make changes.
.SH "SUPPORT"
.IX Header "SUPPORT"
You can find documentation for this module with the perldoc command.
.PP
.Vb 1
\&    perldoc SNMP::Extension::PassPersist
.Ve
.PP
You can also look for information at:
.IP "\(bu" 4
Search \s-1CPAN\s0
.Sp
<http://search.cpan.org/dist/SNMP\-Extension\-PassPersist>
.IP "\(bu" 4
Meta \s-1CPAN\s0
.Sp
<https://metacpan.org/release/SNMP\-Extension\-PassPersist>
.IP "\(bu" 4
\&\s-1RT: CPAN\s0's request tracker
.Sp
<http://rt.cpan.org/Public/Dist/Display.html?Name=SNMP\-Extension\-PassPersist>
.IP "\(bu" 4
AnnoCPAN: Annotated \s-1CPAN\s0 documentation
.Sp
<http://annocpan.org/dist/SNMP\-Extension\-PassPersist>
.IP "\(bu" 4
\&\s-1CPAN\s0 Ratings
.Sp
<http://cpanratings.perl.org/d/SNMP\-Extension\-PassPersist>
.SH "AUTHOR"
.IX Header "AUTHOR"
Se\*'bastien Aperghis-Tramoni, \f(CW\*(C`<sebastien at aperghis.net>\*(C'\fR
.SH "COPYRIGHT & LICENSE"
.IX Header "COPYRIGHT & LICENSE"
Copyright 2008\-2011 Se\*'bastien Aperghis-Tramoni, all rights reserved.
.PP
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.