 
Example scripts
===============

.. toctree::
   :maxdepth: 2

SNMP is not really simple (PySNMP implementation takes over 15K lines of
Python code), but PySNMP tries to isolate the complexities and let you 
perform typical SNMP operations in a quick and intuitive way.

PySNMP offers three groups of programming interfaces to deal with 
SNMP protocol. In the order from most consice to most detailed those 
APIs follow.

High-level SNMP
---------------

The so called high-level API (hlapi) is designed to be simple, concise and
suitable for the most frequent operations. For that matter only
Command Generator and Notification Originator Applications are currently
wrapped into a nearly one-line Python expression.

It comes in several flavours: one synchronous and a bunch of bindings to
popular asynchronous I/O frameworks. Those varieties of APIs bring
subtile differences, mostly to better match particular I/O framework
customs. Unless you have a vary specific task, one of high-level APIs might
solve your SNMP needs.

.. toctree::
   :maxdepth: 2

   /examples/hlapi/asyncore/sync/contents

.. toctree::
   :maxdepth: 2

   /examples/hlapi/asyncore/contents

.. toctree::
   :maxdepth: 2

   /examples/hlapi/asyncio/contents

.. toctree::
   :maxdepth: 2

   /examples/hlapi/trollius/contents

.. toctree::
   :maxdepth: 2

   /examples/hlapi/twisted/contents

Native SNMP API
---------------

Complete implementation of all official Standard SNMP Applications. It 
should let you implement any SNMP operation defined in the standard
at the cost of working at a somewhat low level.

This API also comes in several transport varieties depending on I/O
framework being used.

.. toctree::
   :maxdepth: 2

   /examples/v3arch/asyncore/contents
   /examples/v3arch/asyncio/contents
   /examples/v3arch/trollius/contents
   /examples/v3arch/twisted/contents

Packet-level SNMP
-----------------

In cases where performance is your top priority and you only need to 
work with SNMP v1 and v2c systems and you do not mind writing much 
more code, then there is a low-level API to SNMP v1/v2c PDU and 
PySNMP I/O engine. There's practically no SNMP engine or SMI 
infrastructure involved in the operations of these almost wire-level 
interfaces. Although MIB services can still be used separately.

A packet-level API-based application typically manages both SNMP 
message building/parsing and network communication via one or more 
transports. It's fully up to the application to handle failures on 
message and transport levels.

Command Generator
+++++++++++++++++

.. toctree::

   /examples/v1arch/asyncore/manager/cmdgen/fetching-variables
   /examples/v1arch/asyncore/manager/cmdgen/modifying-variables
   /examples/v1arch/asyncore/manager/cmdgen/walking-operations
   /examples/v1arch/asyncore/manager/cmdgen/transport-tweaks

Command Responder
+++++++++++++++++

.. toctree::

   /examples/v1arch/asyncore/agent/cmdrsp/agent-side-mib-implementations

Notification Originator
+++++++++++++++++++++++

.. toctree::

   /examples/v1arch/asyncore/agent/ntforg/transport-tweaks

Notification Receiver
+++++++++++++++++++++

.. toctree::

   /examples/v1arch/asyncore/manager/ntfrcv/transport-tweaks

Using these examples
--------------------

Before doing cut&paste of the code below into your Python interpreter, 
make sure to install pysnmp and its dependencies by running pip or 
easy_install: ::

    # pip pysnmp

There's a `public SNMP responder <http://snmpsim.sourceforge.net/public-snmp-simulator.html>`_ 
configured at *demo.snmplabs.com:161* to let you run PySNMP examples
scripts in a cut&paste fashion. If you wish to use your own SNMP Agent
with these scripts, make sure to either configure your local snmpd and/or
snmptrapd or use a valid address and SNMP credentials of your SNMP Agent
in the examples to let them work.

Should you want to use a MIB to make SNMP operations more human-friendly,
you are welcome to search for it and possibly download one from our
`public MIB repository <http://mibs.snmplabs.com/asn1/>`_. Alternatively,
you can configure PySNMP to fetch and cache required MIBs from there
automatically.

If you find your PySNMP application behaving unexpectedly, try to enable 
a /more or less verbose/ built-in PySNMP debugging by adding the 
following snippet of code at the beginning of your application:

.. code-block:: python

    from pysnmp import debug

    # use specific flags or 'all' for full debugging
    debug.setLogger(debug.Debug('dsp', 'msgproc', 'secmode'))

Then run your app and watch stderr. The Debug initializer enables debugging 
for a particular PySNMP subsystem, 'all' enables full debugging. More 
specific flags are:

* io
* dsp
* msgproc
* secmod
* mibbuild
* mibview
* mibinstrum
* acl
* proxy
* app

For more details on PySNMP programming model and interfaces, please 
refer to :doc:`library documentation</docs/api-reference>`.
