Introduction¶

There are over nine thousand known methods of communication: most of them follow a typical, simplistic scheme where: a connection is first established, and further conversation occurs through this connection. In such scenarios, the connection can be often thought of as a pipeline, and the conversations being the information and/or data that traverses through it.

The purpose of Connections module is to standardize the above communication scheme: harmonize the look & feel of each connection implementation using templates & base classes, and normalize the model that defines, binds & manages these various connections to Device Objects.

Conception¶

Following object-oriented programming methodology, each independent connection, regardless of its protocol (telnet/ssh/HTTP/SNMP) or technology (CLI/REST/YANG), shall be modelled as a class object, where the communication to and from this pipe is achieved through interaction with its class methods.

Subsequently, all connections (eg: class object instances) to the same target device shall be managed through a dedicated, high-level manager that provides resource allocation, control & conflict management, and finally, seamless integration to topology.Device object instances.

In effect, the connections module is a middleware, providing the basis to how each connection type should be implemented, and interfacing between devices these connection implementations. It features three primary classes:

ConnectionManager: the behind-the-scene director that binds connections to topology.Device objects. Each topology.Device instance is assigned its own ConnectionManager, which controls all connections to the testbed device this object represents.
BaseConnection: template class, providing the basis for various user imitations & implementations of an actual device connection (eg, telnet to console cli).
ConnectionPool: connection-like implementation that allows users to create a “pool” of similar-type connections and share them in a multi-processing environment.

These classes are not intended to be invoked from the user script directly - they work behind the scenes, governing script interactions and library implementations.

Installation¶

Connections module connections is installed by default as part of pyATS installation. It is also a pre-requisite to installing topology module. This package is featured on the PyPI server.

Note

connections module is part of the pyats namespace, and therefore, users should always refer to the full namespace when installing & using it.

pip install pyats.connections

To upgrade an existing installation of Connections package in your environment, do:

pip install pyats.connections --upgrade

Note

always read the Changelog first before you upgrade.