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.