Plankton

Plankton is a Python framework for simulating hardware devices. It is compatible with both Python 2 and 3.

Plankton can be run directly using Python 2.7 or >= 3.4, or using a prepackaged Docker image that includes all dependencies. See relevant usage sections for details.

Resources: GitHub -- DockerHub -- Dockerfile

Purpose and Use Cases

Plankton is being developed in the context of instrument control at the ESS, but it is general enough to be used in many other contexts that require detailed, stateful software simulations of hardware devices.

We consider a detailed device simulation to be one that can communicate using the same protocol as the real device, and that can very closely approximate real device behaviour in terms of what is seen through this protocol. This includes gradual processes, side-effects and error conditions.

The purpose of Plankton is to provide a common framework to facilitate the development of such simulators. The framework provides a common set of tools and abstracts away protocol adapters, which helps minimize code replication and allows the developer of a simulated device to focus on capturing device behaviour.

Potential use cases for detailed device simulators include:

• Replacing the physical device when developing and testing software that interfaces with the device
• Testing failure conditions without risking damage to the physical device
• Automated system and unit tests of software that communicates with the device
• Perform "dry runs" against test scripts that are to be run on the real device

Using a simulation for the above has the added benefit that, unlike most real devices, a simulation may be sped up / fast-forwarded past any lengthy delays or processes that occur in the device.

Features

Brief Terminology

Devices and Interfaces are two independent concepts in Plankton. The Device is model for the device behaviour and internal memory. A Device can be represented using a StateMachine, but it does not have to be. A Device does not include anything specific to the communication protocol with the Device. An Interface provides a protocol binding to a Device. The Device and Interface are created as part of a Simulation that provides a "heart beat" and other environmental aspects.

What Can You Do With Plankton?

• Create new Devices to closely imitate the internal behaviour and memory of something
• Optionally make a Device work as a StateMachine via StateMachineDevice to to give rich behaviours
• Create one or more Interfaces over your Device to expose it as an EPICS IOC, a TCP listener, or on any other bespoke protocol you like
• Access and control the Device while it is running via a "back door"
• Access and control the Simulation while it is running via a "back door"

Additional Documentation

Details on running Plankton, working with Plankton as a device developer, and framework internals are described in the following documents:

• Installation and Usage
  • Using Plankton with Docker: Plankton provides a Docker image that encapsulates all dependencies for ease of use.
  • Using Plankton with Python: Plankton can be run directly via Python once dependencies are installed.
  • Adapter Specific Parameters: Usage details for specific protocol adapters.
• Runtime Control
  • Remote Access to Device: A simulated device can be inspected and manipulated at runtime.
  • Remote Access to Simulation: Simulation parameters and statistics can be inspected and manipulated at runtime.
• Creating Device Simulators
  • Contribution Guidelines: New device simulators can be added to Plankton.
• Framework Internals
  • Detailed Overview of Framework: Description of framework internals and design decisions.

Until the documentation is available online, it can also be generated from the sources:

$ git clone https://github.com/DMSC-Instrument-Data/plankton
$ cd plankton
$ pip install -r requirements-dev.txt
$ sphinx-build -b html docs/ docs/_build/html

The docs/_build/html directory will then contain the full documentation in HTML format.