sila2 0.3.4

Python implementation of the SiLA 2 standard for lab automation

:warning: On 2021-11-15, this project replaced a legacy Python implementation of SiLA 2. That project can be found here and is still installable via pip install sila2lib.

SiLA 2 Python Implementation

Getting started

Installation

Use pip install sila2 to install the library.

On Raspberry Pi systems, you might encounter ImportErrors when using the library. Use the following commands to fix them:

• Error: ImportError: libxslt.so.1: cannot open shared object file: No such file or directory
  • Solution: Uninstall lxml and reinstall it with apt
    • pip uninstall -y lxml
    • sudo apt install python3-lxml
• Error: ImportError: /home/pi/.local/.../cygrpc.cpython-39-arm-linux-gnueabihf.so: undefined symbol: __atomic_exchange_8
  • Solution: Uninstall grpcio and grpcio-tools and reinstall them with apt
    • pip uninstall -y grpcio grpcio-tools
    • sudo apt install python3-grpcio python3-grpc-tools

Guides

Guides on SiLA server generation, feature implementation, and usage of SiLA clients can be found in the docs directory.

Example

The directory example_server contains an example SiLA server application. example_client_scripts contains multiple SiLA client programs that interact with the example server.

Implementation status

Missing parts from SiLA 2 specification

• Encryption
  • currently, communication is not encrypted
• Lifetime handling for binary transfer
  • currently, large binaries are only deleted on request
• Lifetime handling for observable commands
  • currently, no lifetime is reported and execution UUIDs stay valid indefinitely
• Server-initiated connection (SiLA 2 v1.1)
  • currently, only client-initiated connections are supported

Deviations from SiLA 2 specification

• Duration is rounded to microseconds, because datetime.timedelta does not support sub-microsecond precision
• Microseconds of datetime.time and datetime.datetime are ignored since Time and Timestamp don't support sub-second precision

Code generator

• Generates submodules from feature definitions (.sila.xml files)
  • feature implementation abstract base class
  • client typing stub (.pyi file)
• Does not yet support the Structure and Custom data types (fallback to typing.Any)
• Does not yet generate full docstrings (e.g. constraints are missing)

Contributing

Contributions in the form of issues, feature requests and merge requests are welcome. To reduce duplicate work, please create an issue and state that you are working on it before you spend significant time on writing code for a merge request.

Development setup

Clone the repository, initialize the submodule and install it as editable, including the development requirements:

git clone https://gitlab.com/sila2/sila_python
cd sila2
git submodule update --init --recursive
pip install -e .[dev]

Development environment

This project uses black as code formatter and isort for sorting imports.

flake8 is used to check for various code problems. pytest is used for testing, pytest-cov for measuring code coverage.

To apply formatting, the script run-formatting is provided with this repository. For testing, use run-checks afterwards.

To apply formatting and run a fast subset of the full test suite before each commit, link the script pre-commit to .git/hooks/pre-commit: ln -s ./pre-commit ./.git/hooks/pre-commit