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Getting Started

Requirements​

To get started, you will need Python 3.6 or later.

Setting up a Project​

Installing​

Install into an existing application is as simple as:

pip install cadence

The only dependency of core Cadence is schedule, which is used to schedule tasks.

Creating a Sample Project​

The Cadence package (i.e. the package installed using pip) is meant to be run inside of a Cadence application. Here is a minimal example of a Cadence application.

The core of Cadence is the Task object:

# task.py
from cadence import Task

class Test(Task):
  def run(self):
    print("Running test task")
# main.py
from cadence import bootstrap

from task import Test

if __name__ == "__main__":
  bootstrap(tasks=[Test])

The bootstrap method registers start and exit events and runs the task pipeline. The pipeline is responsible for managing the lifecycle of a Cadence application. Multiple pipelines can be created and run in parallel without interfering.

Example Task​

The Task class can utilize lifecycle methods to trigger methods at different points in a tasks lifecycle. Methods are similar to unit tests:

import schedule

from cadence import Task, before_all

class Test(Task):
  id = "12345" # set a unique ID for this task
  job = schedule.every(5).seconds  # set how frequently this task runs

  @before_all()
  def configure(self):
    print("Runs at the beginning of the task")
  
  @step() # equivalent to defining a "run" method
  def test_print(self):
    print("Running test task")

Pipeline Lifecycle​