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Cadence Intro Workshop

This repository contains example code for my Cadence Intro Workshop.

Prerequisites

  1. Git, Make, etc.
  2. Make sure you have Go installed
  3. Make sure Docker and docker-compose are installed.

Usage

  1. Checkout this repository
  2. Run make up
  3. Wait for Cadence to start
  4. Check if Cadence is running with make ps
  5. Start a new shell with make shell
  6. Execute cadence domain register

Running a workflow from the shell

You can run a workflow from the shell using the following command:

cadence workflow run --tasklist workshop --execution_timeout 60 --workflow_type WORKFLOW_TYPE -i 'arg1 arg2...'

For example, running the first example looks like this:

cadence workflow run --tasklist workshop --execution_timeout 60 --workflow_type example01 -i '1 3'

As a best practice, workflows generally have a single input struct (to remain compatible with other languages). By default, Cadence uses JSON encoding, so such workflow execution looks like this:

cadence workflow run --tasklist workshop --execution_timeout 60 --workflow_type example02 -i '{"A": 1, "B": 2}'

You can shorten the command a lot by using shorthands for commands and options:

cadence wf run --tl workshop --et 60 --wt example01 -i '1 3'

Last, but not least, if you want to start a workflow without waiting for its result, you can do so by using the start command instead of run:

cadence wf start --tl workshop --et 60 --wt example01 -i '1 3'

Quering workflow state from the shell

Workflows can register query handlers to expose state about themselves. You can query that state using the following command:

cadence workflow query --workflow_id 72daa600-3cac-49b0-9e86-277a47c80a87 --query_type current_number

Or using a shorter version:

cadence wf query --wid 72daa600-3cac-49b0-9e86-277a47c80a87 --qt current_number

There is a special query type called __stack_trace that gives you the current stack trace of the workflow. Useful if a workflow is stuck for a long time and you want to check where it stopped.

Cleaning up

Once you are finished with the workshop, you can clean up all resources (containers) by running the following command:

make down

License

The MIT License (MIT). Please see License File for more information.