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Your First Workflow

To implement a Tourbillon workflow you will need to:

  • Define a service that will receive a request to execute and a return a workflow response (result)
  • Implement the logic for your service using Starlark

We will use a simple calculator scenario to provide a practical example of how to implement a Tourbillon workflow.

Prerequisites​

Defining your workflow interface​

calculator/service.proto
syntax = "proto3";

package demo;

import "tourbillon/annotations/v1/durable_service.proto";

message CalculatorServiceRequest {
    number x = 1;
    number y = 2;
    string operation = 3;
}

message CalculatorServiceResponse {
    number n = 1;
}

service CalculatorService {
    option (tourbillon.annotations.v1.durable_service) = true;

    rpc Execute(CalculatorServiceRequest) returns (CalculatorServiceResponse);
}

Implementing your workflow logic​

Each workflow definition requires an Execute function that accepts two arguments:

  • ctx: a context object
  • req: the request received for the workflow execution

In this example the req is the Protobuf message demo.CalculatorServiceRequest as defined in the Proto.

demo/CalculatorService.star
def Execute(ctx, req):
    # your code here...

This is where the coordination logic for your workflow will be implemented, using Starlark.

For example; we implement basic arithmetic to our workflow:

demo/CalculatorService.star
def Execute(ctx, req):
    demo = proto.package("demo", contracts=ctx.contracts)
    n = null

    if req.operation == "+":
        n = req.x + req.y
    elif req.operation == "-":
        n = req.x - req.y
    elif req.operation == "*":
        n = req.x * req.y
    elif req.operation == "/":
        n = req.x / req.y

    return demo.CalculatorServiceResponse(n = n)

The return value for the function must be the Protobuf message, as defined in our Proto definition.

Deploying your workflow​

TODO

Executing your workflow​

curl -d '{"x":10,"y":10}' http://localhost:8000/demo.CalculatorService/Execute