SWF: Ruby implementation does not accept a namespaced Workflow class when registering the Workflow

[rantonmattei]

If my workflow class is part of a namespace like shown below, I get the following error: ruby-2.1.2/gems/aws-sdk-1.42.0/lib/aws/core/client.rb:375:in `return_or_raise': Invalid name: MyWorkflows::HelloWorldWorkflow.hello (AWS::SimpleWorkflow::Errors::ValidationException)

A quick look to the doc @ http://docs.aws.amazon.com/amazonswf/latest/apireference/API_RegisterWorkflowType.html confirms that the RegisterWorkflowType API action cannot take a name with a colon.

The specified string must not start or end with whitespace. It must not contain a : (colon), / (slash), | (vertical bar), or any control characters (\u0000-\u001f | \u007f - \u009f). Also, it must not contain the literal string "arn".

So that raises at least 2 main concerns:

• we cannot use namespaces with a Ruby implementation whether we use Flow or not. This is a big issue not only for code structure but that means we cannot build on top the Flow implementation to encapsulate logic or share behaviors across workflows using mixins.
• it results in a pretty big inconsistency between languages. I could use namespaces in Php because it would be "\MyWorkflows\HelloWorldWorkflow", the namespace separator being a backslash whereas in Ruby I cannot because the namespace separator is a double colon. Why?

require_relative "../../swf_init"
require_relative "activities/hello"

# HelloWorldWorkflow class defines the workflows for the HelloWorld sample
module MyWorkflows
  class HelloWorldWorkflow
    extend AWS::Flow::Workflows

    workflow :hello do {
      version: HelloWorldInit::WF_VERSION,
      task_list: HelloWorldInit::WF_TASKLIST,
      execution_start_to_close_timeout: 3600,
    }
    end

    # Create an activity client using the activity_client method to schedule
    # activities
    activity_client(:hello_client) { { :from_class => "HelloActivity" } }

    # This is the entry point for the workflow
    def hello(name)
      # Use the activity client 'client' to invoke the say_hello activity
      hello_client.say_hello(name)
    end
  end
end
# Start a WorkflowWorker to work on the HelloWorldWorkflow tasks
HelloWorldInit.new.workflow_worker(MyWorkflows::HelloWorldWorkflow).start if $0 == __FILE__

# HelloWorldInit.new.workflow_worker eventually calls
# AWS::Flow::WorkflowWorker.new(domain.client, domain, WF_TASKLIST, workflow_class)
# workflow_class being MyWorkflows::HelloWorldWorkflow

[trevorrowe]

It looks like you logged this against the wrong repo. You are probably looking for https://github.com/aws/aws-flow-ruby.

[rantonmattei]

I doubt it is a Flow issue. Flow eventually calls the API with [ClassName].[MethodName] as name param (SimpleWorkflow service with RegisterWorkflowType action).

It is inherent to the SWF service, I guess. The main issue is that we cannot register WorkflowType with a colon in it (like "MyWorkflow::HelloWorld.sayHello"). Therefore, using Ruby namespaces is excluded.

However, I was able to register a Workflow using backslashes in the name from the console. So that means you can register workflow classes within namespaces using Php. Unfortunately, there is no Php implementation of Flow...

I guess a workaround could be implemented at the SDK level and replace those colons with another separator before registration. And then replace them back when retrieving the WorkflowTypes after polling for tasks.

BTW, the same thing is happening when registering Activities.

[trevorrowe]

The Ruby SDK specifically chooses to not modify user supplied input before sending values to the remote service. This can cause lots of downstream issues where values are not formatted as expected.

I suggest opening this as an issue with the flow framework project. They should be providing SWF friendly values.

[trevorrowe]

Closing this issue for now as there is no SDK changes required.