OnboardingSaga

F# Onboarding Saga

This sample demonstrates how to work with Rebus using F#. The project contains a Web API front end and a backend saga that has a timeout and compensating actions.

The project uses the file system as the message transport with c:/rebus being the default hard-wired location. The location can be changed where Rebus is configured in the Web API and the backend saga.

This sample models a made-up business process for onboarding of new customers.
As well as functional requirements, the business also have operational requirements and the saga has a timeout in place to help them meet that requirement. When a new customer is taken on, the business wants the following to happen:

• An account is to be created for the customer.
• A welcome email is to be sent to the customer after the account is created.
• A sales call is scheduled in the CRM after the account has been created.

To support the business' operational requirements that new customers must be processed within a given time, our saga must complete within a given time. If it does not do that then the business wants the following to happen:

• Any placed sales call is to be cancelled.
• The service desk takes over the process.

Note that the SendWelcomeEmail handler simulates a delay resulting in the OLA always being breached.

interface IHandleMessages<SendWelcomeEmail> with
    member x.Handle(m: SendWelcomeEmail) =
        task
            {
                Log.Information($"Sending welcome email for account {m.AccountId}.")
                do! Task.Delay(10000); // This delay will breach our OLA rules!
                do! bus.Reply(WelcomeEmailSent.For m.AccountId)
            } :> Task