workflow-core

# Workflow Core

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Workflow Core is a light weight embeddable workflow engine targeting .NET Standard.  Think: long running processes with multiple tasks that need to track state.  It supports pluggable persistence and concurrency providers to allow for multi-node clusters.

### Announcements

#### New related project: Conductor
Conductor is a stand-alone workflow server as opposed to a library that uses Workflow Core internally. It exposes an API that allows you to store workflow definitions, track running workflows, manage events and define custom steps and scripts for usage in your workflows.

https://github.com/danielgerlag/conductor

## Documentation

See [Tutorial here.](https://workflow-core.readthedocs.io)

## Fluent API

Define your workflows with the fluent API.

```c#
public class MyWorkflow : IWorkflow
{
    public void Build(IWorkflowBuilder<MyData> builder)
    {    
        builder
           .StartWith<Task1>()
           .Then<Task2>()
           .Then<Task3>();
    }
}
```

## JSON / YAML Workflow Definitions

Define your workflows in JSON or YAML, need to install WorkFlowCore.DSL

```json
{
  "Id": "HelloWorld",
  "Version": 1,
  "Steps": [
    {
      "Id": "Hello",
      "StepType": "MyApp.HelloWorld, MyApp",
      "NextStepId": "Bye"
    },        
    {
      "Id": "Bye",
      "StepType": "MyApp.GoodbyeWorld, MyApp"
    }
  ]
}
```

```yaml
Id: HelloWorld
Version: 1
Steps:
- Id: Hello
  StepType: MyApp.HelloWorld, MyApp
  NextStepId: Bye
- Id: Bye
  StepType: MyApp.GoodbyeWorld, MyApp
```

## Sample use cases

* New user workflow
```c#
public class MyData
{
	public string Email { get; set; }
	public string Password { get; set; }
	public string UserId { get; set; }
}

public class MyWorkflow : IWorkflow
{
    public void Build(IWorkflowBuilder<MyData> builder)
    {    
        builder
            .StartWith<CreateUser>()
                .Input(step => step.Email, data => data.Email)
                .Input(step => step.Password, data => data.Password)
                .Output(data => data.UserId, step => step.UserId)
           .Then<SendConfirmationEmail>()
               .WaitFor("confirmation", data => data.UserId)
           .Then<UpdateUser>()
               .Input(step => step.UserId, data => data.UserId);
    }
}
```

* Saga Transactions

```c#
public class MyWorkflow : IWorkflow
{
    public void Build(IWorkflowBuilder<MyData> builder)
    {    
        builder
            .StartWith<CreateCustomer>()
            .Then<PushToSalesforce>()
                .OnError(WorkflowErrorHandling.Retry, TimeSpan.FromMinutes(10))
            .Then<PushToERP>()
                .OnError(WorkflowErrorHandling.Retry, TimeSpan.FromMinutes(10));
    }
}
```

```c#
builder
    .StartWith<LogStart>()
    .Saga(saga => saga