How to achieve a better process rollback workflow

[codecodecookie]

I use json define workflow like the following picture:

but when the steps nodes become more and more,the decision branch may not be a good solution.I have tyied with this funciton:
At the StepType corresponding method in Run(),use
return ExecutionResult.Branch(new List { context.Item }, "A_NODE") statement
or
return ExecutionResult.Persist("A_NODE") statement
to implements the process of going back from the current process node to A NODE.I konw decision branch can do this ,but I want another way to realize this process. who can give me some advice,ungrateful！

[brucezlata]

Use saga pattern
https://workflow-core.readthedocs.io/en/latest/sagas/

[MOwaisfarooq]

@brucezlata Can you please let me know how I can implement saga transaction. I am using EventPublish to forward the workflow step and in each step i have perform some database transaction through service injection. if error raises on any step, it will suspend the workflow and rollback my service transaction for current step only.

[brucezlata]

@MOwaisfarooq you can check the above link, for example, throw exception once there is any error in any of your steps (Tasks), then, compensate entire saga transaction (UndoEverything).

builder
    .StartWith(context => Console.WriteLine("Begin"))
        .Saga(saga => saga
            .StartWith<Task1>()
            .Then<Task2>()
            .Then<Task3>()
    )
        .CompensateWith<**UndoEverything**>()
    .Then(context => Console.WriteLine("End"));

[MOwaisfarooq]

If an error occurs in step B of the workflow, I suspend the workflow to publish this event later from the controller API. The _workflowStepDetailsService.UpdateTransactionForStepB has made a transaction in my table stepTable. I want to revert only the step B service transaction that updated the table. I don't want to undo everything, so that next time I can continue from step B after the error. For example, if I made an insertion in step A using _workflowStepDetailsService.CreateTransactionforStepA in my stepTable, I want to preserve that transaction and only undo the changes made by step B.

builder .StartWith(context => Console.WriteLine("Begin")) .UseDefaultErrorBehavior(WorkflowErrorHandling.Suspend) .Saga(saga => saga .StartWith<stepA>() .Then<stepB>() .Then<stepC>() ) .CompensateWith<**UndoEverything**>() .Then(context => Console.WriteLine("End"));
``

public class stepA: StepBodyAsync
{


    private readonly IWorkflowStepDetailsService _workflowStepDetailsService;

    public stepA(IWorkflowStepDetailsService workflowStepDetailsService)
    {
        _workflowStepDetailsService = workflowStepDetailsService;
    }

    public override async Task<ExecutionResult> RunAsync(IStepExecutionContext context)
    {

        if (!context.ExecutionPointer.EventPublished)
        {
            return ExecutionResult.WaitForEvent("StartWorkflowEvent", context.Workflow.Id, DateTime.Now);
        }

        var workflowsteprequest = (WorkFlowStepDetails)context.ExecutionPointer.EventData;
        await _workflowStepDetailsService.CreateTransactionforStepA(workflowsteprequest);

        return ExecutionResult.Next();
    }
}

``
public class stepB : StepBodyAsync
{
private readonly IWorkflowStepDetailsService _workflowStepDetailsService;

    public stepB: (IWorkflowStepDetailsService workflowStepDetailsService)
    {
        _workflowStepDetailsService = workflowStepDetailsService;
    }

    public override async Task<ExecutionResult> RunAsync(IStepExecutionContext context)
    {

        if (!context.ExecutionPointer.EventPublished)
        {
            return ExecutionResult.WaitForEvent("StartWorkflowEvent", context.Workflow.Id, DateTime.Now);
        }

        var workflowsteprequest = (WorkFlowStepDetails)context.ExecutionPointer.EventData;

        await _workflowStepDetailsService.UpdateTransactionForStepB(workflowsteprequest);

        return ExecutionResult.Next();
    }

}
``