Workflow Actvity Usage vs Event

[stefan-buys]

Can someone explain a scenario where an activity makes sense as opposed to waiting for an event?

I'm trying to understand how the activity id is (should be) used to make it unique for a specific workflow instance. Also, what is the worker id?

builder                
   .StartWith<HelloWorld>()
   .Activity("activity-1", (data) => data.Value1)
       .Output(data => data.Value2, step => step.Result)
   .Then<PrintMessage>()
       .Input(step => step.Message, data => data.Value2);
       
...
...

var activity = host.GetPendingActivity("activity-1", "worker1", TimeSpan.FromMinutes(1)).Result;

if (activity != null)
{
    Console.WriteLine(activity.Parameters);
    host.SubmitActivitySuccess(activity.Token, "Some response data");
}       
       

vs

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);

[danielgerlag]

The activity has an API to get a list of pending work for a given worker, and then implement something to do that work.
The wait for is more simple, in that it only wait for an external event, it could be any event, not necessarily a packet of work that needs to be done, and there is no API for a worker to fetch a list of work items to do.