Question on how to built a data processing workflow

[tomazk8]

I am trying to build a workflow in code to process the data comming from sensors. I tried it using Fork and Join but could not find a way how to connect the activities to work. I have two data channels (producing one double value each) that I need to subtract, get an absolute, then compare this to a constant and output bool if value is above the limit. I want to use separate activities for these operations which are: Channel, Subtract (takes 2 inputs), Absolute, Constant and Compare (takes 2 inputs: value and a constant to compare to). Here is a flow for it:

Ch1 ->
Ch2 -> Subtract -> Absolute -> Compare -> [bool result]
                   Constant ->

Can you maybe help me with building a workflow in code, not the designer?

Thanks

[sfmskywalker]

That is a very nice use case.

The described flow can be implemented with a Fork and Join and continue with Subtract that accessed the output of Ch1 and Ch2, although a more elegant solution would be to implement Subtract as a joinable activity (by subclassing the Join activity).

I'll create a new sample console project demonstrating the described flow.

Besides that, I'm thinking that perhaps an even more elegant solution is if Elsa would natively support any activity to be configurable whether it should continue execution either immediately (as is the case today) or after all incoming activities have executed (i.e. native "join" behavior"). I'll put some more thought into this as a potential enhancement for Elsa 2.

[sfmskywalker]

I created Sample25 that demonstrates the above flow.

As I was creating the example, I discovered a couple of subtle bugs. They have been fixed as well & published to NuGet (i.e. make sure to update any Elsa package references).

[tomazk8]

Thank you very much. I will try it out.