I pass commands to code all the time. When I require data back, I usually include a "Self-Addressed Stamped Envelope" in the form of a newly-created Notifier which the receiving code can use as the return channel. Using this method, I recently ran into some unusual behaviour. Some of the thus created Notifiers seemt o miss notifications. I'm reading them with "ignore previous" set to false, so no data should go missing but it does. I manage my many notifiers in an array and test each one repeatedly until it has returned a certain value (meaning the asynchronous process has finished). When I run the code included below, I run into problems but don't quite see why this should be the case. As usual, I'm probably doing something stupid. I'm using LV 2015 SP1.

LabVIEW

Reliability of SASE (Notifiers)

@Kevin_Price wrote:

Side question about architecture/design when you do this kind of S.A.S.E. stuff:

I think I'm missing something important. My first reaction to the S.A.S.E. idea is, "Hey, cool! Very parallel and decoupled. Processes don't need to know ahead of time whose requests they will respond to or who they will send results to. It's all up for grabs dynamically at run time."

But when thinking through the implementation a little bit, it seems that the datatype of the payload *does* need to be known on both sides of the comm link so that the sender can package it and the receiver can interpret it. So now things are back to being more coupled again, and the advantages are less obvious.

I don't really view things as parallel processes interacting, but rather hierarchal processes, where the higher-level "callers" use the API defined by the lower-level ones. Just as in regular programming API's, the low-level code is not dependant on the higher-level code, and the higher-level code has to deal with the datatypes returned by the low-level code.

As for Datatype coupling, that seems less important than communication coupling. That "the 'Temperature' module publishes a Temperature as a number" is less coupling than "the 'Temperature' module sends its readings only to a single Queue named 'main_UI'".