styrum

Exactly! To implement an actor in LabVIEW one doesn't need LVOOP! Quite a few "asynchronously communicating modules" producer-consumer design patterns, developed by different people independently from each other including my LabHSM and EDQSM show that very clearly. After all, LVOOP didn't even exist when mine were developed. One can get away with just a cluster in a shift register to access any the data from any action case, but, OK, lets instead make an instance of a "regular" (LVOOP) class and make each action case just call a corresponding method of that class. It will look a little cleaner. The main point of creating an actor is to make an object more than just a bunch of data and methods, to give it a "process", "life", to encapsulate its state and enable it to exchange messages with other objects while having that own "life", i.e. the original Alan Kay's idea about what an(y) object is(should be). If your objects are like that (actors), and you build your application with (out of) them instead of the "regular" (data plus methods) objects, then you don't need all those complex "Gang of Four" design patterns which you indeed better use if you stick with "regular" objects. IMHO the main harm from "THE" Actor Framework is that it scares LabVIEW developers away from the actor model.

Quite a lively 😀 discussion on Slashdot: https://developers.slashdot.org/story/19/07/22/0426201/is-object-oriented-programming-a-trillion-dollar-disaster

I think it is important what exactly we call "OO code". If objects are not simply "dead" combinations of data and methods, but rather have their own "life"/"process", exchange messages with the user, "environment", and other objects the way actors do, react to events, I am all for such "OO code". The "regular/"passive"/"C++/Java/C# style" objects indeed have a very limited use and I agree that the attempts to build large applications using only them by constructing and utilizing complicated inheritance hierarchies and design patterns can lead to a disaster.

😂He knew what was coming: " I expect some sort of reaction from the defenders of OOP. They will say that this article is full of inaccuracies. Some might even start calling names. They might even call me a “junior” developer with no real-world OOP experience. Some might say that my assumptions are erroneous, and examples are useless. Whatever. " I think we all still can benefit from a more substantive discussion of his particular points rather than from accusations of "not understanding", let alone "calling names" and insults. A "straw man" demagogic trick is no good either. The author opposes not OOP in general or as coined in by Alan Kay, but rather the C++/Java "kind" of OOP, especially inheritance hierarchies and "promiscuous sharing" of state. Neither he advocates "unstructured coding". And the C++/Java/C# style of OOP is not and never has been the only (let alone "best") alternative to "unstructured coding". Actor model is circa 1973. Smalltalk is even older. Statefulness, messaging and concurrent code organization have everything to do with OOP if/when they need to be present in the same program in which you use OOP. Just because you really have to figure out how to implement them in your OOP code then. And, very softly speaking, they are not easily implementable with "regular"/"passive" objects consisting of only data and methods that need to be called from "outside" of the objects themselves.

Some food for thought: https://medium.com/better-programming/object-oriented-programming-the-trillion-dollar-disaster-92a4b666c7c7 Note that LVOOP is indeed the "C++, Java and C# variety of OOP" too, and is taught the same way, complete with "cats and dogs", all the same "Gang of Four" design patterns, S.O.L.I.D (https://scotch.io/bar-talk/s-o-l-i-d-the-first-five-principles-of-object-oriented-design), etc. " The bitter truth is that OOP fails at the only task it was intended to address. It looks good on paper — we have clean hierarchies of animals, dogs, humans, etc. However, it falls flat once the complexity of the application starts increasing. Instead of reducing complexity, it encourages promiscuous sharing of mutable state and introduces additional complexity with its numerous design patterns. OOP makes common development practices, like refactoring and testing, needlessly hard." I don't agree with everything he says, in particular with a definition of state. A variable is a state variable in a reactive (the vast majority of systems/applications and their components built with LabVIEW are indeed reactive and, hence, best modeled as such https://www.reactivemanifesto.org/) module/system/object in my opinion only if the reaction to some event/message (transition, actions that are run in response to the event, and/or target state) can be different depending on the value of that variable. And each object has its own state. The states of all the objects in the program combined constitute the state of the entire program itself, of course. But the very purpose of breaking a program into objects with their own ("isolated") states is to not have to deal with that combined state. The state of each object can and should be "mutable" in a sense, because real life objects indeed change their state with time and that indeed can have an effect not only on themselves but on their interaction with others. It should not be shared explicitly with other objects though, of course. I totally agree with him on that. Personally, I came to developing my LabVIEW applications as collections of asynchronous modules/active objects/actors which are backed by (hierarchical if needed) state machines and communicate with each other only via queued messages long before LVOOP was created, let alone "THE Actor Framework", DQMH, JKI's "State Machine Objects", etc. showed up. Search for "LabHSM" and "EDQSM", they are both circa 2004-2006. Those two templates/toolkits/design/patterns/frameworks of mine, just like some other similar "asynchronously communicating modules" frameworks, have no explicit sharing of state and are closer to the Alan Kay's/Smalltalk idea of objects, where messaging between objects is "The big idea" and where the state of the receiver object (and, hence, the actual code/action/method that will be run as the reaction to a particular message from the sender) is of no business of the sender (now recall Do method in AF's message class and what it takes to decouple actors exchanging such messages)! "Active" objects and actors are not just data and methods, which need to be called externally, by some other methods of some other objects and ultimately by the "God" main loop (well, technically, for active objects as opposed to actors, it is still their methods that are called but those "method calls" are actually just message sending to its process). The main idea is that in contrast to the "regular" OOP, each of "active" objects (actors, modules) has its own "life", in which it reacts to various events, both internal (resulting from its own actions) and external (messages it receives from environment/other objects). It can and often does react to the same event differently, depending on its current state. The reaction consists of running some other actions (which may include sending messages to other objects) and changing its state (transitions). Ideally, it is a true parallelism, not just concurrency, i.e. while communicating with others (within the same physical machine or over the network), it runs in its own thread, process, container, virtual machine or even its own CPU core or an entire real physical machine, because each such object is a "microservice". It is like a complete computer in a sense, just like Alan Kay imagined it. I counted at least three more similar idea "actor frameworks" presented at the latest NI Week and GDevCon. Some of them even use LVOOP :-) Maybe it is time for many other LabVIEW developers to look at the LVOOP and "regular", "passive", single loop/thread (C++, Java, C# style) OOP more critically too. Some more on the topic: https://medium.com/@richardeng/the-object-oriented-schism-9dedbbc3496b

The NI definitions of tag, stream and message/command are given, for example, in this cRIO guide (p. 29): http://www.ni.com/pdf/products/us/fullcriodevguide.pdf

It is indeed amazing and sad how attractive and popular "straw man argument" is. I won't even say anything else.

The matching discussion on NI forums: https://forums.ni.com/t5/LabVIEW/Eleven-Ways-to-Update-an-Indicator-from-within-a-subVI-Their/td-p/3938618

Yes, checking the watchdog queue takes a lot of time (if not most of) in each sender iteration. Please check out a "sequential version" in the latest posts or try putting a Disable structure around those Preview Queue Element nodes in the sender VIs (you will have to stop everything with the stop button on the toolbar of the Main then).

styrum Member ‎06-18-2019 04:17 PM Set Control By Index added. Wow, it is fast! "Speed" calculation in the "sequential" version corrected to count the iterations of the receiver loops. Fastest update of indicator from subVI (5).zip

Ok, OK, my bad, I left Debugging enabled. This is not a commercial app. This is is just some "food for thought", and something to play with, which you would otherwise not have the time to put together yourself. But now you can find some time (much less) to play with it. The goal was to get people to play with it, find flaws, "unfairness", etc. So I am glad that happened so quickly. Here is a version that has debugging disabled plus a "sequential" flavor of the whole thing. Some disclaimers right away: 1. Yes, I deliberately do not count the iterations completed by sender loops but not completed by the corresponding receivers by the time the senders are done, because I do want to count only fully completed "transactions" in evaluating "performance" 2. No, I don't say that lossy and non-lossy methods are comparable "1 to 1" in general context. But for the declared purpose of this particular experiment, updating an indicator in a UI VI, where the user is interested only in the latest value, it is fair to put them "together". Fastest update of indicator from subVI (3).zip

Sorry, I only have LV.2016.

Well, the very point of putting together this code is for people to see the numbers for themselves and that I didn't "cheat" on any of the tested methods to make some look better than others. Their significantly different performance numbers are real. In summary, the main findings are: 1. (Widely known) Passing a control reference to a subVI or a VI running in parallel to the VI where the control(indicator) is located with the purpose of using that reference to update that control/indicator is the worst you can do. 2. (Not so well known) Using "user events" in event structures for the same purpose mentioned and moreover, for implementing asynchronous communications in messaging architectures between "modules", "actors", parallel loops, etc. instead of regular queues and notifiers and now channels is (softly speaking) not a very good idea either from the performance point of view. 3. Even the fastest "channels" are not better than the "good old" notifiers and queues. At least channels give more features and allow to do things impossible before. Which hardly can be said about user events. DQMH is one of the frameworks which rely heavily on such use of event structures one can recall right away. There are others, I bet.

Yes, I know, you wanted to do this some day too. So I did it for you. Just run (and then stop) the Main VI from the attached set (Saved in LabVIEW 2016 32-bit). I suspect (and hope) the numbers will be quite a surprise and even a shock, especially for the fans of one particular method and some very aggressively promoted frameworks which use that method. Fastest update of indicator from subVI.zip

Maybe that will work too (again with a control, not with a constant). But there is no explanation there regarding the type expected as the Conpane (variant) parameter of that Set Conpane method. How do we get that Conpane from a VI we want to take it from before we can feed it to that method?