DQMH Consortium Toolkits Feature Requests

This is more of a question or request for comments than an actual feature request:

In the dialogue window for creating a new DQMH module, should we rename the caption "Module Type" to "Module Template"? For a vanilla installation of DQMH, there are only two templates to choose from (Singleton and Cloneable), so the caption makes sense. Once you start adding your own templates, not so much anymore. Also, for documentation purposes, it would make things clearer if we separated the term "type" from the term "template".

In addition, it would be nice to see the actual type of the module (singleton or cloneable) added to the name in the dropdown list (see screenshot).

Opinions?

In many cases I launch the cloneable instance(s) and launch the API tester on demand. In this case the API tester doesnt show if any instances are already running, I need to press the refresh button which I forgot in most of the cases. Other developer not that familiar with DQMH forgot it all the time causing confusion.

I have fixed this in the template module we use for cloneables:

When creating a new event for a module and my project contains numerous modules, finding the correct module in the list can be somehow painfull.

Listing the DQMH modules in alphabetic order would help finding the correct module faster.

There is an option to convert Requests to Request and wait for reply but requests can not be converted to Roundtrip, so a broadcast has to be created manually with payload identical to the Request. Creating a Broadcast is not much of a deal but having two identical payloads is not ideal especially if the payload bundles multiple typedefs.

We have identified that, if multiple clonable module instances are executed and a specific module (e.g. the first launched module) is stopped (no waiting) and afterward all open modules are stopped at once (incl. wait) the "stop module.vi" an error 1 is returning.

Steps to reproduce

1. Create a project and add a new clonable module
2. Create a tester VI and implement the code above 
3. Run the VI and see error 1 at second Stop Module.

What is happening in the Background

Situation 1 - "Stall Data Flow" = 0

1. "Stop Module.vi" 2 runs into "Wait on Stop Sync.vi" and synchronizes stop over rendezvous.
   The acquired rendezvous size is 3 (Module 1 which is at stopping, Module 2 and Stop Module)
2. Module 1 is waiting in "Safe to Destroy Refnums.vi"
3. Module 2 runs into "Close Module.vi"
   

    

   1. Last clone instance is fire at (1)
   2. Releasing the Semaphore (2) will wake up module 1 that it is now safe to destroy refnums now.
      Module 2 runs into "Wait on Stop Sync.vi" (3) and synchronizes over rendezvous.
   3. "Stop Module.vi" and Module 2 waiting for a third participation to join the rendezvous.
   4. Module executes case to destroy Master reference.... and executes "Wait on Stop Sync.vi" (3) with no synchronization as the boolean "Wait for Module to stop?" is on false.
   5. Module 1 executes "Destroy Sync Refnums.vi" (4) and is destroying the rendezvous.
   6. Module 2 and "Stop Module.vi" will be release from the waiting of the rendezvous as the reference is now invalid and returning error 1.

Situation 2 - "Stall Data Flow" = e.g. 2000ms

1. In compare to the situation 1 the first module is already removed here. The obtained rendezvous has the expected size of 2.
2. When module 2 enters rendezvous synchronization in "Wait on Stop Sync.vi" (3) the expected amount of participant is reached, and the execution can continue.
3. In most of our tests, this situation worked fine and did not create an error.
4. For some situation, we had the behavior that shutdown of the first module seems to be faster as the wake-up from rendezvous of the second module. The module main of module 2 opened and showed error 1. Module 1 seems to destroy the references to early. 

Situation 3 - First Module will be stopped with last "Stop Module.vi" call

The shutdown of a module is for this scenario delayed (add a wait 1000ms to exit case of the module)

1. Stop Module 2 waits for 11 rendezvous participations. (10 module and itself)
2. One of the previously closed module will destroy the synchronization events and makes the rendezvous reference invalid. => Error 1 at "Stop Module.vi"

Potential Fix

Spoiler

The following screenshots are showing an extension of the "Stop Module.vi" and the "Close Module.vi".

The idea is to use a single element queue (SEQ) containing a map of sets. The key of the map refers to a "Stop Module.vi" which waits for stopping all module at the time when the "Stop Module.vi" is executed. The Set contains all Module ID's which should be stopped. Each module checks in its close condition if the SEQ is existing. If so, the module ID will be removed from the sets which containing the module ID. An empty set refers to all required modules have stopped and a notifier which is used for synchronization will be fired.
Close Module.vi extention
Stop Module.vi extention

 

With those extensions, all three described scenarios should be fixed. In addition, should it be possible to stop all module and launch in the background new ones, the stop and wait will wait until all those modules ID run at the stop execution are finished.

 

I added the project which the extensions and tests to the post.

Addition

I'm not sure, but I think that with the described change, destroy of the Module's Semaphore (1) should be done with the boolean condition of the First & Last Instance (2). (Red line)

Please let me know if you need any additional information and details.

As mentioned in DQMH Forum: VI Reentrance issue VIs which are required to be non-reentrant are not reported from the DQMH validation tool if they were changed (e.g. to shared clone)

Some of the important VIs which should be reported:

• Obtain Broadcast Events.vi
• Obtain Request Events.vi
• Clone Registration AE.vi
• Start Module (is already reported)
• Basically all used FGV's

Steps to reproduce:

1. Create Project with a new clonable module
2. Change all non-reentrant VIs to shared clone
   

    

3. Run module validation and execute fix
   1. Start Module.vi will be updated and changed
4. Rerun module validation
   1. No issues reported

Let developer create own DQMH validation test which allows them to test company specific style and scripting.

At that point, it would although be great to store a test configuration. E.g. which tests should be executed and which severity a failing test hast. 

We are constantly having deployment errors on RT targets, mentioning the Simple Error Handler. Since on RT Targets that function is useless anyway, we've put a conditional disable structure around. This solved the error.

It would be nice, if that CDS would be added to a standard DQMH module.

Today most of our screens support a 1920x1080 resolution.

And the actual space that I can basically use in the MHL is 530x315 pixels (roughly, surface of the MHL minus subdiagram comment).

Which means that my useful coding surface is only 30% of my screen resolution.

I guess the EHL and MHL can be designed wider so that we have more space for our custom code.

Today when an event is removed, no special actions are done in the testers and a 'manual search' has to be done in the module's main VI.

Here is what is suggested in DQMH help :

• In the case of a Request:
• In the Tester VI:
• Open the block diagram and find the event frame configured to test calling this request.
• ...
• In the DQMH Module Main.vi:
• Open the block diagram and find the event frame configured for this request (It might no longer be listed and instead say something like “Unknown Event (0x0)”).
• ...
• In the case of a Broadcast:
• In the Tester VI:
• Open the block diagram and find the event frame configured for this broadcast. (It might no longer be listed and instead say something like “Unknown Event (0x0)”.)
• ...
• In the Module Main VI:
• Open the block diagram and find the places where the broadcast VI is called and remove it.
• ...

It would be nice to attract dev eyes on the places where modifications need to be done post event-removing.

Maybe adding a comment like this would be enough ?

It is not much, but the comment color and hashtag would ease the 'finding' process.

Hi DQMH Enthusiasts,

What we always do by adapting the std DQMH template is adding a logging functionality into the dequeue VI of the MHL of each module (our logger of choice is a LV wrapper around Log4Net, but it doesn't matter). In my recent project, I added this logging functionality also into every request and broadcast. That means I get a XML document that contains all messages that are sent and received. Then I wrote a parser that creates a plantuml sequence diagram out of the xml, because the sent messages had the same title as the received ones.

All I had to do to get a full blown sequence diagram of my application was to run a standard operation once and let the parser do its magic.

So my feature requests would be:

- add automated logging to each notification sent and received

- Create an add-on that takes a logging file and creates a Plantuml text from it

I am happy to help/demonstrate/explain what I did and what would be ideal. I know you guys think about logging, so this might be just a small step ahead.

Cheers, Niko

I sometimes need to implement a DQMH module in isolation. So the first thing I do is create a new blank project and save it (this will be the dev project for the new module). Then I try to create a new DQMH module in the same folder as that project (by editing the 'Module Save Path' to point to the folder containing the new blank project):

When I try to click OK, I get a dialog that says I can't create the module because the specified folder contains LabVIEW files:

Yeah, I know the folder contains a LabVIEW file... it's the blank project. The Add Module dialog wants me to create a new subfolder for the new module, but I don't want that... I want the module and all its files to live in the same folder as the isolated development .lvproj. I propose that this file check be changed to remove ".lvproj" files from the list of LabVIEW file types that it checks for.

IMHO, it would make more sense to have the Stop Module request at the same level than Start and Sync functions.

Reviewing somebody's DQMH code I noticed an error generated in the exit case where they had cleanup code (1) was not captured by the Tester. This is purely because the exit case causes the MHL to terminate (2), so the normal error handling strategy (3) doesn't work (enqueuing another job called Error). Can I propose, unless there's a better technique, that adding the "Error Report" broadcast at the end of the Exit case (4) is a simple way to ensure any errors generated here get reported.

Add Error Broadcast in MHL Exit Case

Hi, I would suggest adding a boolean called 'Include Dependencies' to the function on the scripting API to search for DQMH modules on the project, sometimes we have projects and we call DQMH Modules not listed on the project itself, but the developer should be aware we are calling those DQMH modules under dependencies, the Panther Dashboard for DQMH already is searching for DQMH modules under dependencies but it would be great if the native function does this functionality, also, I suggest adding a boolean array output to know if the resulting modules are located under dependencies or they are in the project.

This is how I visualize the connector pane of the 'Get DQMH Modules in Project.vi'

Thank you!.

By default, in the MHL Error case, the "error out" local variable is written to.  But the error that is written is NOT the error that came into the MHL Error case!

I propose the above be changed to this:

By doing this, the actual error that was raised by the module will be copied to "error out"

As DQMH module templates become more widely used, it would be very nice if, when adding a new DQMH module that was added as a custom template, the overlay pre-populated with the overlay that the template uses.

So maybe thinking about this on a lower level, this feature request comes in two parts. When saving a DQMH module as a template, store the metadata that makes up the current overlay in a config file somewhere. Then, on the Add New DQMH Module window, whenever a custom Module Type is selected, pre-populate the overlay with that metadata.

When opening a DQMH module .lvlib file directly, the LabVIEW IDE allows to call the DQMH Scripting Tools from the Tools menu, which results in an error message when trying to parse the project for modules:

This error should be handled the same way as when calling the DQMH Scripting Tools from a single VI (or even the getting started window):