ExpressionFlow Forums

Enhanced user experience with contextual error messages

PaulG. — Sat, 08 Nov 2008 14:25:44 -0600

Lately I've been doing a some equipment safety check coding. As long as there are operators there will be operator errors - and in our case a possible loss of an expensive UUT and wasted time and data if the operator makes a mistake. I'm sure there are dozens of ways to do it, and my application isn't that complicated, but in this situation comparisons and one button dialog error messages ("Error: test position already in use.") where the test software will not continue until the error is corrected seems to be working very well.

Enhanced user experience with contextual error messages

Yair — Sat, 08 Nov 2008 11:38:24 -0600

You should note that I have actually seen people opposed to disabling OK buttons and instead describing the problem once the button is clicked. In any case, I don't think there's a single correct answer, as there will always be people who will find one method less usable than the other.

Incidentally, in many of the systems I do, errors and faults are not caused by the user, or at least by an action the user does in the PC. What I usually do is pop up an error message and also have a section of the UI which shows the currently active errors. Of course, this is also only relevant for certain cases.

Enhanced user experience with contextual error messages

Tomi Maila — Mon, 03 Nov 2008 13:28:02 -0600

Andrey suggested to check for input errors while to user is typing the input. I was initially against this idea as it can be very distracting for the user if an error message is displayed when user is correctly entering a value into a control. However, we can alter the value validation algorithm slightly to be used with update value while typing. We can check if the string user is typing can lead into a valid value while user is typing the value. If not, we display an error message. If the beginning of the string is valid, we should not distract the user but let her continue. However, we should not allow user to continue until the value is fully completed.

I edited the example in accordance with these principles. The regular expression for checking partial string is constructed from the regular expression for full strings in the following way. Our full regular expression string consists of several components. A partial string user is typing is valid if it is 1) empty or matches 2) partial first part, 3) first part and partial second part, 4) first and second part and partial third part, and so on. You get the point.

The edited example can be downloaded from the blog.

[attachment=10346:bd.gif]

QUOTE (AndyDm @ Nov 3 2008, 08:45 PM) <{POST_SNAPBACK}>

The main goal is reducing the number of actions (mouse clicks should be avoided anyway).
This logic assumed:
- when dialog with text field coming, then the focus should be set on the text field.

Ok. I added this functionality to my modified example as well. Thanks for good feedback.

QUOTE (AndyDm @ Nov 3 2008, 08:45 PM) <{POST_SNAPBACK}>

- For "OK" button we will set Return Key for toggle action, and for Cancel - Esc.

This can be risky as pressing Esc doesn't in general mean close and loose all my changes. I would force users to actually press cancel button to cancel.

Enhanced user experience with contextual error messages

AndyDm — Mon, 03 Nov 2008 12:45:44 -0600

ZITAT(Tomi Maila @ Nov 2 2008, 12:18 PM) <{POST_SNAPBACK}>

I just posted a new ExpressionFlow article

Enhanced user experience with contextual error messages

Don't hesitate to comment and discuss here on the forums

Tomi

I will continue here, because here we can start very nice and long discussion about usability issues for such simple dialog...

The use case for such dialog usually is following:
- Dialog appeared (user has clicked button somewhere, pressed hot-key, etc)
- User immeaditely start with text entering.
- When user ready, then he will press Enter and dialog disappeared immeaditely.

The main goal is reducing the number of actions (mouse clicks should be avoided anyway).
This logic assumed:
- when dialog with text field coming, then the focus should be set on the text field.
- For "OK" button we will set Return Key for toggle action, and for Cancel - Esc.
Now we needed to find better place for error checking inside of the dialog.

Well, error checking can be done when Enter key pressed, but how the realization of the logic above will be possible without setting "Update while typing" property?
In attachment quick example with illustration what I mean.

Andrey.

Enhanced user experience with contextual error messages

Tomi Maila — Sun, 02 Nov 2008 05:18:15 -0600

I just posted a new ExpressionFlow article

Enhanced user experience with contextual error messages

Don't hesitate to comment and discuss here on the forums

Tomi

Subversion hosting - a simple path to LabVIEW source code control

Tomi Maila — Thu, 18 Sep 2008 01:33:10 -0500

I found a comparison chart on subversion hosting providers. Dont read the chart literally, as most providers do have multiple products and not all products are listed. Rather take it as a list of subversion hosting providers aand check yourself what kind of solutions they provide. Not that many subversion hosting companies provide services for open source projects only.

Subversion hosting - a simple path to LabVIEW source code control

Jim Kring — Wed, 17 Sep 2008 12:33:04 -0500

QUOTE (Tomi Maila @ Sep 17 2008, 09:34 AM) <{POST_SNAPBACK}>

Toby, that is a good point. However you must also consider if your intellectual property is actually more safe on a managed third party server or on your own server where security issues are patched on a random basis.

I agree with this sentiment, Tomi.

Hosting companies (more so with highly reputable ones) have a huge incentive to ensure the security of their customers' data -- it's the life-blood of their business. So, it's s something that they must continuously consider, test, and build into their process. I'm sure that service providers can do a much better job of security than most small- and medium-sized companies. However, large companies (with large IT departments) can probably do a good job of security, too. But, they typically tend to do this by severely crippling the usefulness and adaptability of the IT environment. For example, they make sure that your subversion server is secure by not providing you with (or letting you manage your own) subversion server

The good news is that the corporate world is starting to get more comfortable with the idea of software and IT resources as a service. Large companies just move slow and have large IT teams that need to hold onto their jobs.

Subversion hosting - a simple path to LabVIEW source code control

Tomi Maila — Wed, 17 Sep 2008 11:34:07 -0500

Subversion hosting - a simple path to LabVIEW source code control

TobyD — Wed, 17 Sep 2008 11:15:11 -0500

Thanks Tomi. You always have some good tips in your articles. I am still nervous about the idea of storing any company confidential intellectual property on third party servers though. I know a lot of companies (including the one I work for) have starting renting storage space because it's cheaper than having their own IT department manage it (or they have no more physical space in their server rooms), but it makes me nervous.

Subversion hosting - a simple path to LabVIEW source code control

Tomi Maila — Wed, 17 Sep 2008 04:56:54 -0500

This is a discussion topic to my latest article

Subversion hosting - a simple path to LabVIEW source code control

Tomi

Video - Objects and Classes

Aristos Queue — Sun, 13 Jul 2008 17:55:19 -0500

A comment about design patterns drawn from other OO languages in general: The "behavioral" patterns -- the ones that talk about having one object do an action while another object does an action, or about sending a message from one object to another -- are almost always realized in LabVIEW by substituting the word "object" with the word "VI". The data and interface patterns are fulfilled using LabVIEW classes. But the flow-of-control behaviors of LabVIEW are already encapsulated in an object: the virtual instrument.

Video - Objects and Classes

Tomi Maila — Sun, 13 Jul 2008 08:56:29 -0500

For those of you who had problems watching the embedded video from Vimeo, the video is now available from YouTube as well.

Video - Objects and Classes

Tomi Maila — Wed, 09 Jul 2008 13:48:58 -0500

QUOTE (TobyD @ Jul 9 2008, 06:11 PM) <{POST_SNAPBACK}>

Thanks I was using Vimeo because of the excellent 1280x720p HD quality, as it provides ability to download videos and as some users tend to have problems accessing YouTube because of corporate "security" policies.

About green screen, I spent a few weeks painting the ExpressionFlow background to our living room wall You can imagine how lot of and how detailed work that was

Video - Objects and Classes

TobyD — Wed, 09 Jul 2008 10:11:38 -0500

Excellent video Tomi! And let me be the first to say thank you for not using youtube. The increased resolution of vimeo is nice. Did you set up a green screen to insert the expression flow background? Very cool!

I have also enjoyed all the side discussion. I am consistently amazed at how much I learn by following these threads.

-Toby

Video - Objects and Classes

neB — Wed, 09 Jul 2008 06:06:16 -0500

QUOTE (Tomi Maila @ Jul 9 2008, 02:15 AM) <{POST_SNAPBACK}>

Ben,

You may want to take a look at OpenG Active Object Template(.opg) that is part of class templates I wrote for LVOOP. See OpenG Wiki for more details. Active Object Template is a template for by-reference objects that include a single VI that starts executing when an object instance is created and stops executing when the object instance is closed. The template is meant to be used with Endevo GOOP tool but you can simply create a copy of the class from within LabVIEW as well to use it in your project. Use VIPM to install the template to <LabVIEW>resource\OpenG\openg_object\class_templates. The template requires OpenG Object package to be installed as well.

[attachment=9422:OpenG_Ac...plate_BD.png]

Re:Creating these active objects

Going back to my practice app.

I will support multiple picture controls so I set-up a class "Pictures" (note plural) that offers a method "register picture" and uses the picture ref to create an active object Picture". The Picture class object register for events against the picture. The class Pictures maintains a list of registered Picture objects and other methods that are targeted at the class Picture objects. So is good or bad practice to group classes that will have multiple instances into a parent class to allow acces to the children?

This approach effectively gave me by-references access to the unique instances of the Picture objects.

Ben

Video - Objects and Classes

Eugen Graf — Wed, 09 Jul 2008 04:05:19 -0500

Very nice video for LVOOP beginners, very easy to understand.

Thank you

Video - Objects and Classes

Tomi Maila — Wed, 09 Jul 2008 01:15:10 -0500

Video - Objects and Classes

neB — Tue, 08 Jul 2008 11:09:17 -0500

QUOTE (Ton @ Jul 8 2008, 11:59 AM) <{POST_SNAPBACK}>

I wouldn't use a VIT but the following code construct (simple example):
[attachment=9416:LoadDeamon.png]
This also bypasses the 'I don't know which dynamic VIs I need to build' problem.

We recently did this with a class, and it works great!

Ton

Ohh yes!

Ben

Video - Objects and Classes

Ton — Tue, 08 Jul 2008 10:59:55 -0500

QUOTE (neB @ Jul 8 2008, 04:55 PM) <{POST_SNAPBACK}>

The "proxy, which provides an interface" The class provides methods which use queues to post method requests to the back-ground VI (*.VIT).
The "interface which defines the method request " I think I have covered with a type-def'd queue containing an enum that specifies the requested method.
The "list of pending requests " is realized by using the queue.
The "a scheduler, " is implemented in code that checks for method invocations otherwise it handles the "update work" (eg scroll text)
The "the implementation of the active object method. " is realized with appropriate code to handle what is found in the que.
The "a callback or variable for the client to receive the result. " is realized in a response queue that is fed from the results of the code for each method.

Video - Objects and Classes

neB — Tue, 08 Jul 2008 10:47:39 -0500

QUOTE (shoneill @ Jul 8 2008, 11:10 AM) <{POST_SNAPBACK}>

...

It could perhaps also be tied in with Events so that it comes into play whenever certain criteria are met. Queues would be another logical interface choice.

I'm working on such a beast right now. I've recently "discovered" user events and am using them to implement an interface to a process spawned in parallel which then feeds back into the original program via Events. All asynchronous. ...
Shane.

Thanks for that suggestion Shane. I am condicuting some architectural research for an app I have yet to officially design. I will keep that in mind as the design develops.

Another idea that I concidered using for active objects that would have their methods invoked from multiple places it to re-use an idea that was inspired by one of Jim Kring's design patterns (Response with notificaton ?). The idea is to inclue a ref to a "response queue" in the request (method invocation) so that the active object can respond entity that invoked it.

Learning as I go...

Ben

Video - Objects and Classes

shoneill — Tue, 08 Jul 2008 10:10:20 -0500

QUOTE (Aristos Queue @ Jul 8 2008, 04:06 PM) <{POST_SNAPBACK}>

I'm not familiar with the term in this context. Can you post a link to an article describing this "active object" concept? I might be able to suggest a recommendation on how to implement.

Well I have to confess that I don't know what the official meaning of an "active object" is..... Google says this. (DOH! Ben got there first.....)

All the same I'd imagine (in LV context) it's an object which has a background process as Ben describes. It could perhaps also be tied in with Events so that it comes into play whenever certain criteria are met. Queues would be another logical interface choice.

I'm working on such a beast right now. I've recently "discovered" user events and am using them to implement an interface to a process spawned in parallel which then feeds back into the original program via Events. All asynchronous. Of course items defined by their interface are perhaps better called "components" than "objects" but maybe we should leave that discussion for another time....

Edit:

I also see nothing in the Wikipedia definition which dictates the use of OOP at all.

However, given the name, I'm sure it is meant to apply to OOP classes with a suitable interface and scheduler.

I still like the idea of getting values back via Event structure. Having VIs for getting the values back requires either polling or restrictions in the concurrency of the solution, no?

Either way, a nice method is required for making requests from the "active Object". Queues are the natural choice. Are there any other realistic possibilities? User Events could also be used here.... Any performance difference to be expected between queues and user events? Advantages disadvantages?

Shane.

Video - Objects and Classes

neB — Tue, 08 Jul 2008 09:55:35 -0500

QUOTE (Aristos Queue @ Jul 8 2008, 10:06 AM) <{POST_SNAPBACK}>

I'm not familiar with the term in this context. Can you post a link to an article describing this "active object" concept? I might be able to suggest a recommendation on how to implement.

The Wikipedia says

"
The Active Object design pattern decouples method execution from method invocation that reside in their own thread of control.^[1] The goal is to introduce concurrency, by using asynchronous method invocation and a scheduler for handling requests.^[2]

The pattern consists of six elements^[3]:

a proxy, which provides an interface towards clients with publicly accessible methods
an interface which defines the method request on an active object
a list of pending requests from clients
a scheduler, which decides which request to execute next
the implementation of the active object method.
a callback or variable for the client to receive the result.

"
So the approach i am taking is;

The "proxy, which provides an interface" The class provides methods which use queues to post method requests to the back-ground VI (*.VIT).
The "interface which defines the method request " I think I have covered with a type-def'd queue containing an enum that specifies the requested method.
The "list of pending requests " is realized by using the queue.
The "a scheduler, " is implemented in code that checks for method invocations otherwise it handles the "update work" (eg scroll text)
The "the implementation of the active object method. " is realized with appropriate code to handle what is found in the que.
The "a callback or variable for the client to receive the result. " is realized in a response queue that is fed from the results of the code for each method.

The above scheme is just my first attempt at an active object and is my attempt to realize in LV something that matches the description of an "Active Object".

Again thanks all for your replies!

Ben

PS Ton, My boss is already taking a chance by letting me code this app in LVOOP. I'd only make him more nervous if I jumped right to the XControl to handle this part of the design. If I design this properly, I should be able to pass the project to one of my rookies to finish-up.

Video - Objects and Classes

jzoller — Tue, 08 Jul 2008 09:48:02 -0500

QUOTE (Ton @ Jul 8 2008, 08:05 AM) <{POST_SNAPBACK}>

"One NI R&D developer"...

The XControl seems like a good solution, but it doesn't have any built in timing capability to update itself. Aristos' example gets around that.

Correct me if I'm wrong, but is the more general idea to essentially have a state machine behind the control?

Joe Z.

edit: grammar == bad

Video - Objects and Classes

Aristos Queue — Tue, 08 Jul 2008 09:06:34 -0500

QUOTE (neB @ Jul 8 2008, 07:35 AM) <{POST_SNAPBACK}>

So that is what I really had in mind. How do I implement active objects in LV?

I'm not familiar with the term in this context. Can you post a link to an article describing this "active object" concept? I might be able to suggest a recommendation on how to implement.

Video - Objects and Classes

Ton — Tue, 08 Jul 2008 09:05:21 -0500

QUOTE (neB @ Jul 8 2008, 02:35 PM) <{POST_SNAPBACK}>

Say I wanted to mod Tomi's example such that it had a scrolling string field. I'd want that class to regularly update its image without being "tickled" by the GUI.

So that is what I really had in mind. How do I implement active objects in LV?

One NI R&D developer made a scrolling led XControl...
I think you can extend the techniques used there.

Ton

Video - Objects and Classes

neB — Tue, 08 Jul 2008 07:35:53 -0500

QUOTE (Aristos Queue @ Jul 7 2008, 06:41 PM) <{POST_SNAPBACK}>

LabVIEW does not have any metaclasses. LabVIEW Object is a class. It is the ancestor class that all other classes inherit from.
When Tomi dropped the rectangle, he instantiated an object. An object is an instance of a class. There's no such thing as a "metaclass" in LabVIEW*.

* unless you're talking about the C++ code in the LabVIEW.exe which contains a class "LVClass" which is the C++ class that defines what it is to be a LabVIEW class and inherits from class Library which inherits from ... well, something else. I've put this as a footnote because I felt it was important to specify what a metaclass would be -- if G code had one -- but I didn't want to confuse anyone who just wanted a straight answer and would just glaze over footnotes.

No. We name the front panel element "LabVIEW Object" because that is an FP control for the class LabVIEW Object specifically. The data value of that control is an object. What kind of object? LabVIEW Object.

If we add other class FP controls to the palettes in the future, they'll be named for their class.

Already done, and done incredibly well, by the folks over at Endevo. If you need UML, check out their UML tools. Very powerful, very clean user interface.

Thank you Aristos!

Its nice being wrong in this neighborhood. Plenty of people willing to straighten you out. So the term metaclass really does not come into play in LabVIEW applications.

I got all excited about Tomi's video and typical for myslef did not explain myself well. When I was asking about UML what I was actually thinking about was what Craig Larman calls "Sequence Diagrams". I got to the point were he introduced the idea of an "active object" and I am curious about how an active object would be implemented in LabVIEW. From its description I have gone off and created code that spawns off (VI server run no-wait) a VI that is coded to watch an input queue for one of its methods being invoked. The non-active objects appear to quickly and easily manifest themselves from one of the templates. But they return their resluts imediately and there is "nothing hanging around" to do the follow-up work.

Say I wanted to mod Tomi's example such that it had a scrolling string field. I'd want that class to regularly update its image without being "tickled" by the GUI.

So that is what I really had in mind. How do I implement active objects in LV?

Sorry about the tangent all!

Ben

Video - Objects and Classes

crelf — Mon, 07 Jul 2008 18:14:00 -0500

QUOTE (Aristos Queue @ Jul 7 2008, 06:41 PM) <{POST_SNAPBACK}>

Already done, and done incredibly well, by the folks over at Endevo. If you need UML, check out their UML tools. Very powerful, very clean user interface.

Right - all native LabVIEW and allows you to engineer and reverse engineer your classes.

Video - Objects and Classes

Aristos Queue — Mon, 07 Jul 2008 17:41:40 -0500

QUOTE (Yair @ Jul 7 2008, 12:14 PM) <{POST_SNAPBACK}>

If I understand the concept correctly, LabVIEW only has one meta class - LabVIEW object. All other classes are instances of that class (and I'm not even sure if that's correct, since they could also just be described as child classes).

The rectangle is simply a child class of shape (or whatever the hierarchy is in this case) - when you drop one, you are creating an object, not a class.

QUOTE (Ton @ Jul 7 2008, 12:41 PM) <{POST_SNAPBACK}>

Yes that's right, it's the reason LabVIEW names the front panel palette element 'LabVIEW object'

No. We name the front panel element "LabVIEW Object" because that is an FP control for the class LabVIEW Object specifically. The data value of that control is an object. What kind of object? LabVIEW Object.

If we add other class FP controls to the palettes in the future, they'll be named for their class.

QUOTE (neB @ Jul 7 2008, 05:47 AM) <{POST_SNAPBACK}>

Do plan on realizing UML in LV?

Already done, and done incredibly well, by the folks over at Endevo. If you need UML, check out their UML tools. Very powerful, very clean user interface.

Video - Objects and Classes

Tomi Maila — Mon, 07 Jul 2008 13:24:13 -0500

QUOTE (Ton @ Jul 7 2008, 08:41 PM) <{POST_SNAPBACK}>

What program have you used to capture your screen activities, I've used Jing but found it is not real-time.

I've used CamStudio beta together with Lagarith lossless codec. The audio sync sucks and therefore I don't use CamStudio to capture audio. I edit the videos with Sony Vegas Pro 8.

Video - Objects and Classes

Ton — Mon, 07 Jul 2008 12:41:10 -0500

QUOTE (Yair @ Jul 7 2008, 07:14 PM) <{POST_SNAPBACK}>

The rectangle is simply a child class of shape (or whatever the hierarchy is in this case) - when you drop one, you are creating an object, not a class.

Yes that's right, it's the reason LabVIEW names the front panel palette element 'LabVIEW object'

We are using the Endevo by-reference Goop implementation.
It has two kinds of data attributes:
Class attributes which are the same for all the objects of that class
Object attributes which are specific to a single object

The fun thing is you can set and get class attributes from a class constant without creating an object.

On the video:
Respect!
I've done two swf movies for the Code Capture Tool and it is hard.
What program have you used to capture your screen activities, I've used Jing but found it is not real-time.

Ton

Video - Objects and Classes

Yair — Mon, 07 Jul 2008 12:14:19 -0500

QUOTE (neB @ Jul 7 2008, 04:03 PM) <{POST_SNAPBACK}>

The class Rectangle you showed in your project is a metaclass and when you drop one on your picture, you are instaciating a class?

Video - Objects and Classes

Michael_Aivaliotis — Mon, 07 Jul 2008 12:01:08 -0500

QUOTE (Antoine @ Jul 7 2008, 06:33 AM) <{POST_SNAPBACK}>

Great job Tomi! Welcome to the world of video. I'm not alone.

Video - Objects and Classes

Antoine — Mon, 07 Jul 2008 08:33:05 -0500

QUOTE (neB @ Jul 7 2008, 03:03 PM) <{POST_SNAPBACK}>

It may help to drink some beer before trying to understand this.

Video - Objects and Classes

neB — Mon, 07 Jul 2008 08:03:52 -0500

QUOTE (Tomi Maila @ Jul 7 2008, 07:08 AM) <{POST_SNAPBACK}>

I'm afraid you will need to stay unproductive for a while

Ok then I'll fight my way through the fog myself. I you hear a scream, you'll know which direction the abys lies.

Your discision of classes reminded me of a passage I recently read in Craig Larman's "Applying UML and Patterns, An introduction to Object-Oriented Analysis and Design and Iteractive Developement, Third Edition" where on page 236 and 237 he writes;

"
You can show class or static method calls by using a lifeline box label that indicates the receiving object is a class, or more precisely, an instance of a metaclass (see Figure 15.20).

What di I mean? For example, in Java and Smalltalk, all classes are conceptually or literally instances of class Class; in .NET classes are instances of class Type. The classes Class and Type are metaclasses, which means their instances are themselves classes. A specific class, as class Calendar, is itself an instance of class Class. Thus, calss Calendar is an instance of a metaclass! It may help to drink some beer before trying to understand this.

"
All typos are of-course mine. (BTW: I recomend Craig's book for getting into UML)

So ...

The class Rectangle you showed in your project is a metaclass and when you drop one on your picture, you are instaciating a class?

Ben

"

Video - Objects and Classes

martin@aerodynamics — Mon, 07 Jul 2008 06:25:03 -0500

QUOTE (Tomi Maila @ Jul 7 2008, 09:50 AM) <{POST_SNAPBACK}>

I'm very excited to announce a new ExpressionFlow Studio video series that will concentrate on LabVIEW software development. The first episode Objects and Classes starts an ExpressionFlow Studio series introducing to LabVIEW object-oriented programming.

Verry good video - Now I have just to wait till I can use classes on LabVIEW RT ...

Video - Objects and Classes

Tomi Maila — Mon, 07 Jul 2008 06:08:58 -0500

QUOTE (neB @ Jul 7 2008, 01:47 PM) <{POST_SNAPBACK}>

I need to watch the next nine episodes before noon today so I can stay productive.

I'm afraid you will need to stay unproductive for a while

Video - Objects and Classes

neB — Mon, 07 Jul 2008 05:47:49 -0500

QUOTE (Tomi Maila @ Jul 7 2008, 03:50 AM) <{POST_SNAPBACK}>

Great!

I need to watch the next nine episodes before noon today so I can stay productive.

Do plan on realizing UML in LV?

Which episode will cover instaciating active objects?

Ben

Video - Objects and Classes

Tomi Maila — Mon, 07 Jul 2008 02:50:40 -0500

Im very excited to announce a new ExpressionFlow Studio video series that will concentrate on LabVIEW software development. The first episode Objects and Classes starts an ExpressionFlow Studio series introducing to LabVIEW object-oriented programming.

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

shoneill — Tue, 10 Jun 2008 05:22:43 -0500

QUOTE (tcplomp @ May 17 2008, 09:03 PM) <{POST_SNAPBACK}>

I am using Subversion and the LabVIEW integrated tool at home via the PushOK plugin. The repository resides on a local Ubuntu server.
I have hardly a problem with the locked not-checked out items in the LV project.

I am going to enjoy this, at work I created a tool that checked all the files in the project, and reported those that were either old, not checked in or not in SCC. If anyone is interested in testing, PM me. I will try to get it up to CR standars (shouldn't be too hard though it contains express VIs).

Doe anyone know how to setup a https subversion repository on Linux?
Somehow I can't get it right.

Ton

Yeah, add me to a list of poeple interested in getting SVN over HTTPS running on a linux machine......

Shane.

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

ElijahRock — Tue, 10 Jun 2008 01:06:35 -0500

I just wanted to make sure that everyone on this thread is aware of some articles that might be useful concerning Source Code Control and LabVIEW. Here are a list of a few. Note that one is actually a wiki article on ni.com that is open for editing and community contribution.

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

Tomi Maila — Thu, 05 Jun 2008 03:49:04 -0500

QUOTE (Tomi Maila @ Jun 3 2008, 12:32 PM) <{POST_SNAPBACK}>

Actually just today I encountered this issue with LabVIEW 8.5.1 where LabVIEW corrupted my class file because of a dependency issue where there was two classes of the same name in the project.

It seems that the problem we had was much bigger than I thought. One class hierarchy keeps corrupting again and again. The origin of the problem is that I moved a highest class in a hierarchy into a lvlib library. As a result LabVIEW seems to have two different references to this class, one outside the lvlib and one inside the lvlib. It seems LabVIEW sometimes decides that the class is really not part of the lvlib and when it does so, all the hierarchy gets corrupted. I guess I've no other option but to go maybe a week back in my source code control regarding this hierarchy before I added the class to a lvlib. I hate that LabVIEW files are of binary format (including binary fields of class files) and that when something goes wrong with the compiler, there is no way to fix things manually or even investigate what is wrong manually to be able to report a bug. At the moment I cannot report a bug because I really don't know at which point LabVIEW screwed things up and how and I've no means of investigating it.

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

Tomi Maila — Tue, 03 Jun 2008 04:32:30 -0500

Omar has raised up an important subject. Actually just today I encountered this issue with LabVIEW 8.5.1 where LabVIEW corrupted my class file because of a dependency issue where there was two classes of the same name in the project. It also appeared that LabVIEW file search algorithm that searches for missing files cannot locate class control inside class file but tries to locate it from a Windows folder instead. Naturally this fails and all class constants, controls and indicators in the project get broken. I didn't find any way to fix them so my project was ready for carbage bin. Luckily I do use SCC so only one day of work was wasted.

I think it's important not to think that corruptions cannot hapen with certain LabVIEW versions. The truth is that complicated software such as LabVIEW can always fail and developers should protect themselves against these failures.

LVOOP Drawing Tool

neB — Mon, 02 Jun 2008 07:52:33 -0500

QUOTE (Tomi Maila @ Jun 2 2008, 04:59 AM) <{POST_SNAPBACK}>

I just wrote a blog post on this subject. See the discussion in this thread.

Thank you Tomi!

This will be part of my required reading for today.

Ben

LVOOP Drawing Tool

Tomi Maila — Mon, 02 Jun 2008 03:59:54 -0500

QUOTE (neB @ May 27 2008, 05:04 PM) <{POST_SNAPBACK}>

Say I wanted to deploy Tomi's example as an exe that would allow other shapes to be added latter (example:customer wants an octogon added)...

from what I understand I would have to re-compile the library that houses the class.

Are there any other things I'd have to adjust to allow for the addtion of other shapes (aside from the menu that allows which shape to drop)?

I just wrote a blog post on this subject. See the discussion in this thread.

Extending LabVIEW-built applications with LVOOP plugins

Tomi Maila — Mon, 02 Jun 2008 03:56:12 -0500

I've just posted an article Extending LabVIEW-built applications with LVOOP plugins with an example project to ExpressionFlow blog.

There are numerous reasons why you would like to allow your LabVIEW application to be extended with plugins. First you may want to allow your customer or a third party to add some new functionality to your application. LVOOP plugins provide a way for you to allow third parties to extend your application. Second you may want to separate the built and development process of the core application from the development process of the features of the applications. With OOP projects LabVIEW development environment slows down dramatically as the number of classes gets too high. It may be wise to separate your application so that only the core elements form the main application and all other elements are provided as add-on components. Third you may want to control the memory footprint of your application and specify at runtime which components are loaded into memory; there is no need to keep the code for unused features in memory. Consider for example that your application supports multiple file formats or device drivers. You can load the needed file format plugins or device drivers on demand into memory at runtime.

Read more...

LVOOP Drawing Tool

neB — Tue, 27 May 2008 10:04:47 -0500

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

gmart — Sun, 18 May 2008 11:39:58 -0500

QUOTE (tcplomp @ May 17 2008, 01:03 PM) <{POST_SNAPBACK}>

Ton,

Since Jim feels the SVN model doesn't work with the check in/out model of the LabVIEW SCC integration, would you care to give your feeling on working with Push OK from within LabVIEW. Have you just learned to deal with the differences of the development models? Does this impact your productivity? Do you feel working with the plugin within LabVIEW helps you beyond using Tortoise SVN?

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

Gavin Burnell — Sun, 18 May 2008 09:48:12 -0500

QUOTE (Omar Mussa @ May 16 2008, 04:45 PM) <{POST_SNAPBACK}>

I just posted an article: Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files to ExpressionFlow.com.

The article highlights ways that LabVIEW class and project data can be corrupted and some SCC practices that can help you to recover from them.

I've been bitten by a couple of clss/project file mis-features in LabVIEW 8.2.1 (and as far as I know, though I've not exhaustively checked, 8.5.1).
One I detailed in this LAVAG thread - basically you can lock up a class file so that you need to use a text editor (or revert using your SCC system). This method doesn't rely on LabVIEW crashing and doesn't strictly corrupt the class file - it's all a perfectly legal albeit un-editable class.
The second one that strikes with depressing regularity is LabVIEW corrupting the project file. As far as I can work out the sequence goes like this:
* You have a project file that includes several files in different directories with the same name - say dir.mnu for example. Some of these directories are not in the LabVIEW search path (e.g. My Documents\LabVIEW Data\....)
* You move the whole directory structure to a new location using the OS file manager.
* You try to reopen the LabVIEW project. LabVIEW realises that the project has moved because some files aren't where they were supposed to be, so LabVIEW starts searching for them. LabVIEW picks the first matching name it comes to. With a file like dir.mnu that's not going to be too difficult...
* LabVIEW repeats this several times for each missing dir.mnu file, each time locating the same wrong dir.mnu and happily changes the project file.
*You save the project file and then re-open it. LabVIEW now complains that the project file (or library) is corrupt because iit has two or more entries with the same URL.

The immediate problem here is that LabVIEW doesn't check for duplicating URLs when it 're-finds' a moved entry, thus allowing LabVIEW to corrupt its own project and library files. The underlying problem is that the re-finding algorithm isn't as clever as it needs to be. If the project/library files stored their own save path in the file then they could detect and calculate what the move 'vector' was and then before searching the standard search path for a matching name, could try looking for a new relative path. 9 times out of 10 a whole directory structure has been moved so that should relocate entries correctly. Again, a revision control system which can diff two files quikcly puts it right, but it should not be possible for LabVIEW to corrupt its own files except of course in the case of a power loss or program crash.

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

Tomi Maila — Sun, 18 May 2008 08:19:54 -0500

QUOTE (Jim Kring @ May 17 2008, 07:00 PM) <{POST_SNAPBACK}>

By copying the repository in Windows File Explorer you *might* possibly corrupt the new copy, but I can't imagine that you would corrupt your repository. You can avoid problems by using the svnadmin dump command. Here is a high-level tool that might help you (but I have no experience with it): SVNBackupWidget.

The data corrouption of the backup can only occur if there are open connections to the repository at the moment of the backup. On a single user repository this can be easily avoided by not using the repository while backing it up. However, incremental backup is a nice feature if you don't want to keep many duplicates of your entire repository.

p.s. Never rely solely on incremental backups only. I once was using incremental backup software provided with Maxtor external harddrive. It ended up a catasrophy as for some reason the whole incremental backup database was corrupted and I was unable to restore anything from the backup. Of course the backup software never provided any indication that there could be some problems with the incremental backup database. Maxtor customer service never bothered to respond to my support requests when I tried to restore my stuff. Luckily only the boot sector of my backed up hardrive was damaged and I was able to plug the hardrive into another computer as a secondary hardrive and restore everything.

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

rolfk — Sun, 18 May 2008 05:19:04 -0500

QUOTE (gmart @ May 16 2008, 04:44 PM) <{POST_SNAPBACK}>

I understand SVN's development model is different. In general have you worked with an IDE (not client like Tortoise) that doesn't get in your way when using SVN (for example, Visual Studio)? Is the check in/out model such an impediment that even with the third-party SVN plugin for LabVIEW, you feel your productivity is diminished?

Well it's not about for example Visual Studio or not but about if that IDE uses the SCC API. That API was specifically designed around the strict check in/check out philosophy and accordingly uses, enforces and even requires it. And that does not work well with SVN. Visual Studio certainly is not a very good IDE to use with SVN since it does really on the SCC API for its Source Code Control integration.

As others have said there are other IDEs that are a lot more flexible in how they interface to SCC systems and that work a lot better with SVN than Visual Studio.

Rolf Kalbermatter

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

tcplomp — Sat, 17 May 2008 14:03:44 -0500

QUOTE (Jim Kring @ May 16 2008, 11:19 PM) <{POST_SNAPBACK}>

Take a look at any of the Java and/or open source IDEs: e.g., Eclipse, Apple XCode, NetBeans.

> Is the check in/out model such an impediment that even with the third-party SVN plugin for LabVIEW, you feel your productivity is diminished?

QUOTE (Jim Kring @ May 17 2008, 03:02 AM) <{POST_SNAPBACK}>

Hi Val,

For a one person, such as yourself, I would recommend setting up a local subversion repository and regularly backup the local repository onto your external drive/server. A while back, I wrote an article about how do this, using TortoiseSVN:

Creating a local Subversion repository with TortoiseSVN

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

Jim Kring — Sat, 17 May 2008 12:00:36 -0500

QUOTE (Val Brown @ May 16 2008, 10:20 PM) <{POST_SNAPBACK}>

OK, thanks. BTW, was there a follow up article? Also just as a clarification, when you say to "back up the local repository onto <my> external drive<s>/server" I assume that you mean by using Explorer or something similar to "drag and drop" the entire repository file structure over to the external drives/server? I just want to make certain that I understand that and don't somehow corrupt the repository by attempting to back it up. If there's a particular, good resource to point me to as well that would be really helpful. I didn't have a good experience with Subversion before so I want to do it right this time.

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

Val Brown — Sat, 17 May 2008 00:20:17 -0500

QUOTE (Jim Kring @ May 16 2008, 06:02 PM) <{POST_SNAPBACK}>

Creating a local Subversion repository with TortoiseSVN

Cheers,

-Jim

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

Justin Goeres — Fri, 16 May 2008 23:41:25 -0500

QUOTE (Val Brown @ May 16 2008, 05:07 PM) <{POST_SNAPBACK}>

BTW, I do have an external server that is available but, ok call me old school, I don't like the security issues of having to network over the internet to have access to a repository. I would much prefer something that allowed me to keep the external HDs.

I'm mostly in a single-developer situation, using Subversion & TortoiseSVN, but my repository lives on the server in my office and is externally accessible. From a security standpoint I have zero fears about it, for the following reasons:

I access it using https. (is that the webDAV-enabled version? I always forget.)
The SVN directory on the server is sandboxed away from everything else.
I use strong passwords.

That having been said, if you prefer to keep the repository locally, Jim's linked advice above is good.

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

Jim Kring — Fri, 16 May 2008 20:02:47 -0500

QUOTE (Val Brown @ May 16 2008, 05:07 PM) <{POST_SNAPBACK}>

My SR is still open. Also if you (and the rest of JKI??) continue to use Subserversion, do you have any specific recommendations about setting it up for a single developer (yes, like me), working on a single computer (largely) using external HDs for backup (yes three in all) and needing to remain mobile, etc so NOT wanting to have an external server as part of the solution?

BTW, I do have an external server that is available but, ok call me old school, I don't like the security issues of having to network over the internet to have access to a repository. I would much prefer something that allowed me to keep the external HDs.

Creating a local Subversion repository with TortoiseSVN

Cheers,

-Jim

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

Val Brown — Fri, 16 May 2008 19:07:27 -0500

QUOTE (Aristos Queue @ May 16 2008, 03:15 PM) <{POST_SNAPBACK}>

Your article does not specify what LabVIEW version can create these corruptions. There were two corruptions known in LV8.2, both of which were fixed in 8.2.1. There was one corruption associated with 8.5 that was fixed in 8.5.1. I do not have any open bug reports of any corruptions since then.

Please edit your article to specify which versions of LabVIEW are capable of creating these corruptions so that future readers don't continue to wonder if these are issues. It's irresponsible, in my opinion, to post an article such as this one without providing the version information. This article will still be available for reading -- and thus indexed by search engines -- years from now. Without a version number, this article becomes a source of FUD.

Your article opens with "a recent post on LAVA made me realize that this may still be useful." I'd just like to point out that the recent post on LAVA that you cited explicitly mentions that, no, he is not using LV Classes. If you know of any way by which the project and or class files can become corrupted that is not addressed by LV8.5.1, please report them ASAP so they can be fixed.

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

Omar Mussa — Fri, 16 May 2008 18:16:24 -0500

QUOTE (Aristos Queue @ May 16 2008, 03:15 PM) <{POST_SNAPBACK}>

I don't think it matters 'how' classes or projects get corrupted. I was trying to mostly point out that there are aspects of classes (and projects) that if corrupted are irrecoverable. A VI can similarly get corrupted (call it the neutrino effect) but it happens (though luckily very occaisionally for VIs). The point is, unless you are using an SCC system while you're making changes to code (especially code that is binary in nature) then you are risking losing your work and not having an efficient way to recover.

QUOTE (Aristos Queue @ May 16 2008, 03:15 PM) <{POST_SNAPBACK}>

Please edit your article to specify which versions of LabVIEW are capable of creating these corruptions so that future readers don't continue to wonder if these are issues. It's irresponsible, in my opinion, to post an article such as this one without providing the version information. This article will still be available for reading -- and thus indexed by search engines -- years from now. Without a version number, this article becomes a source of FUD.

I've been using 8.5 (I have not been able to switch to 8.5.1 yet) and I've seen the issue related to the corrupt class that I documented in my article appear -- now, you get a dialog that tries to help you recover by asking if you want to 'Add the missing file to the class' but I've seen this operation crash LabVIEW (and I have not reported it -- sorry about that -- I think it mostly is due to my not wanting to try to figure out exactly what the problem is so that I can report it correctly -- am sure I am not alone in this). I will go back to the article and edit some of the version specific info though.

QUOTE (Aristos Queue @ May 16 2008, 03:15 PM) <{POST_SNAPBACK}>

Your article opens with "a recent post on LAVA made me realize that this may still be useful." I'd just like to point out that the recent post on LAVA that you cited explicitly mentions that, no, he is not using LV Classes. If you know of any way by which the project and or class files can become corrupted that is not addressed by LV8.5.1, please report them ASAP so they can be fixed.

I think that what made me realize I needed to finish the article was the fact that the poster was losing productivity due to a corrupt project -- which could have been equally prevented using SCC.

I would contend that it is possible (even probable) that there are still bugs that can corrupt LV Classes in LV 8.5.1 that have either 1) not been reported or 2) not been discovered that will still warrant using an SCC system to prevent loss of productivity. So I think the premise of the article still stands -- use SCC so that you can have less fear of corrupted files.

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

Aristos Queue — Fri, 16 May 2008 17:15:24 -0500

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

Jim Kring — Fri, 16 May 2008 16:19:30 -0500

QUOTE (gmart @ May 16 2008, 01:44 PM) <{POST_SNAPBACK}>

> I understand SVN's development model is different. In general have you worked with an IDE (not client like Tortoise) that doesn't get in your way when using SVN (for example, Visual Studio)?

Take a look at any of the Java and/or open source IDEs: e.g., Eclipse, Apple XCode, NetBeans.

> Is the check in/out model such an impediment that even with the third-party SVN plugin for LabVIEW, you feel your productivity is diminished?

Ya, pretty much.

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

gmart — Fri, 16 May 2008 15:44:51 -0500

QUOTE (Jim Kring @ May 16 2008, 02:24 PM) <{POST_SNAPBACK}>

Omar mentioned that he was using TortoisSVN, so I'd assume (actually, I know) he's using Subversion. Using subversion with LabVIEW's SCC provider is like swimming against a current. Subversion wasn't designed for the check-in/check-out development model that LabVIEW and SCCAPI assumes, and there is no native support for Subversion. You have to use a third-party SCC API adaptor. All this just gets in the way of things, IMO.

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

Jim Kring — Fri, 16 May 2008 15:24:41 -0500

QUOTE (gmart @ May 16 2008, 10:30 AM) <{POST_SNAPBACK}>

8.5 allows you to configure the SCC proejct on a per LabVIEW project level. You still have to enable SCC at an environment level. Also, only one SCC provider is supported even on a per LabVIEW project level. What SCC package do you use?

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

gmart — Fri, 16 May 2008 12:30:11 -0500

QUOTE (Omar Mussa @ May 16 2008, 11:09 AM) <{POST_SNAPBACK}>

Good point, I haven't tried using built in SCC integration for a while. The main reason I stopped was that I have different SCC repositories/servers for different projects and in the past LabVIEW SCC could not handle that. I haven't looked into it for a while but just from quickly looking at the LabVIEW 8.5 SCC options it doesn't look like that has been addressed.

I'm currently using TortoiseSVN from Windows Explorer for all of my SCC operations.

Article - Fighting Corruption: Using Source Code Control Systems (SCC) with LabVIEW Class Files

Omar Mussa — Fri, 16 May 2008 12:09:24 -0500

QUOTE (gmart @ May 16 2008, 09:35 AM) <{POST_SNAPBACK}>

There is no mention of using the built in LabVIEW SCC integration. Do you use it? If not, why?