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Showing content with the highest reputation since 03/28/2020 in all areas

  1. 1 point
    Actually, if you turn your cluster back into JSON you can compare it to the original JSON string to see if there are any differences. The string is empty if every element is defined in the source string. Try this: Extract Parameters.vi Notice the "Differences" string, which lists all differences (missing elements) in your source JSON string.
  2. 1 point
    Help Is there a way to parse this JSON string into this cluster in the following way: - The order of elements inside the "Parameters" cluster does not matter. No error - I can use enums - The name of the elements matter. "TWOoo" shouldn't end up populating "two" (even if the order of elements matches the cluster). I want an error here instead of "two" being the default value - Don't care if JSON text has additional elements that aren't in the cluster. No error In short, features: Strict name checking, order independence, error if element missing I've tried so many things but they all fail in one way or the other. See attached snippet
  3. 1 point
    There is no need to go through external code for this. There have been many attempts at crypto libraries that are written natively in LabVIEW and they didn't fail because it is impossible but because nobody is interested to spend some time in searching for them or what a bad word, fork a few dollars over for them. That way authors have put out libraries in the past only to have them forgotten by the public and that is the most sure way for any maintenance work and improvement to be discouraged. Probably the first one was Enrico Vargas who wrote a pretty versatile Crypto library all in LabVIEW somewhere around 2000. It contained many hash and even symmetric algorithmes that were pretty well tested and he was an expert in that subject. And yes he charged something for that library which I found reasonable, I bought a license too and collaborated with him a little on some algorithmes and testing of them. I doubt he made much money with it though, as most Toolkit providers. Eventually it died of because he pursuaded other carrier options and maybe also partly because providing support for something that many were asking for but very few were willing to pay for is a frustrating exercise. A little googling delivers following solutions currently available: https://github.com/gb119/LabVIEW-Bits/tree/master/Cryptographic Services/SHA256 https://lvs-tools.co.uk/software/encryption-compendium-labview-library/ https://gpackage.io/packages/@mgi/hash Interesting disclaimer in the last link! 😀 I would say whoever understands the implications of this, is already aware of the limits in using such functions, but whoever isn't won't be bothered by it. There are several aspects to this, such that calling the same function in .Net or WinAPI (also a possibility) is not necessarily more safe as the actual string is still possibly somewhere in LabVIEW memory after the function is called, no matter how diligent the external library is about clearing any buffer it uses. Also many hashes are mostly used for hashing known sources. which does not have the problem that the original string or byte stream needs to stay secret at all as it is already in memory anyways elsewhere. So for such applications the use of these functions in LabVIEW would not cause any extra concerns about lingering memory buffers that might contain "the secret" after the function has finished.
  4. 1 point
    So I put something together. It implements NextUp and NextDown. I was thinking it would be nice to have a approximation compare that took a number of up/down steps for tolerance. Let me know if you think there is any interest. https://github.com/taylorh140/LabVIEW-Float-Utility If your curious please check it out, and make sure I don't have any hidden Bugs. 😁
  5. 1 point
    The UAC in Vista and later is designed to prevent even administrator accounts from doing "dangerous" things without user confirmation. Running as Administrator alone is not sufficient to avoid the prompt as Microsoft has tried very hard to ensure that the prompts cannot be worked around. (This is so that virus authors can't go that route.) The "right" way to handle this is to ship a manifest that tells Windows that an application needs elevation. It will ask for it on launch. If there is no manifest, Windows tries to figure out which applications require elevation (for example, an installer named "setup.exe") and request elevation from the user on launch. It is very frequently wrong and this results in cascade of errors later on. I agree with you that disabling UAC entirely on a machine is the wrong approach. I'm no fan of UAC, but it is the world Microsoft wants us to live in. None of them really get rid of the UAC prompt, they just get the user's permission at some more convenient point in the launch process. (I realize not all of these apply to your situation:) Number one recommendation: avoid tasks that Microsoft considers "dangerous". Sometimes elevation is unavoidable but other times it is the result of using deprecated Windows programming techniques like writing a config file to the %ProgramFiles% directory. In these cases I recommend capitulation to the Borg; if Microsoft wants you to write to %AllUserProfile% instead of %ProgramFiles%, just give in and change it. I recommend testing the application in a regular (non-Administrative) user to see where the problems are. If you just want to do a simple SysExec call and you don't mind getting the prompt (i.e. it needs to work, but it doesn't need to work unattended), you can use John Robbins' elevate.exe to run the command (sc start or whatever) with elevation. We use elevate.exe in our installer batch file; the user clicks through one UAC prompt which elevates the batch file that runs multiple installers. (Johannes Passing wrote a version of elevate.exe in regular C; I haven't tried it.) Run your application as a service. Microsoft believes that applications that run unattended should be services. A service running in a privileged account (i.e. LocalSystem) can perform tasks that require elevation without any dialog boxes. The thought here is that since UAC elevation is required to install the service no further prompts are needed. This is how our production application runs. We use FireDaemon to do this and it is quite easy to convert your LV app to a service this way. (There is also the free "srvany.exe" application from Microsoft floating around.) There are other advantages to running as a service, such as automatic restarts when the application quits or crashes. There is, unfortunately, a winkle running an app as a service under Windows 7: starting with Vista, Microsoft no longer allows services to have user interfaces. (This is another security "feature".) Thus to go this route you will have split the functional part of your application from your UI. It's quite doable (especially if you use the VI Server) but if your application has a lot of UI this might be an untenable amount of work. I suppose you could go the other way and have a lightweight helper service that performs just a few tasks that require elevation under the command of your main app. That would be pretty easy. Have your application request elevation on startup. This is the method Microsoft wants you to take. (Well, not really: they want you to have buttons all over the place with little shield logos that only request elevation on the specific tasks that really require elevation.) You can request elevation by embedding a manifest in the application. This is supported by the LV Application Builder, although documentation is extremely sparse. See this PowerPoint presentation on how to construct the manifest. While you are at it, digitally signing the application will avoid another bunch of UAC warnings on installation and launch. You can use self-signed certificate or a "real" certificate backed up by Verisign etc. "Real" certificates cost money but provide traceability. Signing your code shows that your application hasn't been modified since your released it. While we are talking Windows 7, keep in mind that the Program Files directory is now called Program Files (x86) when 32-bit LV is running on a 64-bit versions of windows. So make sure to clean out those hard-coded paths! -Rob
  6. 0 points
    Yesterday I was giving a presentation titled Software Development with LabVIEW Object-Oriented Programming at NIDays in Finland. As part of the talk, I prepared Drawing Tool, an example application that utilizes LabVIEW Object-Oriented Programming and tries to introduce several LabVIEW Object-Oriented Programming techniques. It is a simple drawing application for drawing various shapes of different colors on a drawing area. The application is based on a state-machine where the state of the application is presented with several LabVIEW objects. The application demonstrates how a simple state machines based application can be created using LabVIEW classes as state parameters. ALERT: The intention of the application is to show various LVOOP features and programming techniques. To make the application easily understandable to LVOOP beginners, I used architectural choices that make the application more readable rather than more sophisticated and easier to extend. So the example application is not intended as a guide how to develop LVOOP application but merely as an example introducing how several LVOOP techniques can be used in application development. Download Drawing Tool Download the NIDays presentation slides


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