topic .NET Http/Https Get document in LabVIEW

.NET Http/Https Get document

winterishere8 — Thu, 17 Aug 2006 16:55:56 GMT

Has anyone used .NET to do Http/Https services ? I used activex to talk to a webserver and read the contents using "Get document". I want to see if I can do via .NET since activeX has some inherent problems such as the update speed or cacheing.

Thanks
Sridhar

Re: .NET Http/Https Get document

Khalid — Fri, 18 Aug 2006 07:37:08 GMT

I haven't tried .NET, but one other option is to use DataSocket read function.

-Khalid

Re: .NET Http/Https Get document

winterishere8 — Fri, 18 Aug 2006 13:05:13 GMT

Problem with data socket is: The first few characters sent have a bug. If you send "Passed", you would read it as "PPPPed"

I have used activeX before. It has some kind of cacheing when I do secure communication. ActiveX works fine if it http rather than https.

So I want to use .NET to see if it's any better.

Re: .NET Http/Https Get document

DuffmanSays — Mon, 21 Aug 2006 19:34:40 GMT

Sridhar,

From an NI perspective, I can offer support with how to use LabVIEW as a .NET client (linked below). I can also offer that I have not personally seen an application that utilized .NET to communicate with a web server. As for whether or not the functionality exists, I cannot say for sure. If you are able to utilize .NET to communicate with a web server, please post back to this forum, as I am also interested to know. Thanks,

Mike

Using .NET in LabVIEW:
http://zone.ni.com/reference/en-XX/help/371361A-01/lvconcepts/using__net_with_labview/

Re: .NET Http/Https Get document

Lycangeek — Tue, 22 Aug 2006 14:46:41 GMT

Another aspect to keep in mind - the .NET APIs will let you communicate via HTTP and HTTPS. The next question is what to do with the data. If you are talking to a web service, receiving XML, you might want to use the Web Service Proxy support in .NET instead. If it's custom XML, then you can use the System.Xml classes. If it's HTML, you'll probably be better off using the IE control set in ActiveX.

Speaking from first-hand experience, processing HTML - especially being able to handle the variety out on the web, with CSS and JS additions - is a nightmare and you'd be better off using the MS HTML parser and it's associated DOM.

Guess I'm not answering your question as much as giving you more 🙂

Re: .NET Http/Https Get document

winterishere8 — Thu, 24 Aug 2006 16:37:31 GMT

How you do communicate with HTTPS via .NET. Do you have an example ? I will be extracting the readout as a string and process them. I am thinking or hoping that .NET is better than activeX in communicating with HTTPS or atleast HTTP.

Re: .NET Http/Https Get document

Lycangeek — Thu, 24 Aug 2006 19:54:38 GMT

The class you want is System.Net.HttpWebRequest, and the programming is pretty simple. I wipped up a quick example below. Note that my reading portion is very primative - it's a fixed size array. You'll probaby want to "read until done" or similar actions.

Unfortunately, the ContentLength is usually not helpful as it's often -1. This means that the web server didn't send the length - it expects the client to "read until done".

Re: .NET Http/Https Get document

Wiredup — Tue, 09 Oct 2007 23:55:00 GMT

Just in case someone stumbles on this thread, I've attached an extension to the .NET example shown by Lycangeek. This is a fairly quick web document fetcher (seems to be as fast as IE). There's probably a better way to do the proxy subsitution. That's required to prevent the first call from searching for a proxy (5 to 10 second delay).

The status code is a bitch sketchy right now as I'm searching for a .NET way to get this back using the WebRequest structure (Using .NET 2.0 here).

The image is big (sorry), so you may need to open up your browser window size to see it clearly. If you need help locating the .NET modules/assemblies, just let me know and I'll gather the list. You can likely find them faster searching http://msdn2.microsoft.com/en-us/library/aa139635.aspx for each method or property name.

Re: .NET Http/Https Get document

winterishere8 — Wed, 03 Jun 2009 20:56:29 GMT

One more question. Your code works great on HTTP and HTTPS. When I goto a website which asks me to accept the certificate, the code fails because by default it rejects the authentication.

I see system.security.authentication.authenticationexception and I think it's got to do something with it. Any ideas ?

Message Edited by Spartan00 on 06-03-2009 03:56 PM

Re: .NET Http/Https Get document

mishkin — Fri, 18 Sep 2009 21:34:45 GMT

Here is a VI snippet for those interested in working with this code:

Re: .NET Http/Https Get document

schuller — Mon, 22 Mar 2010 09:19:13 GMT

Note that there are different security protocols for SSL.

These examples here work only for the TLS protocol which is the default.

But if the server doesn't support TLS you won't get a response.

You can change the protocol by adding a property node for the SecurityProtocol of the class System.NET.ServicePointManager.

A possible value would be "Ssl3" for example:

http://msdn.microsoft.com/en-us/library/system.net.servicepointmanager.securityprotocol.aspx

Re: .NET Http/Https Get document

aartjan — Mon, 22 Mar 2010 11:08:58 GMT

I want to download an xml document that has a https url, so this thread should really help me accomplish that. Unfortunately I can't even find the .NET assembly that contains the WebRequest methods. Anayone know which assembly I should choose in the Labview Class browser to find these methods?

BTW. the code snippet has the method nodes removed when I drag it into Labview. Maybe that means that the assembly is not present in my installation?

Thanks!

Aart-Jan

Re: .NET Http/Https Get document

ethmx — Fri, 16 Aug 2013 20:20:36 GMT

Hi, I'm trying to do the exact same thing with no success any ideas?

Re: .NET Http/Https Get document

winterishere8 — Fri, 16 Aug 2013 20:46:49 GMT

What version of .NET is installed ?

Re: .NET Http/Https Get document

ethmx — Fri, 16 Aug 2013 20:50:04 GMT

The webpage i'm trying to parse is: https://192.168.254.254/XML/DeviceInfo.xml where the IP is the device I'm trying to query. I was wondering if there's a way to do the File - Save As of IE explorer programatically?

I'm using LabVIEW 2009 and .NET Framerwork 3.5 SP1

Re: .NET Http/Https Get document

winterishere8 — Fri, 16 Aug 2013 21:17:59 GMT

If you are trying to store the contents of the web page, you could use HttpResponse. I've not done the "Save As" ...

Re: .NET Http/Https Get document

ethmx — Fri, 16 Aug 2013 21:31:21 GMT

I end up doing this (see attached VI). Seems to works, but you need to run it at least twice to get the proper text on the indicator "inner text" Any idea why? or any improvement?

I got this idea from one of the NI Examples.

Thank you!

Re: .NET Http/Https Get document

Andy-C — Mon, 19 Aug 2013 20:42:10 GMT

Hi ethmx,

Have you tried running your code with highlight execution turned on? Does the 'inner text' indicator populate correctly on the first try withe exeuction highlighting turned on?

Cheers,

Andy C.

Applications Engineer

National Instruments

Re: .NET Http/Https Get document

HeavyD — Fri, 30 Aug 2013 16:21:15 GMT

I'm also very interested in seeing this work with .NET . HttpRequest > write to excel file > save to web server..

Re: .NET Http/Https Get document

NTampelloni — Sat, 03 Sep 2016 18:19:54 GMT

Hi,

i was using your fantastic Example To make a HTTPS POST .

But now I have to do to log into a site What use HTTPS , dove I can INSERT into Your "VI" The credentials ( username and password) ???

Thank you