topic Re: CoAP Client for LabVIEW? in LabVIEW

CoAP Client for LabVIEW?

MVidal — Fri, 09 Oct 2015 04:05:13 GMT

Hi!

I would like to be able to acquire data from diverse sensors that implement the CoAP protocol: http://coap.technology

It seems there is no native implementation in LabVIEW for this, but there are plenty for other platforms.

I guess one solution can be to deploy one those implementations and access them as a gateway from LabVIEW (ie a Phyton based one), but it will require to install and maintain additional software.

May I have your pointers on what can I do or where can I look to implement a client for CoAP devices in LabVIEW?

Quite appart, if someone is interested I have found this nice implementation of IBM's IoT services based on MQTT written in LabVIEW: https://developer.ibm.com/recipes/tutorials/national-instruments-labview-for-the-iot-foundation

Thank you guys!

Re: CoAP Client for LabVIEW?

Sam_Sharp — Mon, 12 Oct 2015 11:14:11 GMT

From the looks of it, it's a HTTP REST-based protocol, so you can just use the HTTP Client VIs to make requests and get the response back. The url/headers/content of the request will change according to the specification but you might not need to implement the low-level HTTP functions. If you do, the HTTP protocol isn't too complicated to implement as a wrapper of the TCP/IP VIs.

Re: CoAP Client for LabVIEW?

MVidal — Tue, 13 Oct 2015 18:18:21 GMT

Sam,

Thank you for your kind response.

I'm commited to make it work despite of my huge ignorance on this subject. Actually, now I'm headed in the direction you mention using the HTTPVIEWHTTPClient.lvlib.vi library in LabVIEW 2014 SP1.

However I haven't been able to sucessfully get a valid response from a public test server for CoAP.

First of all, I have to mention that CoAP is UDP based, not TCP. I'm wondering if those libraries can be used...

However, here it is my setup:

Using the URL coap://coap.me:5683/hello it should return "world" (I have tested this with Copper (Cu), an add-on for Firefox which is a CoAP client). Instead, I get the LabVIEW error code 363524 that states that the protocol is not supported.

If instead, I fire the URL http://coap.me/hello, I get the response [:error, "Not Found"] which is okay, as that is the same response I get from any web browser. Using the same with the port 5683, I mean: http://coap.me:5683/hello it provides a 363500 LabVIEW error, that states it does not get response from the server, which is what I expected, the server is not configured to listen at that port http requests...

Currently, I'm trying to figure it out how to work with the UDP functions, but in the meantime, if you have an additional input, I really would appreciate it.

Thank you!

Re: CoAP Client for LabVIEW?

MVidal — Tue, 13 Oct 2015 22:43:14 GMT

Just an update: I concluded that the way to go is to use the UDP palette.

Currently I have been able to get a valid response from the test server after I placed a basic "header" according to the protocol.

Now I'm building on top of that.

Later I'll share my findings about this in case anyone else is interested.

Best regards

Re: CoAP Client for LabVIEW?

JJideani — Thu, 10 Mar 2016 10:35:49 GMT

Hi MVidal,

Have you successfully designed the CoAP client in LabVIEW?

I have a similar problem - I need to design a CoAP server. I wonder if it will be too different from creating a CoAP client?

Regards.

Re: CoAP Client for LabVIEW?

MVidal — Thu, 10 Mar 2016 15:38:26 GMT

Hi!

Yeah I was able to build it. Actually it was quite straight forward to write the client after reading the specification: http://tools.ietf.org/html/rfc7252

Altough I only implemented the parts that are useful in my case, which are quite basic and may not be a fully compliant one (ie. some Methods/Messages not implemented, No observer, etc), but it won't be that hard to add them. What I wasn't able to solve was the support of ipv6, as LabVIEW does not offer it, but it is ok in ipv4.

I'm sorry I don't have info about the server implementation. I haven't read about it. Though for your reference I found this link quite useful during my task: http://trac.tools.ietf.org/wg/core/trac/wiki/PlugFest

Good luck with your project!

Re: CoAP Client for LabVIEW?

Gustav0 — Thu, 05 Jan 2017 21:50:00 GMT

Can you share an example .vi of you implementation? Thank you.

Re: CoAP Client for LabVIEW?

bienieck — Thu, 02 Jun 2022 11:54:33 GMT

This replies with ACK:

Re: CoAP Client for LabVIEW?

Martin_Sokolov — Mon, 29 Aug 2022 13:40:54 GMT

So, you are looking for help, but you are not willing to share?

Re: CoAP Client for LabVIEW?

MVidal — Mon, 29 Aug 2022 13:53:56 GMT

@Martin_Sokolov

What do you mean? Did you notice the original post was about 7 years ago and that I have posted later about my findings the issues I have encountered?

Re: CoAP Client for LabVIEW?

Martin_Sokolov — Mon, 29 Aug 2022 17:41:56 GMT

One of the members asked you to share an example .vi of your implementation, but you didn't.

Re: CoAP Client for LabVIEW?

rolfk — Tue, 30 Aug 2022 06:28:03 GMT

Calm down everybody. If anyone is willing or able to provide his VIs is their own decision. Even if you initially asked for help and then develop your own solution.

So asking for a ready (or not) made library is ok but expecting that it is also posted is quite a different story. Reasons not to post are many:

-You work for an employer and the VIs are part of your normal work: He legally owns your work and needs to be fine with you posting his property.

- The library works for your specific problem but is rather limited, hacky or otherwise not to feel proud about: Posting it either gets no reactions, which feels unsatisfactory, or bad reactions from entitled users who feel everything should be provided free of charge and in perfect functioning condition, implementing all obscure features too. Or they want to use it, but have not even basic knowledge and keep pestering you with basic questions about your library.

- You spend hours of work and don’t feel like giving that away for free.

- You developed it as part of a project for a client that was on the base that the customer pays for the whole development fully and in exchange gets full rights on the source code. In that case you don’t own the VIs anymore and need permission from that client to use them anywhere else, including posting them here.

Each of these reason is perfectly valid.

Can you please point out your submissions to the community that you posted so far, that shows that you are not just expecting others to post their work but also do your own part in providing the fruits of your work to others?

Re: CoAP Client for LabVIEW?

Martin_Sokolov — Wed, 31 Aug 2022 17:08:40 GMT

Is it possible to import python code with CoAP in LabView?

Re: CoAP Client for LabVIEW?

rolfk — Thu, 01 Sep 2022 06:20:06 GMT

Depends what you mean with import.

Generally importing any code into native LabVIEW VIs is not really an option.

Calling other code is definitely an option though.

- precompiled shared libraries can be called with the Call Library Node, Python code can be compiled into shared libraries with the right tools, but I'm not sure why anyone would want to do that.

- .Net assemblies (for .Net Framework, not yet .Net Core) can be called with the LabVIEW .Net functions

- Python code can be called through the new Python Node in LabVIEW 2020 and newer. It requires an installed and supported Python system on the computer, to which the Python script is handed down for execution

- Matlab code can the called through the Matlab Script Node and also requires an installed Matlab system on the machine.

- Lua code can be called through Lua for LabVIEW

- There are a lot of other options like that

So there are definitely many options to use other programming languages. But I wouldn't call any of them importing the code into LabVIEW.

Re: CoAP Client for LabVIEW?

Martin_Sokolov — Thu, 01 Sep 2022 20:11:03 GMT

So, how to fix this CoAP problem?
Is the best option to combine HTTP + UDP?

My idea is to send sensor data to cloud via different protocols (HTTP, MQTT, CoAP...) and to compare the delay.
Can someone help me with that?

Re: CoAP Client for LabVIEW?

rolfk — Thu, 01 Sep 2022 20:47:14 GMT

@Martin_Sokolov wrote:

So, how to fix this CoAP problem?
Is the best option to combine HTTP + UDP?

My idea is to send sensor data to cloud via different protocols (HTTP, MQTT, CoAP...) and to compare the delay.
Can someone help me with that?

All of these protocols are in principle TCP/IP and/or UDP based and could be implemented natively in LabVIEW. I did that in a long ago past for HTTP and that even worked, but it is quite an effort nowadays (my implementation was pre HTTP 1.0 times). The other two are not that different to implement but each is quite an effort to do from scratch. CoAP being a lightweight protocol for resource constrained devices would seem simple enough to actually implement in such a way. But you may have to get your own hands dirty and do the work yourself. Basic MQTT shouldn’t be very hard to implement either but a fully functional protocol stack can get very challenging. HTTP is similar, to just contact a web server for simple GET calls is fairly easy, but a fully functioning HTTP stack is very complicated.

If I would have to do it for a real project I would likely use binary shared libraries such as libcurl (HTTP), libmqtt and libcoap and call them with the Call Library Node. But Call Library Nodes are not everyones hobby and can be challenging to use if you are not a seasoned C programmer.

The more easy approach if you only need to support Windows would be to find out a relevant .Net assembly for each protocol and interface to it with the LabVIEW .Net Nodes.

For MQTT there exist actually some libraries for LabVIEW that are freely available and interface to one of the several open source shared libraries.

The HTTP Client VIs are under the hood based on libcurl and work for most use cases. Unfortunately NI completely shielded the entire libcurl interface behind a wrapper of their own. If the library works for you that is good. If it doesn’t because your device uses non standard HTTP methods or some other involved HTTP speciality, there is no chance to hack it into this library yourself.

Re: CoAP Client for LabVIEW?

MVidal — Fri, 02 Sep 2022 14:36:13 GMT

Thanks to @rolfk for taking the time to explain some of the burdens about sharing code.

While our company have dropped LabVIEW for several years now I just stripped the relevant code about CoAP that we have about that time and published it here:

https://github.com/maovidal/VA_CoAP_LabVIEW

I haven't checked it, but even if it does not work it may serve others to see some details about CoAP.

Regards