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HTTP and OPC UA on Raspberry Pi [message #1832844]

Sat, 26 September 2020 17:07

Manuel Reif

Messages: 2
Registered: September 2020

Junior Member

Hi,
I'm trying to create an OPC UA server on a Rasperry Pi with methods that trigger http GET and POST requests to a REST API to control another device. GET works fine according to the documentation but POST unfortunately does not. I tried a Client FB with:

- ID=http[<IP>:80/<PATH>?apikey=<XYZ>;POST;application/json;*]
- one SD={JSON String} input via a String2String FB
- two RDs to String2String FBs for the responses

So I need to send an "apikey" (as query parameter or header parameter) and a JSON string (as the body). According to the documentation (I guess there it means SD instead of RD in the http client data input section?) the query parameters are ignored when there is a SD input. I tried many variants and always got errors like:
- Client FB Status Output "No_Socket" or "Invalid_ID"
- forte errors like "You can use maximum 1 SD"

Can anybody help me with this issue or succesfully executed a http POST request already?
I'm grateful for every hint. Thanks!

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Re: HTTP and OPC UA on Raspberry Pi [message #1832863 is a reply to message #1832844]

Mon, 28 September 2020 06:42

Jose Maria Jesus Cabral Lassalle

Messages: 199
Registered: February 2016

Senior Member

Hi

you're right. It should be SD instead of RD.

Regarding your specific problem, I assume that you won't be able to do it with the current state of the HTTP layer. As you noted, you can only send either using the SD or in the PARAMETERS.

Regarding the errors you get, check the log in forte. You should get more informaion there. I just rechecked the code, and it has changed the PARAM structure, but it's not in the documentation.

You should have it like:

ttp[IP:PORT/PATH?PARAMETERS; POST | PUT | GET ; content-type]

So the response code is gone, and content-type is optional (default to text/html)

The HTTP layer is not well supported and it was developed just for small testing. Feel free to improve it

Regards,

Jose

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Re: HTTP and OPC UA on Raspberry Pi [message #1832866 is a reply to message #1832863]

Mon, 28 September 2020 07:13

Manuel Reif

Messages: 2
Registered: September 2020

Junior Member

Hi,
thanks for your reply! I will test it a little bit more (and reply here in case I make progress) but as it is now I also have my doubts it will work for my usecase.

Thanks and regards
Manuel

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