How to connect PC App and Web App together

[stefan.erni]

Hi Steve

I have two demo programs, and both work well.

I can set up a PC Web server, and I can use the Web App to retrieve text from the matrix server, which works

But when I try to retrieve text with the Web App from the my web server (localhost), it doesn't work yet.

Webserver_FileSystem (1).fcsx

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WebFetchHTML.fcsx

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[Steve-Matrix]

I've edited your files to show how this could happen.

Some changes I made to the Web Developer app:

• The DataType is now JSON Encoded
• The URL is a local IP address as created by the PC Developer app's Network Comms IP Address
• The ProcessResponse macro extracts the "Data" tag from the received JSON packet

Some changes I made to the PC Developer app:

• Removed the File I/O component
• Changed the HTML source to Embedded
• Added a custom header for CORS and JSON
• Added the "fetchtest.txt" file with a JSON string

When you simulate the PC Developer app, your firewall will probably ask to allow Flowcode access to your network. You will need to allow it.

You can test to see if the PC Developer web server is active by opening page the following in a browser:

Code: Select all

http://192.168.0.90/fetchtest.txt

It should report the JSON string.

The IP address is likely to be different and is the one specified by the Network Comms IP Address property.

Here are some images showing it working:

PC Developer webserver test.png (14.09 KiB) Viewed 174 times

Web Developer app.png (10.4 KiB) Viewed 174 times

[stefan.erni]

Hi Steve

Perfect!

I can use “localhost” instead of the IP address, so I won't have to make any adjustments if it runs on a different computer

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And the result from the Web App:

2026-06-15_10-12-46.PNG (25 KiB) Viewed 88 times

So, connecting the Web App to the PC App is very easy and user-friendly.

One more question:

Do I always have to do pooling from the Web App, or can I also send data from the PC App?

[Steve-Matrix]

I think polling if how I'd do it. If you want the Web app to respond to incoming data without polling, then you could look at using MQTT as a way of routing messages between the PC app and the Web app.

[stefan.erni]

Hi Steve

With your example, polling every 500 milliseconds works very well.
I can simply use a button in the PC-App to set a state (Ledon on/off) in the Web App

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