I want to learn the principles and knowledge of communication between clients written in C ++ on the desktop and programs written in PHP on webpages.

I want to learn the principles and knowledge of communication between clients written in C ++ on the desktop and programs written in PHP on webpages, please come in and give me some advice. I don't know if there is any online customer service function in the company's website. this function should be implemented by the customer service specialist logging on to the desktop client to listen to website customers, as long as you browse a website, you can open a webpage and use a client like QQ. I want to learn the principle and knowledge of communication between a client written in C ++ on the desktop and a program written in PHP on the webpage., please come in and give me some advice.
I don't know if there is any online customer service function in the company's website. this function should be implemented by the customer service specialist logging on to the desktop client to listen to the website's customers, as long as the customer who browsed the website opens a webpage, they can communicate with the customer service specialists who use clients like QQ.
I don't know if you have used the livezilla software. the Function I want to describe is the same as the function it implements, but I am new to this and don't know how to describe the terms.
What I want to ask is obvious: I want to learn to write a program that can implement the main functions. I hope that experienced users can give me a clear direction of effort, now I can use C ++ or PHP to write communications between clients, but the two clients I want to write this program do not use the same language to write communication between them. I don't understand, I have no idea about this ...... I don't care about anything else. I just want to learn how to send a sentence to my webpage, and the desktop client will be able to receive it and then chat,
Thank you for your answers!

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There are many methods
1. point-to-point communication protocols can be customized, such as Lan chat software.
2. transfer the message to the server through the server, and then the server notifies customer service, such as QQ.
The chat room of the Web version is transitioned through the Web server, and the protocol is HTTP. You can use the SOAP protocol for desktop programs.
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Programs written in PHP on the web page, of course, follow the http protocol
Your c ++ program can communicate with php through the http protocol or jsp, asp, and. net.

How can this problem be further detailed? This is the php discussion board! What should I do in the C/C ++ discussion area?