translate from ASP to PHP

I am being forced to work with a database company that only support ASP.NET, despite my employers being well aware that I only code in PHP and the project doesn't have the time to learn the new syntax.

Documentation is scant, and meaning in thin on the ground. Can someone help translate what is happening in this script, so that I can think about doing it in PHP

<%
 QES.ContentServer cs = new Q开发者_开发问答ES.ContentServer();
 string state = "";
 state = Request.Url.AbsoluteUri.ToString();
 Response.Write(cs.GetXhtml(state));
%>

QES.ContentServer cs = new QES.ContentServer();

the code instantiates the class method ContentServer()

string state = "";

Explicit the type var state as string

state = Request.Url.AbsoluteUri.ToString();

here you get the REQUEST URI (as in php) the path and convert it to one line string and put in the before mentioned string statte var

Response.Write(cs.GetXhtml(state));

and here return the message without refresh the page (ajax).

The Request object wraps a bunch of information regarding the request from the client i.e. Browser capabilities, form or querystring parameters, cookies etc. In this case it is being used to retrieve the absolute URI using Request.Url.AbsoluteUri.ToString(). This will be the full request path including domain, path, querystring values.
The Response object wraps the response stream sent from the server back to the client. In this case it is being used to write the return of the cs.GetXhtml(state) call to the client as part of the body of the response.
QES.ContentServer appears to be a third party class and is not part of the standard .NET framework so you would have to get access to the specific API documention to find out what is for and what the GetXhtml method does exactly.

So, in a nutshell, this script is taking the full URI of the request from the client and returning the output from the GetXhtml back in the response.

It would look like this in PHP:

<?php
     $cs = new QES_ContentServer(); //Not a real php class, but doesn't look like a native ASP.NET class either, still, it's a class instantiation, little Google shows it's a class for Qwam E-Content Server.
     $state = "";  //Superfluous in PHP, don't need to define variables before use except in certain logic related circumstances, of course, the ASP.NET could have been done in one line like "string state = Request.Url.AbsoluteUri.ToString();"
     $state = $_SERVER['REQUEST_URI'];  //REQUEST_URI actually isn't the best, but it's pretty close.  Request.Url.AbsoluteUri is the absolute uri used to call the page. REQUEST_URI would return something like /index.php while Request.Url.AbsoluteUri would give http://www.domain.com/index.php
     //$state = $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI']; or something similar might be better in this case given the above
     echo $cs->GetXhtml($state);  //GetXhtml would be a method of QES.ContentServer, Response.Write is like echo or print.
?>