HttpWebRequest请求PHP页面，PHP如何读取request请求的参数

Question

实现功能：提供外部访问PHP接口
    C# 使用 HttpWebRequest 访问 php 页面 
代码如下：
      StringBuilder ss = new StringBuilder();               
                byte[] byt;
                rqst.Timeout = 60000;
                rqst.Method = "post";
                FileStream inStream = new FileStream(path, FileMode.Open, FileAccess.Read);
                long nBytesToRead = inStream.Length;
                byt = new byte[nBytesToRead];
                int m = inStream.Read(byt, 0, byt.Length);
                inStream.Close();            
                Stream reqStream = rqst.GetRequestStream();
                reqStream.Write(byt, 0, byt.Length);
                reqStream.Close();
                HttpWebResponse rps = (HttpWebResponse)rqst.GetResponse();
                retValue = GetStrRd(rps);
？php 服务器端如和获取 请求上传的"RequestStream" 对像和其他参数等