最经典的就是下面这段Post数据流到HTTP地址上,然后获得返回的响应。
参数sXmlMessage格式为:goods_id=18,即url参数goods_id赋值。
//把sXmlMessage发送到指定的DsmpUrl地址上

Encoding encode = System.Text.Encoding.GetEncoding("utf-8");
byte[] arrB = encode.GetBytes(sXmlMessage);

HttpWebRequest myReq = (HttpWebRequest)WebRequest.Create(DsmpUrl);

myReq.Method = "POST" ;

myReq.ContentType = "application/x-www-form-urlencoded";

myReq.ContentLength = arrB.Length;

Stream outStream = myReq.GetRequestStream();

outStream.Write(arrB,0,arrB.Length);

outStream.Close();
//接收HTTP做出的响应

WebResponse myResp = myReq.GetResponse();

Stream ReceiveStream = myResp.GetResponseStream();

StreamReader readStream =
new StreamReader( ReceiveStream, encode );

Char[] read =
new Char[256];
int count = readStream.Read( read, 0, 256 );
string str =
null;
while (count > 0)
{
str += new String(read, 0, count);
count = readStream.Read(read, 0, 256);
}

readStream.Close();

myResp.Close();
看很简单的几句就可以完成HTTP的发送和接收。当然如果你使用soap协议采用Webservice那么原理也相同,只不过是HTTP+XML的方式。
sr:http://www.cnblogs.com/qdwolf/archive/2004/08/13/33119.aspx