客户端如何调用WebService并且POST数据

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;using System.Net;
using System.IO;
namespace ETCRM.WebService.Tester
{
class Program
{
static void Main(string[] args)
{
try
{
//String Url = "http://localhost:3520/SynchDataInterface.asmx?op=SetSynchData";

//WeService Address，需要注意的是SetSynchData是WebService中公开的方法，
//不要用?op=SetSynchData，无法调用，提示500 内部错误
String Url = "http://localhost:3520/SynchDataInterface.asmx/SetSynchData";

byte[] dataArray = Encoding.Default.GetBytes("需要Post到Server-side的data");
WebRequest req = WebRequest.Create(Url);
req.Method = "POST";
req.ContentLength = dataArray.Length;
req.ContentType = "application/x-www-form-urlencoded";

//创建输入流
Stream dataStream = req.GetRequestStream();
//发送请求
dataStream.Write(dataArray, 0, dataArray.Length);
dataStream.Close();

//WebResponse res = req.GetResponse();// GetResponse blocks until the response arrives
HttpWebResponse res = (HttpWebResponse)req.GetResponse();
Stream receiveStream = res.GetResponseStream(); //Read the stream into a string
StreamReader sr = new StreamReader(receiveStream);
string resultstring = sr.ReadToEnd();
Console.WriteLine(resultstring);
Console.Read();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
Console.Read();
}
}
}
}

byte[] dataArray = Encoding.UTF8.GetBytes(XmlObjectHelper.ObjectToXML(postData));