How to dynamically invoke Web Services in .Net - asp.net

Question

I am writing a Web service client in C# which takes the URL of the web Service, and a web method name.
I want to check if thew Web method actually receives an int and returns a DataTable, and if this is true, it should call it and return the DataTable.
I have found a couple of posts where this is accomplished compiling dynamically the Proxy class.
But for my case this'd be too expensive, because the client is actually a WSS WebPart, and I don't want to do this every time the page is rendered; only when the properties are changed.

Answer 1

In the end of the day web service description is just an XML file. You can grab it by requesting service.asmx?WSDL:
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://localhost:1753/Service1.asmx?WSDL");
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
string xml = reader.ReadToEnd();
Once you have service description you can parse it and check method signature. Then, you can invoke the method using HTTP POST:
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://localhost:1753/Service1.asmx?HelloWorld");
request.Method = "POST";
request.ContentType = "application/soap+xml; charset=utf-8";
byte[] data = Encoding.UTF8.GetBytes(
#"<?xml version='1.0' encoding='utf-8'?>
<soap12:Envelope xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xmlns:xsd='http://www.w3.org/2001/XMLSchema' xmlns:soap12='http://www.w3.org/2003/05/soap-envelope'>
<soap12:Body>
<HelloWorld xmlns='http://tempuri.org/' />
</soap12:Body>
</soap12:Envelope>");
request.ContentLength = data.Length;
Stream requestStream = request.GetRequestStream();
requestStream.Write(data, 0, data.Length);
requestStream.Close();
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
string xml = reader.ReadToEnd();

Answer 2

If the Web Service is always the same (i.e. the method is the same as well as what it returns) and uit's just the url that might change, then just add a web reference to the project with the webpart in it, the set the Url of the proxy like so:
using (var serviceProxy = new ServiceProxy())
{
serviceProxy.Url = somepropertysetbythewebpart;
// make call to method here
}

Answer 3

After a lot of resarching I found out how to do it. The code of the selected answer is almost there, but I had to add the SOAPAction in the header and also change the ContentType.
Here is the entire code:
var strRequest = #"<soap12:Envelope>
...
</soap12:Envelope>";
string webServiceUrl = "http://localhost:8080/AccontService.svc";
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(webServiceUrl);
request.Method = "POST";
request.ContentType = "text/xml;charset=UTF-8";
request.Accept = "text/xml";
request.Headers.Add("SOAPAction", "http://tempuri.org/IAccountService/UpdateAccount");
byte[] data = Encoding.UTF8.GetBytes(strRequest);
request.ContentLength = data.Length;
Stream requestStream = request.GetRequestStream();
requestStream.Write(data, 0, data.Length);
requestStream.Close();
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
string responseXmlString = reader.ReadToEnd();
return new HttpResponseMessage()
{
Content = new StringContent(responseXmlString, Encoding.UTF8, "application/xml")
};