Why am I getting a "NotSupportedException" with this code? - asp.net-web-api

Question

I am trying to call a Web API method from a handheld device (Compact Framework) with this code:
// "fullFilePath" is a value such as "\Program Files\Bla\abc.xml"
// "uri" is something like "http://localhost:28642/api/ControllerName/PostArgsAndXMLFile?serialNum=8675309&siteNum=42"
SendXMLFile(fullFilePath, uri, 500);
. . .
public static string SendXMLFile(string xmlFilepath, string uri, int timeout)
{
uri = uri.Replace('\\', '/');
if (!uri.StartsWith("/"))
{
uri = "/" + uri;
}
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
request.KeepAlive = false;
request.ProtocolVersion = HttpVersion.Version10;
request.Method = "POST";
StringBuilder sb = new StringBuilder();
using (StreamReader sr = new StreamReader(xmlFilepath))
{
String line;
while ((line = sr.ReadLine()) != null)
{
sb.AppendLine(line);
}
byte[] postBytes = Encoding.UTF8.GetBytes(sb.ToString());
if (timeout < 0)
{
request.ReadWriteTimeout = timeout;
request.Timeout = timeout;
}
request.ContentLength = postBytes.Length;
request.KeepAlive = false;
request.ContentType = "application/x-www-form-urlencoded"; // not "text/xml" correct?
try
{
Stream requestStream = request.GetRequestStream();
requestStream.Write(postBytes, 0, postBytes.Length);
requestStream.Close();
using (var response = (HttpWebResponse)request.GetResponse())
{
return response.ToString();
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
request.Abort();
return string.Empty;
}
}
}
Somewhere in SendXMLFile(), it is failing with "NotSupportedException" though... As it's running on a handheld device, I can't put a breakpoint in it and step through it; I could sprinkle a bunch of debug statements throughout (MessageBox.Show()), but I'd rather not do that.
The server code never even reaches the breakpoint I put on the "XDocument doc =" line below:
[Route("api/ControllerName/PostArgsAndXMLFile")]
public void PostArgsAndFile([FromBody] string stringifiedXML, string serialNum, string siteNum)
{
XDocument doc = XDocument.Parse(stringifiedXML);
Is it that the Compact framework can't call a (RESTful) Web API method for some reason? Obviously, the client (handheld/Compact Framework) compiles and runs, it just refuses to actually follow through with the runtime realities of it all.
Does my code require a small alteration for it to fit, or do I need to take a completely different tack?

Answer 1

Web API is not going to be able to handle your body content. You declared it as application/x-form-urlencoded, but it is actually XML formatted and your method signature is expecting it to be a XMLDataContract serialized string.
Instead of using the parameter stringifiedXML, instead, just read the body inside your method..
[Route("api/ControllerName/PostArgsAndXMLFile")]
public async void PostArgsAndFile(string serialNum, string siteNum)
{
XDocument doc = XDocument.Parse(await Request.Content.ReadAsStringAsync());
}
Or event better, use a stream directly.
[Route("api/ControllerName/PostArgsAndXMLFile")]
public async void PostArgsAndFile(string serialNum, string siteNum)
{
XDocument doc = XDocument.Load(await Request.Content.ReadAsStreamAsync());
}
This way, you can put the ContentType on the client back to application/xml as it should be.

Answer 2

Using Darrel's code on the server side (I'm using the second one, the Stream), this works on the Client side:
public static string SendXMLFile(string xmlFilepath, string uri, int timeout)
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
request.KeepAlive = false;
request.ProtocolVersion = HttpVersion.Version10;
request.ContentType = "application/xml";
request.Method = "POST";
StringBuilder sb = new StringBuilder();
using (StreamReader sr = new StreamReader(xmlFilepath))
{
String line;
while ((line = sr.ReadLine()) != null)
{
sb.AppendLine(line);
}
byte[] postBytes = Encoding.UTF8.GetBytes(sb.ToString());
if (timeout < 0)
{
request.ReadWriteTimeout = timeout;
request.Timeout = timeout;
}
request.ContentLength = postBytes.Length;
request.KeepAlive = false;
request.ContentType = "application/x-www-form-urlencoded";
try
{
Stream requestStream = request.GetRequestStream();
requestStream.Write(postBytes, 0, postBytes.Length);
requestStream.Close();
using (var response = (HttpWebResponse)request.GetResponse())
{
return response.ToString();
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
request.Abort();
return string.Empty;
}
}
}
Which can be called like so:
private void buttonNose_Click(object sender, EventArgs e)
{
String fullFilePath = #"C:\McMurtry\LonesomeDove.XML";
String uri = #"http://localhost:21608/api/inventory/sendxml/ff/gg/42";
SendXMLFile(fullFilePath, uri, 500);
}