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MonoTouch: Simple Web Server

A web server can be a very flexible solution to transferring data from your application. MonoTouch makes it extremely easy to add a web server to your iPhone/iPad application by using the HttpListener class. You can actually implement one with just two methods.

Now this is a very simple example that will just serve up some HTML but you can start from it and extend it to whatever your needs may be. Download the solution file here.

You’ll need to declare two member variables:
[sourcecode language=”csharp”]
private HttpListener listener;
private bool listenerRunning = false;
[/sourcecode]

I used a button click event to both start and stop the server:
[sourcecode language=”csharp”]
partial void startOrStopServer (UIButton sender)
{
if (!listenerRunning) {
listener = new HttpListener();
//Add generic prefix using port 8080
listener.Prefixes.Add("http://*:8080/");

//Start the server
listener.Start();
txtInfo.Text += "Server Started\n";
btnStart.SetTitle("Stop Server", UIControlState.Normal);

//Begin listening for requests asynchronously
listener.BeginGetContext(new AsyncCallback(HandleRequest), listener);
} else {
//Close the server
listener.Close();
listener = null;
txtInfo.Text += "Server Stoped\n";
btnStart.SetTitle("Start Server", UIControlState.Normal);
}

listenerRunning = !listenerRunning;
}
[/sourcecode]

Request handler method:
[sourcecode language=”csharp”]
private void HandleRequest(IAsyncResult result) {
if (!listenerRunning) return;

//Get the listener context
HttpListenerContext context = listener.EndGetContext(result);
//Start listening for the next request
listener.BeginGetContext(new AsyncCallback(HandleRequest), listener);

//Update status on the UI thread
InvokeOnMainThread( delegate {
txtInfo.Text += "Received request from: " + context.Request.UserHostAddress + "\n";
});

//Here you can create any response that you want. You can serve text or a file or whatever else you need.
string response = "<html><head><title>Sample Response</title></head><body>Response from mtouchwebserver.</body></html>";
byte[] responseBytes = System.Text.Encoding.UTF8.GetBytes(response);

//Set some response information
context.Response.ContentType = "text/html";
context.Response.StatusCode = (int)HttpStatusCode.OK;
context.Response.ContentLength64 = responseBytes.Length;

//Write the response.
context.Response.OutputStream.Write(responseBytes, 0, responseBytes.Length);
context.Response.OutputStream.Close();
}
[/sourcecode]

You can run the example solution in the iPhone simulator, start the server, then open a browser and go to http://localhost:8080 to see the results.

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