Multiple HTTP Requests in WinRT / Win8 - windows-8

Question

Is it possible to send more than two HTTP requests concurrently in WinRT? I'm trying to load multiple JSON documents from a server and HttpWebRequest fails to respond after the second call. Here is a sample snippet that illustrates this:
protected async override void OnNavigatedTo(NavigationEventArgs e)
{
const string url = "http://www.bom.gov.au/fwo/IDV60901/IDV60901.94868.json";
const int iterations = 3;
var tasks = new List<Task>();
var ticks = DateTime.Now.Ticks;
for (var i = 0; i < iterations; i++)
{
// Create unique URL by appending a generated number.
var uniqueUrl = string.Format("{0}?v={1}", url, (i + ticks));
// Create the request.
var request = WebRequest.CreateHttp(uniqueUrl);
// Create the async task and store it for later.
var task = request.GetResponseAsync();
tasks.Add(task);
}
// Await all tasks in collection.
await Task.WhenAll(tasks);
Debugger.Break(); // <----- This will never break when iterations > 2
}
Put this code in a blank MainPage.xaml.cs and play around with the iterations value. If you set it to 2, then it works. Anything above that, it will fail.
NOTE :: Do not use Fiddler when testing this. Fiddler does something funny and it allows all these connections to go through. I don't know how nor why. You can test this yourself. If you run the code above with fiddler open, then success.
NOTE :: This is not real code. I'm only using this example to illustrate the issue.

Answer 1

I haven't tried using the WebClient API in WinRT, I've only used the HttpClient API (which I'm using quite extensively in my application).
This code works:
const string url = "http://www.bom.gov.au/fwo/IDV60901/IDV60901.94868.json";
const int iterations = 10;
var tasks = new List<Task<HttpResponseMessage>>();
var ticks = DateTime.Now.Ticks;
for (var i = 0; i < iterations; i++)
{
// Create unique URL by appending a generated number.
var uniqueUrl = string.Format("{0}?v={1}", url, (i + ticks));
var handler = new HttpClientHandler();
var client = new HttpClient(handler)
{
BaseAddress = new Uri(uniqueUrl)
};
var task = client.GetAsync(client.BaseAddress);
tasks.Add(task);
}
// Await all tasks in collection.
await Task.WhenAll(tasks);
It is a bit more tedious to get out the response body though as you need to do an async read of all the responses like so:
var responseTasks = tasks.Select(task => task.Result.Content.ReadAsStringAsync());
await Task.WhenAll(responseTasks);
Then you can iterate through the responseTask objects and take their result.