Where are my cookies?

var req = (HttpWebRequest)HttpWebRequest.Create("http://mydomain.com/myservice");
var resp = (HttpWebResponse)req.GetResponse();
var cookies = resp.Cookies;
Console.WriteLine("Cookie count: 开发者_StackOverflow社区{0}", cookies.Count);

Output is:

Cookie count: 0

I can see using Charles that the call to my web service is returning cookies. Why don't they show up in my response's cookie collection?

Try creating a CookieContainer in your request object to accomodate the cookies:

var req = (HttpWebRequest)HttpWebRequest.Create("http://mydomain.com/myservice");
req.CookieContainer = new CookieContainer();
var resp = (HttpWebResponse)req.GetResponse();
var cookies = resp.Cookies;
Console.WriteLine("Cookie count: {0}", cookies.Count);

From the Remarks section of the documentation for the CookieContainer property:

CookieContainer is null by default. You must assign a CookieContainer object to the property to have cookies returned in the Cookies property of the HttpWebResponse returned by the GetResponse method.