open method
Specify the desired url, and method to use in making the request.
By default the request is done asyncronously, with no user or password
authentication information. If async is false, the request will be sent
synchronously.
Calling open again on a currently active request is equivalent to
calling abort.
Note: Most simple HTTP requests can be accomplished using the getString,
request, requestCrossOrigin, or postFormData methods. Use of this
open method is intended only for more complex HTTP requests where
finer-grained control is needed.
Implementation
void open(String method, String url,
{bool async, String user, String password}) native;