When I understand your question correctly, the server part of your client server application
is a .NET web service. So you try to write the client side in Dart (the part that runs in the browser)?
You don't need to import dart.core
.
If you want to run an app in the browser you must not import dart:io
. dart:io
is for Dart applications that run locally like commands you execute on the command line or launch using an icon on your desktop or that run as a background service.
In Browser applications you normally import dart:html
instead. dart:html
doesn't provide a lot of functionality that dart:io
has. This is because the browser doesn't allow for example to access the local file system due to security reasons. Imagine you browse to a website and the code in this website could read, delete or upload to any server any file on your computer ...
When you have imported dart:html
you can use the class HttpRequest
to connect to the server.
Did you develop the .NET web service yourself?
You can easily access web services that provide a REST or JSON API.
I don't know how to access .NET SOAP webservice with Dart though?
You can find basic instructions how to make a request to the server here https://www.dartlang.org/articles/json-web-service/