Since others have said what you need to hear: Learn programming. I would continue and give you an overview of what you need to learn in order to get started on this or a similar project. Ok, have your answers in the following list:
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What is the best approch?? It can be lead slowness issue?
Drop Web Services. Instead of this, use ASP.NET Web API. I have personally stated on multiple occasions, that ASP.NET Web API is a much better approach as compared to Web Services. First of them being, Web API can be consumed from any platform using HTTP protocol — almost every framework supports networking and HTTP communication. Web Service does provide multiple solutions, like SOAP, but that isn't used anymore nowadays. Use JSON instead of XML too.
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How to prevent unauthorized user to access Service url.
One more time, where ASP.NET Web API beats Web Services. You just need to add one attribute to the actual endpoint (controller), and framework itself will handle the authentication for you.
[Authorize]
public class ServiceController : ApiController {
}
Authentication is possible in WCF too, but that is not as easy.
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I want keep control over Service Url.
Are you the web admin? If so, you already have that. I am starting to doubt this a bit — every programmer has the control over their service, unless they write the frameworks poorly.
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How can be check user is valid to access service url??
See the answer to your second question. Also, the user profile can hold the information about their subscription (if that is what you are looking for). Then you can allow them access, or deny them access based on your own logic.
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How can i start to develop project??
Download
Visual Studio 2015 Community[
^]. Good luck.
For more please read the following,
AuthorizeAttribute Class (System.Web.Mvc)[
^]