I have written a web service in an asmx file (stored under Umbraco\WebServices) and use methods I have in a class in a separate cs file.

I would like to access the Umbraco loggedin user id - so in my calls I am

using Umbraco.Core.Security;
using Umbraco.Core.Models.Membership;

...

var authenticationTicket = new HttpContextWrapper(HttpContext.Current).GetUmbracoAuthTicket();
        IUser user = null;
        if (authenticationTicket != null)
        {
            user = UmbracoContext.Current.Application.Services.UserService.GetByUsername(authenticationTicket.Name);
        }
        else
        {
            // not logged into backoffice
        }                       

        // use it if not null
        var lUserId = "";
        if(user != null)
        {

            lUserId =  user.Id.ToString();

        }

This is actually returning the logged in user, which suggests that the web service is part of the main application session and has access to HttpContext.

My question is - is this reliable, ie is the web service always going to be able to query HttpContext, or is this going to be flaky?