I wanted to ResolveUrl() from WCF service and found
However the function assumes that the call is synchronous, in asynchronous call (e.g called from TPL task) HttpContext.Current==null.
I had to split my asynchronous method into two-a long asynchronous one, invoked as task and generating relative URL and a post-task, that is calling wwWebUtils.ResolveServerUrl(relativeUrL)
The http://www.codeproject.com/Articles/205425/ASP-NET-ResolveUrl-Without-Page article suggests to use
but i expect, it wouldn’t work from asynchronous thread as well.