Web Service exits on any file close operation via
StreamWriter, TextWrtier or FileStream. This is inefficient because the Web Service has to be reloaded on every function call. Also Static or Public Shared variables become useless.
Sample code below.

Dim Success As StreamWriter = File.AppendText(CurDir + User + "_Success.Log")
Success.AutoFlush = True
Success.WriteLine(Record + ", " + DateTime.Now())
Success.Flush()
Success.Close()