I can\'t seem to find a clear answer as to how to import the proper namespace for ReportingService http://msdn.microsoft.com/en-us/library/aa258073(v=SQL.80).aspx.
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you have a full example on how to do this from a Console Application in MSDN, here: ReportExecutionService.Render Method which also requires you to read this one: http://msdn.microsoft.com/en-us/library/ms160695.aspx
in general if you create a .NET 4 Console App you can right click on References in Solution Explorer and select Add Service Reference, it works also with Web Services, not only for WCF.
For a Report Server running SSRS 2005 or 2008 the web service to reference has this form:
http://myserver/reportserver/ReportExecution2005.asmx
scroll the pages I linked above to find the console application example starting like this...
static void Main(string[] args)
{
ReportExecutionService rs = new ReportExecutionService();
rs.Credentials = System.Net.CredentialCache.DefaultCredentials;
rs.Url = "http://myserver/reportserver/ReportExecution2005.asmx";
...
...