In creating the service section you say:

“But before we can do that we need a DataContract class called LiveDataMessage – this is the simple class that our service will send to Silverlight.”

I’m not seeing where you create that, your not as explicit as you were in everything else so I am getting the impression I’m missing something obvious.

Any help?

I eventually discovered that I had to add to the web.config as well as [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Required)] (Allowed may work too) to the service definition in order to get a System.Web.HttpContext.Current that was not null. However System.Web.HttpContext.Current.Session remained null and it turns out this is always so when using duplexing. I also found that enabling ASP.NET compatibility slowed my service calls way down (they didn’t even execute for between 8 minutes and over a minute) so I ripped out ASP.NET compatibility (it didn’t get me my session variable anyway).

In my implementation I’m trying to get something out of System.Web.HttpContext.Current.Session (System.Web.HttpContext.Current.Session["MyVariable"].ToString()) but when I run the sample I get an exception because System.Web.HttpContext.Current is null.

At first I thought the problem was because of [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single)] however I’ve tried PerSession and PerCall with no success. (I had to modify some things to make those two possible.)

The reason I’m trying to get to the Session is that I’m working with an existing web application and there’s a value I need from there. Session was accessible using a plain WCF/Silverlight implementation however I’m working on replacing that with a duplexing version because we have calls that take longer than 1 minute and later we will probably be pushing data from the server.

Can you shed any light on why System.Web.HttpContext.Current is null (even when I have changed things to make it PerSession/PerCall)?

Thanks,
Phil

public System.Net.CookieContainer CookieContainer {

Which throws up a type namespace error.
How do I fix this please?

Thanks from me and my colleges!

Is there a magic setting that i need to look at?

I ran into the same issue. I’d bet that it is because you copied the contents of the LiveDataService.svc file right into the text file you added. The quotes didnt copy right for me, so just deleting the quotes and re-adding them resolved this issue and I can now add the service reference fine.
Hope this helps.