I also ran into this problem. The answer is in the tutorial, but I missed it.
To add a link to the Microsoft.SharePoint.Client.ServerRuntime that contains the services provided by the SharePoint Foundation, use the Browse tab of the Add Link window to browse to the Microsoft.SharePoint.Client.ServerRuntime.dll file inside% Windows% \ assembly \ GAC_MSIL \ Microsoft.SharePoint.Client.ServerRuntime, select the DLL and click OK.
Then you will need to use Microsoft.SharePoint.Client.Services; above the attribute. I have no reference to this namespace using the using statement alone. Also make sure you have the microsoft.sharepoint.client and microsoft.sharepoint.client.serverruntime files I am stuck after deploying myself. I got 404 errors and could not add a link to the service to check it. If you find a fix, email me mondo at shaw.ca thanks and good luck!
Ray letts
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