Ambiguous references when adding a WebService to Silverlight (3.0)?

Question

When I add my WebService I started getting all these errors:

'Stream' is an ambiguous reference between 'System.IO.Stream' and 'MultiSelectFileUploader.ServiceReference.Stream'

This wasn't happening when all I had in there was the GetFiles(). And I can go ahead and change my Streams to System.IO.Stream, but then I get the error that it isn't a ServiceReference.Stream when I try to pass to the UploadFiles(). Thanks for the assitance.

Here's my WebService...

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;
using System.IO;

namespace MultiSelectFileUploader.Web
{
    /// <summary>
    /// Summary description for FileService
    /// </summary>
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.ComponentModel.ToolboxItem(false)]
    // To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line. 
    // [System.Web.Script.Services.ScriptService]
    public class FileService : System.Web.Services.WebService
    {

        [WebMethod]
        public List<string> GetFiles()
        {
            List<string> l = new List<string>();

            foreach (FileInfo fi in (new DirectoryInfo(Server.MapPath("~/Temp/")).GetFiles()))
                l.Add(fi.Name);

            return l;
        }

        [WebMethod]
        public void UploadFiles(string filename, Stream file)
        {
            string filepath = AppDomain.CurrentDomain.BaseDirectory + @"Temp\";

            if (!Directory.Exists(filepath)) { Directory.CreateDirectory(filepath); }

            WriteFile(file, File.Create(Context.Server.MapPath("~/Temp/" + filename)));
        }

        private void WriteFile(Stream stream, FileStream fs)
        {
            int bytesRead;
            byte[] buffer = new byte[4096];

            while ((bytesRead = stream.Read(buffer, 0, buffer.Length)) != 0)
                fs.Write(buffer, 0, bytesRead);
        }
    }
}

Answer 1

Streaming is not supported in ASMX services. You have to use WCF.

Answer 2

It sounds like you have two classes called Stream, in two namespaces, in separate assemblies (DLLs).

If you need to use both classes called Stream in the same C# class, you would be best to fully qualify the class names where you use them (there are other ways, but imho this is the cleanest).

You're getting isn't a ServiceReference.Stream presumably because you changed the declaration somewhere to System.IO.Stream where in fact a MultiSelectFileUploader.ServiceReference.Stream is expected.

Answer 3

Since you have two different versions of Stream (one in System.IO and one in MultiSelectFileUploader.ServiceReference), you'll need to have a way of differentiating between them.

In addition, the error you're getting now is because you are not using the MultiSelectFileUploader.ServiceReference namespace anywhere, so your code doesn't know of a MultiSelectFileUploader.ServiceReference.Stream class.

I would recommend using aliases for System.IO and MultiSelectFileUploader.ServiceReference, like so:

using IO = System.IO;
using Uploader = MultiSelectFileUploader.ServiceReference;

and then using the aliases to specify which stream you are using, like so (assuming this is where you're using the MultiSelectFileUploader.ServiceReference.Stream class):

private void WriteFile(Uploader.Stream stream, FileStream fs)
{
    ...
}

The reason it didn't happen before was that GetFiles had no explicit reference to a Stream class.