I ve uploaded a file to ADO.NET dataservices using POST although I m not sure whether it s the recommended approach. The way I went about it is:

On the dataservice I ve implemented a service operation called UploadFile (using the WebInvoke attribute so that it caters for POST calls):

[WebInvoke]
public void UploadFile()
{
   var request = HttpContext.Current.Request;

   for (int i = 0; i < request.Files.Count; i++)
   {
       var file = request.Files[i];
       var inputValues = new byte[file.ContentLength];

       using (var requestStream = file.InputStream)
       {
           requestStream.Read(inputValues, 0, file.ContentLength);
       }

       File.WriteAllBytes(@"c:	emp" + file.FileName, inputValues);
   }
}

Then on the client side I call the data service using:

var urlString = "http://localhost/TestDataServicePost/CustomDataService.svc/UploadFile";
var webClient = new WebClient();
webClient.UploadFile(urlString, "POST", @"C:	emp	est.txt");

This uses a WebClient to upload the file which places the file data in the HttpRequest.Files collection and sets the content type. If you would prefer to send the contents of the file yourself (eg from an Asp FileUpload control) rather than the webClient reading a file using a path to the file, you can use a WebRequest similar to the way that it s done in this post. Although instead of using

FileStream fileStream = new FileStream(uploadfile, 
                                FileMode.Open, FileAccess.Read);

you could use a byte array that you pass in.

I hope this helps.

I m not 100% sure how to do this directly to a file server per se, but ADO.Net Data Services definitely support something similar to a database. The code below is how a similar goal of putting a file into a database has been accomplished. Not sure how much that will help, but

var myDocumentRepositoryUri = new Uri("uri here");
var dataContext = new FileRepositoryEntities(myDocumentRepositoryUri);
var myFile = new FileItem();
myfile.Filename = "upload.dat";
myFile.Data = new byte[1000]; // or put whatever file data you want to here
dataContext.AddToFileItem(myFile);
dataContext.SaveChanges();

Note: this code is also using Entity Framework to create a FileItem (representation of a database table as an object) and to save that data.