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Remote callback not working in .NET Remoting
f#server.net

Hi,

I thought I'd use pattern-matching for a simple chat client/server application. I chose .NET Remoting in F# and have run into a couple of problems. No matter how many variations of the event system in F# that I try I cannot seem to get remote callbacks to function properly. I create a remote publisher and a local subscriber. The problem arises when I try to add the subscribers handler to the publishers event. The remote call generates this error :

'Soap Serializer does not support serializing Generic Types : Microsoft.FSharp.Control.IEventModule+ev@30[System.Int32].'

When I change the Soap Serializer to a BinaryServerFormatterSinkProvider I get the error:

System.ArgumentNullException: No message was deserialized prior to calling the DispatchChannelSink.
Parameter name: requestMsg
at System.Runtime.Remoting.Channels.DispatchChannelSink.ProcessMessage(IServerChannelSinkStack sinkStack, IMessage requestMsg, ITransportHeaders requestHeaders, Stream requestStream, IMessage& responseMsg, ITransportHeaders& responseHeaders, Stream& responseStream)
at System.Runtime.Remoting.Channels.BinaryServerFormatterSink.ProcessMessage(IServerChannelSinkStack sinkStack, IMessage requestMsg, ITransportHeaders requestHeaders, Stream requestStream, IMessage& responseMsg, ITransportHeaders& responseHeaders, Stream& responseStream)
at System.Runtime.Remoting.Channels.Http.HttpServerTransportSink.ServiceRequest(Object state)
at System.Runtime.Remoting.Channels.SocketHandler.ProcessRequestNow()

Though I'm no expert on .NET Remoting I coded an identical example in C# and it works fine.

I experimented with replacing IEvent.create_HandlerEvent() with delegate of obj * int -> unit, and other event incantations to no avail.

To run the code you need to compile 3 projects, Network.Core.dll, Network.Server.exe and Network.Client.exe, all placed in the ../bin folder.
You then run Network.Server.exe and Network.Client.exe in order.
You should then be able to type text into the client and it will appear at the server console window.
If you type 'sub' into the client it will attempt to subscribe to the remote callback. (If this works typing 'pub' will trigger the remote callback)

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// compile to network.core.dll
namespace Network.Core

#light

open System
open System.IO
open System.Net
open System.Threading
open System.Windows.Forms
open System.Runtime.Remoting
open System.Runtime.Remoting.Messaging

module Utils =
    let write str = Console.WriteLine(str: string)
    let print str = Console.Write(str: string)
    let read () = Console.ReadLine()
                
type MyPublisher() =
    inherit MarshalByRefObject()
    
    let mutable counter = 0
    let triggerNumberChanged, numberChanged = IEvent.create_HandlerEvent()
    member x.NumberChanged = numberChanged
    member x.TriggerNumberChanged () = counter <- counter + 1;  triggerNumberChanged(box x, counter)
    member x.WriteLine text = Console.WriteLine (text: string)

type MySubscriber() =    
    inherit MarshalByRefObject()
    
    [<OneWay>] 
    member x.OnNumberChanged (num: int) = Console.WriteLine("{0}", num)


// compile to network.server.exe  
module Network.Server

#light
#r "../bin/network.core.dll"

open System
open System.Collections
open System.Runtime.Remoting
open System.Runtime.Remoting.Channels
open System.Runtime.Remoting.Channels.Http
open System.Runtime.Remoting.Channels.Tcp
open System.Runtime.Serialization.Formatters

open Network.Core
open Network.Core.Utils

try 
    // Create channel and register remote type
    RemotingConfiguration.RegisterWellKnownServiceType(typeof<MyPublisher>, "MyPublisher", WellKnownObjectMode.Singleton)
    
    // Create remote callback channel
    let formatter = BinaryServerFormatterSinkProvider(TypeFilterLevel = TypeFilterLevel.Full)
    let props = Hashtable()
    props.[box "name"] <- box "FullHostHttpChannel"
    props.[box "port"] <- box "8080"
    ChannelServices.RegisterChannel(HttpChannel(props, null, formatter), false)
        
    print_endline "Type 'exit' to exit"
    while Console.ReadLine() <> "exit" do ()
with e -> printf "Error: %s\nPress any key to exit...\n" e.Message; Console.ReadKey() |> ignore


// compile to network.client.exe  
  
module Network.Client

#light
#r "../bin/network.core.dll"

open System
open System.Collections
open System.Runtime.Remoting
open System.Runtime.Remoting.Channels
open System.Runtime.Remoting.Channels.Http
open System.Runtime.Remoting.Channels.Tcp
open System.Runtime.Serialization.Formatters

open Network.Core
open Network.Core.Utils

// <A href="http://localhost:8080/MyPublisher">http://localhost:8080/MyPublisher</A> not rendered correctly by forum in the code block

RemotingConfiguration.RegisterWellKnownClientType(typeof<MyPublisher>, "<A href="http://localhost:8080/MyPublisher">http://localhost:8080/MyPublisher</A>")

// Create remote callback channel
let formatter = BinaryServerFormatterSinkProvider(TypeFilterLevel = TypeFilterLevel.Full)
let props = Hashtable()
props.[box "port"] <- box "0"
ChannelServices.RegisterChannel(TcpChannel(props, null, formatter), false)
    
write "Network Client"

let pub = MyPublisher()
let sub = MySubscriber()
let mutable text = ""

while text <> "exit" do
    text <- Console.ReadLine()
    match text with
    | "sub" ->  try pub.NumberChanged.Add( sub.OnNumberChanged )  with e -> write e.Message
    | "pub" -> pub.TriggerNumberChanged( )
    | _ -> pub.WriteLine  text

Any help much appreciated.

regards,

Daniel

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