Hi,

I have a problem with WCF and F#. I am not sure if this is just a problem with F# and casting, or there is some more fundamental mistake.

In my architecture, I have many executables installed in a LAN, each of which must be able to act as a client or as a server, depending on the user's configuration. In particular, the user will configure one executable to behave as server, and the others to behave as clients. The database is centralized and will only be kept on the server; the clients will read the data they need from the server via WCF.

So my application must have functions which behave differently depending on whether the executable is currently configured as a client or as a server. If the application is configured as client, these functions must read from (or write to) the remote database via WCF, whereas, if it is a server, they can directly update the local database. An example of such functions is:

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let getDataOfFormula (fk: formula_key) : formula_data =
    match gClient with
    | None ->
        // I am the server. Read directly from the internal database, which is a Dictionary<formula_key, formula_data>.
        _gDataOfFk.Item fk
    | Some (c: TabblesServClient) ->
        // I am the client. Read the required data from the remote database, on the server, via WCF.
        (c.getDataOfFk fk)  // <<<< ERROR. This will not compile. Cannot convert formula_key to Tabbles_logicformula_key.

The problem is I cannot write that function. The line marked with "ERROR" above will not compile. The reason is that the method getDataOfFk which I am calling, being generated by svcutil.exe, does not use the "real" types defined in F#, but uses their WCF "clones", which are structurally identical (I believe) but cannot apparently be converted to their F# counterparts. Casting from formula_key to Tabbles_declformulakey with the :?> does not work.

I am looking for suggestions how to approach this problem. Thanks for any help.

____

Additional informations:

here is how I defined the wcf contract:

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[< ServiceModel.ServiceContract(Namespace = "http://www.tabbles.net") >]
type ITabblesServ =      
		[< ServiceModel.OperationContract >]
		abstract getDataOfFk:  fk:formula_key -> formula_data

[< ServiceModel.ServiceBehavior(ConfigurationName="TabblesConfigName") >]   
type TabblesServ() = 
		let dpServ = dpNormal
		interface ITabblesServ with
				member x.getFks() = 
						inv2Loc dpServ (fun () ->
								gDataOfFk.Keys )

and here is how I defined one of the data types:

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[< DataContract() >]                        
[<KnownType("KnownTypes")>]
type formula_key = 
        | FkAtomic of atom_key | FkAnd of atom_key  list
        static member KnownTypes() = 
                typeof<formula_key>.GetNestedTypes(System.Reflection.BindingFlags.Public ||| System.Reflection.BindingFlags.NonPublic) 
                        |> Array.filter Microsoft.FSharp.Reflection.FSharpType.IsUnion