////////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File:   ServiceProviderContract.sg
//

//
// Every leaf in the Directory communicates to a service by connecting through this contract 
//

namespace Microsoft.Singularity.Directory
{
    contract ServiceProviderContract
    {
        in  message Connect(ServiceContract.Exp:Start! exp);
        out message AckConnect();
        out message NackConnect(ServiceContract.Exp:Start exp);
        // return the unconnected endpoint if possible.
        
        state Start: Connect? ->  Ack; 
        
        state Ack: one 
        {
            AckConnect!  -> Start;
            NackConnect! -> Start;
        }
    }
 }