namespace GPTransmissionStatus
{
    [DataContract]
    public class Supplier : IDisposable
    {
        [DataMember]
        public virtual long Id { get; set; }

        [DataMember]
        public virtual String Name { get; set; }

        [DataMember]
        public virtual IList<GPPractice> GPPractices { get; set; }

        #region IDisposable Members

        public void Dispose()
        {

        }

        #endregion
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.Web;

namespace GPTransmissionStatus
{
    [DataContract]
    public class DocmanInstallation : IDisposable
    {
        [DataMember]
        public virtual long Id { get; set; }

        [DataMember]
        public virtual String Installation { get; set; }

        [DataMember]
        public virtual IList<GPPractice> GPPractices { get; set; }

        #region IDisposable Members

        public void Dispose()
        {

        }

        #endregion
    }
}

namespace GPTransmissionStatus
{
    [DataContract]
    [KnownType(typeof(DocmanInstallation))]
    [KnownType(typeof(Supplier))]
    public class GPPractice : IDisposable
    {

        #region IDisposable Members

        public void Dispose()
        {
            throw new NotImplementedException();
        }

        #endregion

        [DataMember]
        public virtual int Id { get; set; }

        [DataMember]
        public virtual String PracticeCode { get; set; }

        [DataMember]
        public virtual String PracticeName { get; set; }

        [DataMember]
        public virtual DateTime ConnectionProcessStarted { get; set; }

        [DataMember]
        public virtual DateTime EndpointSetup { get; set; }

        [DataMember]
        public virtual DateTime EDTWebServiceAccessible { get; set; }

        [DataMember]
        public virtual DateTime ProfileConfigured { get; set; }

        [DataMember]
        public virtual DateTime EndpointSetupRequested { get; set; }

        [DataMember]
        public virtual DateTime EndpointSetupComplete { get; set; }

        [DataMember]
        public virtual DateTime EndpointActivated { get; set; }

        [DataMember]
        public virtual DateTime TestDocumentSent { get; set; }

        [DataMember]
        public virtual DateTime FirstPatientDocumentSent { get; set; }

        [DataMember]
        public virtual DateTime FirstPatientDocumentDelivered { get; set; }


        // foreign keys
        [DataMember]
        public virtual Supplier Supplier { get; set; }

        [DataMember]
        public virtual DocmanInstallation DocmanInstallation { get; set; }


    }
}

context.Response.ContentType = "text/plain";

    try
    {
        list = gp_practices.Select();


        ms = new MemoryStream();
        serializer = new DataContractJsonSerializer(typeof(List<GPPractice>));

        serializer.WriteObject(ms,list);

        ms.Position = 0;
        sr = new StreamReader(ms);


        context.Response.Write(sr.ReadToEnd());
    }
    catch (Exception ex)
    {
        context.Response.Write(ex.Message);
    }
}