WCF works in mysterious ways
time to read 8 min | 1522 words

Here is the result of about two hours of trying to figure out what WCF is doing:

class Program
    {
        static private readonly Binding binding = new NetTcpBinding
        {
            OpenTimeout = TimeSpan.FromMilliseconds(500),
            CloseTimeout = TimeSpan.FromMilliseconds(250),
            ReaderQuotas =
                {
                    MaxArrayLength = Int32.MaxValue,
                    MaxBytesPerRead = Int32.MaxValue,
                    MaxNameTableCharCount = Int32.MaxValue,
                    MaxDepth = Int32.MaxValue,
                    MaxStringContentLength = Int32.MaxValue,
                },
            MaxReceivedMessageSize = Int32.MaxValue,
        };
        static void Main()
        {
            try
            {
                var uri = new Uri("net.tcp://" + Environment.MachineName + ":2200/master");
                var serviceHost = new ServiceHost(new DistributedHashTableMaster(new NodeEndpoint
                {
                    Async = uri.ToString(),
                    Sync = uri.ToString()
                }));
                serviceHost.AddServiceEndpoint(typeof(IDistributedHashTableMaster),
                                               binding,
                                               uri);

                serviceHost.Open();

                var channel =
                    new ChannelFactory<IDistributedHashTableMaster>(binding, new EndpointAddress(uri))
                        .CreateChannel();
                channel.Join();
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
            }

        }
    }

    [ServiceBehavior(
        InstanceContextMode = InstanceContextMode.Single,
        ConcurrencyMode = ConcurrencyMode.Single,
        MaxItemsInObjectGraph = Int32.MaxValue
        )]
    public class DistributedHashTableMaster : IDistributedHashTableMaster
    {
        private readonly Segment[] segments;

        public DistributedHashTableMaster(NodeEndpoint endpoint)
        {
            segments = Enumerable.Range(0, 8192).Select(i =>
                                                        new Segment
                                                        {
                                                            AssignedEndpoint = endpoint,
                                                            Index = i
                                                        }).ToArray();
        }

        public Segment[] Join()
        {
            return segments;
        }
    }

    [ServiceContract]
    public interface IDistributedHashTableMaster
    {
        [OperationContract]
        Segment[] Join();
    }

    public class NodeEndpoint
    {
        public string Sync { get; set; }
        public string Async { get; set; }
    }

    public class Segment
    {
        public Guid Version { get; set; }

        public int Index { get; set; }
        public NodeEndpoint AssignedEndpoint { get; set; }
        public NodeEndpoint InProcessOfMovingToEndpoint { get; set; }

        public int WcfHatesMeAndMakeMeSad { get; set; }
    }

The problem? On my machine, executing this results in:

Maximum number of items that can be serialized or deserialized in an object graph is '65536'. Change the object graph or increase the MaxItemsInObjectGraph quota.

The freaky part? Do you see the WcfHatesMeAndMakeMeSad property? If I comment that one out, the problem goes away. Since MaxItemsInObjectGraph is set to int.MaxValue, I don’t know what else to do, and frankly, I am getting mighty tired of WCF doing stuff in unpredictable ways.

Protocol Buffers & TcpClient, here I comes.

Tweet Share Share 34 comments
Tags: