WCF Routing with custom filter: No matching MessageFilter was found for the given message

Question

Im writing a routing service for some WCF services. I want to use a custom message filter that filters out my message.

Here is my custom message filter:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.ServiceModel.Dispatcher;
using System.IO;
using System.Xml;

namespace AMA_ISE.Router.MessageFilter
{
    /// <summary>
    ///     This message filter implements the custom filtering for the routing services to re-route the incoming messages
    ///     correctly.
    /// </summary>
    public class CustomMessageFilter : System.ServiceModel.Dispatcher.MessageFilter
    {
        /// <summary>
        ///     The sales channel for which the filter is configured.
        /// </summary>
        private string _salesChannel;

        /// <summary>
        ///     The service, for which the filter is configured.
        /// </summary>
        private string _service;

        /// <summary>
        /// Initializes a new instance of the <see cref="CustomMessageFilter"/> class.
        /// </summary>
        /// <param name="messageData">The message data.</param>
        public CustomMessageFilter(string messageData)
        {
            var splitted = messageData.Split("|".ToCharArray());
            _salesChannel = splitted[0];
            _service = splitted[1];
        }

        /// <summary>
        /// When overridden in a derived class, tests whether a message satisfies the filter criteria. The body cannot be examined.
        /// </summary>
        /// <param name="message">The <see cref="T:System.ServiceModel.Channels.Message"/> object to test.</param>
        /// <returns>
        /// true if the <see cref="T:System.ServiceModel.Channels.Message"/> object satisfies the filter criteria; otherwise, false.
        /// </returns>
        public override bool Match(System.ServiceModel.Channels.Message message)
        {
            return true;
        }

        /// <summary>
        /// When overridden in a derived class, tests whether a buffered message satisfies the criteria of a filter.
        /// </summary>
        /// <param name="buffer">The <see cref="T:System.ServiceModel.Channels.MessageBuffer"/> object to test.</param>
        /// <returns>
        /// true if the <see cref="T:System.ServiceModel.Channels.MessageBuffer"/> object satisfies the filter criteria; otherwise, false.
        /// </returns>
        public override bool Match(System.ServiceModel.Channels.MessageBuffer buffer)
        {
            using (var memStream = new MemoryStream())
            {
                var msgText = GetMessageEnvelope(buffer);
                // check sales channel
                if (GetValueByTagName(msgText, "SalesChannel") != _salesChannel)
                    return false;
                // check the requested service
                var toValue = GetValueByTagName(msgText, "To");
                File.AppendAllText("C:\\temp\\filter.txt", toValue + " - " + _service + " - " + toValue.Trim().EndsWith(_service) + "\r\n");
                return toValue.Trim().EndsWith(_service);
            }
        }

        /// <summary>
        /// Gets the message envelope.
        /// </summary>
        /// <param name="buffer">The buffer.</param>
        /// <returns></returns>
        private static string GetMessageEnvelope(System.ServiceModel.Channels.MessageBuffer buffer)
        {
            using (MemoryStream memStream = new MemoryStream())
            {
                var msg = buffer.CreateMessage();
                XmlDictionaryWriter xmlDictWriter =
                    XmlDictionaryWriter.CreateTextWriter(memStream);
                msg.WriteMessage(xmlDictWriter);
                xmlDictWriter.Flush();
                memStream.Seek(0, SeekOrigin.Begin);
                var reader = new StreamReader(memStream);
                var text = reader.ReadToEnd();
                return text;
            }
        }

        /// <summary>
        /// Gets the name of the value by tag.
        /// </summary>
        /// <param name="text">The text.</param>
        /// <param name="tagName">Name of the tag which content we are searching for.</param>
        /// <returns></returns>
        private static string GetValueByTagName(string text, string tagName)
        {
            var txt = text.Substring(text.IndexOf("<" + tagName+" ") + 1);
            txt = txt.Substring(txt.IndexOf(">") + 1);
            return txt.Substring(0, txt.IndexOf("<"));
        }
    }
}

As you can see, Im writing some information in a log file located in c:\temp. I expect to match the current filter when Match() returns true; that is not happening. When using this filter, I have the following text file:

http://localhost/AMA-ISE.Router/BookingService.svc - RetrieveService.svc - False
http://localhost/AMA-ISE.Router/BookingService.svc - CancelService.svc - False
http://localhost/AMA-ISE.Router/BookingService.svc - BookingService.svc - True
http://localhost/AMA-ISE.Router/BookingService.svc - AvailService.svc - False
http://localhost/AMA-ISE.Router/BookingService.svc - RebookingService.svc - False

That Looks nice, the BookingService.svc does fits and Match() will give true back. But it doesnt work. When I now use the routing service, I get the following error:

Unhandled Exception: System.AggregateException: One or more errors occurred. ---> System.ServiceModel.FaultException`1[System.ServiceModel.ExceptionDetail]: No matching MessageFilter was found for the given Message.

Whats wrong? Have I misunderstood something with the message filters? Please help me!

Michael Baarz

Answer 1

not all XML are formed in the same manner. Sometimes tags containing namespaces directly and sometimes the namespace is prefixed and used. That was why my method has not worked. Here is the working code for a custom filter manager (maybe someone is interested in):

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.ServiceModel.Dispatcher;
using System.IO;
using System.Xml;
using System.Xml.Linq;

namespace AMA_ISE.Router.MessageFilter
{
    /// <summary>
    ///     This message filter implements the custom filtering for the routing services to re-route the incoming messages
    ///     correctly.
    /// </summary>
    public class CustomMessageFilter : System.ServiceModel.Dispatcher.MessageFilter
    {
        /// <summary>
        ///     The sales channel for which the filter is configured.
        /// </summary>
        private string _salesChannel;

        /// <summary>
        ///     The service, for which the filter is configured.
        /// </summary>
        private string _service;

        /// <summary>
        /// Initializes a new instance of the <see cref="CustomMessageFilter"/> class.
        /// </summary>
        /// <param name="messageData">The message data.</param>
        public CustomMessageFilter(string messageData)
        {
            var splitted = messageData.Split("|".ToCharArray());
            _salesChannel = splitted[0];
            _service = splitted[1];
        }

        /// <summary>
        /// When overridden in a derived class, tests whether a message satisfies the filter criteria. The body cannot be examined.
        /// </summary>
        /// <param name="message">The <see cref="T:System.ServiceModel.Channels.Message"/> object to test.</param>
        /// <returns>
        /// true if the <see cref="T:System.ServiceModel.Channels.Message"/> object satisfies the filter criteria; otherwise, false.
        /// </returns>
        public override bool Match(System.ServiceModel.Channels.Message message)
        {
            return true;
        }

        static int counter = 0;

        /// <summary>
        /// When overridden in a derived class, tests whether a buffered message satisfies the criteria of a filter.
        /// </summary>
        /// <param name="buffer">The <see cref="T:System.ServiceModel.Channels.MessageBuffer"/> object to test.</param>
        /// <returns>
        /// true if the <see cref="T:System.ServiceModel.Channels.MessageBuffer"/> object satisfies the filter criteria; otherwise, false.
        /// </returns>
        public override bool Match(System.ServiceModel.Channels.MessageBuffer buffer)
        {
            using (var memStream = new MemoryStream())
            {
                var document = GetMessageEnvelope(buffer);
                var salesChannel = GetValueOfNamedNode(document.Root, "SalesChannel");
                var toService = GetValueOfNamedNode(document.Root, "To");
                return salesChannel == _salesChannel && toService.EndsWith(_service);
            }
        }

        private static string GetValueOfNamedNode(XElement element, string findName)
        {
            if (element.Name.LocalName == findName)
                return element.Value;
            foreach (var ele in element.Elements())
            {
                var foundValue = GetValueOfNamedNode(ele, findName);
                if (foundValue != null)
                    return foundValue;
            }
            return null;
        }

        /// <summary>
        /// Gets the message envelope.
        /// </summary>
        /// <param name="buffer">The buffer.</param>
        /// <returns></returns>
        private static XDocument GetMessageEnvelope(System.ServiceModel.Channels.MessageBuffer buffer)
        {
            using (MemoryStream memStream = new MemoryStream())
            {
                var msg = buffer.CreateMessage();
                XmlDictionaryWriter xmlDictWriter =
                    XmlDictionaryWriter.CreateTextWriter(memStream);
                msg.WriteMessage(xmlDictWriter);
                xmlDictWriter.Flush();
                memStream.Seek(0, SeekOrigin.Begin);
                var doc = XDocument.Load(memStream);
                return doc;
            }
        }
    }
}