Question

I have a WCF service that send/receives data and work perfectly with all my utf-8 clients.

But, one of my customers is trying to access this service with a Oracle 9i/Linux call, that works with ISO-8859-1 encoding, and we are having problems with special characters.

I can’t use this suggested solution, since the client is Linux and cannot install DLLs.

Based on this scenario, can anyone please suggest me another solution (wich can involve changes in the client, in the service or in both)?

Thanks in advance.

Answer 1

That solution (using the CustomTextEncoder) should work in your scenario as well? The linux client can continue sending the data as it pleases (i.e., in iso-8859-1), and the encoder, used on the server only, would be able to read it. The encoder then can decide how to encode the response back to the client (UTF-8 or iso-8859-1 again).

If you want the response to be in iso-8859-1 as well you may also need something like a message inspector to update the content-type header with the appropriate charset.

Update: example with the custom encoder using ISO-8859-1

public class StackOverflow_7033442
{
    [ServiceContract]
    public interface ITest
    {
        [OperationContract]
        string Echo(string text);
    }

    public class Service : ITest
    {
        public string Echo(string text)
        {
            return text;
        }
    }

    public static void Test()
    {
        string baseAddress = "http://" + Environment.MachineName + ":8000/Service";
        ServiceHost host = new ServiceHost(typeof(Service), new Uri(baseAddress));
        CustomBinding binding = new CustomBinding(
            new CustomTextMessageBindingElement("iso-8859-1", "text/xml", MessageVersion.Soap11),
            new HttpTransportBindingElement());
        host.AddServiceEndpoint(typeof(ITest), binding, "");
        host.Open();
        Console.WriteLine("Host opened");

        string request = @"<?xml version=""1.0"" encoding=""iso-8859-1""?>
<s:Envelope xmlns:s=""http://schemas.xmlsoap.org/soap/envelope/"">
  <s:Body>
    <Echo xmlns=""http://tempuri.org/"">
      <text>Hello áéíóú</text>
    </Echo>
  </s:Body>
</s:Envelope>";
        HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(baseAddress);
        req.Method = "POST";
        req.ContentType = "text/xml; charset=iso-8859-1";
        req.Headers["SOAPAction"] = "http://tempuri.org/ITest/Echo";
        Stream reqStream = req.GetRequestStream();
        Encoding encoding = Encoding.GetEncoding("iso-8859-1");
        byte[] reqBytes = encoding.GetBytes(request);
        reqStream.Write(reqBytes, 0, reqBytes.Length);
        reqStream.Close();

        HttpWebResponse resp = (HttpWebResponse)req.GetResponse();
        Console.WriteLine("HTTP/{0} {1} {2}", resp.ProtocolVersion, (int)resp.StatusCode, resp.StatusDescription);
        foreach (var header in resp.Headers.AllKeys)
        {
            Console.WriteLine("{0}: {1}", header, resp.Headers[header]);
        }

        if (resp.ContentLength > 0)
        {
            Console.WriteLine(new StreamReader(resp.GetResponseStream(), encoding).ReadToEnd());
        }

        Console.Write("Press ENTER to close the host");
        Console.ReadLine();
        host.Close();
    }

    #region Custom Text Message Encoder sample, verbatim
    public class CustomTextMessageEncoder : MessageEncoder
    {
        private CustomTextMessageEncoderFactory factory;
        private XmlWriterSettings writerSettings;
        private string contentType;

        public CustomTextMessageEncoder(CustomTextMessageEncoderFactory factory)
        {
            this.factory = factory;

            this.writerSettings = new XmlWriterSettings();
            this.writerSettings.Encoding = Encoding.GetEncoding(factory.CharSet);
            this.contentType = string.Format("{0}; charset={1}",
                this.factory.MediaType, this.writerSettings.Encoding.HeaderName);
        }

        public override string ContentType
        {
            get
            {
                return this.contentType;
            }
        }

        public override string MediaType
        {
            get
            {
                return factory.MediaType;
            }
        }

        public override MessageVersion MessageVersion
        {
            get
            {
                return this.factory.MessageVersion;
            }
        }

        public override Message ReadMessage(ArraySegment<byte> buffer, BufferManager bufferManager, string contentType)
        {
            byte[] msgContents = new byte[buffer.Count];
            Array.Copy(buffer.Array, buffer.Offset, msgContents, 0, msgContents.Length);
            bufferManager.ReturnBuffer(buffer.Array);

            MemoryStream stream = new MemoryStream(msgContents);
            return ReadMessage(stream, int.MaxValue);
        }

        public override Message ReadMessage(Stream stream, int maxSizeOfHeaders, string contentType)
        {
            XmlReader reader = XmlReader.Create(stream);
            return Message.CreateMessage(reader, maxSizeOfHeaders, this.MessageVersion);
        }

        public override ArraySegment<byte> WriteMessage(Message message, int maxMessageSize, BufferManager bufferManager, int messageOffset)
        {
            MemoryStream stream = new MemoryStream();
            XmlWriter writer = XmlWriter.Create(stream, this.writerSettings);
            message.WriteMessage(writer);
            writer.Close();

            byte[] messageBytes = stream.GetBuffer();
            int messageLength = (int)stream.Position;
            stream.Close();

            int totalLength = messageLength + messageOffset;
            byte[] totalBytes = bufferManager.TakeBuffer(totalLength);
            Array.Copy(messageBytes, 0, totalBytes, messageOffset, messageLength);

            ArraySegment<byte> byteArray = new ArraySegment<byte>(totalBytes, messageOffset, messageLength);
            return byteArray;
        }

        public override void WriteMessage(Message message, Stream stream)
        {
            XmlWriter writer = XmlWriter.Create(stream, this.writerSettings);
            message.WriteMessage(writer);
            writer.Close();
        }
    }
    public class CustomTextMessageEncoderFactory : MessageEncoderFactory
    {
        private MessageEncoder encoder;
        private MessageVersion version;
        private string mediaType;
        private string charSet;

        internal CustomTextMessageEncoderFactory(string mediaType, string charSet,
            MessageVersion version)
        {
            this.version = version;
            this.mediaType = mediaType;
            this.charSet = charSet;
            this.encoder = new CustomTextMessageEncoder(this);
        }

        public override MessageEncoder Encoder
        {
            get
            {
                return this.encoder;
            }
        }

        public override MessageVersion MessageVersion
        {
            get
            {
                return this.version;
            }
        }

        internal string MediaType
        {
            get
            {
                return this.mediaType;
            }
        }

        internal string CharSet
        {
            get
            {
                return this.charSet;
            }
        }
    }
    public class CustomTextMessageBindingElement : MessageEncodingBindingElement, IWsdlExportExtension
    {
        private MessageVersion msgVersion;
        private string mediaType;
        private string encoding;
        private XmlDictionaryReaderQuotas readerQuotas;

        CustomTextMessageBindingElement(CustomTextMessageBindingElement binding)
            : this(binding.Encoding, binding.MediaType, binding.MessageVersion)
        {
            this.readerQuotas = new XmlDictionaryReaderQuotas();
            binding.ReaderQuotas.CopyTo(this.readerQuotas);
        }

        public CustomTextMessageBindingElement(string encoding, string mediaType,
            MessageVersion msgVersion)
        {
            if (encoding == null)
                throw new ArgumentNullException("encoding");

            if (mediaType == null)
                throw new ArgumentNullException("mediaType");

            if (msgVersion == null)
                throw new ArgumentNullException("msgVersion");

            this.msgVersion = msgVersion;
            this.mediaType = mediaType;
            this.encoding = encoding;
            this.readerQuotas = new XmlDictionaryReaderQuotas();
        }

        public CustomTextMessageBindingElement(string encoding, string mediaType)
            : this(encoding, mediaType, MessageVersion.Soap11WSAddressing10)
        {
        }

        public CustomTextMessageBindingElement(string encoding)
            : this(encoding, "text/xml")
        {

        }

        public CustomTextMessageBindingElement()
            : this("UTF-8")
        {
        }

        public override MessageVersion MessageVersion
        {
            get
            {
                return this.msgVersion;
            }

            set
            {
                if (value == null)
                    throw new ArgumentNullException("value");
                this.msgVersion = value;
            }
        }


        public string MediaType
        {
            get
            {
                return this.mediaType;
            }

            set
            {
                if (value == null)
                    throw new ArgumentNullException("value");
                this.mediaType = value;
            }
        }

        public string Encoding
        {
            get
            {
                return this.encoding;
            }

            set
            {
                if (value == null)
                    throw new ArgumentNullException("value");
                this.encoding = value;
            }
        }

        // This encoder does not enforces any quotas for the unsecure messages. The 
        // quotas are enforced for the secure portions of messages when this encoder
        // is used in a binding that is configured with security. 
        public XmlDictionaryReaderQuotas ReaderQuotas
        {
            get
            {
                return this.readerQuotas;
            }
        }

        #region IMessageEncodingBindingElement Members

        public override MessageEncoderFactory CreateMessageEncoderFactory()
        {
            return new CustomTextMessageEncoderFactory(this.MediaType,
                this.Encoding, this.MessageVersion);
        }

        #endregion


        public override BindingElement Clone()
        {
            return new CustomTextMessageBindingElement(this);
        }

        public override IChannelFactory<TChannel> BuildChannelFactory<TChannel>(BindingContext context)
        {
            if (context == null)
                throw new ArgumentNullException("context");

            context.BindingParameters.Add(this);
            return context.BuildInnerChannelFactory<TChannel>();
        }

        public override bool CanBuildChannelFactory<TChannel>(BindingContext context)
        {
            if (context == null)
                throw new ArgumentNullException("context");

            return context.CanBuildInnerChannelFactory<TChannel>();
        }

        public override IChannelListener<TChannel> BuildChannelListener<TChannel>(BindingContext context)
        {
            if (context == null)
                throw new ArgumentNullException("context");

            context.BindingParameters.Add(this);
            return context.BuildInnerChannelListener<TChannel>();
        }

        public override bool CanBuildChannelListener<TChannel>(BindingContext context)
        {
            if (context == null)
                throw new ArgumentNullException("context");

            context.BindingParameters.Add(this);
            return context.CanBuildInnerChannelListener<TChannel>();
        }

        public override T GetProperty<T>(BindingContext context)
        {
            if (typeof(T) == typeof(XmlDictionaryReaderQuotas))
            {
                return (T)(object)this.readerQuotas;
            }
            else
            {
                return base.GetProperty<T>(context);
            }
        }

        #region IWsdlExportExtension Members

        void IWsdlExportExtension.ExportContract(WsdlExporter exporter, WsdlContractConversionContext context)
        {
        }

        void IWsdlExportExtension.ExportEndpoint(WsdlExporter exporter, WsdlEndpointConversionContext context)
        {
            // The MessageEncodingBindingElement is responsible for ensuring that the WSDL has the correct
            // SOAP version. We can delegate to the WCF implementation of TextMessageEncodingBindingElement for this.
            TextMessageEncodingBindingElement mebe = new TextMessageEncodingBindingElement();
            mebe.MessageVersion = this.msgVersion;
            ((IWsdlExportExtension)mebe).ExportEndpoint(exporter, context);
        }

        #endregion
    }
    #endregion
}