MessageEncoder Class

Definition

Namespace:

System.ServiceModel.Channels

Assembly:

System.ServiceModel.Primitives.dll

Package:

System.ServiceModel.Primitives v8.0.0

Source:

MessageEncoder.cs

The encoder is the component that is used to write messages to a stream and to read messages from a stream.

public ref class MessageEncoder abstract

public abstract class MessageEncoder

type MessageEncoder = class

Public MustInherit Class MessageEncoder

Inheritance

Object

MessageEncoder

Examples

The following code shows an example of a class that is derived from MessageEncoder.

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 bool IsContentTypeSupported(string contentType)
    {
        if (base.IsContentTypeSupported(contentType))
        {
            return true;
        }
        if (contentType.Length == this.MediaType.Length)
        {
            return contentType.Equals(this.MediaType, StringComparison.OrdinalIgnoreCase);
        }
        else
        {
            if (contentType.StartsWith(this.MediaType, StringComparison.OrdinalIgnoreCase)
                && (contentType[this.MediaType.Length] == ';'))
            {
                return true;
            }
        }
        return false;
    }

    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();
    }

Remarks

MessageEncoder is a base class that provides implementations that support a Multipurpose Internet Mail Extensions (MIME) content type and message version, and defines the interface for the serialization and deserialization of messages according to that content type. Use it as a base class for writing your own custom encoder.

Use this class if you want to implement a custom message encoder. To implement your own custom message encoder, you must provide custom implementations of the following abstract base classes:

• MessageEncodingBindingElement

• MessageEncoderFactory

• MessageEncoder

Override the Encoder to return an instance of your custom MessageEncoder. Then wire up your custom MessageEncoderFactory to the binding element stack used to configure the service or client by overriding the CreateMessageEncoderFactory method to return an instance of this factory.

The task of converting between the in-memory representation of a message and an XML Information Set (Infoset) representation that can be written to a stream is encapsulated within the MessageEncoder class, which most commonly serves as a factory for XML readers and XML writers that support specific types of XML encodings.

The key methods on MessageEncoder are WriteMessage and ReadMessage. WriteMessage takes a Message object and writes it into a Stream object. ReadMessage takes a Stream object and a maximum header size and returns a Message object.

Constructors

MessageEncoder()

Initializes a new instance of the MessageEncoder class.

Properties

ContentType	When overridden in a derived class, gets the MIME content type used by the encoder.
MediaType	When overridden in a derived class, gets the media type value that is used by the encoder.
MessageVersion	When overridden in a derived class, gets the message version value that is used by the encoder.

Methods

Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetProperty<T>()	Returns a typed object requested, if present, from the appropriate layer in the channel stack.
GetType()	Gets the Type of the current instance. (Inherited from Object)
IsContentTypeSupported(String)	Returns a value that indicates whether a specified message-level content-type value is supported by the message encoder.
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ReadMessage(ArraySegment<Byte>, BufferManager)	When overridden in a derived class, reads a message from a specified buffer.
ReadMessage(ArraySegment<Byte>, BufferManager, String)	When overridden in a derived class, reads a message from a specified stream.
ReadMessage(Stream, Int32)	When overridden in a derived class, reads a message from a specified stream.
ReadMessage(Stream, Int32, String)	When overridden in a derived class, reads a message from a specified stream.
ReadMessageAsync(ArraySegment<Byte>, BufferManager, String)
ReadMessageAsync(Stream, Int32, String)
ToString()	Returns the content type that is used by the message encoder.
WriteMessage(Message, Int32, BufferManager)	Writes a message less than a specified size to a byte array buffer.
WriteMessage(Message, Int32, BufferManager, Int32)	When overridden in a derived class, writes a message of less than a specified size to a byte array buffer at the specified offset.
WriteMessage(Message, Stream)	When overridden in a derived class, writes a message to a specified stream.
WriteMessageAsync(Message, Int32, BufferManager, Int32)
WriteMessageAsync(Message, Stream)