WF4 Custom activities for message mediation

//*****************************************************************************
//    Description.....WF4 Message Mediation Library
//                                
//    Author..........Roman Kiss, rkiss@pathcom.com
//    Copyright © 2009 ATZ Consulting Inc. (see included license.rtf file)         
//                        
//    Date Created:    07/07/09
//
//    Date        Modified By     Description
//-----------------------------------------------------------------------------
//    07/07/09    Roman Kiss     Initial Revision
//
//*****************************************************************************
//
#region Namespaces
using System;
using System.Activities;
using System.Activities.Presentation.PropertyEditing;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.ServiceModel.Channels;
using System.Text;
using System.Windows.Markup;
using System.Xml;
using System.Xml.Linq;
using System.Xml.Xsl;

#endregion

namespace RKiss.MessageMediationActivityLibrary
{
    [ContentProperty("Parameters")]
    public sealed class CreateMessage : CodeActivity
    {
        private IDictionary<string, InArgument> parameters;
   
        #region Properties    
        [Category("Input")]
        [RequiredArgument]
        [EditorBrowsable]
        [EditorReuse(false)]
        //[Editor(typeof(XmlValueExpressionEditor), typeof(PropertyValueEditor))]
        public InArgument<XElement> Mediator { get; set; }

        [Category("Input")]
        [Browsable(true)]
        [Editor(typeof(RKiss.MessageMediationActivityLibrary.Editors.DynamicArgumentDictionaryEditor), typeof(PropertyValueEditor))]
        public IDictionary<string, InArgument> Parameters
        {
            get
            {
                if (this.parameters == null)
                {
                    this.parameters = new Dictionary<string, InArgument>();
                }
                return this.parameters;
            }
        }

        [Category("Input")]
        [EditorBrowsable(EditorBrowsableState.Advanced)]
        [DefaultValue(MessageVersionOption.Default)]
        public MessageVersionOption MessageVersion { get; set; }

        [Category("Output")]
        [RequiredArgument]
        public OutArgument<Message> Message { get; set; }

        [Browsable(false)]
        public string SourceUri { get; set; }
        #endregion


        protected override void Execute(CodeActivityContext context)
        {
            XslCompiledTransform xsltprocessor = new XslCompiledTransform(false);
            XsltArgumentList xsltArgList = new XsltArgumentList();

            #region Step 1: Add functions to the XsltArgumentList
            // this feature was not implemented
            #endregion

            #region Step 2: Add parameters to the XsltArgumentList
            if (this.Parameters != null && this.Parameters.Count > 0)
            {
                foreach (var param in this.Parameters)
                {               
                    if (string.IsNullOrEmpty(param.Key) || param.Value == null || param.Value.Expression == null) continue;
                    XName xname = XName.Get(param.Key);
                    xsltArgList.AddParam(xname.LocalName, xname.NamespaceName, Convert.ToString(param.Value.Get(context)));
                }
            }
            #endregion

            #region Step 3: Load metadata
            try
            {
                using (MemoryStream msMetadata = new MemoryStream(UTF8Encoding.UTF8.GetBytes(this.Mediator.Get(context).ToString())))
                {
                    XmlDictionaryReader rdMetadata = XmlDictionaryReader.CreateTextReader(msMetadata, XmlDictionaryReaderQuotas.Max);
                    xsltprocessor.Load(rdMetadata);
                }
            }
            catch (Exception ex)
            {
                throw new Exception(string.Format("XslCompiledTransform loading in the activity '{0}' failed, error={1}", this.DisplayName, ex.Message), ex);
            }
            #endregion

            #region Step 4: Transform empty Input and create MessageOutput

            try
            {
                using (MemoryStream msMessageOutput = new MemoryStream())
                using (XmlDictionaryWriter wrMessageOutput = XmlDictionaryWriter.CreateTextWriter(msMessageOutput, Encoding.UTF8, true))
                using (XmlDictionaryReader rdEmptyInput = XmlDictionaryReader.CreateTextReader(UTF8Encoding.UTF8.GetBytes("<Root/>"), XmlDictionaryReaderQuotas.Max))
                {
                    xsltprocessor.Transform(rdEmptyInput, xsltArgList, wrMessageOutput);
                   
                    msMessageOutput.Position = 0;
                    XmlDictionaryReader rdMessageOutput = XmlDictionaryReader.CreateTextReader(msMessageOutput.ToArray(), XmlDictionaryReaderQuotas.Max);
                    Message outputMessage = System.ServiceModel.Channels.Message.CreateMessage(rdMessageOutput, int.MaxValue, LibHelper.MessageVersion(this.MessageVersion));
                    this.Message.Set(context, outputMessage);                
                }
            }
            catch (Exception ex)
            {
                throw new Exception(string.Format("Xslt transformation or creating an output message version '{0}' in the activity '{1}' failed", this.MessageVersion, this.DisplayName), ex);
            }
            #endregion
        }      
    }
}