给Orchestration Message添加二进制MessagePart

//Sourcecode from tomas_restrepo, a great BTS developer
using System;
using System.Collections.Generic;
using System.IO;
using System.Runtime.Serialization;
using System.Text;

using Microsoft.XLANGs.BaseTypes;
using Microsoft.XLANGs.RuntimeTypes;
using Microsoft.XLANGs.Core;

namespace Winterdom.BizTalk.Samples.BinaryHelper
{
   public class BinaryStreamFactory : RefCountedBase, IRefCountedStreamFactory
   {
      private Stream _stream;

      public BinaryStreamFactory(Stream stream)
      {
         if ( stream == null )
            throw new ArgumentNullException("stream");
         if ( stream.Position != 0 )
         {
            stream.Position = 0;
         }
         _stream = stream;
      }

      public Stream CreateStream()
      {
         return _stream;
      }

      public override void Dispose()
      {
         _stream.Dispose();
      }

   }
}

分析：IRefCountedStreamFactory接口继承于IStreamFactory。IStreamFactory接口包含唯一的方法public Stream CreateStream()。MessagePart的Stream必须通过IStreamFactory进行封装。

  //In Orchestration, invoke this method to add new MessagePart, using stream, with partName as MessagePart Name
  public static void AttachStream(XLANGMessage message, string partName, Stream stream)
   {
      if ( message == null )
         throw new ArgumentNullException("message");
      if ( partName == null )
         throw new ArgumentNullException("partName");
      if ( stream == null )
         throw new ArgumentNullException("stream");

      IStreamFactory factory = new BinaryStreamFactory(stream);
      message.AddPart(factory, partName);

      XLANGPart part = message[partName];
      part.SetPartProperty(typeof(MIME.FileName), partName);
   }

message参数代表原有的Orchestration Message。AttachStream方法的功能是：把stream包装为message消息的名为partName的一个MessagePart。XLANGMessage添加MessagePart有3个重载方法：
        public  void AddPart(XLANGPart part);
        public  void AddPart(object part, string partName);
        public  void AddPart(XLANGPart part, string partName);
   对于第2个重载方法，part参数必须实现IStreamFactory接口。如果采用第1个或者第3个重载方法，那么需要调用part.LoadFrom(object source),其中source需要实现IStreamFactory接口(包含了stream来源)。记住XLANGMessage和XLANGPart都是抽象类。

part.SetPartProperty(typeof(MIME.FileName), partName)  表示该MessagePart会被SMTP解析为附件。