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我使用Remoting也有很长的一段时间了。一直以来，我心中最痛的就是 DataRow不能序列化！

这使我无法这样地写 DataRow GetEmployee(int empid) ， 而必须改为 DataTable GetEmployee(int empid) ;

自从发明了CBM后，这个也变成可能了。详细的代码如下：

namespace Test.TestDataRowMarshalerAttribute { using System; using System.Collections; using System.Data; using System.Runtime.Remoting; using System.Runtime.Remoting.Messaging; using R=System.Runtime.Remoting; using Lostinet.ContextBoundModel; using Lostinet.ContextBoundModel.Messaging; #region public class DataRowMashalerAttribute : Attribute,IMessageHandlerAttribute /// <summary> /// Marshal the DataRow /// </summary> [AttributeUsage(AttributeTargets.Interface|AttributeTargets.Class|AttributeTargets.Method)] public class DataRowMashalerAttribute : Attribute,IMessageHandlerAttribute { public string HandlerName { get { return "DataRowMashaler"; } } public IMessageHandler CreateMessageHandler(bool bserver) { if(bserver) return new ServerHandler(); return new ClientHandler(); } [Serializable] class DataContainer { DataSet ds; DataRowState state; private DataContainer(DataRow row) { state=row.RowState; DataTable table=row.Table.Clone(); ds=new DataSet(); ds.Tables.Add(table); table.Rows.Add(row.ItemArray); ds.AcceptChanges(); } public object PopupValue() { DataTable table=ds.Tables[0]; ds.Tables.Clear(); DataRow row=table.Rows[0]; switch(state) { case DataRowState.Detached: DataRow newrow=table.NewRow(); newrow.ItemArray=row.ItemArray; table.Rows.Remove(row); return newrow; case DataRowState.Added: table.Rows.Remove(row); table.Rows.Add(row); break; case DataRowState.Modified: row.ItemArray=row.ItemArray; break; case DataRowState.Deleted: row.Delete(); break; } return row; } static public DataContainer Marshal(object arg) { if(arg is DataRow) { return new DataContainer((DataRow)arg); } return null; } } [Serializable] class MarshalInfo : ILogicalThreadAffinative { public DataContainer[] Args; public DataContainer Ret; } class ClientHandler:IMessageHandlerWithPriority { public string HandlerName { get { return "DataRowMashaler"; } } public MessageHandlerPriority HandlerPriority { get { return MessageHandlerPriority.FinalImplementation; } } public IMethodReturnMessage ProcessMessage(IMethodCallMessage mcm, AspectObjectProxy proxy, MessageHandlerQueue queue) { object[] args=(object[])mcm.Args; MarshalInfo requestdata=new MarshalInfo(); for(int i=0;i<args.Length;i++) { DataContainer data=DataContainer.Marshal(args[i]); if(data!=null) { if(requestdata.Args==null) requestdata.Args=new DataContainer[args.Length]; requestdata.Args[i]=data; args[i]=null; } } try { if(requestdata.Args!=null) { MethodCallWrapper mcw=AspectServices.CreateMethodCallWrapper(mcm); mcw.SetArgs(args); mcm=mcw; } CallContext.SetData("RequestDataRowMashaler",requestdata); IMethodReturnMessage mrm=queue.InvokeNext(mcm,proxy); if(mrm.Exception!=null) return mrm; MarshalInfo responsedata=(MarshalInfo)CallContext.GetData("ResponseDataRowMashaler"); if(responsedata!=null&&(responsedata.Args!=null||responsedata.Ret!=null)) { args=mrm.Args; if(responsedata.Args!=null) { for(int i=0;i<args.Length;i++) { if(responsedata.Args[i]!=null) { args[i]=responsedata.Args[i].PopupValue(); } } } object retval=mrm.ReturnValue; if(responsedata.Ret!=null) retval=responsedata.Ret.PopupValue(); MethodReturnWrapper mrw=AspectServices.CreateMethodReturnWrappr(mrm); mrw.SetReturnValue(retval); mrw.SetArgs(args); mrm=mrw; } return mrm; } finally { CallContext.SetData("RequestDataRowMashaler",null); CallContext.SetData("ResponseDataRowMashaler",null); } } } class ServerHandler:IMessageHandlerWithPriority { public string HandlerName { get { return "DataRowMashaler"; } } public MessageHandlerPriority HandlerPriority { get { return MessageHandlerPriority.TraceMessageHandling; } } public IMethodReturnMessage ProcessMessage(IMethodCallMessage mcm, AspectObjectProxy proxy, MessageHandlerQueue queue) { MarshalInfo requestdata=(MarshalInfo)CallContext.GetData("RequestDataRowMashaler"); //direct invoke? if(requestdata==null) return queue.InvokeNext(mcm,proxy); CallContext.SetData("RequestDataRowMashaler",null); object[] args; if(requestdata.Args!=null) { args=mcm.Args; for(int i=0;i<args.Length;i++) { if(requestdata.Args[i]!=null) { args[i]=requestdata.Args[i].PopupValue(); } } MethodCallWrapper mcw=AspectServices.CreateMethodCallWrapper(mcm); mcw.SetArgs(args); mcm=mcw; } IMethodReturnMessage mrm=queue.InvokeNext(mcm,proxy); if(mrm.Exception!=null) return mrm; MarshalInfo responsedata=new MarshalInfo(); args=mrm.Args; object retval=mrm.ReturnValue; DataContainer data=DataContainer.Marshal(retval); if(data!=null) { responsedata.Ret=data; retval=null; } for(int i=0;i<args.Length;i++) { data=DataContainer.Marshal(args[0]); if(data!=null) { if(responsedata.Args==null) responsedata.Args=new DataContainer[args.Length]; responsedata.Args[i]=data; args[i]=null; } } if(responsedata.Args!=null||responsedata.Ret!=null) { MethodReturnWrapper mrw=AspectServices.CreateMethodReturnWrappr(mrm); mrw.SetReturnValue(retval); mrw.SetArgs(args); mrm=mrw; CallContext.SetData("ResponseDataRowMashaler",responsedata); } return mrm; } } } #endregion public class MyService : Lostinet.ContextBoundModel.AspectComponent { public MyService() { Console.WriteLine(" MyService() "); } [DataRowMashaler] public DataRow GetDataRow(bool indataset) { DataTable table=new DataTable("TableOfGetDataRow"); if(indataset) { DataSet ds=new DataSet("DataSet1"); ds.Tables.Add(table); ds.AcceptChanges(); } table.Columns.Add("name",typeof(string)); table.Rows.Add(new object[]{"hello world"});//this would not be marshaled! table.AcceptChanges(); DataRow row=table.NewRow(); row["name"]="I'am new row"; return row; } [DataRowMashaler] public void ReportDataRow(DataRow row) { Console.WriteLine("ReportDataRow : "); Console.WriteLine(row.Table.DataSet==null); Console.WriteLine(row.Table.TableName); Console.WriteLine(row.Table.Columns.Count); Console.WriteLine(row.Table.Rows.Count);// 0 ! Console.WriteLine(row.RowState); Console.WriteLine(row["name"]); } } public class RemoteDomainManager { static public void Start() { AppDomain domain=AppDomain.CreateDomain("RemoteDomain"); domain.DoCallBack(new CrossAppDomainDelegate(Setup)); } static public void Setup() { R.Channels.ChannelServices.RegisterChannel(new R.Channels.Tcp.TcpChannel(123)); R.RemotingConfiguration.RegisterWellKnownServiceType(typeof(MyService),"MyService.rem",R.WellKnownObjectMode.Singleton); } } public class EntryPoint { static public void Test() { RemoteDomainManager.Start(); R.RemotingConfiguration.RegisterWellKnownClientType(typeof(MyService),"tcp://localhost:123/MyService.rem"); MyService ms=new MyService(); Console.WriteLine("in dataset:"); Console.WriteLine(); Test(ms,true); Console.WriteLine("----------------"); Console.WriteLine("no dataset:"); Console.WriteLine(); Test(ms,false); } static void Test(MyService ms,bool indataset) { Console.WriteLine("GetDataRow :"); DataRow row=ms.GetDataRow(indataset); Console.WriteLine(row.Table.DataSet==null); Console.WriteLine(row.Table.TableName); Console.WriteLine(row.Table.Columns.Count); Console.WriteLine(row.Table.Rows.Count);// 0 ! Console.WriteLine(row.RowState); Console.WriteLine(row["name"]); ms.ReportDataRow(row); } } }

这个代码的原理是，在客户端与服务器端通信的时候，如果发现有DataRow需要传输，则先把，这个参数换成null,

然后把DataRow打包在某个DataSet中，通过CallContext来进行传输。传输完毕后，再进行解包，把参数换会DataRow。

如果你有兴趣测试这个代码，可以到 http://www.contextboundmodel.net/ 里下载 CBM 的源代码。