WF4.0自定义持久化

    WF4提供了强大的持久化的功能，ms提供了SqlWorkflowInstanceStore 来进行SqlServer的持久化，我研究了一下，DB里面有10个数据表，24个存储过程。功能非常强大，但是也逻辑也比较复杂。这里我介绍自定义的持久化。持久化的存储器也SqlServer。

1、设计数据表，表结构非常简单，如下图所示：

  

2、自定义的SqlServerWorkflowInstanceStore继承了InstanceStore：

代码

  public   class  SqlServerWorkflowInstanceStore : InstanceStore
    {
       public   Guid ownerInstanceID;
        
         public  SqlServerWorkflowInstanceStore() :  this (Guid.NewGuid())
        {

        }

         public  SqlServerWorkflowInstanceStore(Guid id)
        {
            ownerInstanceID  =  id;
        }

         // Synchronous version of the Begin/EndTryCommand functions
         protected   override   bool  TryCommand(InstancePersistenceContext context, InstancePersistenceCommand command, TimeSpan timeout)
        {
             return  EndTryCommand(BeginTryCommand(context, command, timeout,  null ,  null ));
        }

         // The persistence engine will send a variety of commands to the configured InstanceStore,
         // such as CreateWorkflowOwnerCommand, SaveWorkflowCommand, and LoadWorkflowCommand.
         // This method is where we will handle those commands
         protected   override  IAsyncResult BeginTryCommand(InstancePersistenceContext context, InstancePersistenceCommand command, TimeSpan timeout, AsyncCallback callback,  object  state)
        {
            IDictionary < System.Xml.Linq.XName, InstanceValue >  data  =   null ;

             // The CreateWorkflowOwner command instructs the instance store to create a new instance owner bound to the instanace handle
             if  (command  is  CreateWorkflowOwnerCommand)
            {
                context.BindInstanceOwner(ownerInstanceID, Guid.NewGuid());
            }
             // The SaveWorkflow command instructs the instance store to modify the instance bound to the instance handle or an instance key
             else   if  (command  is  SaveWorkflowCommand)
            {
                SaveWorkflowCommand saveCommand  =  (SaveWorkflowCommand)command;
                data  =  saveCommand.InstanceData;
                Save(data);
            }
             else   if  (command  is  LoadWorkflowCommand)
            {

                 try
                {
                        InstancesTable obj  =  InstancesTableBiz.GetInstancesTable( this .ownerInstanceID);
                        System.Text.UTF8Encoding utf8  =   new  System.Text.UTF8Encoding();
                         byte [] bs  =  utf8.GetBytes(obj.InstanceXML);
                        System.IO.MemoryStream memoryStream  =   new  System.IO.MemoryStream(bs);
                        data  =  LoadInstanceDataFromFile(memoryStream);
                        context.LoadedInstance(InstanceState.Initialized, data,  null ,  null ,  null );
                }
                 catch  (Exception exception)
                {
                     throw   new  PersistenceException(exception.Message);
                }
            }

             return   new  CompletedAsyncResult < bool > ( true , callback, state);
        }

         protected   override   bool  EndTryCommand(IAsyncResult result)
        {
             return  CompletedAsyncResult < bool > .End(result);
        }

        IDictionary < System.Xml.Linq.XName, InstanceValue >  LoadInstanceDataFromFile(Stream inputStream)
        {
            IDictionary < System.Xml.Linq.XName, InstanceValue >  data  =   new  Dictionary < System.Xml.Linq.XName, InstanceValue > ();

            NetDataContractSerializer s  =   new  NetDataContractSerializer();

            XmlReader rdr  =  XmlReader.Create(inputStream);
            XmlDocument doc  =   new  XmlDocument();
            doc.Load(rdr);

            XmlNodeList instances  =  doc.GetElementsByTagName( " InstanceValue " );
             foreach  (XmlElement instanceElement  in  instances)
            {
                XmlElement keyElement  =  (XmlElement)instanceElement.SelectSingleNode( " descendant::key " );
                System.Xml.Linq.XName key  =  (System.Xml.Linq.XName)DeserializeObject(s, keyElement);

                XmlElement valueElement  =  (XmlElement)instanceElement.SelectSingleNode( " descendant::value " );
                 object  value  =  DeserializeObject(s, valueElement);
                InstanceValue instVal  =   new  InstanceValue(value);

                data.Add(key, instVal);
            }

             return  data;
        }

         object  DeserializeObject(NetDataContractSerializer serializer, XmlElement element)
        {
             object  deserializedObject  =   null ;

            MemoryStream stm  =   new  MemoryStream();
            XmlDictionaryWriter wtr  =  XmlDictionaryWriter.CreateTextWriter(stm);
            element.WriteContentTo(wtr);
            wtr.Flush();
            stm.Position  =   ;

            deserializedObject  =  serializer.Deserialize(stm);

             return  deserializedObject;
        }

         void  Save(IDictionary < System.Xml.Linq.XName, InstanceValue >  instanceData)
        {
            XmlDocument doc  =   new  XmlDocument();
            doc.LoadXml( " <InstanceValues/> " );
            
             foreach  (KeyValuePair < System.Xml.Linq.XName,InstanceValue >  valPair  in  instanceData)
            {
                XmlElement newInstance  =  doc.CreateElement( " InstanceValue " );

                XmlElement newKey  =  SerializeObject( " key " , valPair.Key, doc);
                newInstance.AppendChild(newKey);

                XmlElement newValue  =  SerializeObject( " value " , valPair.Value.Value, doc);
                newInstance.AppendChild(newValue);

                doc.DocumentElement.AppendChild(newInstance);
            }
             if  ( ! string .IsNullOrEmpty(InstancesTableBiz.GetInstancesTable( this .ownerInstanceID).InstanceXML))
            {
                InstancesTable obj  =  InstancesTableBiz.GetInstancesTable( this .ownerInstanceID);
                obj.InstanceXML  =  doc.InnerXml;
                InstancesTableBiz.UpdateInstancesTable(obj);
            }
             else
            {
                InstancesTable obj  =   new  InstancesTable();
                obj.id  =   this .ownerInstanceID;
                obj.InstanceXML  =  doc.InnerXml;
                InstancesTableBiz.AddInstancesTable(obj);
            }
   
       }

        XmlElement SerializeObject( string  elementName,  object  o, XmlDocument doc)
        {
            NetDataContractSerializer s  =   new  NetDataContractSerializer();
            XmlElement newElement  =  doc.CreateElement(elementName);
            MemoryStream stm  =   new  MemoryStream();
            s.Serialize(stm, o);
            stm.Position  =   ;
            StreamReader rdr  =   new  StreamReader(stm);
            newElement.InnerXml  =  rdr.ReadToEnd();
             return  newElement;
        }  
    }

3、设计书签类：

代码

     public   sealed   class  Read < TResult >  : NativeActivity < TResult >
    {
         public  Read()
            :  base ()
        {
        }

         public   string  BookmarkName {  get ;  set ; }

         //  Must return true for a NativeActivity that creates a bookmark
         protected   override   bool  CanInduceIdle
        { 
             get  {  return   true ; } 
        } 

         protected   override   void  Execute(NativeActivityContext context)
        {
            context.CreateBookmark( this .BookmarkName,  new  BookmarkCallback( this .Continue));
        }

         void  Continue(NativeActivityContext context, Bookmark bookmark,  object  obj)
        {
             this .Result.Set(context, (TResult)obj); 
        }
    }

 4、设计三个书签的流程：

5、自定义持久化的使用

代码

  SqlServerWorkflowInstanceStore  instanceStore  =   new   SqlServerWorkflowInstanceStore ();

            WorkflowApplication application  =   new  WorkflowApplication( new  Activity1());

            application.InstanceStore  =  instanceStore;

            application.PersistableIdle  =  (e)  =>
            {
                 return  PersistableIdleAction.Unload;
            };
            application.Completed  =  (workflowApplicationCompletedEventArgs)  =>
            {
                Console.WriteLine( " \nWorkflowApplication has Completed in the {0} state. " , workflowApplicationCompletedEventArgs.CompletionState);
            };

            application.Unloaded  =  (workflowApplicationEventArgs)  =>
            {
                Console.WriteLine( " WorkflowApplication has Unloaded\n " );
                instanceUnloaded.Set();
            };

            instanceStore.ownerInstanceID  =  application.Id;
        
             //  continue executing this instance
            application.Run();

            // string a= application.GetBookmarks()[0].BookmarkName;

            instanceUnloaded.WaitOne();

             return  application.Id; ;

6、Demo说明：

    在Start.aspx，启动一个流程

    在Default.aspx，进行A,B,C三个站的审核。

备注：运行环境是VS2010 BETA2。

代码：/Files/zhuqil/WorkflowConsoleApplication3.rar

 

原文链接： http://www.cnblogs.com/zhuqil/archive/2010/01/12/1644710.html