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ServiceObject的TransactionMode有三个取值：不需要交易，需要交易，需要新的交易。ServiceObject的方法被调用时会建立一个TTransactionContext，并随着子元件，子子元件的调用传递，子元件，子子元件只是对这个Transaction投票，是需要Commit还是Rollback，根元件根据最后结果来决定最后该Commit还是Rollback。

TCustomServiceObject=class(TObject)<br /> private<br /> FServiceName:string;<br /> FDataObjectCreated:Boolean;<br /> //自己使用,每个ServiceObject按需要拥有IDBService<br /> FDataObject:TCustomServiceObject;<br /> FContext:TTransactionContext;<br /> FContextCreated:Boolean;<br /> function GetContext: TTransactionContext;<br /> procedure LeaveActivity;<br /> private<br /> FStatus:TServiceObjectStatus;<br /> FIsLocked:Boolean;<br /> FThreadHandle:THandle;<br /> FTimeout:integer;<br /> procedure SetStatus(const Value: TServiceObjectStatus);<br /> protected<br /> procedure Activate;virtual;<br /> procedure Deactivate;virtual;<br /> function IsCanBePooled:Boolean;virtual;<br /> function GetTransactionMode:TServiceTransactionMode;virtual;<br /> function GetDataObject: TCustomServiceObject;virtual;<br /> function GetDataService: IDBService;virtual;<br /> function GetIsInTransaction: Boolean;virtual;<br /> function CallMethod(const AMethodName: string; const AParams: OLEVariant;<br /> const AAsyncCallContent:TASyncCallContent;<br /> const AClientContent:TClientContent):OLEVariant;virtual;<br /> public<br /> constructor Create(AServiceName:string);virtual;<br /> destructor Destroy;override;<br /> //调用自己的某个函数<br /> function Call(const AMethodName: string; const AParams: OLEVariant;<br /> const AASyncCallContent:TASyncCallContent=nil;<br /> const AClientContent:TClientContent=nil): OLEVariant;virtual;<br /> //调用其它的元件<br /> function CallOther(const AServiceName,AMethodName:string;<br /> const AParams:OLEVariant;<br /> const AASyncCallContent:TASyncCallContent=nil;<br /> const AClientContent:TClientContent=nil):OLEVariant;virtual;<br /> //在activity线程中获得一个服务元件<br /> function BeginUseServiceObject(const AServiceName:string;const AServiceObjectStub:integer=-1):TCustomServiceObject;virtual;<br /> //结束activity中的物件使用<br /> procedure EndUseSerivceObject(AService:TCustomServiceObject);virtual;<br /> //投票确认activity的交易<br /> procedure VoteCommitTransaction;virtual;<br /> //投票拒绝activity的交易<br /> procedure VoteRollbackTransaction;virtual;<br /> //某个函数在调用时是否需要记录日志<br /> function IsMethodNeedLog(AMethodName:string):Boolean;virtual;</p> <p> property DataObject:TCustomServiceObject read GetDataObject;<br /> property DataService:IDBService read GetDataService;<br /> property Context:TTransactionContext read GetContext;<br /> property IsInTransaction:Boolean read GetIsInTransaction;<br /> property Status:TServiceObjectStatus read FStatus write SetStatus;<br /> end;</p> <p>function TCustomServiceObject.Call(const AMethodName: string;<br /> const AParams: OLEVariant;<br /> const AASyncCallContent:TASyncCallContent=nil;<br /> const AClientContent:TClientContent=nil): OLEVariant;<br /> const<br /> UseDTCTransaction=false;<br /> var<br /> //单个Connection执行“BEGIN DISTRIBUTED TRANSACTION”并不能将多个Connection纳入分布式事务<br /> IsRoot:Boolean;<br /> procedure CheckTransactionStart;<br /> begin<br /> case GetTransactionMode of<br /> tmNeedNew:<br /> begin<br /> //开始新的activity,这个交易沿新的activity传递<br /> if not FContextCreated then FContext:=nil;<br /> //不使用activity传下来的DataOject<br /> if not FDataObjectCreated then FDataObject:=nil;<br /> if not IsInTransaction then<br /> begin<br /> if UseDTCTransaction then<br /> begin<br /> Context.FTransaction:=DTCTransaction.DTCTransactionStart;<br /> DataService.JoinDistributeTransaction(Context.FTransaction);<br /> end<br /> else<br /> DataService.StartTransaction;<br /> end;<br /> end;<br /> tmNeed:<br /> begin<br /> if not IsInTransaction then<br /> begin //根元件启动交易<br /> IsRoot:=true;<br /> if UseDTCTransaction then<br /> begin<br /> Context.FTransaction:=DTCTransaction.DTCTransactionStart;<br /> DataService.JoinDistributeTransaction(Context.FTransaction);<br /> end<br /> else<br /> DataService.StartTransaction;<br /> end;<br /> end;<br /> end;<br /> end;</p> <p> procedure CheckTransactionCommit;<br /> begin<br /> if GetTransactionMode=tmNeedNew then<br /> begin<br /> if UseDTCTransaction then<br /> DTCTransaction.DTCTransactionCommit(Context.FTransaction)<br /> else<br /> DataService.CommitTransaction;<br /> end<br /> else if IsRoot then<br /> begin<br /> //根元件根据activity的投票结果，决定确认交易还是回滚交易<br /> if Context.FVoteTransactionRollbacked then<br /> begin<br /> if UseDTCTransaction then<br /> DTCTransaction.DTCTransactionRollback(Context.FTransaction)<br /> else<br /> DataService.RollbackTransaction;<br /> end<br /> else<br /> begin<br /> if UseDTCTransaction then<br /> DTCTransaction.DTCTransactionCommit(Context.FTransaction)<br /> else<br /> DataService.CommitTransaction;<br /> end;<br /> end;<br /> //投票确认activity交易<br /> VoteCommitTransaction;<br /> end;</p> <p> procedure CheckTransactionRollback;<br /> begin<br /> if GetTransactionMode=tmNeedNew then<br /> begin<br /> if IsInTransaction then<br /> if UseDTCTransaction then<br /> DTCTransaction.DTCTransactionCommit(Context.FTransaction)<br /> else<br /> DataService.RollbackTransaction;<br /> end<br /> else if IsRoot then<br /> begin<br /> if IsInTransaction then<br /> if UseDTCTransaction then<br /> DTCTransaction.DTCTransactionCommit(Context.FTransaction)<br /> else<br /> DataService.RollbackTransaction;<br /> end;<br /> //表决回滚activity的交易<br /> VoteRollbackTransaction;<br /> end;</p> <p> procedure CheckClearTransaction;<br /> begin<br /> if (GetTransactionMode=tmNeedNew) or IsRoot then<br /> begin<br /> if IsInTransaction then<br /> if UseDTCTransaction then<br /> DataService.UnJoinDistributeTransaction;<br /> ConText.FTransaction:=nil;<br /> ConText.FVoteTransactionRollbacked:=false;<br /> end;<br /> end;<br /> var<br /> ATime:TDateTime;<br /> begin<br /> Result:=null;<br /> ATime:=Now;<br /> if ServiceLog<>nil then<br /> ServiceLog.ServiceObjectBeforeMethodCalled(FServiceName,AMethodName);<br /> IsRoot:=false;<br /> try<br /> try<br /> CheckTransactionStart;<br /> Result:=CallMethod(AMethodName,AParams,AAsyncCallContent,AClientContent);<br /> CheckTransactionCommit;<br /> except<br /> CheckTransactionRollback;<br /> Raise;<br /> end;<br /> finally<br /> CheckClearTransaction;<br /> if ServiceLog<>nil then<br /> ServiceLog.ServiceObjectAfterMethodCalled(<br /> FServiceName,AMethodName,Round((Now-ATime)*86400000));<br /> end;<br /> end;

如果是多个数据库的分散式Transaction，需要调用MSDTC来控制。

unit DTCTransaction;</p> <p>interface<br /> uses<br /> SysUtils,OleDB,ComObj,Windows;</p> <p> function DTCTransactionStart:ITransaction;<br /> procedure DTCTransactionCommit(ATransaction:ITransaction);<br /> procedure DTCTransactionRollback(ATransaction:ITransaction);</p> <p>const<br /> TransactionISOLATIONLEVEL=ISOLATIONLEVEL_SERIALIZABLE;<br /> CLSID_MSDASQL :TGUID='{C8B522CB-5CF3-11CE-ADE5-00AA0044773D}'; //oledb for ODBC<br /> CLSID_SQLOLEDB :TGUID='{0C7FF16C-38E3-11D0-97AB-00C04FC2AD98}'; //oledb for sql server</p> <p>implementation</p> <p> function DtcGetTransactionManager(<br /> hostName:PChar;<br /> tmName:PChar;<br /> iid:Pointer;//pointer of TGUID;<br /> dwReserved1:DWord;<br /> wReserved2:Word;<br /> pvReserved:Pointer;<br /> out txnDispenser:ITransactionDispenser):HResult;cdecl;external 'xolehlp.dll';</p> <p>function DTCTransactionStart:ITransaction;<br /> var<br /> ID:ITransactionDispenser;<br /> begin<br /> Result:=nil;<br /> OLECheck(DtcGetTransactionManager(<br /> nil,<br /> nil,<br /> @IID_ITransactionDispenser,<br /> 0,0,<br /> nil,<br /> ID));</p> <p> OLECheck(ID.BeginTransaction(nil,<br /> TransactionISOLATIONLEVEL,<br /> ISOFLAG_RETAIN_DONTCARE,nil,Result));<br /> end;</p> <p>procedure DTCTransactionCommit(ATransaction:ITransaction);<br /> begin<br /> OLECheck(ATransaction.Commit(false,0,0));<br /> end;</p> <p>procedure DTCTransactionRollback(ATransaction:ITransaction);<br /> var<br /> B:BOID;<br /> begin<br /> OLECheck(ATransaction.Abort(@B,false,false));<br /> end;</p> <p>end.