支援分散式交易

SQL Server Native Client OLE DB 提供者取用者可以使用 ITransactionJoin::JoinTransaction 方法來參與 Microsoft 分散式交易協調器 (MS DTC) 協調的分散式交易。

MS DTC 會公開 COM 物件，讓用戶端跨各種資料存放區的多個連接，起始並參與協調的交易。為起始交易，SQL Server Native Client OLE DB 提供者取用者會使用 MS DTC ITransactionDispenser 介面。ITransactionDispenser 的 BeginTransaction 成員會傳回分散式交易物件的參考。此參考會使用 JoinTransaction，傳遞到 SQL Server Native Client OLE DB 提供者。

MS DTC 在分散式交易上支援非同步認可和中止。為取得非同步交易狀態的通知，取用者會實作 ITransactionOutcomeEvents 介面，並將介面連接到 MS DTC 交易物件。

若是分散式交易，SQL Server Native Client OLE DB 提供者會實作 ITransactionJoin::JoinTransaction 參數，如下所示。

參數	描述
punkTransactionCoord	MS DTC 交易物件的指標。
IsoLevel	SQL Server Native Client OLE DB 提供者會忽略。取用者從 MS DTC 取得交易物件時，會判斷 MS DTC 協調交易的隔離等級。
IsoFlags	必須是 0。如果取用者指定其他任何值，SQL Server Native Client OLE DB 提供者會傳回 XACT_E_NOISORETAIN。
POtherOptions	如果不是 NULL，SQL Server Native Client OLE DB 提供者會從介面要求選項物件。如果選項物件的 ulTimeout 成員不是零，SQL Server Native Client OLE DB 提供者會傳回 XACT_E_NOTIMEOUT。SQL Server Native Client OLE DB 提供者會忽略 szDescription 成員的值。

這個範例會使用 MS DTC 協調交易。

// Interfaces used in the example.
IDBCreateSession*       pIDBCreateSession   = NULL;
ITransactionJoin*       pITransactionJoin   = NULL;
IDBCreateCommand*       pIDBCreateCommand   = NULL;
IRowset*                pIRowset            = NULL;

// Transaction dispenser and transaction from MS DTC.
ITransactionDispenser*  pITransactionDispenser = NULL;
ITransaction*           pITransaction       = NULL;

    HRESULT             hr;

// Get the command creation interface for the session.
if (FAILED(hr = pIDBCreateSession->CreateSession(NULL,
     IID_IDBCreateCommand, (IUnknown**) &pIDBCreateCommand)))
    {
    // Process error from session creation. Release any references and
    // return.
    }

// Get a transaction dispenser object from MS DTC and
// start a transaction.
if (FAILED(hr = DtcGetTransactionManager(NULL, NULL,
    IID_ITransactionDispenser, 0, 0, NULL,
    (void**) &pITransactionDispenser)))
    {
    // Process error message from MS DTC, release any references,
    // and then return.
    }
if (FAILED(hr = pITransactionDispenser->BeginTransaction(
    NULL, ISOLATIONLEVEL_READCOMMITTED, ISOFLAG_RETAIN_DONTCARE,
    NULL, &pITransaction)))
    {
    // Process error message from MS DTC, release any references,
    // and then return.
    }

// Join the transaction.
if (FAILED(pIDBCreateCommand->QueryInterface(IID_ITransactionJoin,
    (void**) &pITransactionJoin)))
    {
    // Process failure to get an interface, release any references, and
    // then return.
    }
if (FAILED(pITransactionJoin->JoinTransaction(
    (IUnknown*) pITransaction, 0, 0, NULL)))
    {
    // Process join failure, release any references, and then return.
    }

// Get data into a rowset, then update the data. Functions are not
// illustrated in this example.
if (FAILED(hr = ExecuteCommand(pIDBCreateCommand, &pIRowset)))
    {
    // Release any references and return.
    }

// If rowset data update fails, then terminate the transaction, else
// commit. The example doesn't retain the rowset.
if (FAILED(hr = UpdateDataInRowset(pIRowset, bDelayedUpdate)))
    {
    // Get error from update, then abort.
    pITransaction->Abort(NULL, FALSE, FALSE);
    }
else
    {
    if (FAILED(hr = pITransaction->Commit(FALSE, 0, 0)))
        {
        // Get error from failed commit.
        //
        // If a distributed commit fails, application logic could
        // analyze failure and retry. In this example, terminate. The 
        // consumer must resolve this somehow.
        pITransaction->Abort(NULL, FALSE, FALSE);
        }
    }

if (FAILED(hr))
    {
    // Update of data or commit failed. Release any references and
    // return.
    }

// Un-enlist from the distributed transaction by setting 
// the transaction object pointer to NULL.
if (FAILED(pITransactionJoin->JoinTransaction(
    (IUnknown*) NULL, 0, 0, NULL)))
    {
    // Process failure, and then return.
    }

// Release any references and continue.

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概念

交易