Data Access and Transactions

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Using Database Access Interfaces with Component Services

Because the ODBC Driver Manager is a Component Services resource dispenser, data accessed via ODBC is automatically protected by your object’s transaction. For object transactions, an ODBC-compliant database must support the following features:

Table 7.6 summarizes database requirements for full COM+ application support.

Table 7.6   ODBC Driver Requirements for Component Services Compliance

Requirements Description
Support for the OLE transactions specification, or support for XA protocol Enables direct interaction with the Distributed Transaction Coordinator (DTC) by using the XA Mapper.
ODBC driver Platform requirement for COM+ application server.
Support for ODBC version 3.0’s SqlAttrEnlistInDtc attribute COM+ applications use this call to pass the transaction identifier to the ODBC driver. The ODBC driver then passes the transaction identifier to the database engine.
Fully thread-safe ODBC driver ODBC driver must be able to handle concurrent calls from any thread at any time.

Because ADO is an indirect consumer of ODBC data sources, it makes a good candidate for data access from COM components. In fact, there is very little semantic difference between using ADO inside a COM component, and using it from a Web page.


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