Understanding Transactions

A transaction in the eCommerce world involves a series of operations where if one operation fails, the whole transaction fails. For example, when you buy a book from an online store, the operations may include updating the store's inventory, verifying that your credit card number is valid, charging your credit card, and initiating the shipment of your book. If any one of these operations fails, all changes must be cancelled or reversed. This technology, called transaction processing, is handled by COM+.

Transaction processing is available to COM components and to ASP pages. Implementation in COM components involves calling the right COM interfaces. Implementation in ASP pages involves using the @TRANSACTION directive and the ASP built-in object called ObjectContext Object. Transaction processing in an ASP page can work with transaction processing in a COM component so long as the component is called from within the ASP page that starts the transaction.

Code examples for transaction processing are provided at @TRANSACTION, ObjectContext Object, and Samples.

Note In IIS versions 5.1 and previous, when IIS compiled script code in an ASP page, a new instance of the IIS Web Application Manager (IISWAM) was created. IISWAM was a Component Object Model (COM) component that IIS used to manage applications. Beginning with IIS version 6.0, IIS no longer creates a COM component to house a transaction but accesses the COM+ transaction service directly, thus greatly improving the speed of transaction processing. However, the IISWAM component is still installed for backward compatibility.