SPECIAL CAPABILITIES FOR E-COMMERCE TRANSACTIONS

10 October 2003

Recently a Holiday Package System has been developed by Auckland University Software Engineering students, using the Gnosis Transaction Manager on Microsoft SQL Server.

From our theoretical understanding of the problem, we could see the Holiday Package system was a classic long transaction problem. A holiday package may take days or weeks to complete. A package may start with tentative dates and places for a holiday and later move on to specific bookings over a period of time. Which required rules about completion, such as bookings made for all flight plans, all nights accommodation accounted for and full payment made, to name only a few business rules.

We have developed a prototype Holiday Package system for use by Travel Agents, that makes bookings in several example disparate systems, via the internet, and holds these as booking reference numbers.

What we found when working on the Holiday Package system, was that there was a need to define rules, firstly about going forward, that is completion of the Package, and secondly, to define rules about going back, that is, reversing parts or all of a holiday package, as well.

Here is a probable scenario, the user plans and books the Australian leg of his holiday and places a save point. The user then goes about booking the American leg of his holiday package, may make some plans and a few bookings, and then decide to reverse out the American plans and bookings, say the conference is cancelled, or he does not have enough money. So what about the bookings held in the external systems? These would have to be cancelled, before the reversal could proceed. Hence we understood the need for rules about reversing (rolling back) a transaction, as well as for completing a transaction.

For our system, we did not go to extraordinary lengths to make cancellations automatic. As these could easily be done manually, we were most interested in seeing that the integrity rules were enforced. Which meant that we did not reverse our side of the system until the appropriate cancellation had been made to the external system. In Gnosis terminology we created rollback constraints, to enforce these reversal rules.

"This has been a very interesting project, and we feel very pleased to have worked with some new concepts that are applicable in many E-Commerce scenarios, especially were there are links to other disparate systems, there are some powerful features available here.", says Mohit Wadan, Software Engineering Student.