How Web Services Can Help Solve Legacy Systems Incompatibility Problems

This scenario resembles the previous Sabre scenario in that Dollar Rent A Car Systems is using Web services to make a reservation system available to its business partners and customers. This example is used in this section because Dollar Rent A Car uses Web services on the back end (between UNIX- and Windows-based systems) for data-transfer interoperability purposes.

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Dollar Rent A Car: Using Web Services for Systems Interoperability

Headquartered in Tulsa, Oklahoma, Dollar Rent A Car Systems Inc. is one of the world's largest rental car agencies. The company has 430 worldwide offices located in 26 countries and has almost 100,000 vehicles in inventory in the United States.

In the first quarter of 2000 one of Dollar's business partners, Southwest Airlines, offered Dollar the opportunity to put a link to the Dollar rental car reservations system on Southwest's Web site such that customers could make plane and car reservations at the same time. But to do this required Dollar to be able to link its Windows-based reservation system with Southwest's UNIX/CORBA-based systems.

Instead of building a fixed-address CORBA-compliant application (which is how Dollar might have had to interface with Southwest in pre-Web services days), Dollar chose to make use of XML as the data default format and SOAP protocols for binding the UNIX- and Windows-based databases together. By taking this approach Dollar was able to build a flexible solution that it could potentially offer to other airlines as well as being able to avoid a long-term code maintenance commitment (to maintain CORBA code). Using this approach, Dollar was able to architect a data translation system between its database and Southwest's differing database.

Source: http://www.microsoft.com/BUSINESS/casestudies/b2c/dollarrentacar.asp.

Used by Permission.

What is particularly interesting about this scenario is that Dollar used Web services products to build a bridge between two disparate system types and databases. In other words, Dollar used Web services to foster systems interoperability between back-end UNIX- and Windows-based systems. From a customer/user's perspective this database translation is transparent the user is completely unaware that any data translation is taking place between the Southwest and Dollar systems platforms.

Not So Fast…

What is not immediately apparent in this scenario is that Southwest remained faithful to its CORBA-based approach to handling distributed applications. What Dollar did was build a Web services-based system that could take CORBA requests and translate them into SOAP requests for data on Dollar systems. Going the other way, the Dollar Web services system translated the SOAP data back into an envelope that Southwest's CORBA system could handle (and sent that data to a specified port). In this case Web services was used to foster system-to-system interoperability, but notice that the translations to and from the CORBA system all took place at Dollar (because Southwest does not use Web services protocols for this application at this time).