Dollar Rent a Car has been banking more bucks since deciding to go with Web services in its system infrastructure.

As one of the world's largest car rental agencies, Dollar has more than 400 locations in 26 countries. This includes about 250 locations and a fleet of 75,000 cars in the United States, along with significant presences in Australia, Canada, the Caribbean, and Latin America. Dollar posted more than $1 billion in combined revenues for 2001.

Using Microsoft .NET connected software, Dollar created an XML Web services interface to expose its existing mainframe-based reservation system for access by existing and potential business partners. So far, this has resulted in millions of additional rate requests, thousands of new reservations, millions of dollars in additional revenue and significant savings on fees per transaction.

Direct access to back-end system mandatory

To open new business opportunities, Dollar wanted to provide partners with direct access into its reservation system—a VMS-based application known as Quick Keys. For Dollar, a key benefit of this capability would be the relatively low cost of acquisition for new reservations. The company currently receives the majority of its reservations through global distribution systems such as Sabre or Apollo, paying a fee for each transaction. By integrating directly with partners, Dollar would be able to drive incremental reservations while lowering its customer acquisition costs—a very attractive combination.

Coming into the project, Dollar already had two interfaces into Quick Keys. The first was an internally developed EDI interface running on a Compaq Alpha server, which parsed flat files that were FTPed to Dollar on a daily basis by several tour operators. The second path interface was through dollar.com-built in 1997 using Microsoft Windows NT Server, CGI, Perl, and an Oracle database. As the first car rental Web site to provide real-time reservation capabilities, it relied on a custom COM component and Compaq's TP-Web Connector to interface with the mainframe.

Finding the Right Solution

Dollar's Advanced Technology Group initially decided that it would be better to integrate partners through dollar.com rather than attempting to connect them directly to the mainframe. Unfortunately, the existing connectivity between dollar.com and Quick Keys could not be easily adapted to solve this attractive business opportunity. A simpler way would have to be found. Dollar's Advanced Technology Group identified four possible technologies for connecting with other systems—CORBA and the Internet Interoperability ORB Protocol (IIOP), Java RMI, DCOM, and socket programming—but uncovered significant issues with each option:

· CORBA/IIOP: In a UNIX-to-UNIX environment, CORBA and IIOP are commonly used to connect two systems. The team determined that the cost of a CORBA ORB would be in the neighborhood of six figures—which was cost prohibitive. In addition, taking this approach would have required opening ports in Dollar's firewall for outside access, which did not please the company's IT security team. Finally, Dollar had no experience with CORBA and felt that it would not meet their requirement for a generic, re-usable interface. "Purchasing the ORB, training our staff, and building the interface would have taken too long," said Peter Osbourne, Group Manager, Advanced Technology Group at Dollar. "Combined with the high price tag, it wasn't a viable option."

· Java RMI: In a Java-to-Java environment, Java Remote Method Invocation (RMI) is frequently used to connect two systems. Java was not in use at Dollar and this would have required adding another complex technology to their existing environments. Since Dollar didn't have any experience with Java, ramping up the development effort would also take some time. Speed-to-market was a primary requirement, so this option was dismissed.

· DCOM: For the past several years, DCOM has been the norm for connecting Windows-based solutions. However, DCOM was created several years ago, and is optimized to work over high-speed local area networks rather than a non-deterministic channel such as the Internet. Since Dollar had no way of ensuring that potential partners would all be running Windows, this option was also dismissed.

· Socket Programming: When no standards-based protocol exist, a last resort is to fall back on low-level socket programming to connect disparate systems. To make this work, Dollar would have needed to define and implement a protocol to handle all possible conditions. "Socket development is low level and requires quite a bit of knowledge," said Osbourne. "Had we taken this approach, it would have taken quite a long time to implement, and would have ended up becoming a one-off project that could not be re-used in the future."

XML Web Services: A Better Way

Unhappy with all commercially available options, Dollar did have one other choice: XML Web services. Osbourne attended a Microsoft Developer Network seminar on Microsoft Visual Basic, where the last 10 minutes were devoted to SOAP and how it could be used to create XML Web services—programmable application components that can be accessed over the Internet via standard Web protocols. "When the integration project came up, XML Web services seemed like a natural fit," said Osbourne. "I didn't know much about building them, just that they seemed like the answer to our problem." There were a number of technical concerns, one being the fact that XML uses text-based tags to describe fields—a characteristic Dollar was afraid would enlarge each message and impact its transfer time. Another concern was that a Web-based solution might not be able to handle the proposed transaction volumes. The final issue was the newness of XML Web services—some people at Dollar were uncomfortable transitioning to a new technology.

To address performance concerns, Osbourne turned to Internet newsgroups. "I posted a fictitious question regarding whether SOAP could support the transaction volumes suggested for this interface," he said. "To my luck, the question was answered by Kent Sharkey, a Microsoft evangelist for SOAP and XML Web services. We talked about it and determined that our target transaction volume could easily be supported."

Benefits are bountiful

By integrating directly with business partners using the Microsoft platform and XML Web services, Dollar cost-effectively opened up another sales channel that has provided millions of additional rate requests and thousands of new reservations per year, equating to millions of dollars in additional revenue. Furthermore, the company expects to save a significant amount in annual GDS fees. Just as important, the company put in place a simple, re-usable interface into its reservation system that could be accessed by any system via the Internet.

"We knew exposing our reservation system as an XML Web service would provide a standard interface that could be used by a wide range of other applications, both internal and external," said Osbourne. "However, at the time, we had no idea just how often we would use it, or the magnitude of the benefits it would deliver. We've already re-used the interface four more times, each time extending our market reach with very little additional effort."

Moving Forward with .NET

Looking forward, Osbourne sees several opportunities to reduce costs and improve his team's ability to deliver using the .NET platform. He plans on consolidating dollar.com and mobile.dollar.com on the same physical set of servers, which will reduce the administrative overhead associated with maintaining two separate Web sites. He then plans on upgrading dollar.com to ASP.NET, allowing developers working on that site to realize the same productivity improvements that were provided when developing mobile.dollar.com.

Osbourne also sees .NET Services playing a role in the company's future, as a means of providing incremental value to users. Based on XML Web services, .NET Services can be easily integrated with Dollar's .NET-based systems using just a few lines of code—just like calling the internal Web service. "With .NET Passport, we'll be able to improve the customer experience by automatically recognizing each user and allowing them to make reservations without having to enter in all their basic data," he said.

Breathing new life into an old system

Using the .NET connected software, Dollar was able to breathe new life into its existing mainframe application several times over, with very little incremental effort. By exposing the functionality of its reservation system via XML Web services, Dollar is well-positioned to capitalize on new business opportunities without having to worry about its technology being up to the challenge.