We see the transition of Web services, from intriguing demonstration to genuine tool, in offerings such as the Mainframe Express Enterprise Edition product launched this month by Maryland-based Micro Focus International Ltd. The product gives developers new power to combine the availability and integrity of mainframes with the management flexibility and developer productivity of Web services. At months end, we hope to see more such offerings at the JavaOne Conference in San Francisco. But it would be a sad repetition of past errors if IT vendors seized upon the success of Web services as their latest excuse for locking customers into product stacksperversely building proprietary structures from standards-based components, for example, by devising proprietary XML schemas for their applications and documents.Are Web services ready for prime time? Find out here.IT buyers need resolution to avoid being seduced by the accompanying convenience of one-stop shopping: Fulfilling the potential of Web services requires a long view of future needs for testing tools, security infrastructures and other building blocks for which only open architectures can enable best-of-breed integration. eWEEK is interested in your Opinion. Send your comments to eWEEK@ziffdavis.com. To read more eWEEK editorials, subscribe to eWEEK magazine. Check out eWEEK.coms Developer & Web Services Center at http://developer.eweek.com for the latest news, reviews and analysis in programming environments and developer tools.