But not many are ready to settle on either Sun or Microsoft. The reality is they’re struggling to build distributed Web applications the old-fashioned way - with plenty of hard work - and to achieve some interoperability between the rival technologies. They’re using tools that make sense for them given current technology investments and business goals.

The Sun-Microsoft challenge - and the subsequent pressure on enterprise IT managers - began heating up again about six months ago. That’s when Microsoft unveiled its .Net strategy.

.Net consists of four technologies. One is Visual Studio.Net, along with the .Net Framework and a new language called C#. This new language is based on C and C++ and, like Java, uses a virtual machine. Second are the .Net enterprise servers, including new versions of products such as the Microsoft SQL Server database. These are for running and managing .Net applications.

Third is a set of reusable ’Net-based services, similar to Microsoft Passport, that hold credit card numbers and other personal information. These services will save users from having to enter data for each transaction. Lastly are third-party end-user devices, ideally equipped with the Windows CE client software.

Final versions for all .Net technologies are expected in 2001.For now, only the Visual Studio.Net beta tool set is available.

Initially, Visual Studio.Net will be used for building applications that run on Microsoft operating systems. Eventually, Microsoft says, .Net developers will be able to code in several languages, not just one. This will be possible because Microsoft plans on embedding XML, for representing and exchanging data over the Internet, and other Web standards, such as Simple Object Access Protocol (SOAP), in the .Net architecture.

Java, although it has matured dramatically over the past five years, still doesn’t integrate closely with XML and other key Web standards. However, loads of Java development tools are available, and Java is the heart of application servers such as BEA Systems’ WebLogic. These servers act as middlemen running Java software components and linking browser users with back-end corporate databases.

Market research firm Giga Information Group estimates that 35% to 40% of customers are adopting Microsoft products for low-end Web commerce sites. They’re using Windows NT and Windows 2000 Datacenter Server operating systems, built-in messaging and transaction services, Visual Basic and Visual C++, the Component Object Model and Microsoft APIs. However, Giga drops the percentage to about 20% for sites with heavy traffic and high-transaction volume.

Microsoft hopes .Net will capture the attention of all users moving to the next level of Web development. It’s already achieved surprising credibility among experienced programmers for its .Net strategy, sketchy as it is right now.

"If I’m becoming a 100% Microsoft shop, then .Net is going to become my platform of choice over time," says Greg DuPertuis, president of The Adrenaline Group, a Washington, D.C., firm that builds custom Web applications. "We’ll keep working with Java applications on Linux and Solaris servers. We can do this knowing that those using Microsoft’s .Net will be able to interoperate."

That interoperability will be possible, over time, as applications become "services," a concept that Microsoft and Sun advocate now. Under this model, application functions are accessed over the Internet using standard formats such as XML and standard protocols like HTTP.

Interoperability should become simpler because of emerging standards like Universal Description, Discovery and Integration (UDDI) plus XML and SOAP. You could create an application or service, and register it via UDDI in an online registry. Any other application can query the registry via XML, interrogate the object, then use SOAP to access it and XML to exchange data with it.

But today, with the ink on many of these standards specifications barely dry, most enterprise users will be building fairly conventional Web commerce sites, based on Web servers and application servers that run the business logic as a set of components and connect to back-end data and enterprise applications.