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The great debate: .Net vs. J2EE

Does one Web services platform dominate the other?

By Jonathan Lurie and R. Jason Belanger, JavaWorld.com, 03/08/02

Page 2 of 6

What is a Web service?

The Web service emerged as the solution for providing a standard way to retrieve data without proprietary software and hardware. A Web service cornerstone is its ability to transfer data from the provider to the consumer, or requester, using the ubiquitous HTTP protocol; the data format is XML. Formatting the data in XML greatly facilitates raw data's conversion into a renderable format. Extensible Stylesheet Language Transformations (XSLT) perform the transformation rather easily, without complex parsing programs, as Figure 2 illustrates.

Figure 2. A conceptual depiction of an XSL transformation

A commissioned whitepaper for Sun defines a Web service as:

An application that accepts requests from other systems across the Internet or an intranet, mediated by lightweight, vendor-neutral communications technologies.

In "Defining the Basic Elements of .Net," Microsoft describes a Web service as:

XML Web services let applications share data, and -- more powerfully -- invoke capabilities from other applications without regard to how those applications were built, what operating system or platform they run on, and what devices are used to access them.

You can deduce some good news from the above definitions: both Sun and Microsoft seem to tacitly agree. From a purely intuitive level, a Web service is a service consumed via the Internet. More specifically, a Web service is invoked via HTTP and returns data to the consumer in XML.

Paradigm shift

Web services signify a shift in software development paradigms. While many companies still debate Web services' viability, companies like Concord EFS reap millions of dollars from their in-production credit card-processing Web service. Web services advocate that we should segment large applications so individual components can exist as Web services. This model would arguably replace the current paradigm: segmentation into dynamic link libraries (DLL) and COM (Component Object Model) components.

In fact, we can draw a strong analogy between Web services and DLLs. Both centralize related functionality; for example, business rules and database access. However, Web services and DLLs differ significantly. First, you can access Web services through the HTTP protocol, thus allowing any Web client to invoke Web services. This is not the case with DLLs, which are typically invoked from clients within the same intranet. Thus, Web services will usher in a new distributed computing era. Second, Web services return data to the client in XML. DLLs typically return data through programming language-specific data types.

These differences between Web services and their DLL ancestors result from the major industry trends that preceded Web services:

1. The acceptance of HTTP as a protocol through which users access the Internet
2. The acceptance of XML as the de facto standard for data transfer

These two trends provide the foundations upon which the Web service is built. Figure 3 illustrates how Know-Can-Do would use Web services. Notice the absence of leased lines and proprietary data formats.

 

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