1.5 QA: A time to recap and reflect

A: Web services are a new genre of Web-specific software component methodology that deal with modular, self-contained, self-describing software components whose public interfaces are described using XML. Hence, one can build applications by reusing or assembling existing components from within and outside of an enterprise. Thanks to Web services, these applications will be able to cross systems, programming language, and platform boundaries. New applications being developed can obtain software functionality in the form of Web services. All data transfers that occur between applications and the Web services they invoke are in the form of XML documents that are exchanged using a messaging mechanism ”with SOAP being the preferred and recommended messaging scheme.

A: No. These are enabling technologies that are used by Web services. Web services are software components that solve problems or perform some business logic. They are not just networking protocols provided by middleware.

A: XML is the underlying basis for today s Web services (with Web services, in this context, being used, per common usage, to describe reusable, remotely invoked software components), so much so that they are referred to within some technical circles as XML Web services. Web services are defined and described using XML. Web services operate by exchanging XML documents. Thus, the input parameters to a Web service are always in the form of an XML document, whereas the output of a Web service will also always be an XML document.

A: Web services dramatically and positively alter everything related to applications, both on the supply and demand side. Web services expedite, simplify, and reduce the cost of new application development by providing application developers with systematic access to standards-compliant third-party software functionality that is invoked across the Web. It also allows valuable software functionality embedded within existing applications to be isolated and reused. Since they are totally Web-centric, developers looking for sources for best-of-breed software functionality now have ready access to the entire worldwide software community without the hindrance of geographic, political, or trade boundaries.

A: Web services are truly platform independent. The platform independence, furthermore, applies to both sides of a Web services configuration (i.e., the usage side as well as the provision side). This is because a Web service is a run time “invoked external subroutine, which runs on a machine different from that of the application invoking it. Therefore, applications that use Web services can run on any platform. Web services themselves , in turn , are also totally platform independent and can run on any platform. There is never a need for any commonality . It is a true any-to-any scheme. Web services also may be developed on any platform without any implication whatsoever as to where or how they are going to be deployed.

A: No. The platform independence of Web services is not in any way related to Java. In addition to being platform independent, Web services are also programming language neutral. Web services may be written in any programming language (including Java). In turn, Web services may also be used by any application, written in any programming language.

A: Yes. Web services are an application development “related methodology. The economic downturn that started in 2001 has impacted and slowed down the whole software industry. This has delayed the promulgation of Web services. It is also true that all of the pertinent standards to cover the security, manageability, and reliability aspects of Web services were yet to be formalized in the spring of 2003. These factors, understandably, have slowed down the widespread adoption of Web services, though it should be noted that the UDDI registries testify to the availability of a relatively large number of bona fide Web services. Note, however, that UDDI only comes into play when you are looking for Web services from hitherto unknown external sources (i.e., a bit like looking for a florist in some distant city in a foreign country in an online Yellow Pages directory). Enterprises, however, can also source and use Web services from within the enterprise or from trusted partners ”without obviously having to resort to UDDI.

A: To an extent, yes. Portals, or, to be more specific, portal applications, whether they are for public or corporate portals, are likely, at present, to be the leading candidates for Web services consumption. Portal applications thrive on functionality. Providing value-added, best-of-breed functionality is the primary raison d tre for Web services. Thus, Web services are ideally poised to provide portal application developers with the value-added functionality that they constantly crave.

A: UDDI is a directory and corresponding search mechanism that enables Web services to be readily located and checked out on the Web ”online and dynamically. WSDL is an XML dialect used to describe the external interfaces of Web services. These WSDL descriptions will typically be maintained in a UDDI registry. SOAP is the remote procedure call mechanism preferred by Web services. It is a platform and programming language messaging scheme that is XML based.

A: Web services are modular, self-contained, self-describing, self-advertising, uniquely addressable over the Web, XML-centric, standards based, platform independent, programming language agnostic , and amalgamative in mix-and-match mode.