4.6 QA: A time to recap and reflect

4.6 Q&A: A time to recap and reflect

	Q: What is UDDI?
	Q: Is UDDI a standard?
	Q: Is it possible to use Web services without UDDI?
	Q: How does UDDI relate to WSDL?
	Q: What is a UDDI Registry?
	Q: Is UDDI based on LDAP?
	Q: What is the UBR?
	Q: Is there a charge for using the UBR?
	Q: Is it possible to have a private UBR?
	Q: Are Web services the only type of service that can be included in the UBR?

Answers

	A: Universal Description, Discovery, and Integration is a scheme for Web-based electronic directories that contain detailed information about businesses, the services they provide, and the means for utilizing these services. A UDDI directory, referred to as a registry, is meant to be platform independent and can be readily accessible via a Web browser “based GUI or by applications via published APIs. Its goal is to ensure that enterprises and individuals can quickly, easily, and dynamically locate and make use of services, in particular Web services, that are of interest to them.
	A: Yes, it is a de facto industry standard under the auspices of OASIS (http://www.oasis- open .org). OASIS, which was formed as a consortium in 1993 to promote SGML, is now an accepted standards body for XML and e-business “ related initiatives. Thus, it makes sense for UDDI to be under the stewardship of OASIS ”which is a not-for-profit agency with more than 2,000 participants representing over 600 organizations and individual members in 100 countries . In addition, UDDI is based entirely on XML and SOAP, which in turn are acknowledged industry standards.
	A: Yes. Unlike XML or SOAP, UDDI is not a prerequisite protocol that has to be used by a Web service in order for it to be deemed a Web service. UDDI is essentially an optional adjunct to publicize the availability, characteristics, and activation requirements of Web services. It is possible to write applications (and Web services) that can dynamically locate and invoke Web services by programmatically interrogating a UDDI Registry. However, this is by no means mandatory; it is an option. Most applications developers are unlikely to opt for such a dynamic approach, given the variables and uncertainty of this type of on-the-fly run-time binding. Though not a prerequisite per se, UDDI is the accepted means for realizing the self-advertising mandate for Web services ”and as such should be considered as an integral part of a Web services landscape.
	A: Despite what would appear to be a common goal when it comes to describing the characteristics of Web services, there is no prespecified relationship between UDDI and WSDL. In contrast to SOAP, WSDL is not one of the prerequisite standards used by UDDI. They do, however, complement each other. One of UDDI s express missions is to publicize the technical requirements and invocation criteria for Web services. WSDL happens to be the preferred and accepted way to describe the interface of a Web service. Thus, there is an obvious and natural role that WSDL can play vis--vis UDDI. The tModel information for a Web service within a UDDI Registry could thus point to a WSDL description of that Web service, as can the bindingTemplate.
	A: A UDDI Registry is an instance of one complete set of UDDI-related data about businesses, the services they provide, and technical details of these services. A UDDI Registry is made up of one or more UDI nodes, where a UDDI node is a software system that supports at least one of the UDDI API sets. A given UDDI node can, at any one time, only be a member of just one UDDI Registry. In the case of a multinode registry, all the nodes are expected to work collaboratively with each other, representing one unified view of the data managed by that registry.
	A: No. UDDI is not built upon any of the popular directory schemes. UDDI is meant to be a high-level, logical overlay architecture that deals with data structures, in the form of XML schema, and SOAP-based messages, invoked from APIs, to manage and manipulate these data structures. The UDDI specification, now in its third version, does not specify or even suggest how one should go about realizing these data structures or the SOAP messaging. Those are left as individual implementation decisions. Thus, there is no formal relationship for the Lightweight Directory Access Protocol (LDAP) or even X.500. There are, however, specifications available on the Web as to how a UDDI node could be implemented on top of LDAP or X.500. At present, however, many of the UDDI implementations are realized using popular relational database systems such as IBM s DB2, though BEA, for one, offers an LDAP-based UDDI implementation.
	A: The Universal Business Registry, also referred to as the UDDI Business Registry, is a global, public UDDI service available on the Web that is open to all ”currently on a no-charge basis. It has been in operation since late 2000. The UBR was initially operated by Ariba, IBM, and Microsoft. Today, the UBR consists of four UBR nodes, working collaboratively, with these nodes being run by IBM, Microsoft, NTT Communications, and SAP. You can locate the UBR by going to http://www.uddi.org and clicking on the Register tab at the top of the page.
	A: At present there is no charge for using the UBR ”whether to publish information or to search for information. The UBR nodes, however, require those who wish to publish information in the UBR to be registered with them beforehand so that they can be authenticated. Anybody can freely search the UBR without being registered. Down the road it is highly likely that the UBR nodes will require potential publishers to be digitally authenticated and certified before they can apply for registration. There is likely to be a charge for this digital certification.
	A: Yes. Version 3 of the UDDI specification, which was published in July 2002, endorses the concept of multiregistry environments consisting of a root registry (typically the UBR) and multiple affiliate registries. Today, IBM, Microsoft, BEA, Sun, and others offer products for implementing so-called enterprise UDDI registries. An enterprise UDDI Registry could be private (i.e., restricted for use by one company) or semiprivate (i.e., shared between trusted partners ). Microsoft s flagship Windows Server 2003, which started shipping in June 2003, includes a full-function UDDI Registry capability as a built-in feature.
	A: No. Though UDDI and the UBR were conceived to promote e-business, and in particular Web services, neither the UDDI specification nor the UBR insists that the only services that can be included in a UDDI Registry are Web services. In reality the UBR is extremely generic and flexible. One can register any type of business, organization, or even an individual, as well as any arbitrary type of service.