Microservices Expo Authors: Elizabeth White, Mehdi Daoudi, Pat Romanski, Flint Brenton, Gordon Haff

Related Topics: Microservices Expo

Microservices Expo: Article

Understanding UDDItModels and Taxonomies

Understanding UDDItModels and Taxonomies

The Universal Description, Discovery, and Integration (UDDI) specifications provide a standardized way for businesses to discover each other over the Internet and find details of services provided. UDDI is a combination of White Pages (contacts, addresses, telephone numbers), Yellow Pages (listing by industry classification), and Green Pages (technical details of services offered). UDDI is indeed universal in scope, in that the services offered can be anything from a telephone number to a SOAP endpoint for a Web service.

Businesses that want to publish their details on the Internet can use either a Web interface provided by one of the public UDDI operators (currently IBM and Microsoft), or a programmatic interface from within their IT systems. Information published to one public UDDI repository becomes replicated to the other public repositories automatically.

UDDI also has great value behind the firewall in intranet environments. There are advantages to using Web services to connect internal systems, rather than implementation-specific protocols, such as RMI, CORBA, or DCOM. Web services are truly independent of vendor, platform, and language, and can minimize the pain of integration issues. An internal, private UDDI repository can then be used as a logically centralized database of these systems. This repository can be replicated across sites within the company using the same techniques as public UDDI repositories.

Web Services Fundamentals
Before we go into the details behind UDDI, it's important to have an understanding of two other standards - SOAP and WSDL.

The Simple Object Access Protocol (SOAP) specification provides an XML-based dialect for invoking Web services across Internet or intranet environments. The specification details a particular XML structure for making a request, including detailed rules on encoding different data types to ensure that SOAP implementations from different vendors are compatible. SOAP defines the structure of the message but, contrary to its name, isn't really a protocol. Instead, SOAP is usable with existing Internet protocols, such as HTTP and SMTP.

The Web Service Description Language (WSDL) is another XML-based specification that provides a format for describing the interface to a Web service. The WSDL file lists the operations, parameters and data types used by that service and is all a developer needs to write a client application that can use that Web service.

Although WSDL documents describe a programmatic interface to a Web service, they're not enough to enable Web services to be published or discovered over the Internet. UDDI is roughly equivalent to a DNS for Web services, allowing companies to change details about where services are hosted. Applications connecting to those services should always locate the service through UDDI first.

UDDI Basics
The UDDI specification provides four core XML data structures to describe a business and the services it offers:

  • businessEntity
  • businessService
  • bindingTemplate
  • tModel
The first three data structures are simple to understand. A businessEntity structure provides information about a business, such as the head office address. Each business entity can have multiple businessService structures associated with it - one for each service offered by that business. Each business service can have multiple bindingTemplate entries. The binding template represents the way that the business service is accessed. For instance, a binding template can represent a telephone number, a Web site, or a Web service.

Introducing tModels
All three of these data structures can have relationships with tModels, but the meaning of the tModel differs in each context. tModels are an abstract concept representing standards, specifications, and docu-ments. They're designed to be very general purpose so perhaps this is why they appear so confusing at first.

A tModel could be used to represent a taxonomy system such as the North American Industry Classification System (NAICS), which allows companies to be classified depending on the nature of their business activities.

Another use of a tModel is to represent a "service type" offered, such as a Stock Quote service. Table 1 shows the meaning of a tModel in different contexts.

What Is a Taxonomy?
A taxonomy is simply a classification system with a finite set of values. For instance, a geo graphic taxonomy such as ISO3166 allows classification of a business by its location.

Each taxonomy system is represented by a tModel and the classification of a particular entity within that taxonomy system is represented through use of the categoryBag structure, defined by UDDI. A categoryBag is a collection of keyedReference structures. Each keyedReference provides a name-value pair within the scope of the taxonomy system referred to by its tModelKey.

The XML fragment shown in Listing 1 demonstrates the use of the cate-goryBag and keyedReference structures within a businessEntity.

In this example, Cape Clear Software is categorized as "Software Publishers" within the NAICS taxonomy and "US" within the ISO3166 taxonomy. These taxonomies are referred to by their tModelKey references. When new tModels are registered, they're automatically given tModelKeys, which are guaranteed to be a Universally Unique Identifier (UUID).

tModel Categorization and Identification
In the previous section, we saw how business entities and business services can be identified and categorized according to taxonomies described by tModel structures. We've also seen how binding templates refer to a technical specification described in a tModel structure. We'll now look at how tModels themselves are identified and classified.

The UDDI specification provides some core tModels that must be supported in all UDDI repositories. These include standard industry classification and identification taxonomies, such as NAICS, UNSPC, and D-U-N-S. Another key tModel is one representing the "UDDI Types Taxonomy."

The purpose of the UDDI Types Taxonomy is to allow tModels to be classified according to their purpose. For instance, the NAICS taxonomy tModel is classified as a "categorization taxonomy" within the UDDI Types Taxonomy. Other valid values within the UDDI Types Taxonomy are "identifier" and "namespace." Table 2 shows the valid classifications within the UDDI Types Taxonomy.

Registering a Web Service
Now that we've covered the main structures within a UDDI entry, we'll look at a real-world example of publishing a Web service within UDDI. The example is that of an Airport Weather service that can provide weather information for international airports. As a starting point, assume the Web service has already been developed and there's a valid WSDL document to describe the interface to the service.

The first step is to create a "Service Type" tModel to represent the Airport Weather service. This tModel is the generic specification of the Airport Weather service and this allows for the creation of actual Web services (business service entries) that are classified as being of type "Airport Weather." This is the equivalent of the separation of interface and implementation in object-oriented languages, such as Java. Any business entity may register business services referring to this service type.

Because this Web service is based on WSDL, this tModel should be classified within the UDDI Types Taxonomy (uddi-org:types) as being of type "wsdlSpec." This implies that the overviewDoc within the tModel contains a URL pointing to the WSDL document describing the interface to the Web service. Without this classification, there would be no standardized way for consumers of the service to know where to find a definition of the interface.

Listing 2 is the resulting tModel for the Airport Weather service. It's listed in the public UDDI operator cloud and can be queried from either the IBM or the Microsoft Web site.

The next step is to list a business service to implement this tModel. The business service uses the bindingTemplate structure to reference the Service Type tModel (see Listing 3).

Software applications can make use of the UDDI Types Taxonomy to limit searches to Web services that are based on WSDL, as shown in this sample UDDI request:

<find_tModel xmlns="urn:uddi-org:api" generic="1.0" maxRows="1000">
keyName="Specification for a web service described in WSDL"
UDDI provides a technical infrastructure for publishing details of Web services on the Internet for use by other companies, or on the intranet for use by other depart xments. UDDI will become the key integration point for products supporting Web services. Runtime products will expose their capabilities through UDDI and developer tools will use UDDI to find those services.

There are still many business issues to be addressed around the use of UDDI on the Internet, such as how to ensure the validity or usefulness of data registered and how businesses will agree on contractual terms for the use of these services. It's unlikely that technology alone will be able to solve these problems but UDDI does provide a good framework for enabling both human and programmatic interaction between organizations. In the short term, the use of private UDDI repositories within intranets is likely to play a bigger role in the proliferation of the Web services paradigm.


More Stories By Andy Grove

Andy Grove is a product manager at Cape Clear Software. He cofounded Orbware, a J2EE application server vendor, in 1999, and has extensive experience in building business systems using J2EE and XML technology.

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.

@MicroservicesExpo Stories
The dynamic nature of the cloud means that change is a constant when it comes to modern cloud-based infrastructure. Delivering modern applications to end users, therefore, is a constantly shifting challenge. Delivery automation helps IT Ops teams ensure that apps are providing an optimal end user experience over hybrid-cloud and multi-cloud environments, no matter what the current state of the infrastructure is. To employ a delivery automation strategy that reflects your business rules, making r...
"We started a Master of Science in business analytics - that's the hot topic. We serve the business community around San Francisco so we educate the working professionals and this is where they all want to be," explained Judy Lee, Associate Professor and Department Chair at Golden Gate University, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
For over a decade, Application Programming Interface or APIs have been used to exchange data between multiple platforms. From social media to news and media sites, most websites depend on APIs to provide a dynamic and real-time digital experience. APIs have made its way into almost every device and service available today and it continues to spur innovations in every field of technology. There are multiple programming languages used to build and run applications in the online world. And just li...
There is a huge demand for responsive, real-time mobile and web experiences, but current architectural patterns do not easily accommodate applications that respond to events in real time. Common solutions using message queues or HTTP long-polling quickly lead to resiliency, scalability and development velocity challenges. In his session at 21st Cloud Expo, Ryland Degnan, a Senior Software Engineer on the Netflix Edge Platform team, will discuss how by leveraging a reactive stream-based protocol,...
The general concepts of DevOps have played a central role advancing the modern software delivery industry. With the library of DevOps best practices, tips and guides expanding quickly, it can be difficult to track down the best and most accurate resources and information. In order to help the software development community, and to further our own learning, we reached out to leading industry analysts and asked them about an increasingly popular tenet of a DevOps transformation: collaboration.
We call it DevOps but much of the time there’s a lot more discussion about the needs and concerns of developers than there is about other groups. There’s a focus on improved and less isolated developer workflows. There are many discussions around collaboration, continuous integration and delivery, issue tracking, source code control, code review, IDEs, and xPaaS – and all the tools that enable those things. Changes in developer practices may come up – such as developers taking ownership of code ...
Cloud Governance means many things to many people. Heck, just the word cloud means different things depending on who you are talking to. While definitions can vary, controlling access to cloud resources is invariably a central piece of any governance program. Enterprise cloud computing has transformed IT. Cloud computing decreases time-to-market, improves agility by allowing businesses to adapt quickly to changing market demands, and, ultimately, drives down costs.
Modern software design has fundamentally changed how we manage applications, causing many to turn to containers as the new virtual machine for resource management. As container adoption grows beyond stateless applications to stateful workloads, the need for persistent storage is foundational - something customers routinely cite as a top pain point. In his session at @DevOpsSummit at 21st Cloud Expo, Bill Borsari, Head of Systems Engineering at Datera, explored how organizations can reap the bene...
How is DevOps going within your organization? If you need some help measuring just how well it is going, we have prepared a list of some key DevOps metrics to track. These metrics can help you understand how your team is doing over time. The word DevOps means different things to different people. Some say it a culture and every vendor in the industry claims that their tools help with DevOps. Depending on how you define DevOps, some of these metrics may matter more or less to you and your team.
"CA has been doing a lot of things in the area of DevOps. Now we have a complete set of tool sets in order to enable customers to go all the way from planning to development to testing down to release into the operations," explained Aruna Ravichandran, Vice President of Global Marketing and Strategy at CA Technologies, in this SYS-CON.tv interview at DevOps Summit at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"We are an integrator of carrier ethernet and bandwidth to get people to connect to the cloud, to the SaaS providers, and the IaaS providers all on ethernet," explained Paul Mako, CEO & CTO of Massive Networks, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"Grape Up leverages Cloud Native technologies and helps companies build software using microservices, and work the DevOps agile way. We've been doing digital innovation for the last 12 years," explained Daniel Heckman, of Grape Up in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"NetApp's vision is how we help organizations manage data - delivering the right data in the right place, in the right time, to the people who need it, and doing it agnostic to what the platform is," explained Josh Atwell, Developer Advocate for NetApp, in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
"Outscale was founded in 2010, is based in France, is a strategic partner to Dassault Systémes and has done quite a bit of work with divisions of Dassault," explained Jackie Funk, Digital Marketing exec at Outscale, in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
"I focus on what we are calling CAST Highlight, which is our SaaS application portfolio analysis tool. It is an extremely lightweight tool that can integrate with pretty much any build process right now," explained Andrew Siegmund, Application Migration Specialist for CAST, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Let's do a visualization exercise. Imagine it's December 31, 2018, and you're ringing in the New Year with your friends and family. You think back on everything that you accomplished in the last year: your company's revenue is through the roof thanks to the success of your product, and you were promoted to Lead Developer. 2019 is poised to be an even bigger year for your company because you have the tools and insight to scale as quickly as demand requires. You're a happy human, and it's not just...
The enterprise data storage marketplace is poised to become a battlefield. No longer the quiet backwater of cloud computing services, the focus of this global transition is now going from compute to storage. An overview of recent storage market history is needed to understand why this transition is important. Before 2007 and the birth of the cloud computing market we are witnessing today, the on-premise model hosted in large local data centers dominated enterprise storage. Key marketplace play...
Cavirin Systems has just announced C2, a SaaS offering designed to bring continuous security assessment and remediation to hybrid environments, containers, and data centers. Cavirin C2 is deployed within Amazon Web Services (AWS) and features a flexible licensing model for easy scalability and clear pay-as-you-go pricing. Although native to AWS, it also supports assessment and remediation of virtual or container instances within Microsoft Azure, Google Cloud Platform (GCP), or on-premise. By dr...
With continuous delivery (CD) almost always in the spotlight, continuous integration (CI) is often left out in the cold. Indeed, it's been in use for so long and so widely, we often take the model for granted. So what is CI and how can you make the most of it? This blog is intended to answer those questions. Before we step into examining CI, we need to look back. Software developers often work in small teams and modularity, and need to integrate their changes with the rest of the project code b...
Kubernetes is an open source system for automating deployment, scaling, and management of containerized applications. Kubernetes was originally built by Google, leveraging years of experience with managing container workloads, and is now a Cloud Native Compute Foundation (CNCF) project. Kubernetes has been widely adopted by the community, supported on all major public and private cloud providers, and is gaining rapid adoption in enterprises. However, Kubernetes may seem intimidating and complex ...