Welcome!

Industrial IoT Authors: Elizabeth White, Maria C. Horton, Liz McMillan, Ed Featherston, Stackify Blog

Related Topics: Industrial IoT

Industrial IoT: Article

Combining XQuery and Web Services

Combined entities can lead to sophisticated solutions

The XML world is driving new emerging technologies that can be utilized to provide solutions to a variety of problems. This article focuses on two of these technologies: Web services and XQuery. As separate entities, these technologies provide a powerful set of features; but when combined they have the potential to present ever more sophisticated feature sets designed for very specific goals.

Web services, while not strictly an XML technology, depends heavily on XML for both its definition language, Web Services Description Language (WSDL), and its messaging protocol, Simple Object Access Protocol (SOAP). Alongside its various descendants, WSDL itself builds on previous XML technologies, such as XML Schema, to provide an abstraction layer over which service endpoints can be defined in terms of messages and operations. Similarly, SOAP provides a mechanism for issuing remote procedural calls and document transactions between distributed systems.

Correspondingly, XQuery provides a rich, data-oriented language for interacting with XML and XML-mapped data sources. It builds on existing XML technologies such as XPath and XML Schema to provide a unified query language over both weakly typed (streams, Web sites) and strongly typed (databases, messages) XML sources. Unlike other query languages, such as SQL, it is intended to not only be a database query language, but a general language for natively interacting with XML as well.

Both technologies have starring roles in new methodologies for solving old problems. Service-oriented architecture (SOA) promises to open up all of the applications in the enterprise via Web services. With it, application developers can build new applications from the functions and features of existing applications. Enterprise Information Integration (EII), utilizing XQuery, makes a similar promise: to present a single front end to all of the databases and data sources available on the network. In both cases, the goal is to bring together the processes and data we interact with individually in a manner that reduces the amount of custom mapping required for each source.

Our ultimate goal herein will be to demonstrate how Web services and XQuery combined can ease the task of developing applications on top of heterogeneous distributed systems. Essentially, we're looking to these technologies to hide all of the differences between the systems with which we wish to interact and allow developers to concentrate on the applications being developed.

Integrating XQuery with Web Services
Whether you look at adding XQuery to Web services or Web services to XQuery, the respective technology will gain something it did not previously have. On one hand XQuery, a language intended to manage, restrict, and combine static data from multiple sources of data (relational databases, XML databases, static Web content), can simplify interactions with XML-based Web services. On the other hand, Web services open XQuery up to more sophisticated interactions with systems outside its local scope. By combining XQuery and Web services, XQuery receives a new interaction model with external sources and Web services along with a sophisticated language for handling its input and output.

To illustrate just one possibility offered by the interaction, consider the following scenario. Super Travel Agency (STA) wishes to present a new feature on its Web site, awarding its repeat customers with fare estimates based not only on best fares but on their participation in frequent flyer programs. STA has a complete customer database with profiles listing their frequent flyer codes for each airline. For this system, STA needs to interact with the airlines via Web services that are defined using completely different result formats.

This fairly straightforward usecase can be accomplished in a discrete series of steps. First, the user profile is accessed and the relevant frequent flyer codes extracted. Combining these codes with destinations and dates, we then pass them to the appropriate airline services and receive a quote from each in a different XML format. We then have to define either a transformation or a custom extraction routine to extract the prices. Finally, we have to take this correlated data and produce a single report for consumption by the client.

In traditional modern programming languages, this problem could be solved by defining a number of discrete modules. One module would access and interpret the client database result, one would be defined for interacting with each airline Web service, one each for the extraction routines to parse the XML results and extract the relevant information, and finally a module for generating the final report. All of the interactions are defined in terms of XML messages, but given the disparate requirements of each such message format the solution will typically have to define a number of custom parsers to convert in and out of the data-oriented XML and object-oriented language paradigms. Simply put, this requires specialized coding and, while extensible, usually requires much more code to integrate new airlines and new client profiling data.

By allowing existing WSDL definitions to be referenced in the query and their services exposed as standard XQuery functions, the steps followed to achieve the solution can be more concise using XQuery. The simplicity is achieved by leaving the entire sequence of interactions in the XML world and taking advantage of XQuery's rich set of features for dealing with XML data to seamlessly interact with all of the various data and function points.

In order to facilitate this interaction between XQuery and Web services, we'll employ an extension to the XQuery language. This syntax parallels the built-in schema import facility in XQuery and was first proposed in XQuery at your Web service. We'll see below how it allows the query author to specify the services to be used in the query by simply importing the WSDL documents defining those services.

Bridging the Gap
In technology, gaps force us to build new technology to bridge disparate paradigms. XQuery sought to bridge the gap between modern programming languages and data. Web services sought to bridge the gap between those same programming languages and distributed processes. We've defined how to bridge the gap between XQuery and Web services; now in closing the gap between the posited airline scenario and the XQuery/Web services solution, we'll hopefully demonstrate how many of the gaps in existing solutions are now bridged.

Recall that the basic problem STA faced could be solved in a discrete series of steps. All steps essentially revolved around the disparate data requirements at each point in the interaction: the client, the database, and the airline services. We'll take each in turn and build up to a total solution. The inputs to our scenario are the client's identification ($client-id) and request parameters ($city and $date).

More Stories By Jeff Dexter

Jeff Dexter is the lead architect of XML Query technologies at Raining Data Corporation, and their representative on the W3C?s XML Query working group. Jeff has spent the last six years in the field of information aggregation and database query, specifically focusing on the realm of XML query at Raining Data. Jeff was the designer and main implementer of the TigerLogic 1.0 high-performance query engine, and the architect and principal engineer on the TigerLogic 2.0 data server.

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.


@ThingsExpo Stories
It is of utmost importance for the future success of WebRTC to ensure that interoperability is operational between web browsers and any WebRTC-compliant client. To be guaranteed as operational and effective, interoperability must be tested extensively by establishing WebRTC data and media connections between different web browsers running on different devices and operating systems. In his session at WebRTC Summit at @ThingsExpo, Dr. Alex Gouaillard, CEO and Founder of CoSMo Software, presented ...
Most people haven’t heard the word, “gamification,” even though they probably, and perhaps unwittingly, participate in it every day. Gamification is “the process of adding games or game-like elements to something (as a task) so as to encourage participation.” Further, gamification is about bringing game mechanics – rules, constructs, processes, and methods – into the real world in an effort to engage people. In his session at @ThingsExpo, Robert Endo, owner and engagement manager of Intrepid D...
Recently, WebRTC has a lot of eyes from market. The use cases of WebRTC are expanding - video chat, online education, online health care etc. Not only for human-to-human communication, but also IoT use cases such as machine to human use cases can be seen recently. One of the typical use-case is remote camera monitoring. With WebRTC, people can have interoperability and flexibility for deploying monitoring service. However, the benefit of WebRTC for IoT is not only its convenience and interopera...
Michael Maximilien, better known as max or Dr. Max, is a computer scientist with IBM. At IBM Research Triangle Park, he was a principal engineer for the worldwide industry point-of-sale standard: JavaPOS. At IBM Research, some highlights include pioneering research on semantic Web services, mashups, and cloud computing, and platform-as-a-service. He joined the IBM Cloud Labs in 2014 and works closely with Pivotal Inc., to help make the Cloud Found the best PaaS.
Everything run by electricity will eventually be connected to the Internet. Get ahead of the Internet of Things revolution. In his session at @ThingsExpo, Akvelon expert and IoT industry leader Sergey Grebnov provided an educational dive into the world of managing your home, workplace and all the devices they contain with the power of machine-based AI and intelligent Bot services for a completely streamlined experience.
Cloud-enabled transformation has evolved from cost saving measure to business innovation strategy -- one that combines the cloud with cognitive capabilities to drive market disruption. Learn how you can achieve the insight and agility you need to gain a competitive advantage. Industry-acclaimed CTO and cloud expert, Shankar Kalyana presents. Only the most exceptional IBMers are appointed with the rare distinction of IBM Fellow, the highest technical honor in the company. Shankar has also receive...
Business professionals no longer wonder if they'll migrate to the cloud; it's now a matter of when. The cloud environment has proved to be a major force in transitioning to an agile business model that enables quick decisions and fast implementation that solidify customer relationships. And when the cloud is combined with the power of cognitive computing, it drives innovation and transformation that achieves astounding competitive advantage.
Personalization has long been the holy grail of marketing. Simply stated, communicate the most relevant offer to the right person and you will increase sales. To achieve this, you must understand the individual. Consequently, digital marketers developed many ways to gather and leverage customer information to deliver targeted experiences. In his session at @ThingsExpo, Lou Casal, Founder and Principal Consultant at Practicala, discussed how the Internet of Things (IoT) has accelerated our abilit...
In his session at Cloud Expo, Alan Winters, U.S. Head of Business Development at MobiDev, presented a success story of an entrepreneur who has both suffered through and benefited from offshore development across multiple businesses: The smart choice, or how to select the right offshore development partner Warning signs, or how to minimize chances of making the wrong choice Collaboration, or how to establish the most effective work processes Budget control, or how to maximize project result...
To get the most out of their data, successful companies are not focusing on queries and data lakes, they are actively integrating analytics into their operations with a data-first application development approach. Real-time adjustments to improve revenues, reduce costs, or mitigate risk rely on applications that minimize latency on a variety of data sources. In his session at @BigDataExpo, Jack Norris, Senior Vice President, Data and Applications at MapR Technologies, reviewed best practices to ...
Data is the fuel that drives the machine learning algorithmic engines and ultimately provides the business value. In his session at Cloud Expo, Ed Featherston, a director and senior enterprise architect at Collaborative Consulting, discussed the key considerations around quality, volume, timeliness, and pedigree that must be dealt with in order to properly fuel that engine.
In his keynote at 19th Cloud Expo, Sheng Liang, co-founder and CEO of Rancher Labs, discussed the technological advances and new business opportunities created by the rapid adoption of containers. With the success of Amazon Web Services (AWS) and various open source technologies used to build private clouds, cloud computing has become an essential component of IT strategy. However, users continue to face challenges in implementing clouds, as older technologies evolve and newer ones like Docker c...
"Akvelon is a software development company and we also provide consultancy services to folks who are looking to scale or accelerate their engineering roadmaps," explained Jeremiah Mothersell, Marketing Manager at Akvelon, 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.
Two weeks ago (November 3-5), I attended the Cloud Expo Silicon Valley as a speaker, where I presented on the security and privacy due diligence requirements for cloud solutions. Cloud security is a topical issue for every CIO, CISO, and technology buyer. Decision-makers are always looking for insights on how to mitigate the security risks of implementing and using cloud solutions. Based on the presentation topics covered at the conference, as well as the general discussions heard between sessio...
To Really Work for Enterprises, MultiCloud Adoption Requires Far Better and Inclusive Cloud Monitoring and Cost Management … But How? Overwhelmingly, even as enterprises have adopted cloud computing and are expanding to multi-cloud computing, IT leaders remain concerned about how to monitor, manage and control costs across hybrid and multi-cloud deployments. It’s clear that traditional IT monitoring and management approaches, designed after all for on-premises data centers, are falling short in ...
Organizations planning enterprise data center consolidation and modernization projects are faced with a challenging, costly reality. Requirements to deploy modern, cloud-native applications simultaneously with traditional client/server applications are almost impossible to achieve with hardware-centric enterprise infrastructure. Compute and network infrastructure are fast moving down a software-defined path, but storage has been a laggard. Until now.
DXWorldEXPO LLC announced today that the upcoming DXWorldEXPO | CloudEXPO New York event will feature 10 companies from Poland to participate at the "Poland Digital Transformation Pavilion" on November 12-13, 2018.
Digital Transformation is much more than a buzzword. The radical shift to digital mechanisms for almost every process is evident across all industries and verticals. This is often especially true in financial services, where the legacy environment is many times unable to keep up with the rapidly shifting demands of the consumer. The constant pressure to provide complete, omnichannel delivery of customer-facing solutions to meet both regulatory and customer demands is putting enormous pressure on...
The best way to leverage your CloudEXPO | DXWorldEXPO presence as a sponsor and exhibitor is to plan your news announcements around our events. The press covering CloudEXPO | DXWorldEXPO will have access to these releases and will amplify your news announcements. More than two dozen Cloud companies either set deals at our shows or have announced their mergers and acquisitions at CloudEXPO. Product announcements during our show provide your company with the most reach through our targeted audienc...
In an era of historic innovation fueled by unprecedented access to data and technology, the low cost and risk of entering new markets has leveled the playing field for business. Today, any ambitious innovator can easily introduce a new application or product that can reinvent business models and transform the client experience. In their Day 2 Keynote at 19th Cloud Expo, Mercer Rowe, IBM Vice President of Strategic Alliances, and Raejeanne Skillern, Intel Vice President of Data Center Group and ...