|By Gregory Burd, Kimbro Staken||
|May 26, 2005 01:00 PM EDT||
Developers tend to use the most familiar technologies. For data storage, that is the relational database. During design it's easy to see tables of data everywhere; however, not everything is relational in nature. When dealing with XML data or data easily expressed as XML, XQuery-based native XML databases (NXDs) present a viable and cost-effective alternative to relational databases, file system storage, or custom developed storage implementations. So, when is it time to consider an NXD?
Can native XML databases really provide a better answer for your data storage needs? In this article we'll examine some guidelines to help answer that question.
When to Consider a Native XML Database
- Do you have thousands of XML files?
- Is your XML data larger than 200MB?
- Are you trying to build a hierarchy into tables?
- Could your data change over time?
- Have you spent more that $100 on books explaining SQLXML?
The first two questions are practical in nature. If estimates indicate more than 1000 XML files or 200MB of XML data exist, the file system isn't the right tool for the job. File systems are not built to manage large numbers of files in a single directory or huge directory hierarchies. Managing concurrency, out of disk space conditions, and other common problems will plague your application unless you use a database.
The third reason to consider an NXD really has to do with the impedance mismatch between relational databases and XML data. Fundamentally, XML data is hierarchical and is a poor match for a relational database's rows and columns. Relational databases have always had a hard time modeling hierarchies. You'll find dozens of workarounds for this, but no real simple and efficient solution. Any XML-to-relational mapping tool will have to pick one of these techniques and manage this common case as best as possible. Regardless of the solution, performance will suffer. The end result will also be more brittle over time. Changing the structure of the data - which is easy, natural, and useful to do in XML - forces a redesign of the relational database and changes to the mapping layer. A single mapping mistake could completely skew an entire data set. As an XML document structure changes over time, it's possible for attributes to become elements, and vice versa. Over time, incremental changes to the logical structure of the XML data can force physical changes to the database, and wholesale dump and reload may be required of the relational system to keep pace.
Structured Yet Flexible Data
The fourth question suggests that requirements change over time, something true of most real world business systems. Once a relational database schema has been set in stone, only the database administrator (DBA) is qualified to change it without disrupting services. The contract between a relational database and the program that use it becomes the weakest link in the system. As requirements change, the DBA will spend endless hours mitigating the issues that arise. Contrast that with XML databases. XML is both structured and flexible. Even XML documents conforming to a DTD or XML Schema maintain a high degree of flexibility when compared to relational schemas. Most NXDs will optionally validate document structure. Even when document validation is not enforced, XML documents maintain a high degree of implicit structure. Therefore in either case, XML documents are flexible and structured and as a result the contract between the database and the programs using it is not brittle. It can withstand change without requiring a DBA.
Data Mapping Is Wasted Time, Money, and Effort
The last question is really a reality check. Take a second to consider the amount of time and money you've spent trying to make a solution workable. The best thing you can do when digging a hole is to stop digging and get out of the hole. With that in mind, let's look at SQLXML. If you need to mix and match SQL data and XML data, it's not a horrible way to go. However, if you view it as a way to squeeze XML into a relational system in which you've already invested, you might want to reconsider. You are going to pay a performance penalty for every document stored in terms of CPU and memory. Your ability to query, index, and optimize will be impacted as well. Executing XQuery against XML data mapped into relational tables will be hindered by the non-native storage format. An optimized native XML database won't have the same penalty.
Let's take a look at how to use an NXD to learn more about its advantages over a relational database.
Examples and Code
Berkeley DB XML is an open source XQuery implementation built atop the Berkeley DB transactional database system. It supports optimized XML storage, XQuery query planning, massive scale and concurrency, and is available for download as source code for multiple platforms and as a Windows installer from Sleepycat Software (www.sleepycat.com). Berkeley DB XML has also been integrated with Stylus Studio if you're more comfortable using an IDE for development. Berkeley DB XML is readily available to anyone, so we'll use it for the following examples.
First let's create an in-memory container for XML documents. Follow along using the "dbxml" command line provided with Berkeley DB XML.
Line 1 creates the container, while line 2 places a simple document into the container. The third line performs a query on the container returning each document that matches the XPath query /names/name[.=joe]. Finally it displays what we returned by the query statement.
dbxml> createContainer ""
dbxml> putDocument myDoc <names><name>joe</name><name>fred</
dbxml> query collection('')/names/name[.='joe']
That's all quite useful, but let's say that you need to access your XML storage programmatically. Because Berkeley DB XML is a library, and as such is linked into your application just as any other library would be, it does not incur the overhead of client/server communication. You interact with Berkeley DB XML using one of the supported language APIs. The primary one is C++, as the product is written in C++. Java, Python, Perl, PHP, and TCL are all supported API languages. Many other languages are supported by third parties and are readily available on the Internet.
With that in mind, let's next try some simple C++ code that calls for the same thing as the dbxml commands used in the previous example (see Listing 1).
The underlined sections of the code relate back to the first example. The first underlined section creates a container. This container is called 'test.dbxml,' and is on disk, and rather than in memory. The next underlined section places the same simple XML document into the new container. The last underlined section issues the query, and the while loop equates to the print statement. Put it all together and you have essentially the same result as before. In Java the code looks much the same; again the underlined areas are the common key sections of code (see Listing 2).
As you can see, the API is fairly straightforward and similar across languages. You'll note that the C++ and Java examples create a database on disk rather than in memory simply by giving the container a name.
Let's move back to the dbxml shell and try a more complicated example. This time let's add a few documents, so we can explore the performance of the system.
First let's populate an imaginary parts database.
That created an empty container and opened it as the default container in the shell. We can now use the putDocument command to run our XQuery and insert the sample data.
dbxml> createContainer parts
Creating document storage container
Things are being built upon cloud foundations to transform organizations. This CEO Power Panel at 15th Cloud Expo, moderated by Roger Strukhoff, Cloud Expo and @ThingsExpo conference chair, will address the big issues involving these technologies and, more important, the results they will achieve. How important are public, private, and hybrid cloud to the enterprise? How does one define Big Data? And how is the IoT tying all this together?
Oct. 31, 2014 07:45 AM EDT Reads: 1,853
We certainly live in interesting technological times. And no more interesting than the current competing IoT standards for connectivity. Various standards bodies, approaches, and ecosystems are vying for mindshare and positioning for a competitive edge. It is clear that when the dust settles, we will have new protocols, evolved protocols, that will change the way we interact with devices and infrastructure. We will also have evolved web protocols, like HTTP/2, that will be changing the very core of our infrastructures. At the same time, we have old approaches made new again like micro-services...
Oct. 31, 2014 07:00 AM EDT Reads: 1,617
The only place to be June 9-11 is Cloud Expo & @ThingsExpo 2015 East at the Javits Center in New York City. Join us there as delegates from all over the world come to listen to and engage with speakers & sponsors from the leading Cloud Computing, IoT & Big Data companies. Cloud Expo & @ThingsExpo are the leading events covering the booming market of Cloud Computing, IoT & Big Data for the enterprise. Speakers from all over the world will be hand-picked for their ability to explore the economic strategies that utility/cloud computing provides. Whether public, private, or in a hybrid form, clo...
Oct. 30, 2014 05:30 PM EDT Reads: 1,277
SYS-CON Events announces a new pavilion on the Cloud Expo floor where WebRTC converges with the Internet of Things. Pavilion will showcase WebRTC and the Internet of Things. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago. All major researchers estimate there will be tens of billions devices--computers, smartphones, tablets, and sensors – connected to the Internet by 2020. This number will continue to grow at a rapid pace for the next several decades.
Oct. 30, 2014 05:30 PM EDT Reads: 2,184
SYS-CON Events announced today that Gridstore™, the leader in software-defined storage (SDS) purpose-built for Windows Servers and Hyper-V, will exhibit at SYS-CON's 15th International Cloud Expo®, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Gridstore™ is the leader in software-defined storage purpose built for virtualization that is designed to accelerate applications in virtualized environments. Using its patented Server-Side Virtual Controller™ Technology (SVCT) to eliminate the I/O blender effect and accelerate applications Gridsto...
Oct. 30, 2014 02:00 PM EDT Reads: 2,558
SYS-CON Events announced today that Red Hat, the world's leading provider of open source solutions, will exhibit at Internet of @ThingsExpo, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Red Hat is the world's leading provider of open source software solutions, using a community-powered approach to reliable and high-performing cloud, Linux, middleware, storage and virtualization technologies. Red Hat also offers award-winning support, training, and consulting services. As the connective hub in a global network of enterprises, partners, a...
Oct. 30, 2014 12:15 PM EDT Reads: 2,065
As the Internet of Things unfolds, mobile and wearable devices are blurring the line between physical and digital, integrating ever more closely with our interests, our routines, our daily lives. Contextual computing and smart, sensor-equipped spaces bring the potential to walk through a world that recognizes us and responds accordingly. We become continuous transmitters and receivers of data. In his session at Internet of @ThingsExpo, Andrew Bolwell, Director of Innovation for HP’s Printing and Personal Systems Group, will discuss how key attributes of mobile technology – touch input, senso...
Oct. 30, 2014 12:00 PM EDT Reads: 1,728
The Internet of Things (IoT) is making everything it touches smarter – smart devices, smart cars and smart cities. And lucky us, we’re just beginning to reap the benefits as we work toward a networked society. However, this technology-driven innovation is impacting more than just individuals. The IoT has an environmental impact as well, which brings us to the theme of this month’s #IoTuesday Twitter chat. The ability to remove inefficiencies through connected objects is driving change throughout every sector, including waste management. BigBelly Solar, located just outside of Boston, is trans...
Oct. 30, 2014 11:00 AM EDT Reads: 2,174
Connected devices and the Internet of Things are getting significant momentum in 2014. In his session at Internet of @ThingsExpo, Jim Hunter, Chief Scientist & Technology Evangelist at Greenwave Systems, will examine three key elements that together will drive mass adoption of the IoT before the end of 2015. The first element is the recent advent of robust open source protocols (like AllJoyn and WebRTC) that facilitate M2M communication. The second is broad availability of flexible, cost-effective storage designed to handle the massive surge in back-end data in a world where timely analytics...
Oct. 30, 2014 08:00 AM EDT Reads: 1,570
Internet of @ThingsExpo Silicon Valley announced on Thursday its first 12 all-star speakers and sessions for its upcoming event, which will take place November 4-6, 2014, at the Santa Clara Convention Center in California. @ThingsExpo, the first and largest IoT event in the world, debuted at the Javits Center in New York City in June 10-12, 2014 with over 6,000 delegates attending the conference. Among the first 12 announced world class speakers, IBM will present two highly popular IoT sessions, which will take place November 4-6, 2014 at the Santa Clara Convention Center in Santa Clara, Calif...
Oct. 30, 2014 07:30 AM EDT Reads: 2,269
The Internet of Things (IoT) promises to evolve the way the world does business; however, understanding how to apply it to your company can be a mystery. Most people struggle with understanding the potential business uses or tend to get caught up in the technology, resulting in solutions that fail to meet even minimum business goals. In his session at Internet of @ThingsExpo, Jesse Shiah, CEO / President / Co-Founder of AgilePoint Inc., will show what is needed to leverage the IoT to transform your business. He will discuss opportunities and challenges ahead for the IoT from a market and tec...
Oct. 29, 2014 11:00 PM EDT Reads: 1,545
SYS-CON Events announced today that TeleStax, the main sponsor of Mobicents, will exhibit at Internet of @ThingsExpo, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. TeleStax provides Open Source Communications software and services that facilitate the shift from legacy SS7 based IN networks to IP based LTE and IMS networks hosted on private (on-premise), hybrid or public clouds. TeleStax products include Restcomm, JSLEE, SMSC Gateway, USSD Gateway, SS7 Resource Adaptors, SIP Servlets, Rich Multimedia Services, Presence Services/RCS, Diame...
Oct. 29, 2014 05:00 PM EDT Reads: 1,637
From a software development perspective IoT is about programming "things," about connecting them with each other or integrating them with existing applications. In his session at @ThingsExpo, Yakov Fain, co-founder of Farata Systems and SuranceBay, will show you how small IoT-enabled devices from multiple manufacturers can be integrated into the workflow of an enterprise application. This is a practical demo of building a framework and components in HTML/Java/Mobile technologies to serve as a platform that can integrate new devices as they become available on the market.
Oct. 29, 2014 02:15 PM EDT Reads: 2,068
SYS-CON Events announced today that O'Reilly Media has been named “Media Sponsor” of SYS-CON's 15th International Cloud Expo®, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. O'Reilly Media spreads the knowledge of innovators through its books, online services, magazines, and conferences. Since 1978, O'Reilly Media has been a chronicler and catalyst of cutting-edge development, homing in on the technology trends that really matter and spurring their adoption by amplifying "faint signals" from the alpha geeks who are creating the future. An...
Oct. 29, 2014 01:00 PM EDT Reads: 1,613
The Transparent Cloud-computing Consortium (abbreviation: T-Cloud Consortium) will conduct research activities into changes in the computing model as a result of collaboration between "device" and "cloud" and the creation of new value and markets through organic data processing High speed and high quality networks, and dramatic improvements in computer processing capabilities, have greatly changed the nature of applications and made the storing and processing of data on the network commonplace.
Oct. 29, 2014 10:00 AM EDT Reads: 2,050
SYS-CON Events announced today that Aria Systems, the recurring revenue expert, has been named "Bronze Sponsor" of SYS-CON's 15th International Cloud Expo®, which will take place on November 4-6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Aria Systems helps leading businesses connect their customers with the products and services they love. Industry leaders like Pitney Bowes, Experian, AAA NCNU, VMware, HootSuite and many others choose Aria to power their recurring revenue business and deliver exceptional experiences to their customers.
Oct. 29, 2014 10:00 AM EDT Reads: 2,123
The Internet of Things (IoT) is going to require a new way of thinking and of developing software for speed, security and innovation. This requires IT leaders to balance business as usual while anticipating for the next market and technology trends. Cloud provides the right IT asset portfolio to help today’s IT leaders manage the old and prepare for the new. Today the cloud conversation is evolving from private and public to hybrid. This session will provide use cases and insights to reinforce the value of the network in helping organizations to maximize their company’s cloud experience.
Oct. 29, 2014 09:00 AM EDT Reads: 2,084
As a disruptive technology, Web Real-Time Communication (WebRTC), which is an emerging standard of web communications, is redefining how brands and consumers communicate in real time. The on-going narrative around WebRTC has largely been around incorporating video, audio and chat functions to apps. In his session at Internet of @ThingsExpo, Alex Gouaillard, Founder and CTO of Temasys Communications, will look at a fourth element – data channels – and talk about its potential to move WebRTC beyond browsers and into the Internet of Things.
Oct. 29, 2014 08:00 AM EDT Reads: 1,647
SYS-CON Events announced today that Gigaom Research has been named "Media Sponsor" of SYS-CON's 15th International Cloud Expo®, which will take place on November 4-6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Ashar Baig, Research Director, Cloud, at Gigaom Research, will also lead a Power Panel on the topic "Choosing the Right Cloud Option." Gigaom Research provides timely, in-depth analysis of emerging technologies for individual and corporate subscribers. Gigaom Research's network of 200+ independent analysts provides new content daily that bridges the gap between break...
Oct. 28, 2014 11:45 PM EDT Reads: 1,684
The Industrial Internet revolution is now underway, enabled by connected machines and billions of devices that communicate and collaborate. The massive amounts of Big Data requiring real-time analysis is flooding legacy IT systems and giving way to cloud environments that can handle the unpredictable workloads. Yet many barriers remain until we can fully realize the opportunities and benefits from the convergence of machines and devices with Big Data and the cloud, including interoperability, data security and privacy.
Oct. 28, 2014 12:00 PM EDT Reads: 1,953