Category Archives: OWL

October 28, 2009

OWL news you can use

The W3C released OWL 2 today. Most readers of this blog are IT management people (whether they call it “cloud computing” or “boring old system management”) and don’t follow RDF, OWL, SPARQL etc too closely (if at all). Yet there is a lot of potential value in using these technologies for IT management, so I thought it might be helpful to provide some practical resources on the topic. I have selected articles that cover the special (some may say “twisted”) approach of using OWL and its friends for validation rather than just inference, as this use case is very relevant to IT management.

Of course you can also go to the W3C standard itself, starting with the overview of OWL 2.

Just so you don’t feel lonely if you decide to explore this path, have a look at Elastra’s sexy technology stack. ECML, EDML and EMML are all defined as OWL ontologies.

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Filed under Application Mgmt, Everything, IT Systems Mgmt, Mgmt integration, Modeling, OWL, RDF, Semantic tech, Specs, Standards

August 26, 2008

All I know about RDF/OWL I learned in preschool

I don’t want to seem pretentious, but back in preschool I was a star student. At least when it came to potatoes. I am not sure what it’s called in US preschools, but what we meant by a potato, in my French classroom, was an oval shape in which you put objects. The typical example had two overlapping ovals, one for green things and the other for animals. A green armchair goes in the non-overlapping part of the “green” oval. A lion goes in the non-overlapping part of the “animal” oval. A green frog goes in the intersection. A non-green bus goes outside of both ovals. Etc.

As you probably remember, there are many variations on this, including cases where more than two ovals overlap. The hardest part was when we had to draw the ovals ourselves as opposed to positioning objects in pre-drawn ovals: we had to decide whether to make these ovals overlap or not. Typically they would first be drawn separately until an object that belonged to both would come up, prompting some head-scratching and, hopefully, a redrawing of the boundaries. Some ovals were even entirely contained within a larger oval! Hours of fun! I loved it.

[Side note: meanwhile, of course, the cool kids were punching one another in the face or stealing somebody’s lunch money. But they are now stuck with boring million-dollar-a-year jobs as cosmetic surgeons or Wall Street bankers (respectively) while I enjoy the glamorous occupation of modeling IT systems. Who’s laughing now?]

To a large extent, these potatoes really are all you need to understand about RDFS and OWL classes. OO people, especially, are worried about “multiple inheritance”. But we are not talking about programmatic objects here, in which inheritance brings methods with it. Just about intersecting potatoes. Subclassing is just putting a potato inside another one. Unions and intersections are just misshaped potatoes made by following the contours of existing potatoes. How hard can all that be?

Sure there are these “properties” you’ve heard about, but that’s just adding an arrow to show that the lion is sitting on the armchair. Or eating the frog.

Just don’t bring up the fact that these arrows can themselves be classified inside their own potatoes, or the school bully (Alex Emmel) will get you.

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Filed under Everything, OWL, RDF, Semantic tech

May 19, 2008

At the Semantic Technology Conference this week

I am going to spend some time, starting tomorrow, at the 2008 Semantic Technology Conference in San Jose. I have a few ideas (on ways to use semantic technologies for IT management) that I am trying to validate, improve or kill, as appropriate. I will of course be interested in any discussion/presentation related to applying semantic technologies to IT management. But I am going there in a pretty open frame of mind. Peripheral vision is important when considering technology that is so generic in nature and that has been used in many different fields. In general, I am more interested in concrete projects, lessons learned, best practices etc than new raw technology. There is already a lot more raw semantic web technology available than we can hope to make use of in IT management anytime soon. The question is more around the best ways to practically and opportunistically deliver value in a field that has plenty of existing relational schemas, XML descriptors, semi-standard class models, semi-structured events and in-Joe’s-head-only domain knowledge nuggets floating around.

If you are going to go there and have any interest in the application of semantic technologies to IT management, I’d be happy to hook up.

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Filed under Conference, Everything, IT Systems Mgmt, OWL, RDF, Semantic tech

March 18, 2008

Ontology governance?

How do organizations that make heavy use of ontologies implement design-time governance?

A quick search tonight didn’t return much on that topic (note to Google: “governance” is not synonymous with “government”). Am I imagining a problem that doesn’t really exist? Am I too influenced by SOA governance use cases?

Sure, a lot of the pain that SOA governance tries to address is self-inflicted. When used to deal with contract versioning hell (hello XSD) and brittle implementations (hello stub generation), SOA governance is just a bandage on a self-shot foot. Thanks to the open-world assumption, deliberate modeling decisions (e.g. no ordering unless required), a very simple metamodel and maybe some built-in versioning support (e.g. owl:backwardCompatibleWith, owl:incompatibleWith, owl:priorVersion, owl:versionInfo, etc, with which I don’t have much experience), in the RDF/OWL world these self-inflicted wounds are a lot less likely.

On the other hand, there are aspects of SOA governance that are more than lipstick on a pig and it seems that some of those should apply to ontology governance. You still need to discover artifacts. You may still have incompatible versions. You still have to deal with the collaborative aspects of having different people responsible for different parts. You may still need a review/approval process, or other lifecycle aspects. And that’s just at the ontology design level. At the service level you have the same questions of discovery, protocol, query capabilities, etc.

What are the best practices for this in the semantic world? What are the tools? Or alternatively, why is this less important than I think?

Maybe this upcoming book will have some answers to these practical concerns. It was recommended to me by someone who reviewed a draft and had good things to say about it, if not quite as enthusiastically as Toru Ishida from Kyoto University (from the editorial reviews on Amazon):

“At the time when the world needs to find consensus on a wide range of subjects, publication of this book carries special importance. Crossing over East-West cultural differences, I hope semantic web technology contributes to bridge different ontologies and helps build the foundation for consensus towards the global community.”

If semantic technologies can bring world peace, surely they can help with IT management integration…

PS: if you got to this page through a Web search along the lines of “XSD versioning hell” I am sorry that you won’t find the solution to your problems here. Tim Ewald and Dave Orchard have recommendations for you. But the fact that XML experts like Tim and Dave have some kind of (partial) workarounds doesn’t mean the industry doesn’t have a problem. Or you can put your hopes in XSD 1.1 if you are so inclined (see these slides for an overview of the versioning-related changes).

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Filed under Everything, Governance, OWL, Semantic tech

March 7, 2008

Oracle semantic technologies resources

I have started to look at the semantic technologies available in Oracle’s portfolio and so far I like what I see. At HP, I had access to top experts on semantic technologies (mostly from HP Labs) but no special product (not counting Jena which is available to everyone). At Oracle, I find both top experts and very robust products. If you too are looking into Oracle’s offering related to semantic technologies, here are a few links to publicly-available resources that I have found useful. This is filtered based on my interests (yours may be different, for example I skip content related to life sciences applications).

The main page (and what should be your starting point on that topic) is the Semantic Technologies Center on OTN. Most of the other resources listed below are only a click or two away from there. The Semantic Technologies Forum is the right place for questions. The Semantic Web page on the Oracle Wiki doesn’t contain much right now but that may change.

For an overview of the semantic technology capabilities and their applicability, start with Semantic Data Integration for the Enterprise (white paper) and Why, When, and How to Use Oracle Database 11g Semantic Technologies (slides). Then look at Enterprise Semantic Web in Practice (slides) for many real-life examples.

When you are ready to take advantage of the Oracle semantic technologies capabilities, start with The Semantic Web for Application Developers (slides) followed by RDF Support in Oracle RDBMS (these are more detailed slides but they seem based on 10gR2 rather than 11g so not as complete, no OWL for example). Then grab a thermos of coffee and lock yourself in the basement for a while with the Oracle Database Semantic Technologies Developer’s Guide (also available as a hundred-page PDF).

At that point, you may chose to look into the design choices (with performance analysis) that where made in the Oracle implementation by reading A Scalable RDBMS-Based Inference Engine for RDFS/OWL. There is also a Wiki page on OWLPrime to describe the subset of OWL supported in 11g. Finally, you can turn to the Inference Best Practices with RDFS/OWL white paper for tuning tips on 11g.

To get the actual bits, you can download the Oracle 11g Database on OTN. The semantic technologies support is in the Spatial option for the database, which is included in the base download.

I will keep updating this page as interesting new resouces are created (or as I discover existing ones). For resources on semantic technologies in general (non Oracle specific) good sources are Dave Beckett’s page, the W3C (list of resources or standardization activities) or the Cover Pages.

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Filed under Everything, Oracle, OWL, RDF, Semantic tech