- Ubiquitous Computing
- Web Services
- The Semantic Web
- Spaces Computing
- Peer-to-Peer Computing
- Collaborative Computing
- Dependable Systems
- Security
- Languages
- Pervasive Computing
- Cluster Concepts
- Distributed Agents
- Distributed Algorithms
- Distributed Databases
- Distributed Filesystems
- Distributed Media
- Distributed Storage
- Grid Computing
- Massively Parallel Systems
- Middleware
- Mobile and Wireless Computing
- Network Protocols
- Operating Systems
- Real-Time and Embedded Systems
- Commentary
- Endnotes
This chapter is from the book
This chapter is from the book
This chapter is from the book
The Semantic Web
The Semantic Web will bring structure to the meaningful content of Web pages, creating an environment where software agents, roaming from page to page can readily carry out sophisticated tasks for users.
—Tim Berners-Lee, et al.
Homo sapiens is a culture-creating species. Our social expressions serve to reduce our needs, individually and institutionally. A hierarchy of needs, identified by Abraham Maslow,[5] is as applicable to institutions as it is to individuals, as a benchmark of cultural provisioning. Language, traditions, economics, and social and political arrangements, all reflect need-reduction epistemologies, which run the gamut from physical survival at the bottom of the pyramid to self-actualization at the summit. Each successive step in the virtuous climb toward a shared peak involves creation of a shared meaning, which itself constitutes an abstract fitscape: culture and meaning.
According to clinical psychologist Paul Watzlawick, the question of whether there is order in our shared reality has one of three possible answers:
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There is no order, in which case reality is tantamount to confusion and chaos, and life is a psychotic nightmare.
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We relieve our existential state of disinformation by inventing an order, forgetting that we have invented it and experiencing it as something "out there" that we call reality.
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There is an order. It is the creation of some higher Being on whom we depend but who Himself is quite independent of us. Communication with this Being, therefore, becomes man's most important goal.[6]
Either there is order or there is not. If there is not, we perceptively impose order. If there is, we discern it. But in either case, the point Watzlawick makes should be clear with respect to semantics: meaning too is either something we create by perception or something we similarly discern. Regardless, there is a cultural imperative to articulate meaning in such a manner as to facilitate communication.
Although human communication mechanisms are highly redundant and equally ambiguous, the paradoxical nature of communication itself, the handmaiden of culture, never seems to prevent heroic attempts to engineer to its essence. The Semantic Web is perhaps the most ambitious of such efforts to date.[7]
Semantic Web activities, chartered by the W3C, proffer and articulate the following general layers of software, which would ostensibly lead to a meaningful realization of the vision:
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XML— eXtensible Markup Language
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RDF— Resource Description Framework
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Ontologies— Formal definitions of relationship
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Agent— An agent language providing for exchange of proofs (i.e., trust)
In specifying data that can self-describe, XML provides data portability. It was proposed in 1996 by John Bosak of Sun Microsystems and accepted for standardization by the W3C, partially in response to proprietary extensions to HTML that resulted from the now-historic browser conflict of that era.[8] As a language describing language for portability, XML is misnamed. The language would more accurately be described by its ability to provide a basis for the creation of portable metadata—stories about the stories that data would tell.
RDF builds upon XML, providing a framework for representing that metadata. RDF does not require XML, per se. The specification for RDF is not bound to XML, though XML can (and likely will) be used for implementation of the RDF model. The ultimate goal of RDF is to enable the automation of activities (such as discovery) that are germane to dynamic, ad hoc assemblies of data and behavior.
A standardized metadata framework is not yet enough. Once we can portably express meaning, meaning must be meaningfully expressed as ontologies. Ontologies are collections of information that provide an organizational basis for expression.
The term ontology, borrowed from philosophy and referring to a theory regarding the nature of existence, implies a study and classification of that which exists. AI research uses the word to mean a collection of formally defined relations among terms, the most common being a set of inference rules and a taxonomy therein. (A taxonomy specifies classes of objects and relations among them; for example, an address may contain a street, a street number, a city, a zone, a nation, and so on.)
The term ontology, borrowed from philosophy and referring to a theory regarding the nature of existence, implies a study and classification of that which exists. AI research uses the word to mean a collection of formally defined relations among terms, the most common being a set of inference rules and a taxonomy therein. (A taxonomy specifies classes of objects and relations among them; for example, an address may contain a street, a street number, a city, a zone, a nation, and so on.)
Once data can be represented in a standard manner and organized to provide a basis for common semantic agreement, we can realize the potential of NDC by dynamically knitting together meaningful collections of information, thereby yielding levels of services heretofore only imagined. Widespread, standardized, distributed agents can become viable. Knowledge management, edge-to-edge services, integrated information pools—with the realization of the Semantic Web, the foundation of ubiquitous computing itself is theoretically in place.