Research of Ontology Building in Semantic Web

The Semantic Web is a web of data and is about two things (Ivan Herman et al., 2010). One is common formats for integration and combination of data drawn from diverse sources. Another is about language for recording how the data relates to real world objects. In simple terms it provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries. Fig. 1 shows the Semantic Web layer cake. The philosophy was thought up by Berners-Lee.

The Web is a system interlinking lots of documents via the Internet.In the Web, people can read lots of books, watch the online TV, publish contents in blogs and so on.
The Semantic Web is a web of data and is about two things (Ivan Herman et al., 2010).One is common formats for integration and combination of data drawn from diverse sources.Another is about language for recording how the data relates to real world objects.In simple terms it provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries.Fig. 1 shows the Semantic Web layer cake.The philosophy was thought up by Berners-Lee.
Where, the Table 1 describes the specifications each layer.

Ontology
Ontology as a branch of philosophy is the science of what is, of the kinds and structures of the objects, properties and relations in every area of reality(Smith Barry et al., 2003, 155-166).Each scientific field will of course have its own preferred ontology, defined by the field's vocabulary and by the canonical formulations of its theories.Ontologies play an important role in fulfilling semantic interoperability as described in the seminal article on the Semantic Web (Berners-Lee et al., 2001, pp.35-43).
Why Ontology is so essential in the Semantic Web?The first reason is that the search for XML, RDF and RDFS have being rather ripper, which provided the language basis.Another reason is that the upper projects, researched on rules, logic framework, proof and trust, could not get improving smoothly and quickly without the support of Building Ontology.However, it is a hard work and needs a lot of research by scholars and engineers.In all the difficulties, what is the most important?
The answer is how to build a available Ontology.Meantime, it must to meet five rules, veracity and objectivity, integrity, consistency, extensibility and the least restriction (Peng Bo, 2009Bo, , pp.2610Bo, -2611)).

Double-Channel Helix Methodology
Nowadays, there are many methodologies of Ontologies building, e.g., methodology by Ushold and King for Enterprise Ontology, METHONTOLOGY, On-To-Knowledge Methodology and so on (AIAI et al., 2003;Fermandez-Lopez et al., 1999, pp.37-46;Staab et al., 2001, pp.26-34).But un-commonality is the important limitation.Fig. 2 shows a Double-Channel Helix Methodology, a better methodology.Its process of Ontology building is step-and-step.It has two "channel", each of which can make the process be shifted backward or forward.Considering from the engineering theory of ontologies building, the methodology is satisfied to people's acknowledge and logic thinking.

Semantic Web knowledge
In this layer, the Semantic Web, next generation of the World Wide Web, will consist of data defined and linked in such a way that it can be used for effective discovery, automation, integration, and reuse across various applications (S.Bechhofer et al., 1999, pp.33-36).Moreover, the distributed and dynamic character of the Semantic will cause that many versions and variants of Ontology knowledge will arise.To build a real Semantic Web, it is essential that the knowledge that is represented in the different versions of ontologies is interoperable.

Conception Extraction
The extraction of conception in the Semantic Web is not an easy task.It requires skills and is still an art rather technology.As below, it shows a method.
Firstly, we have to gather all conception in brain storming, by clustering collected and by investigating refined.Though this step, decide the scope defined for conceptions in the Semantic Web.Secondly, make sure the attribution of every conception.Select a natural word which one meaning for each concept.If there is no accessible word for representing a concept, then create a new one.Thirdly, sum up the relation between the different conceptions.Organize these concepts in an is-a hierarchy.
In practice, these three steps are done not in a waterfall manner.Users can go back and forth during the process.

Tools Chosen
Sincerely, many of tools has been developed for enterprises, which include mainly Ontolingua, Ontosaurus, WebOnto, WebODE, OntoEdit, OILEd, Protégé and so on.All tools are assistant well for Ontology to edit, modify, explore and maintain.In Table 2 (Wang Chang-xia et al., 2009, pp.26-28, 31) , it shows the scheme of key identification among seven tool.Users should select an available tool for Ontology building and even that choose the different tools for different stage to finish task better.

Ontology Building
Edit the coding about the conceptions, attributes and relations using the basic elements, e.g.Class, Property, subClassOf, subPropertyOf and so on.Finally, provide main interface for Ontology merging, Ontology mapping, Ontology translation resolution in the next stage.

Ontology Evaluation
Same to software engineering, Ontology needs also to evaluate.However, there is no authoritative software to detect new Ontology building.Recently, it is evaluated by extensibility, visibility and inferenceability and so on.Finally, if new Ontology building does not meet standards, the process will be shifted backward continuing loop.Otherwise, the process of Ontology building ends.

Conclusion
After analyzing the limitations of traditional methodology on Ontology building, the author give a better Double-Channel Helix model.Of course, there are something worthy to refine in the further task.
Table 1.The description of the Semantic Web Layer Cake

URI Uniform Resource Identifiers
This layer makes sure of providing the uniform identifiers of lots of resource.It likes the strings starting with "http:" or "ftp:" that often find on the World Wide Web.

Unicode
This layer provides the uniform standards for all kinds of languages in the world to coding characters.

XML
Extensible Markup Language XML replaces HTML for its individual advantages.In addition, it gives a definition on the methods describing data.

Namespace
This layer provides many ways to differentiate names, so the resources which have same names and different means are still used.

RDF M&S
Resource Description Framework

Model and syntax
Here reserve specifications refer to model and syntax of RDF.

RDF Schema Resource Description Framework Schema
It is a kind of languages for describing RDF vocabularies and has some basic elements, e.g.Resource, Class, Property, subClassOf, subPropertyOf, range, domain.

Ontology
It is a formal, explicit specification of a shared conceptualization.It need to make sure all knowledge can be known by people and computer.

Rules
Many principles or regulations between the upper and the lower in the level structure; Logic Framework It provides a logic inferenceability on the knowledge of Ontology describing.

Proof
On being logic inferenceability, give a proof on whether a statement is right or wrong.
Trust Detect whether the web information is trusted or not.

Signature
A method to make sure the environment more safety Encryption A method to make the environment more safety

Table 2 .
The comparison on the Ontology building tools