If you are reading this book, chance is you are a software engineer who makes a living by developing applications on the Web – or, more precisely, on the Web that we currently have.
This chapter is probably the most important chapter in this whole book: it covers RDF in detail, which is the building block for the Semantic Web. A solid understanding of RDF provides the key to the whole technical world that defines the foundation of the Semantic Web: once you have gained the understanding of RDF, all the rest of the technical components will become much easier to comprehend, and in fact, much more intuitive as well.
So far at this point, we have learned the concept of the Semantic Web, and we have learned RDF. Let us think about these two for a moment.
Recall that the vision of the Semantic Web is to add meaning into the current Web so machines can understand its contents. Based on what we have learned about RDF, we understand that RDF can be used to express the meaning of a Web document in a machine-processable way. More specifically, for a given Web document, we can create a set of RDF triples to describe its meaning and somehow indicate to the machine that these RDF statements are created for the machine to understand this document.
Even after you have read the previous two chapters carefully, you probably still have lots of questions that remain unanswered on your mind. This chapter is a natural continuation of those two chapters, especially Chap. 2. After reading this chapter, you will be able to find answers to most of your questions.
This chapter is a natural extension of the previous chapter. As a key technical component in the world of the Semantic Web, OWL is the most popular language to use when creating ontologies. In this chapter, we will cover OWL in great detail and after finishing this chapter, you will be quite comfortable when it comes to defining ontologies using OWL.
This chapter covers SPARQL, the last core component of the Semantic Web. With SPARQL, you will be able to locate specific information on the machine-readable Web, and the Web can therefore be viewed as a gigantic database, as many of us have been dreaming about.
At this point, we have learned the major technical components of the Semantic Web, and it is time for us to take a look at some real-world examples. Starting from FOAF is a good choice since it is simple and easy to understand, yet it does tell us a lot about how the Semantic Web looks like, especially in the area of social networking.
In last chapter we have studied FOAF project and the concept of semantic markup. Personal Web sites have made up a large portion of the current Web, and as we have discussed, FOAF ontology together with semantic markup has changed this large portion from linked Web documents into the Semantic Web.
In Chap. 7, we have discussed the topic about semantic markup. As we have concluded, semantic markup by the general public on the whole Web seems to be too challenging to implement. However, for a much smaller domain and scope, semantic markup is feasible, largely due to the fact that publishing and sharing a collection of core ontologies within this smaller domain is much more easier.
This chapter will provide one such example so that you can get a detailed understanding about when and where manually semantic markup can be a useful solution.
At the end of Chap. 7, we have discussed the topic about semantic markup. More specifically, it is possible to automatically generate markup documents for some Web content especially when there is pre-existing structured information contained in these content.
This chapter will provide one such example, and this is the popular DBpedia project. In fact, it is important to understand DBpedia, not only as an example of automatically generating structured data from Web content, but also because of its key position in the Web of Linked Data, as we will see in Chap. 11.
In Chap. 9 we have studied semantic wiki, where semantic information is manually added to the Web content. In Chap. 10, we have studied DBpedia project, where semantic documents are automatically generated. As we have discussed in Chap. 7, besides annotating the pages manually or generating the markup documents automatically, there is indeed another solution: to create a machine-readable Web all from the scratch.
Finally, with what you have learned from this book, you are now ready to start your own development on the Semantic Web.
To better prepare you for this work, we will present an overview in this chapter that covers two major topics. With the knowledge presented in this chapter, your future development work will start with a solid foundation.
Part of the previous chapter has presented an overview of available development frameworks you can use. This chapter will focus on Jena as a concrete example as well as our main development environment.
Developing applications on the Semantic Web requires a set of complex skills, yet this skill set does land itself on some basic techniques. In the previous chapter, we have learned some basics, and in this chapter, we will continue to learned some more.
The goal of this chapter is to continue showing you the How-To part on the Semantic Web. We will build two application examples, which are more complex than the ones we have created in the last two chapters. To some extent, none of these two applications here is final yet; it is up to you to make them more intelligent and powerful.
Liyang Yu
Backmatter
Metadaten
Titel
A Developer’s Guide to the Semantic Web
verfasst von
Liyang Yu
Copyright-Jahr
2011
Verlag
Springer Berlin Heidelberg
Electronic ISBN
978-3-642-15970-1
Print ISBN
978-3-642-15969-5
DOI
https://doi.org/10.1007/978-3-642-15970-1
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