טכנולוגיות אינטרנט מתפתחות - הווב הסמנטי ויישומיו - אייל סלע
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טכנולוגיות אינטרנט מתפתחות - הווב הסמנטי ויישומיו - אייל סלע
- 1. 0102/5/4 טכנולוגיות אינטרנט מתפתחות: הווב הסמנטי ויישומיו אייל סלע מנהל פרויקטים, איגוד האינטרנט הישראלי ומשרד ה- W3Cהישראלי www.w3c.org.il 1
- 2. j.mp/w3cdoc www.w3c.org.il 2
- 3. תוכן עניינים • מבוא - איגוד האינטרנט הישראלי ו-W3C • אודות ה-Semantic Web • דוגמאות www.w3c.org.il 3
- 4. אודות: איגוד האינטרנט הישראלי • שלוחת האיגוד הבינלאומי: • עמותה ללא מטרת רווח פועל לקידום האינטרנט והטמעתו בישראל כתשתית טכנולוגית, מחקרית, חינוכית, חברתית ועסקית. www.w3c.org.il 4
- 5. W3C ארגון בינלאומי • כ-053 ארגונים • פורום ניטראלי ליצירת תקני רשת באינטרנט. • משימה: • להוביל את הרשת למיצוי הפוטנציאל על ידי פיתוח פרוטוקולים וקווים מנחים שיאפשרו את צמיחתה לטווח ארוך. www.w3c.org.il 5
- 6. Semantic Web www.w3c.org.il 6
- 7. דף אינטרנט רגיל בנוי באופן שבני אדם יכולים להבין את תוכנו 4j.mp/w3cyd www.w3c.org.il 7
- 8. www.w3c.org.il 8
- 9. אבל המחשב יודע רק להציג את המידע. הוא אינו מבין איזה תוכן קיים בו. www.w3c.org.il 9
- 10. j.mp/w3cyd4 www.w3c.org.il 10
- 11. מטרת הווב הסמנטי היא לגשר את הפער www.w3c.org.il 11
- 12. Semantic web is about… machine interpretability of Web content applications can process the content of information instead of just presenting it to humans j.mp/w3cowl 12 www.w3c.org.il
- 13. תאור מידע, ברמת הקוד (כלומר, הוספת משמעות, סמנטיקה), כך שמכונות יכולות להבין את תוכנו. www.w3c.org.il
- 14. Machines can read information about me www.w3c.org.il 14
- 15. j.mp/b7cIO9 www.w3c.org.il 15
- 16. זהו בעצם מנגנון מוסכם (סטנדרט) לייצוג נתונים. www.w3c.org.il
- 17. הרשת הופכת מאוסף של מסמכים (שרק בני אדם מבינים) למאגר נתונים (שמכונות יכולות "להבין"). 71 www.w3c.org.il
- 18. נתונים ב-RDF XML דפי אינטרנט מאגרי נתונים j.mp/w3civan www.w3c.org.il
- 19. ....למשל 19 www.w3c.org.il
- 20. Decentralization: The Future of Online Social Networking you (will) have a personal Website, with your photos, your family tree, your business details, and aggregators then (will) turn this into added value by finding the links across the whole web. ]Economist 2008[ )illustration by David Simonds( j.mp/w3cweb 20 www.w3c.org.il
- 21. j.mp/w3civn j.mp/w3cfoafe 21 www.w3c.org.il
- 22. דוגמא there is a Person identified by http://www.w3.org/People/EM/contact#me, whose name is Eric Miller, whose email address is em@w3.org, and whose title is Dr. j.mp/w3crdf www.w3c.org.il 22
- 23. רגע. כשאומרים GivenNameמתכוונים לשם של אדם או אולי משתנה בתוכנה? www.w3c.org.il 32
- 24. ...לא יודע www.w3c.org.il 24
- 25. URIs לכן משתמשים ב www.w3c.org.il 25
- 26. http://xmlns.com/foaf/0.1/givenname The given name of some person. j.mp/9tGcBh www.w3c.org.il 26
- 27. These are known as Vocabularies set of URIs defined for some specific purpose (E.g. identify employees) www.w3c.org.il 27
- 28. Another person/program familiar with the Dublin Core vocabulary will know what is meant by this relationship. www.w3c.org.il 28
- 29. Let us put it together What we need for a Web of Data: use URI-s to publish data, not only full documents allow the data to link to other data characterize/classify the data and the links (the “terms”) to convey some extra meaning and use standards for all these! www.w3c.org.il
- 30. The semantic technology stack 30 www.w3c.org.il
- 31. דוגמאות 32 www.w3c.org.il
- 32. (RDFa) 33 www.w3c.org.il
- 33. www.w3c.org.il 34
- 34. www.w3c.org.il 35
- 35. RelFinder j.mp/w3cda2 www.w3c.org.il 36
- 36. ThisWeKnow j.mp/w3cda3 www.w3c.org.il 37
- 37. dbrec http://dbrec.net www.w3c.org.il 38
- 38. תודה אייל סלע eyal@isoc.org.il @isociltech @eyalsela www.w3c.org.il 39
Editor's Notes
- The ability to exchange information between different applications means that the information may be made available to applications other than those for which it was originally created .
- The Semantic Web is an evolution of the World Wide Web that, rather than just linking from one document to another, focuses on their meaning in relation to each other. Linked Data is a set of technologies to achieve this for data, creating a web of data.s
- 1identifying things using Web identifiers (called Uniform Resource Identifiers , or URIs ) Figure 1 illustrates that RDF uses URIs to identify: individuals, e.g., Eric Miller, identified by http://www.w3.org/People/EM/contact#me kinds of things, e.g., Person, identified byhttp://www.w3.org/2000/10/swap/pim/contact#Person properties of those things, e.g., mailbox, identified byhttp://www.w3.org/2000/10/swap/pim/contact#mailbox values of those properties, e.g. mailto:em@w3.org as the value of the mailbox property (RDF also uses character strings such as "Eric Miller", and values from other datatypes such as integers and dates, as the values of properties)
- Distinguish properties one person may use from different properties someone else may use that would otherwise be identified by the same character string. in Figure 4 , example.org uses "name" to mean someone's full name written out as a character string literal (e.g., "John Smith"), but someone else may intend "name" to mean something different (e.g., the name of a variable in a piece of program text). A program encountering "name" as a property identifier on the Web (or merging data from multiple sources) would not necessarily be able to distinguish these uses. However, if example.org writes http://www.example.org/terms/name for its "name" property, and the other person writes http://www.domain2.example.org/genealogy/terms/name for hers, it is clear that there are distinct properties involved (even if a program cannot automatically determine the distinct meanings) using URIrefs to identify properties enables the properties to be treated as resources themselves. Since properties are resources, additional information can be recorded about them (e.g., the English description of what example.org means by "name"), simply by adding additional RDF statements with the property's URIref as the subject.
- In the rest of the Primer, the term vocabulary will be used when referring to a set of URIrefs defined for some specific purpose, such as the set of URIrefs defined by RDF for its own use, or the set of URIrefs defined by example.org to identify its employees. ex:index.html dc:creator exstaff:85740 . the predicate dc:creator, when fully expanded as a URIref, is an unambiguous reference to the "creator" attribute in the Dublin Core metadata attribute set (discussed further in Section 6.1 ), a widely-used set of attributes (properties) for describing information of all kinds. The writer of this triple is effectively saying that the relationship between the Web page (identified byhttp://www.example.org/index.html ) and the creator of the page (a distinct person, identified byhttp://www.example.org/staffid/85740 ) is exactly the concept identified byhttp://purl.org/dc/elements/1.1/creator. Another person familiar with the Dublin Core vocabulary, or who finds out what dc:creator means (say by looking up its definition on the Web) will know what is meant by this relationship. In addition, based on this understanding, people can write programs to behave in accordance with that meaning when processing triples containing the predicate dc:creator. Of course, this depends on increasing the general use of URIrefs to refer to things instead of using literals; e.g., using URIrefs likeexstaff:85740 and dc:creator instead of character string literals like John Smith and creator. Even then, RDF's use of URIrefs does not solve all identification problems because, for example, people can still use different URIrefs to refer to the same thing. For this reason, it is a good idea to try to use terms from existing vocabularies (such as the Dublin Core) where possible, rather than making up new terms that might overlap with those of some other vocabulary. Appropriate vocabularies for use in specific application areas are being developed all the time, as illustrated by the applications described in Section 6 . However, even when synonyms are created, the fact that these different URIrefs are used in the commonly-accessible "Web space" provides the opportunity both to identify equivalences among these different references, and to migrate toward the use of common references.
- RDF is a datamodel for objects ("resources") and relations between them, provides a simple semantics for this datamodel, and these datamodels can be represented in an XML syntax. RDF Schema is a vocabulary for describing properties and classes of RDF resources, with a semantics for generalization-hierarchies of such properties and classes. OWL adds more vocabulary for describing properties and classes: among others, relations between classes (e.g. disjointness), cardinality (e.g. "exactly one"), equality, richer typing of properties, characteristics of properties (e.g. symmetry), and enumerated classes.
- In addition to the classic “Web of documents” W3C is helping to build a technology stack to support a “Web of data,” the sort of data you find in databases. The ultimate goal of the Web of data is to enable computers to do more useful work and to develop systems that can support trusted interactions over the network. The term “ Semantic Web” refers to W3C’s vision of the Web of linked data . Semantic Web technologies enable people to create data stores on the Web, build vocabularies, and write rules for handling data. Linked data are empowered by technologies such as RDF , SPARQL , OWL , and SKOS .