This video continues an introduction to the Semantic Web. The idea of how data is stored in the Semantic Web framework was compared to the relational database model. The concept of 'open-data' was introduced. In an open-data model, the data is exposed as part of a global database, in a standardized way so that it can be combined with other data (information) and shared. The traditional relational database model embedded the meaning and the relationships in the software that runs on the server. You would have to know how the database was structured on any particular domain or website before you could use that data or information/knowledge. There was no standard way of encoding the meaning or the structure of the database. This meant that you had islands or silos of data or information and one website could not ask or use data that was on another website - unless a particular website happened to publish a way to interface with that database. Obviously no one is going to learn about how each of the millions of websites that have relational database back-ends are exposing their data.
The solution is to have a standard way of representing knowledge, data or information. This is the Resource Descriptive Framework (RDF). RDF allows for expressing explicit knowledge or explicit statements - later we will learn about how to infer more knowledge beyond what is explicitly stated. The RDF represents knowledge, information or assertions in the form of triples - Subject Predicate Object. This might be thought of in the same way as subject verb object, but that doesn't fit in all instances. I might say "Bruce knows Jean." That is a triple and it represents an explicit statement. Subject is Bruce, predicate is knows and object is Jean. I might also say "Person1 hasFirstName Bruce" and "Person1 hasLastName Whealton." This is a way of expressing using two triples, two facts about me. I have a first name of Bruce and in the next statement, I state that I have a last name of Whealton. This can also be represented in a graph format using ellipses and arrows.
