14 Σεπτεμβρίου 2013

Μεταδεδομένα: μια εισαγωγή





video




Okay. So, now that I've hopefully gotten you excited about metadata, let's actually talk about what metadata is.
So, the most common and honestly, a little bit flippant definition of metadata is that it is data about data.
Which is a perfectly accurate definition, but it really doesn't tell you anything.
So, I don't generally like that definition.
I think we can do better.I think a better definition of metadata is that, metadata is description.
Which is pretty accurate as we ll, but it raises two more questions.
and the first question that this definition raises is, description of what?
And that's a practical question.And the second is a more philosophical question, which is, what does it mean to describe
something?
Now, I'm going to put off the philosophical question for the
next video segment, and just deal with the practical question.
Description of what now.
So, to answer this question, I'm going to give
you a slightly lame answer up front and then we'll fill in a better answer as we go along.
So, description of what. Description for anything.
Now, you can divide the world up in any number of ways.
two ways that we divide the world up in information science pretty frequently, are that the world is divided up into natural
objects and artificial objects.
The world's divided up into natural objects and artificial objects.
And very often in information science we deal with the distinction between physical and digital objects.
Right?
These are only two ways of dividing up the world that are pretty common in information science.
You can obviously divide the world up in any number of other ways, and that's very much a philosophical question.
Which I will stay out of.
But, what we're interested in here is what it means to describe any of these types of things.
So, when you describe something, you make a statement about it.
And just like making a statement in any natural language, you have the subject of the sentence.
You have the, the object, which is the thing that is acted upon by the subject.
And the predicate, which is the nature of the relationship between the subject and the object.
For example, the sky is blue.
Right? My name is Jeff. I am the subject. Jeff is the object.
And the relationship between the to is, is.
Right? We are going to come back to this three part relationship
later, once we start talking about how metadata schemas are created. the point now is just that, when you describe something.
The something is the subject, the sky.
Right? The descriptor, blue is the object.
So, when you provide a description of something,
you're providing information about that thing.
Description is information about something.
About anything, really, depending on what entities you think are important in the universe.
Right?
Information is what's used to describe things.
The thing being described may be natural or an artificial object.
A physical or a digital object.
Whatever.The thing may. Excuse me. The thing being described may be an information objects as well.
Right? Which brings us full circle back to our bad definition of what metadata is, which is data about data.
Now, you may have noticed that I just did a slight verbal slight of hand, just there.
I used the terms data and information more or less interchangeably.
And I want to point out that they're not interchangeable terms.
but I don't want to get into the question of what information is, versus data or anything else, just yet.
We will come to that before the end of this unit, but I want to leave that alone for the moment.
At any rate, metadata is data or information, about something.
Anything. Metadata provides information about something.
That something may be data or other information, which is recursive and kind of problematic.
And we'll deal with that problem later. Data about something is description of that something.
Now, of course, you can say things about other things that are not descriptive.Okay.
You can say things like, this side up. Which is not descriptive of this box for example.
This side up is a set of instructions for how to handle this box.
Right? They're instructions for how to use something.
Or this label. Which you see very frequently at least in the United States on the label of medicine bottles.
Right? Push down and turn, they're child locks, so kids can't get into your medicines.
Right? That's instructions for action. Or food labels.
The kind of food labels, again, that we see in the United States.
I don't know about where you live.
Store in a cool, dry place. Or refrigerate after opening.
Right? Those are instructions for how to preserve something, how to care for something. Their not necessarily descriptive.
I think you could argue though, that descriptive statements are
the simplest kind of things that you can say about something.
The sky is blue.
Right? My name is Jeffrey. Those are descriptive statements and
fairly simple descriptive. Alright? We'll get to other kinds of
non-descriptive statements that you can make in metadata
later.
But for now, let's just say metadata is description.
So, if metadata is description, the next question we have to ask is, what does it mean to describe something?
And that's the topic that I want to take up right now.

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