What is an information resource, anyway?
Wooden stumps, Moss, Norway
Robert Cerny asked me if I could write a blog entry on what an information resource really is, since the TMDM has little depth on it beyond the definition. So I figured I would dig into this a bit, since there is actually quite a lot to be said about it.
The concept of an information resource comes up in Topic Maps in connection with locators (that is, URIs), which reference information resources. So an information resource is what you get when you dereference a URI. Any sequence of bits is really an information resource, so this includes files, web pages, email messages, etc.
Standard web terminology talks about "resources", a concept that is not defined very clearly anywhere, but it's evidently a very wide concept, probably equivalent to the Topic Maps concept of a "subject". The TMDM uses the term "information resource" in order to make it clear that this is not the same thing as a resource. Interestingly, the web architecture recommendation independently uses the same term, with the same meaning.
Topic Maps also use the concept of information resources in connection with occurrences, because occurrences connect information resources to a topic. Another place where it crops up is in connection with subject locators, because topics with a subject locator represent the information resource referred to by that locator. Note that this actually implies that the topic is an instance of the (undefined) topic type "information resource".
It is at this point that some of the less obvious questions about information resources crop up, because if you use subject locators you are modelling information resources in your topic map, and need to make some ontological commitments about them. So Robert asks how information resources relate to concepts like "book", "movie", "document", etc. And this is not entirely obvious from the spec, it must be admitted.
Unfortunately, concepts like "book" and "document" are themselves not terribly precise, and so to really set this straight more precision is needed. At this point I like to refer to the FRBR conceptual model, which divides these concepts into four layers. (Note that Sam Oh did a presentation on FRBR and Topic Maps at Topic Maps 2008, which you may find interesting.) The layers are actually easiest to describe from the bottom up, so we'll start with the lowest layer:
- The lowest layer is item. An item is a physical representation of a document, so one example of this would be the Complete Works of William Shakespeare on my shelf. Note that here we really are talking about the particular dog-eared physical collection of paper on my shelf. If you manage to find an identical copy from the same print run in a second-hand book store that will be a different item.
- The layer above it is manifestation. This is a set of items, basically, so the identical copy example above would be another item from the same manifestation as my book. Any changes to the book, such as changing font size, changing the date of print, etc, would create a new manifestation. So the next edition of the book from the same publisher would most likely be a different manifestation.
- Above manifestation comes expression, which is a specific artistic rendering. So the text of, say, Hamlet in this book would be one expression of Hamlet. Changes to font size and suchlike would not change the expression, only the manifestation. A shortened version, or a translation, would be a different expression.
- And finally, at the top, we have work, which is the abstract concept that unifies all of the layers below. So Shakespeare's Hamlet, the play, is a work. Different translations and editions of the text all represent the same work, whereas movie adaptations, for example, would constitute new works.
So, where in this does information resource belong? At the lowest level, that of item. Information resource is really a subclass of what FRBR calls item, because many things are items (such as that Shakespeare book on my shelf) which are not information resources. Only sequences of bits are information resources.
Staircase, Oslo, Norway
Of course, in a practical ontology one typically would not include all of these layers. Usually, one works with just one of the layers. For example, the Italian opera topic map is firmly on the level of "work", since it models only the abstract works, and makes only statements that are completely independent of things like different expressions of the works.
However, there is often a certain conflation of the levels in practical applications. For example, my photo topic map uses subject locators, but ignores things like scaling (every photo is shown in three different sizes in the application), cropping (I don't make a new topic when I crop a photo), etc, and so one could argue that it's representing any of these four layers. In practice, this doesn't really cause any problems, and a certain pragmatism is common in cases like this.
So to return to the original question, how does information resource relate to book? Well, it doesn't really relate directly. A book is not an information resource, since it's a physical object, and not an electronic one. A PDF of the book's contents, however, might be an information resource. As for document, that's not the most precise of terms, but it probably belongs with manifestation above, and could be seen as a subclass of information resource.
URIs are used to refer to both information resources (which are downloadable over the net) and abstract concepts and physical objects (which are not)
Read | 2007-10-08 08:54
I've argued for a long time that the RTM vocabulary for mapping RDF to Topic Maps makes it possible to use RDF vocabularies in Topic Maps
Read | 2005-10-24 21:57
Marc de Graauw - 2008-06-04 07:07:14
'So an information resource is what you get when you dereference a URI. Any sequence of bits is really an information resource, so this includes files, web pages, email messages, etc.'
In WWW Arch parlance, as well as in Roy Fieldings thesis, the sequence of bits which you get from dereferencing an URI is called a 'representation'. 'Information resource' is a higher abstraction, though not always very well defined.
abdulalh Al-Rasheed - 2008-10-25 07:26:36
What's Main Concept of Information resouces ?
Fahad M Ali - 2013-03-26 07:21:09
I want the general difinition of information rerource....
Khaizarani Ibrahým bako - 2014-03-28 04:34:20
Why is it dt all informati÷ sources are information resource but not all information resorces are infor source
Jibrin Usman..B - 2014-06-22 16:56:47
Its because there are some information resource, that are not needed in the day to day either individual or organizations in the glob where information is seen as part of living in the present technological generation.. Since such information has nothing...
elmarie - 2015-05-20 10:54:02
What is the components of information resources.