Fluidinfo has a special tag known as the about tag.
When an application creates an object, it can (optionally) specify what it intends the object to be about. This is just a convention, but it is a highly useful one as it allows users and applications certainty as to what their tags will be associated with.
For example, suppose an application wishes to add new information about New York to Fluidinfo. While that information could be added to any object at all, it likely makes sense to put it somewhere where there is other information about New York. So an application might choose to create an object with an about tag with the value New York.
This is just an informal example. More likely, an application would put its information onto an object whose about tag had a more canonical value, for example http://en.wikipedia.org/wiki/New_York. Information about a book might be put onto an object about ISBN:0394705947. Other possibilities include NASDAQ:GOOG, user@hostname.com, user:jane, ip 88.221.11.50, WOEID 24865675, etc.
There are some special properties of the about tag:
Together, these properties ensure that applications have a way to find a permanent, useful, and canonical suggested place to put information about something.
The about tag is only useful if only one object can have any given about tag. Fluidinfo ensures that this condition is maintained. So when an application asks for the object about, e.g., country:france, it is guaranteed that the result is the only object with that about tag.
Because any about tag can be created by anyone, applications that follow the same about tag conventions do not need to wait for one another, to ask permission, or even to be aware of one another, before putting new information into its most natural location. This allows them to create data at their own pace, and guarantees that independent applications with information about the same thing can naturally put that information onto the same Fluidinfo object.
The about tag makes it simple to use Fluidinfo as a metadata engine for everything. It gives disparate applications and users an obvious canonical place to put information about the same thing.
You can ask Fluidinfo for the object about something, and immediately add any metadata or personalization data you like to that object. The Fluidinfo query language can be used to retrieve the object based on its shared tags.
Obvious conventions, such as using URLs or ISBN numbers as about tags, will arise quickly. You are also free to start your own.
In a sense Fluidinfo already has an object for everything. It’s just a matter of asking for it, at which point it will be created if it doesn’t already exist. In this way, Fluidinfo provides support for what has informally been called the web of things.
It should be emphasized that use of the about tag is optional. It is perfectly valid and common for applications to create objects that are not formally about anything. For example, an object that is used to hold information tying together other objects, or an object that is used for temporary storage.
There is also no reason why an application, or set of applications, could not start and use another tag for canonically identifying objects - and publicize their convention for others to adopt, or do it privately.
