FluidDB is another database in the NoSQL category. It is a cloud based data store and follows the Wiki style approach for data storage. By Wiki style user can create objects in the FluidDB space and modify the existing one. Yet it uses a permission model which differentiates the it from being exact Wiki like.
FluidDB provides HTTP API interface with JSON and provides the HTTP Basic Authentication. FluidDB is in the early private Alpha stage and exposed to only limited number of users. A Sandbox is available where anyone can play with the database and for more detail look one can request the private access by sending the FluidDB Team a Mail request.
FluidDB is basically divided into four parts: 1)User 2)Namespace 3)Tag 4)Object. The User is the primary entity like in any other case. User will create Namespaces, Tags or Objects. Namespace is a logical name and physical separation which primarily describes the Subject the User is interested in like Movie, Sport, Book, etc. Tags are the attributes which describe the subject further in detail like Genre, Year and Awards Tags in Movies Namespace. Tags can exist without Namespaces also like Event, Hot, New can be used irrespective of the subject. Objects are the key entities as they contains actual data. An Object can be created with a String value like http://twitter.com/dhavaln or Die Hard With Vengeance as a topic which can be expressed in detail with various Tags.
An Object can be annotated with Tags from any User or any Namespace. By attaching a Tag to an Object user can provide additional information as a Tag Value for that Object like:
Object: Die Hard With Vengeance
As you can see same name can be used as a Namespace and as a Tag also. Tag may not contain any value alternatively known as Marker Tags.
FluidDB provides a simple query mechanism through which Objects can be search in the FluidDB space with Tag and Tag values. The following query will return all the Objects having Movie/Year value as 1995.
/Movie/Year = 1995
/Movie/Year > 1995 will return all Objects having Movie/Year value greater than 1995. There are many other conditional approaches provided by FluidDB for searching and can be found here.
Many developers has started using the interesting FluidDB and created API libraries for various languages which can be found here. I have already started using the database with JFluidDB and finding its usefulness in many cases.
The simple HTTP and JSON based interface makes FluidDB widely acceptable in many problem domains in various languages and frameworks.