Databases Reference
In-Depth Information
4.1.3 EXAMPLES OF END-USER WEB DATA INTERFACES
We all interact with web data whenever we use Amazon or make an online booking, and most blogs
are implemented over a backend SQL database. However, sometimes the data are more 'up front,'
enabling one to see that there is a database behind the scenes.
One example of this is Swivel (see Figure
4.3
), which allows end-users to enter tabular data
and then visualize them using a variety of charts. The key 'web' feature of Swivel is the focus on
allowing users to share numeric and tabular data on the web just as pictures are shared in Flickr.
A similar application is Freebase (Figure
4.4
). It also allows users to enter and share data, but
unlike tabular data used in Swivel and Google docs, it is based on an ontology. That is, in Swivel
and Google docs, the meaning of the data in the tables is only available in human-readable form of
column headings. In contrast, in Freebase users can add data to standard base classes such as People
or Places, or they can create their own classes and relationships. This means that the data in Freebase
are linked to each other - if one user adds data on famous Latvian authors including their place of
birth, then the birth town can be linked to data that another user has entered about Latvian towns.
Structured data can also occur in web pages that are primarily intended to be human readable.
We have already mentioned micro-formats and will return to them later. However, anything that has
some form of structure can also be available as a data source. A well-known example is Wikipedia,
which is primarily designed for people to read. However, for certain sorts of pages, including those
describing places, airports and software applications, there is an 'info box' on the right-hand side
that has structured data. For example, Figure
4.5
shows the web page for the island of Tiree and in
the info box are its population, land area, and the local government authority.
