Databases Reference
In-Depth Information
Figure 9: Unpack and Pack
different schemes to query and restructure data and to specify the layout of the
result. For example, typical Web application development environments require
the user to use SQL for query specification and offer visual tools for designing the
layout of the result.
In contrast, InfoWeaver/AQUA provides a visual facility which amalgamates
those tasks. The interface looks like just a common authoring tool for HTML and
SMIL documents: The user is only required to drag and drop data objects shown
in windows into a blank window named the
Canvas
. He can put data objects
anywhere he likes, and specify the size of data objects with mouse operations. It is
a feature of AQUA that the user can designate an existing data object as an
example
.
Then, the data object (the example) serves as the representative of a set of data
objects. A drag-and-drop operation of the example is interpreted as manipulation
of the set of data objects. Therefore, the object-at-a-time authoring framework
and the set-at-a-time data manipulation (querying and restructuring) framework
are integrated in a seamless way.
In AQUA, a
DataBox
is used to display a set of data objects stored in the
underlying information sources. Figure 10(a)(b)(c) shows example DataBoxes.
The DataBox (a) is used to display the relation GAME_VIDEO. In this case, the
display unit is a tuple. The user can click the Next and Previous buttons to browse
other tuples in the relation. The DataBoxes (b) and (c) are used to display Web
pages in the baseball information Web site. In this case, each DataBox is associated
with one or more Web pages. The display unit is a Web page. The Web page(s) to
be displayed is designated either by specifying a URL or by using a querying facility
to gather Web pages. On the screen, there are also
Palettes
(Figure 10(d)) and
Canvas
(Figure 10(e)). Palettes contain decorative objects to be used in Web page
design. The Canvas is a blank window into which the user can drag-and-drop
data objects from the DataBoxes and Palettes.
A set of objects an example represents is called the
target set
. As a default, the
target set is defined as a set of objects each of which appears at the same position
on a page as the example object. The user can change the default target set by
specifying 'Another' example objects.
When the user specifies multiple examples (and their target sets), he often has
