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their favorite channels provided by a service server in advance, and then the system
will transmit information for each user at regular intervals. Recently, several push
technologies, such as Pointcast 1.0
1)
and Castanet 2.0
2)
, have been developed. These
systems are not only applied to transmit text data but also hypertext and
hypermedia data. In these data broadcasting systems, where data at the server side
is often updated, one of the important problems is how to maintain the
temporal
consistency
of the transmitted data because not all the transmitted data is received
by the clients since client equipments are not always powered on. In this paper,
first, we will describe our new version control mechanism by which the temporal
consistency is kept at both the server and its clients
3,
4,
5)
.
Rapid progress in the Internet, especially Web technology, brought a powerful
information environment. Now, Web is regarded as the largest information resource.
The Web browsing operation is easy for computer users, but it is still difficult for
non computer users and ordinary TV audiences. Current Web browsers enforce
users to have knowledge about computer operations. In order to acquire necessary
information, users must
read and scroll
a Web page and
click and navigate
its
hyperlinks. We call such a user browsing interface a
read and click interface
. On
the other hand, TV audiences usually
watch and listen
to the TV programs in a
passive manner, and acquire necessary information. Our idea is to introduce the
passiveness
into Web data viewing environment
6,
7)
. We propose a new type of
Web viewing to obtain information from the Web. We call this interface a
watch
and listen
interface. The proposed watch and listen interface presents Web pages
like ordinary TV programs, where the content is presented by CG character's
speech and images appearing in Web pages.
Broadcasting-type information dissemination systems on the Internet are
becoming increasingly popular due to advances in the area of Web technology and
information delivery. One of the notable features of push-based, multiple-channel-
based information dissemination systems is to send information to users in a form
of time-series articles. Conventional information filtering method does not consider
well the
worth
of an article from the standpoint of the
time-series feature
. Finally,
in this paper, we will describe our new information filtering mechanism
9,
10)
which
considers the worth of an article compared with past delivered articles, that is,
their time-series features (freshness, popularity, and urgency).
2
A Version Control Mechanism for Data Braodcasting
Systems
2.1
Problems
In data broadcasting systems, contents are often updated and delivered periodically.
All versions of contents are stored on the server whenever they are changed, and
all versions received by clients are assumed to be stored in the clients. The clients
are not neccesarily able to receive all the versions since the clients are not always
