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Claims  |
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What is claimed is:
1. A system for delivering Web content over a broadcast medium, comprising:
a webcast center to actively gather Web content from sites on the Internet
by visiting the sites and fetching content from the sites, the webcast
center storing the gathered Web content, the webcast center having a
broadcast transmitter to transmit the gathered Web content over the
broadcast medium; and
multiple clients equipped with filters to receive a portion of the gathered
Web content from one or more selected sites; and
wherein the Web content comprises Web pages, and a packager is configured
to organize the pages in alphabetical order according to their URLs
(Universal Resource Locator) and to form package files that contain pages
from same sites.
2. A system as recited in claim 1, wherein the webcast center is configured
to continuously gather the Web content.
3. A system is recited in claim 1, wherein the webcast center actively
gathers the Web content by retrieving a Web page at a root URL (Universal
Resource Locator) and any additional Web pages within a Predetermined
depth below the root URL.
4. A system as recited in claim 1, wherein the webcast center gathers Web
pages and any in-line image files referenced by the Web pages.
5. A system as recited in claim 1, wherein the packager packages the Web
content in the content cache into broadcast package files, and wherein the
webcast center further comprises:
a content cache to store the Web content gathered from the sites; and
a package store to store the broadcast package files prior to broadcast
transmission.
6. A system has recited in claim 1, wherein the webcast center has a
scheduler to schedule the sites and times to actively gather the Web
content from the Internet.
7. A system as recited in claim 1, wherein each client has a subscription
database to store a user's Web content preferences, the subscription
database being utilized by the client's filter to selectively receive the
preferred Web content.
8. A system as recited in claim 1, further comprising a content server
configured to receive the broadcast Web content and to serve the Web
content to one or more of the clients.
9. A system for delivering Web content over a broadcast medium, comprising:
a webcast center to actively gather Web content from sites on the Internet
by visiting the sites and fetching content from the sites, the webcast
center storing the gathered Web content, the webcast center having a
broadcast transmitter to transmit the gathered Web content over the
broadcast medium;
multiple clients equipped with filters to receive a portion of the gathered
Web content from one or more selected sites; and
wherein:
the broadcast transmitter at the webcast center transmits the Web content
in individual packages; and
each client has an unpackager to reconstruct the Web content from the
packages, the unpackager being configured to determine whether the Web
content received from the webcast center is more recent than any Web
content from an identical site that may already be stored on the client.
10. A system for delivering Web content over a broadcast medium,
comprising:
a webcast center to actively gather Web content from sites on the Internet
by visiting the sites and fetching content from the sites, the webcast
center storing the gathered Web content, the webcast center having a
broadcast transmitter to transmit the gathered Web content over the
broadcast medium;
multiple clients equipped with filters to receive a portion of the gathered
Web content from one or more selected sites; and
wherein each client has an annotator configured to annotate hyperlinks
within the Web content to differentiate among first hyperlinks that access
content not stored locally at the client and second hyperlinks that access
content stored locally at the client.
11. A webcast center comprising:
a gatherer to actively gather Web content from sites on the Internet by
visiting the sites and fetching content from the sites;
a content cache to store the Web content actively gathered from the sites
by the gatherer;
a packager to package the Web content stored in the content cache into
broadcast package files;
a package store to store the broadcast package files prior to broadcast
transmission;
a broadcast transmitter to segment the package files from the package store
into individual packages and transmit the packages over a broadcast
medium; and
wherein:
the gatherer retrieves the Web content from the sites and stores the Web
content in the content cache at a first data rate; and
the broadcast transmitter transmits the packages from the package store at
a second data rate different from the first data rate.
12. A webcast center as recited in claim 11, wherein the broadcast
transmitter continuously transmits the package files in the package store
multiple times before the packager updates the package files in the
package store.
13. For use in a system for delivering Web content in individual data
packages over a broadcast medium to multiple clients, a package handling
unit at each of the clients comprising:
a receiver to reconstruct package files from the data packages;
a package store to temporarily hold the package files containing the Web
content; and
an unpackager to reconstruct the Web content from the package files, the
unpackager being configured to determine whether the Web content received
in the package files from the broadcast medium is more recent than any
duplicative Web content that may already be stored at the client as a
result of the client retrieving the duplicative Web content from a same
Web site from which the Web content in the package files came.
14. For use in a system for delivering Web content over a broadcast medium
to multiple clients, an annotator program executing on each of the clients
to annotate hyperlinks within the Web content to differentiate among first
hyperlinks that access content not stored locally at the client and second
hyperlinks that access content stored locally at the client.
15. An annotator program as recited in claim 14, further configured to
annotate the hyperlinks to differentiate among third hyperlinks that have
been actuated at least one by a user at the client.
16. A system for delivering Web content over a broadcast medium,
comprising:
(A) a webcast center comprising:
(1) a gatherer to actively gather Web content from sites on the Internet by
visiting the sites to retrieve the Web content;
(2) a scheduler to schedule for the gatherer the sites and times to
actively gather the Web content;
(3) a content cache to store the Web content gathered from the sites by the
gatherer;
(4) a packager to package the Web content stored in the content cache into
broadcast package files;
(5) a package store to store the broadcast package files; and
(6) a broadcast transmitter to segment the package files from the package
store into individual packages and transmit the packages over a broadcast
medium;
(B) a client comprising:
(1) a receiver to receive the broadcast packages;
(2) a subscription database to store a directory of the Web content
gathered by the webcast center;
(3) a subscriber user interface executing at the client to enable a user to
select preferred Web content from the directory of the subscription
database;
(4) a filter to direct the receiver to accept the packages carrying the
preferred Web content selected by the user, while rejecting other packages
carrying non-preferred Web content, and to reconstruct the package files
from the accepted packages;
(5) a client-side package store to temporarily hold the package files
received by the receiver; and
(6) an unpackager to determine whether the Web content in the package files
received from the broadcast medium is more recent than any other version
of the Web content that may already be stored at the client.
17. A system as recited in claim 16, wherein the gatherer is configurable,
for each of the sites, to gather a home Web page at a root URL (Universal
Resource Locator) and any additional Web pages within a predefined depth
below the root URL.
18. A system as recited in claim 16, wherein the gatherer is configured to
retrieve Web pages and any in-line image files referenced by the home Web
pages.
19. A system as recited in claim 16, wherein:
the gatherer retrieves the Web content from the sites and stores the Web
content in the content cache at a first data rate; and
the broadcast transmitter transmits the packages from the package store at
a second data rate different from the first data rate.
20. A system as recited in claim 16, wherein the broadcast transmitter
continuously transmits the package files in the package store multiple
times before the packager updates the package files in the package store.
21. A system as recited in claim 16, wherein the webcast center further
comprises an announcement generator to send announcements informing the
client of the Web content to be transmitted in future broadcast
transmissions.
22. A system as recited in claim 16, wherein the client further comprises
an annotator to annotate hyperlinks within the preferred Web content, the
annotated hyperlinks differentiating between first hyperlinks that access
content not stored locally at the client and second hyperlinks that access
content stored locally at the client.
23. A method for delivering Web content to clients, comprising:
actively gathering the Web content from sites on the Internet by visiting
the site to retrieve the Web content;
storing the Web content in a first cache;
packaging the Web content from the first cache into package files;
storing the package files in a second cache;
broadcasting the package files from the second cache over the broadcast
medium; and
receiving the package files at a client;
filtering the package files to retain files containing the Web content
preferred by a user;
reconstructing the preferred Web content from the retained package files;
and
annotating hyperlinks within the Web content to differentiate among first
hyperlinks that access content not stored locally at the client and second
hyperlinks that access content stored locally at the client.
24. A method as recited in claim 23, further comprising retrieving, at each
of the sites, a Web page at a root URL (Universal Resource Locator) and
any additional Web pages within a predetermined depth below the root URL.
25. A method as recited in claim 23, further comprising retrieving Web
pages and any in-line image files referenced by the Web pages.
26. A method as recited in claim 23, further comprising scheduling the
sites and times to gather the Web content from the Internet.
27. A method as recited in claim 23, further comprising gathering the Web
content at a first data rate and broadcasting the package files at a
second data rate that is different from the first data rate.
28. A method as recited in claim 23, further comprising examining the
preferred Web content after reconstructing to determine whether the Web
content is more recent than any other version of the Web content that may
already be stored at the client.
29. In a system for delivering Web content over a broadcast medium from a
webcast center to multiple clients, a computer-implemented method for
cumulating Web content at the webcast center comprising instructions for:
gathering the Web content from sites on the Internet by visiting the site
to retrieve the Web content;
storing the Web content in a first cache;
packaging the Web content from the first cache into package files;
storing the package files at a second cache;
gathering the Web content from the sites; and
storing the Web content in the content cache at a first data rate that is
different from and independent of a second data rate at which the packages
from the package store are transmitted over the broadcast medium.
30. A computer-implemented method as recited in claim 29, further
comprising:
segmenting the package files from the package store into individual
packages; and
transmitting the packages over a broadcast medium.
31. A computer-implemented method as recited in claim 29, further
comprising transmitting the packages multiple times between updating the
Web content in the package files.
32. In a system for delivering Web content over a broadcast medium from a
webcast center to multiple clients, a computer-implemented method
comprising annotating, at a client, hyperlinks within the Web content to
differentiate among first hyperlinks that access content not stored
locally at the client and second hyperlinks that access content stored
locally at the client.
33. A method as recited in claim 32, further comprising annotating the
hyperlinks to differentiate among third hyperlinks that have been actuated
at least one by a user at the client.
34. A computer-readable medium having computer-readable instructions for
performing the method recited in claim 32. |
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Claims |
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Description |
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TECHNICAL FIELD
This invention relates to systems and methods for delivering Web related
information over a broadcast medium. This invention further relates to
computer devices and software used to implement aspects of the systems and
methods.
BACKGROUND OF THE INVENTION
Public networks, and most notably the Internet, are emerging as a primary
conduit for communications, entertainment, and business services. The
Internet is a network formed by the cooperative interconnection of
computing networks, including local and wide area networks. It
interconnects computers from around the world with existing and even
incompatible technologies by employing common protocols that smoothly
integrate the individual and diverse components.
The Internet has recently been popularized by the overwhelming and rapid
success of the World Wide Web (WWW or Web). The Web links together various
topics in a complex, non-sequential web of associations which permit a
user to browse from one topic to another, regardless of the presented
order of topics. The Web is rapidly evolving as a standard for
distributing, finding, and accessing information of any type. A "Web
browser" is an application that executes on the user's computer to
navigate the Web. The Web browser allows a user to retrieve and render
hypermedia content from the WWW, including text, sound, images, video, and
other data.
The amazing growth rate in the demand for data over the Internet is partly
due to an increasing audience. The World Wide Web has crossed the
threshold that makes it affordable and interesting to a much larger
audience. There is information available on a very wide variety of topics,
and tools exist to help people find and view the information cost
effectively. Another factor fueling the Internet growth is the increasing
data demands per individual user. There is a trend for web sites to evolve
from using pure text to richer media, such as pictures, sound, and video.
Adding these richer media is popular because they present information more
clearly, thereby enhancing a site's impact and popularity.
Unfortunately, a problem facing the continued growth and acceptance of the
Internet is that conventional methods for accessing the Web do not scale
well to meet the rapid growth in demand. The quality of service for the
Web is intuitively measured by the user as the amount of time between
requesting a Web page and being able to view it. Internet users have been
conditioned through their experiences with television and standalone
multimedia applications to expect instantaneous results on demand. Users
are accustomed to changing the channel and instantaneously viewing the
video content for that channel on the screen. The Internet is unable,
however, to deliver data instantaneously. For the most part, the Internet
has significant latency problems that reduce fairly routine Web browsing
exercises to protracted lessons in patience.
The basic dilemma is that the quality of service degrades as more people
try to use the Web. More unsettling is the corollary that service for
popular Web sites is typically much worse than service for unpopular
sites. At the root of the service problem is the inability to serve Web
data rapidly as a result of too little bandwidth in the distribution
network. "Bandwidth" is the amount of data that can be moved through a
particular network segment at any one time. The Internet is a conglomerate
of different technologies with different associated bandwidths.
Distribution over the Internet is usually constrained by the segment with
the lowest available bandwidth.
Consider the Internet system 20 shown in FIG. 1. The Internet system 20
includes a Web server 22 that stores and serves data over the Internet 24
to regional point of presence (POP) operators or independent service
providers (ISPs), as represented by ISP 26. The ISP 26 provides
connectivity to the Internet 24 to many users, as represented by
subscriber computers 28, 30, and 32.
The ISP 26 is connected to the Internet 24 via a network connection 34. In
this example illustration, the network connection 34 is a "T1" connection.
"T1" is a unit of bandwidth having a base throughput speed of
approximately 1.5 Mbps (Megabits per second). Another common high
bandwidth connection is a T3 connection, which has a base throughput speed
of approximately 44.7 Mbps. For purposes of explaining the state of the
technology and the practical problems of delivering content over the
Internet, it is sufficient to understand that there is also a limited
bandwidth connection between the Web server 22 and the Internet 24.
The subscriber computers 28, 30, and 32 are connected to their host ISP 26
via home entry lines, such as telephone or cable lines, and compatible
modems. As examples of commercially available technology, subscriber
computer 28 is connected to ISP 26 over a 14.4K connection 36, which
consists of a standard telephone line and a V.32bis modem, to enable a
maximum data rate of 14.4 Kbps (Kilobits per second). Subscriber computer
30 is connected to the ISP 26 with a 28.8K connection 38 (telephone line
and V.34 modem) which supports a data rate of 28.8 Kbps. Subscriber
computer 32 is connected to the ISP 26 with an ISDN connection 40, which
is a special type of telephone line that facilitates data flow in the
range of 128-132 Kbps. Table 1 summarizes connection technologies that are
available today.
TABLE 1
Connection Technologies and Throughput
Connection Type Base Speed (Kbps)
V.32bis modem 14.4
V.34 modem 28.8
56K Leased Line 56
ISDN BRI (1 channel) 56-64
ISDN BRI (2 channels) 128-132
Frame Relay 56-1,544
Fractional T1 256-1,280
ISDN PRI 1,544
Full T1 (24 channels) 1,544
ADSL 2,000-6,000
Cable Modem 27,000
T3 44,736
With a T1 connection to the primary distribution network 24, the ISP 26 can
facilitate a maximum data flow of approximately 1.5 Mbps. This bandwidth
is available to serve all of the subscribers of the ISP. When subscriber
computer 28 is connected and downloading data files, it requires a 14.4
Kbps slice of the 1.5 Mbps bandwidth. Subscriber computers 30 and 32
consume 28.8 Kbps and 128 Kbps slices, respectively, of the available
bandwidth.
The ISP 26 can accommodate simultaneous requests from a number of
subscribers. As more subscribers utilize the ISP services, however, there
is less available bandwidth to satisfy the subscriber requests. If too
many requests are received, the ISP 26 becomes overburdened and may not be
able to adequately service the requests in a timely manner, causing
frustration to the subscribers. If latency problems persist, the ISP can
purchase more bandwidth by adding additional capacity (e.g., upgrading to
a T3 connection or adding more T1 connections). Unfortunately, adding more
bandwidth may not be economically wise for the ISP. The load placed on the
ISP typically fluctuates throughout different times of the day. Adding
expensive bandwidth to more readily service short duration high-demand
times may not be profitable if the present capacity adequately services
the subscriber traffic during most of the day.
The latency problems are perhaps most pronounced when working with video.
There are few things more frustrating to a user than trying to download
video over the Internet. The problem is that video requires large
bandwidth in comparison to text files, graphics, and pictures.
Additionally, unlike still images or text files, video is presented as
moving images that are played continuously without interruption. Video
typically requires a 1.2 Mbps for real-time streaming data. This 1.2 Mbps
throughput requirement consumes nearly all of a T1 bandwidth (1.5 Mbps).
Accordingly, when multiple subscribers are coupled to the ISP and one
subscriber requests a video file, there is generally not enough capacity
to stream the video in real-time from the Web server 22 over the Internet
24 to the requesting subscriber. Instead, the video file is typically
delivered in its entirety and only then played on the subscriber computer.
Unfortunately, even downloading video files in the block data format is
often inconvenient and usually requires an excessive amount of time.
Consider the following example. Suppose a subscriber wishes to access a Web
site having a 20-second video clip. At 1.2 Mbps, the 20-second video clip
involves downloading a 24 Mbyte file over the Internet. If the user has a
modest 14.4 Kbps connection, it would take approximately twenty-eight
minutes to download the entire file.
Now, assume that the subscriber/ISP connection is sufficiently large to
handle real-time video streaming of the video file, meaning that the
subscriber computer can render the video data as it is received from the
ISP. Despite the bandwidth of the subscriber/ISP connection, real-time
video streaming may still be unachievable if the T1 connection 34 between
the ISP 26 and the distribution network 24 is unable, or unwilling due to
policy reasons, to dedicate 1.2 Mbps of its bandwidth to the video file.
Requests for the 20-second video clip made during peak traffic times at
the ISP most certainly could not be accommodated by the ISP/network
connection. Since adding more bandwidth may be a poor investment for the
ISP, the ISP may have no economic incentive to remedy the latency problem.
The result is that some users might be inconvenienced by the lack of
ability to receive streaming video despite their own connection to the ISP
being capable of accommodating streaming video.
The latency problem is further aggravated if the connection between the
content server 22 and the distribution network 24 is equally taxed. The
lack of sufficient bandwidth at the content server/network link could also
prevent real-time video streaming over the Internet, regardless of the
bandwidths of the network/ISP link or the ISP/subscriber link. If all
links lack sufficient bandwidth, the latency problem can be compounded.
Accordingly, traditional techniques of adding more bandwidth at each
connection do not offer an acceptable architecture that scales to meet
rising demand. There remains a need to develop improved techniques for
facilitating distribution of Web content over the Internet.
SUMMARY OF THE INVENTION
This invention concerns a system for delivering Web content over a
broadcast medium from a webcast center to many clients. The webcast center
has a server that gathers Web content from sites on the Internet and a
broadcast unit that delivers the Web content to the clients over the
broadcast medium.
The server includes a gatherer to continuously gather Web content,
typically in the form of Web pages, from selected sites. A scheduler tells
the gatherer which sites, and what times, to gather the Web content.
Preferably, the scheduler sets gathering times during off-peak hours at
the sites. The scheduler maintains a schedule database of desired Web
sites and content based upon preferences entered by an administrator at
the webcast center. The gatherer fetches the content and stores it in a
content cache to maintain a current copy of the Web content at the webcast
center.
The gatherer is configurable to gather from each site a home Web page at a
root URL (Universal Resource Locator) and any additional Web pages within
a predefined depth below the root URL. The administrator sets the desired
depth for each site. The gatherer also collects any in-line image files
referenced by the gathered Web pages.
The webcast server has a packager to retrieve the Web content from the
content cache and package the Web content into package files. The packager
stores the package files in a package store which is separate from the
content cache. The packages include data from the Web content and other
information provided by the server, such as the size and modification
time.
The broadcast unit takes the packages files from the package store,
segments them into individual packages, and transmits the packages over
the broadcast medium. Preferably, the broadcast unit employs a broadcast
transmitter configured as a fault tolerant broadcast file transfer system.
The broadcast medium may be any medium that supports multicast package
transports. Possible transports include local area Ethernet networks
(LANs), and encoding onto digital satellite or broadcast television
signals.
Each client is equipped with a receiver to receive the broadcast packages.
The client maintains a subscription database to store a directory of the
Web content gathered by the webcast center. A subscriber user interface
enables a user to select preferred Web content from the directory of the
subscription database. The client creates a filter based on the user's
preferences. The filter directs the receiver to collect only the preferred
Web content, while ignoring packages carrying unwanted Web content.
As the preferred Web content is received, the client reconstructs the
package files and temporarily stores them in a package store. An
unpackager reconstructs the Web content from the package files in the
package store. The unpackager is configured to determine whether the Web
content received in the broadcast packages is more recent than the same
Web content that the user might have collected on his/her own from the
same site. If the broadcast content is a more recent copy, the client
retains that version; otherwise, the client discards the broadcast package
files in favor of the more recent version.
The client annotates any hyperlinks contained in the Web pages. The
annotations differentiate among links that have been actuated, links that
go to content stored locally at the client as a result of the broadcast
transmission, and links that go to content stored remotely from the
client. The annotation may be in the form of color variations, or
stylistic changes.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic illustration of a prior art Internet system.
FIG. 2 is a diagrammatic illustration of a webcasting system for delivering
Web content from a webcast center over a broadcast medium to multiple
clients.
FIG. 3 is a functional block diagram of the webcast center.
FIG. 4 is a functional block diagram of a client.
FIG. 5 is a diagrammatic illustration of a subscription user interface
implemented at the client to enable a user to select preferred Web content
to be delivered over the broadcast medium.
FIG. 6 is a diagrammatic illustration of the subscription user interface
according to a second implementation.
DETAILED DESCRIPTION
FIG. 2 shows a webcast system 50 for delivering Web content from a webcast
center 52 over a broadcast medium 54 to multiple clients 56(1)-56(M). The
webcast center 52 gathers Web content from the World Wide Web by visiting
web sites 58(1)-58(N) via the Internet 60 and fetching content from those
sites. The Web content is typically in the form of Web pages found at the
sites. A Web page is a title, collection of information, and pointers or
"hyperlinks" to other information. A Web page may be constructed from
various types of content including computer data, audio, video, animation,
bit maps or other graphics, applications or other executable code, text,
hypermedia, or other multimedia types.
The webcast center 52 collects Web pages from the Internet's World Wide Web
60 and stores them in a page cache 62. A system administrator sets a
schedule that establishes which sites are visited by the webcast center
52, the time and frequency of the visits, and the type of content
collected.
Apart from the gathering process, the webcast center 52 retrieves the pages
from the page cache 62, bundles them into composite package files, and
stores them in a package store 64. The package store 64 is preferably a
separate database than the page cache 62. The webcast center 52 fetches
the package files from the package store 64, segments the package files
into individual packages (or packets), and transmits the packages over the
broadcast medium 54.
The broadcast medium 54 is a unidirectional network in which packages are
delivered from the webcast center 52 to the clients 56(1)-56(M) without
requiring return communication from the clients. The broadcast medium 54
can be characterized as a shared, highly asymmetrical, network resource
with a limited, if not completely absent, low speed return path that does
not need to be active to receive broadcast transmissions. The broadcast
medium 54 may comprise the entire distribution network between the webcast
center and clients, or it may be a single link in a larger distribution
network.
The broadcast medium 54 may be implemented in a variety of ways. The
broadcast medium 54 might be implemented, for example, as a wireless
network configured for one-way transmission (i.e., satellite, radio,
microwave, etc.). The broadcast medium 54 might also be configured as a
network that supports two-way communication (i.e., Internet, LAN (local
area network), and WAN (wide area network)), but can be used for
unidirectional multicasting from the webcast center to the clients.
The clients 56(1)-56(M) represent various types of constructions. The
clients can be implemented as essentially any type of computing device
that can receive and reconstruct data packages, and render the packages on
a display. As one possible implementation, the client may be constructed
as a desktop computer, as represented clients 56(1) and 56(2), that are
specially configured with software/hardware components described below
with respect to FIG. 4. Client 56(1) receives broadcast Web content from
the broadcast medium 54 via an Independent Service Provider (ISP) 66,
rather than receiving the broadcasts directly. On the other hand, client
56(2) is a broadcast-enabled personal computer that is capable of
receiving the broadcast packets directly.
One example implementation of a broadcast-enabled PC is described in a
co-pending U.S. patent application Ser. No. 08/653,663, filed Jan. 29,
1996, which is a continuation of U.S. patent application Ser. No.
08/503,055, entitled "Broadcast-Enabled Personal Computer," filed Jan. 29,
1996, which is now abandoned. These applications were filed in the names
of Gabe L. Newell, Dan Newell, Steven J. Fluegel, David S. Byrne, Whitney
McCleary, James O. Robarts, Brian K. Moran; William B. McCormick, T. K.
Backman, Kenneth J. Birdwell, Joseph S. Robinson, Alonzo Gariepy, Marc W.
Whitman, and Larry Brader. This application is assigned to Microsoft
Corporation, and is incorporated herein by reference.
Another implementation of a client is a Web-enabled television, as
represented by client 56(3), which has a set-top box or internal computing
unit that permits receipt and rendering of Web content. In addition to
desktop computers and Web-enabled TVs, other possible clients include
workstations, laptop computers, palmtop computers, network computers, and
the like.
According to an aspect of this invention, another distribution entity may
act as a "client" to the webcast center 52. As shown in FIG. 2, the
regional Independent Service Provider (ISP) 66 might be a subscriber to
the broadcast transmissions received over the broadcast medium 54 from the
webcast center 52. The ISP 66 stores the webcast content and distributes
it to its own clientele, such as client 56(1), using conventional
distribution techniques.
As another example of an intermediary distribution entity, a secondary
webcast center 68 may function as a "client" to the primary webcast center
52. In addition to its own independent gathering process, the secondary
webcast center 68 also receives and re-broadcasts the Web content received
from the primary webcast center 52 to a set of clients 56(4)-56(M) over a
broadcast medium 70. One implementation of this dual webcast center
architecture is that the primary webcast center 52 is a primary head end
that distributes nationally or globally via satellites, and the secondary
webcast center 54 is a regional distributor that distributes the Web
content via RF (radio frequency) or microwave transmission.
The webcast system 50 advantageously distributes Web content to many
clients (potentially millions) without burdening the limited bandwidth of
the Internet. Broadcasting the Web pages over a one-to-many broadcast
medium avoids the bottlenecks caused by overburdened ISP connections or
slow client modem connections. Since the ISP might be a client of the
broadcast medium, the broadcast alternative offers additional bandwidth at
a fraction of the cost that would be incurred if the ISP installed
additional Internet connections, such as T1 or T3 connections.
The webcast system 50 also addresses the server scalability problem. Many
clients can be added to the system to receive broadcast data at no
incremental cost to the webcast center 52. The load on the webcast center
52 is constant because only it accesses the sites on the Internet,
regardless of the number of clients receiving the broadcast transmissions.
Webcast Center
FIG. 3 shows the architecture of the webcast center 52 in more detail. It
generally comprises a server unit 80 and a broadcast unit 82. The server
unit 80 is responsible for gathering Web pages from the Web 60 and
converting the pages to package files suitable for broadcast transmission.
The broadcast unit 82 is responsible for transmitting the package files
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