U.S. patent application number 12/110459 was filed with the patent office on 2008-08-21 for system and method for server-side optimization of data delivery on a distributed computer network.
Invention is credited to Kenneth W. Colby, Brian Kenner, Robert N. Mudry.
Application Number | 20080201488 12/110459 |
Document ID | / |
Family ID | 25371929 |
Filed Date | 2008-08-21 |
United States Patent
Application |
20080201488 |
Kind Code |
A1 |
Kenner; Brian ; et
al. |
August 21, 2008 |
System and method for server-side optimization of data delivery on
a distributed computer network
Abstract
A system and method for the optimized storage and retrieval of
video data at distributed sites calls for the deployment of "Smart
Mirror" sites throughout a network, each of which maintains a copy
of certain data managed by the system. User addresses are assigned
to specific delivery sites based on an analysis of network
performance with respect to each of the available delivery sites.
Generalized network performance data is collected and stored to
facilitate the selection of additional delivery sites and to ensure
the preservation of improved performance in comparison to
traditional networks.
Inventors: |
Kenner; Brian; (Encinitas,
CA) ; Colby; Kenneth W.; (San Diego, CA) ;
Mudry; Robert N.; (Carlsbad, CA) |
Correspondence
Address: |
LAW OFFICE OF DAVID H. JUDSON
15950 DALLAS PARKWAY, SUITE 225
DALLAS
TX
75248
US
|
Family ID: |
25371929 |
Appl. No.: |
12/110459 |
Filed: |
April 28, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10949984 |
Sep 24, 2004 |
7366793 |
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12110459 |
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09633021 |
Aug 4, 2000 |
6799221 |
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10949984 |
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08878385 |
Jun 18, 1997 |
6112239 |
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09633021 |
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Current U.S.
Class: |
709/245 |
Current CPC
Class: |
H04L 67/1021 20130101;
H04L 67/1038 20130101; H04L 67/1008 20130101; H04L 67/101 20130101;
H04L 67/1014 20130101; H04L 67/1029 20130101; H04L 67/1023
20130101; H04L 67/1002 20130101 |
Class at
Publication: |
709/245 |
International
Class: |
G06F 15/16 20060101
G06F015/16 |
Claims
1. A method of content delivery managed by a service provider on
behalf of participating content providers in a distributed computer
network, wherein machines make requests for participating content
provider content, comprising: locating delivery sites at network
locations, wherein a given delivery site supports content from
multiple participating content providers; generating a table that
is indexed by a set of values each corresponding to a byte of a
given IP address, wherein for each such value, the table includes
IP addresses identifying a subset of delivery sites, where the
table is generated based on network performance data collected by
the server provider; and in response to a machine at a given IP
address making a request for content being managed by the service
provider, using a byte of the machine's IP address as an index into
the table to associate the request with an IP address of at least
one of the subset of delivery sites.
2. The method of content delivery as described in claim 1 further
including modifying the table as a function of the network
performance data.
3. The method of content delivery as described in claim 2 wherein
the table is modified to alter the one or more IP addresses
identifying the subset of delivery sites.
4. The method of content delivery as described in claim 3 wherein,
as a result of the modification, requests for content are directed
to an alternate delivery site.
Description
[0001] This application is a continuation of U.S. Ser. No.
10/949,984, filed Sep. 24, 2004, which application was a
continuation of Ser. No. 09/633,021, filed Aug. 4, 2000, now U.S.
Pat. No. 6,799,221, which was a continuation of U.S. Ser. No.
08/878,385, filed Jun. 18, 1997, now U.S. Pat. No. 6,112,239.
[0002] The invention relates to a system and method for distributed
data storage and retrieval, and more particularly, to a system and
method whereby a user can acquire network performance information
for a dynamic and distributed multipurpose network.
BACKGROUND OF THE INVENTION
[0003] The Internet is a loose network of connected computers
spread throughout the world. A message can be sent from any
computer on the Internet to any other by specifying a destination
address and passing the message from computer to computer via a
series of "hops." Each computer, router, or "node" on the Internet
has a unique Internet address. When an intermediate computer or
router receives a message in transit, the computer checks the
intended destination of the message and passes it along
accordingly.
[0004] The Internet is growing, in terms of both size and
sophistication, at a rapid rate. In the past, most users of the
Internet were academic, research, or institutional users; the
Internet was primarily used at that time to transmit and receive
electronic mail and network news and to allow transfer of computer
files. However, since the introduction of the World Wide Web (also
known as the "Web", or the "WWW") several years ago, the Internet
has begun to host increasing amounts of other types of data of
general interest, namely representations of images, articles,
etc.
[0005] The Web protocol and language establish a graphical means to
navigate the expanses of the Internet. "Web pages," often
consisting primarily of text and graphical material, are stored on
numerous computers, known as "Web servers," throughout the
Internet. A software program known as a "browser" can be used to
access and view Web pages across the Internet by specifying the
location (i.e. Internet address) of the desired Web page. When a
Web page is accessed, its information is transmitted from the
remote computer (server or delivery site), wherever in the world it
may be located, across the Internet, to the user.
[0006] In recent times, the Web has begun to host highly
sophisticated types of multimedia content, such as audio and video
data, and computer software. Compared to first generation Web
content, namely text and still images, audio clips, video clips,
and software programs have extremely high storage and bandwidth
requirements.
[0007] At present, it is difficult, if not impossible, to provide
sustained high-speed transmission of large audio/video files over a
multi-node link on the Internet. Because the data is often
transferred from afar, many factors can cause the delay or even
loss of parts or all of a transmission. It is generally not
critical if a user experiences minor delays in receiving small
graphic or text files. However, it is recognized that real-time
data such as video has very specific and stringent timing
requirements for data transfer and display.
[0008] Unfortunately, the present design of traditional
Internet-like data networks is based on the principle that delays
and significant data transmission rate variations are acceptable
for ordinary data (e.g. text and still images). Consequently,
because of the high value of permitting access to text and
graphical information from locations around the world, such
transmission defects are considered acceptable, and the base
capacity of the Internet is somewhat "oversubscribed" to reduce
data transmission costs. In other words, the timeliness of network
data transmission has been significantly compromised in order to
render relatively insignificant the aggregate cost of long distance
communication connections.
[0009] In order to successfully transfer audio-video data across a
message-oriented network such as the Internet, for any more than a
few users, network resources should be committed in a manner
facilitating timeliness of transmittal. A system using committed
network resources generally cannot take advantage of the existing
pricing scheme of shared networks like the Internet, since it
cannot participate in the sharing of network resources on a data
packet by data packet basis. Video data must be transmitted to the
exclusion of lower-priority data. Transmission costs thus become
significant, especially when the connection is "long distance" or
when the connection is continued over an extended period of
time.
[0010] Another consequence of the timeliness vs. cost compromise
discussed above has been the seemingly indiscriminate topographical
design of the network. Since delays and throughput variations have
traditionally been excused in favor of low cost, the configuration
of the Internet infrastructure has also been driven by cost
considerations. Accordingly, the interconnection efficiency of the
network has rarely been considered. The rapid growth of real time
data is changing this requirement.
[0011] It is recognized that inadequate data transfer performance
of time-sensitive data on the Internet is typically caused by four
factors: packet loss, excessive server utilization, the relatively
low capacity of the network infrastructure, and inherent delays in
the network hardware. Packet loss, in particular, is caused by
inadequate infrastructure and lack of robustness in routing. The
inherent delays are believed to be caused by, among other things,
the lack of flow control between adjacent nodes in a multiple-node
path on the Internet.
[0012] Unlike smaller text and graphic files, relatively large
video files can take several minutes (or more) of "streaming," or
constant data flow. Consequently, the usual network performance
problems are exacerbated. Network bandwidth, or the data-carrying
capacity of a particular network, is limited. Thus, packet loss and
delays increase. Long delivery times consume a large amount of
server capacity for a long time, decreasing the resources available
to other users. Accordingly, because the network infrastructure
becomes increasingly congested, packet loss and delays continue to
increase, transmission times rise, and server load increases
further.
[0013] This pattern exemplifies a "downward spiral" of network
performance, which can be driven by the attempted transmission of
large data files such as video clips. As long as network traffic
remains within the limits imposed by network bandwidth, network
performance will remain acceptable. However, whenever peak network
loads exceed capacity, the downward spiral described above will
begin, causing increasing periods of poor network performance.
[0014] As discussed above, a browser program can be used to access
and view Web pages across the Internet by specifying the location
(i.e. Internet address) of the desired Web page, or more commonly,
by "hotlinking" to Web pages. Common browsers are Lynx, NCSA
Mosaic, Netscape Navigator, and Microsoft Internet Explorer. The
desired Web page is specified by a uniform resource locator
("URL"), indicating the precise location of the file using the
syntax "http://internet.address/directory/filename.html".
[0015] Web pages are generally described, in terms of layout and
content, by way of a language known as "HTML" (HyperText Markup
Language). Any particular computer linked to the Internet can store
one or more Web pages, i.e. computer files in HTML format, for
access by users.
[0016] Hotlinking from one HTML Web page to another is accomplished
as follows. The user first accesses a Web page having a known
address, often on the computer located at the user's ISP (Internet
Service Provider). The ISP is the organization providing Internet
connectivity to the user. That Web page can contain, in addition to
textual and visual data specified in HTML format, "links," or
embedded information (in the form of URLs) pointing to the Internet
addresses of other Web pages, often on other computers throughout
the Internet. The user, by selecting a link (often by pointing and
clicking with a mouse), can then access other Web pages, which can
in turn contain further data and/or additional links.
[0017] Various extensions to HTML, such as Netscape's EMBED tag,
allow references to other data to be embedded into Web pages. Some
browsers are not capable of handling data other than text and
images. Other browsers can handle the data in various ways. NCSA
Mosaic, for example, handles references to unknown types of data by
allowing the data to be downloaded to the user's computer, and then
optionally invoking an external program to view or manipulate the
data. Recent releases of Netscape Navigator and Microsoft Internet
Explorer take the concept one step further: a browser extension, or
"plug-in," can be automatically invoked to handle the data as it is
received from the remote Web page. Other means, such as network
program "applets" written in the Java language (or a similar
language), can be used to extend the functionality of the browser
environment or network.
[0018] Digital multimedia data can have extremely high storage and
bandwidth requirements. In particular, video files can be very
large, from approximately 10 megabytes to 10 gigabytes. In order to
play video files at speeds approaching their recorded rate at a
user's terminal, the files have to be delivered at a fast, constant
speed. Too slow, and the image plays back slower than originally
recorded. If the speed is uneven, then the video appears jerky,
like an old-time movie.
[0019] The network design compromises discussed above generally
adversely impact the transmission of audio and video data across
the Internet. While a user using a browser to "surf" the Web might
not notice minor delays and transmission rate variations while
retrieving text and still images, such defects become apparent and
significant when real-time audio and video information is
accessed.
[0020] In an attempt to solve these problems, Internet content
providers sometimes spread popular content around the Internet on
various servers or delivery sites known as "mirror sites." Each
mirror site contains information that is essentially identical to
that of the original site. For example, if a popular Web site is
located in New York, mirror sites might be located in Los Angeles,
London, and Tokyo. Accordingly, if a European user is having
difficulty accessing the original New York site, he can hotlink to
the mirror site that is geographically closest, i.e. London.
However, mirror sites have several disadvantages. For example,
mirror sites may be widely distributed geographically, but may not
be efficiently distributed on the network in terms of actual usage,
network traffic, etc. Thus, New York and Los Angeles mirror sites
might both be connected to the same national Internet service
provider's network, meaning that difficulty in accessing one of the
sites might also affect the other.
[0021] Furthermore, mirror sites might not be optimally placed to
reduce load on each server. Although an "educated guess" might be
made as to where a mirror site should be located, actual usage
patterns might differ. Furthermore, there is no guarantee of
enhanced performance. The bandwidth of the mirror site might be
lower than that of the original site, or it might be overloaded for
other reasons.
[0022] Moreover, mirror sites are often hosted on a voluntary
basis. If a Web site is extremely popular, and a service provider
determines that the subject matter might be of interest to its
subscribers, that service provider might agree to host a mirror
site of the original Web site. Such an arrangement would be
attractive to host of the mirror site because people would be drawn
to the mirror site, and might hotlink to other content hosted
there. On the other hand, such voluntary alliances typically are
not reliable and might be severed at any time.
[0023] In essence, a mirror site offers a secondary source for
data, which may or may not be available, and which may improve user
convenience, but which does not address network bandwidth or
efficiency. A mirror site does not account for performance
characteristics of the network, nor identify available bandwidth
which could be used to efficiently transmit video data while still
taking advantage of the existing low-cost pricing schemes such as
those on the Internet.
[0024] Currently, there is no guidance in selecting optimal
locations for delivery sites, nor is there a known method
permitting a user to determine which mirror site to connect to that
will ensure optimum performance. In fact, the use of a traditional
mirror site is voluntary. Typically, a user will try to access the
original site (or a known mirror site), and will switch to another
mirror site only if performance is found to be insufficient after
one or more attempts. This approach is an inefficient utilization
of network resources. Clearly, mirror sites are not an optimum
solution to the problem of overloaded Web sites. A principal reason
for this, among others, is the failure to consider network
performance.
[0025] Network analysis, particularly the performance of specific
paths and links over the Internet, is well known and developed. For
example, the "ping" program allows a computer connected to the
Internet to determine whether a remote host is accessible. However,
the ping program uses a low-priority network protocol known as the
ICMP protocol, and accordingly does not provide meaningful
performance analysis information. The "traceroute" program follows
the transmission of a message from a computer to a remote host,
tracking delays along each link, and determining the path taken by
the message. The traceroute application can be used to map the flow
of data. However, it lacks the ability to provide meaningful
performance analysis information. Traceroute only provides route
information for a message propagating in one direction, and only
for one instant in time.
[0026] Moreover, only the connectivity characteristics of paths
leading to and from the single computer running the tests are
typically determined; expanding the scope of testing is possible
but logistically impracticable, since the Internet is so large.
[0027] Traditional network analysis techniques such as the "ping"
and "traceroute" programs offer a view of network connectivity but
provide little understanding of what performance can be expected
from providers and mirror sites across the Internet. Therefore,
only "guesses" can be made as to where delivery or mirror sites
should be located or which mirror sites should be used to optimize
performance.
[0028] Accordingly, a need exists for a method of determining
overall network performance. A further need exists for a system
applying that method to enable content providers to dynamically
locate data delivery or mirror sites at optimum network locations,
and to allow users to select optimum mirror sites from which to
receive data.
SUMMARY OF THE INVENTION
[0029] The invention is directed to a system and method for the
optimized distribution of Web content to sites located around the
Internet. An intelligent mirroring scheme, called here "Smart
Mirroring," is used to determine the need for and distribution of
mirror sites and to direct user requests for certain Web content to
an optimum mirror site.
[0030] A number of "smart" delivery or mirror sites are used to
distribute popular Web content to various parts of the Internet. A
comprehensive scheme of network analysis, based on tests performed
by a large number of users, is used to interactively determine the
preferred locations for the sites, and to determine the optimum
sites to be used by each individual user.
[0031] Accordingly, because each individual user is routed to a
Smart Mirror or delivery site that provides improved performance,
overall network congestion is reduced. In most cases, the improved
server is located electronically close to a user in order to
decrease the number of network connections over which data must
travel, thereby reducing packet loss and delay.
[0032] Furthermore, network analysis results allow message traffic
to be routed away from those delivery sites and network regions
that are already overloaded, and toward underutilized servers and
networks. This results in an improvement in throughput as seen by
each user, and will thereby increase the appeal of the content
offered by content providers using the system. Content providers
are able to reach a larger number of users across the Internet
without suffering significant decreases in performance.
[0033] A system according to the invention begins with an original
Web site and at least one additional delivery (or mirror) site.
Each user desiring to use the system will be provided, in a
preferred embodiment, with software which includes a configuration
utility and a client program. The configuration utility is used
first to determine which delivery sites provide improved
performance for that particular user.
[0034] In one embodiment of the invention, the configuration
utility first downloads a "delivery site file" from a service
provider. This delivery site file contains a list of available
delivery sites and a list of network tests to be run. The types of
tests and frequency of testing to be performed may be specified in
the delivery site file, as dependent on the number of users testing
the network and the estimated drain on network or delivery system
capacity.
[0035] The configuration utility will run a subset of the tests
specified in the delivery site file. The test results show which
delivery sites yield improved performance for the user, and also
contain information on various generalized network capabilities
from the standpoint of the user running the tests. The network test
results and the identity of the chosen delivery site will be sent
(via e-mail in one possible configuration) back to the delivery
service provider for incorporation into the service provider's
database.
[0036] The delivery site chosen by the configuration utility is
then used by that user for the retrieval of all content managed by
the delivery system service provider. Consequently, when the user
is browsing Web content, and finds a particular item, e.g. a video
clip, that is managed by the service provider's delivery system,
the client software will automatically retrieve it from the
specified "Smart Mirror" delivery site. Site preferences and
default sites can be updated periodically on request, at specified
times, or in response to changes in network load and traffic.
[0037] Moreover, because the configuration utility of the invention
is performing various network tests and providing the test results
to the service provider, valuable data on system and network
performance is available. Such data provides information on which
"Smart Mirror" delivery sites are performing effectively and which
are not, which Smart Mirror delivery sites are overloaded, and what
portions of the Internet might benefit from the addition of more
delivery sites or capacity. Such data also makes it possible to
perform such sophisticated network analysis as end-to-end
performance measurements, workload characterization, route
stability, and outage metrics.
[0038] In an embodiment of the invention, the mirror service
provider uses the network performance data provided by the end
users to derive a look-up table which correlates Internet IP
addresses with "electronically close" delivery sites. When a user
is browsing web pages and requests a file, e.g. an advertising
banner or video clip that is managed by the service provider's
delivery system, the service provider can map the user's IP address
to the look-up table and determine which delivery sites are
"electronically close" to the user. The service provider can then
provide the user's configuration utility or client program with a
single delivery site address or a list of delivery site addresses
for these servers. In the latter case, the user terminal acts as a
router making the final delivery site selection.
[0039] In general, an improved delivery site for a particular user
can be predicted in advance by analyzing aggregate network
performance data collected from network tests previously performed
by a group of users. Thus, delivery site selection can occur
on-the-fly each time the user requests a file managed by the mirror
service provider's delivery system. From the perspective of the
user, the selection of the delivery site happens automatically and
transparently such that there appears to be no delay between
selecting a file from a web page and having the file delivered to
the user's terminal. The look-up list maintained by the service
provider is constantly updated to reflect changes in network
performance, making it possible for the service provider to
effectively load-balance network traffic.
[0040] Thus, from an engineering standpoint, the mirror service
provider can continue to ensure that improved performance is being
provided. From a marketing perspective, content providers can be
told where to locate Smart Mirror or delivery sites for improved
performance, and what ISP provides improved delivery.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIG. 1 is a block diagram of an illustrative network
topology of a system according to the invention, including multiple
users and multiple content providers;
[0042] FIG. 2 is a flowchart describing the operation of the
configuration utility used in a system according to the
invention;
[0043] FIG. 3 is a flowchart describing the operation of a client
program used in a system according to the invention; and
[0044] FIG. 4 is a flowchart illustrating how site selection is
performed in an embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0045] The invention is described below, with reference to detailed
illustrative embodiments. It will be apparent that the invention
can be embodied in a wide variety of forms, some of which may be
quite different from those of the disclosed embodiments.
Consequently, the specific structural and functional details
disclosed herein are merely representative and do not limit the
scope of the invention.
[0046] Referring initially to FIG. 1, the Internet 10, which is
intended to be representative of wide-area communications networks
in general, is depicted as a "cloud." The Internet is known to be
an interconnected network of a large number of computers. Although
Internet-connected computers that are "geographically" near each
other can be "electronically" near each other on the Internet, such
is not usually the case. However, one computer connected to the
Internet can communicate with any other computer connected to the
Internet; the message will most likely travel over a path
comprising a sequence of links, or "hops," between computers that
are directly connected to each other.
[0047] A first user terminal 12 is also depicted in FIG. 1. The
first user terminal 12 is connected to an Internet service provider
(ISP) 14, which is typically just a computer, router, or terminal
server connected to the Internet 10. An ISP 14 can host additional
user terminals, such as a second user terminal 16. Other ISPs, such
as a second ISP 18, are also connected to the Internet 10. A third
user terminal 20 is shown connected to the second ISP 18. Only
three user terminals are shown; however, it should be recognized
that the number of concurrent users of the invention is unlimited,
subject to the operational details set forth below.
[0048] As is known in the art, content providers are also connected
to the Internet 10. A first content provider 22 might provide a
certain kind of content, for example sports scores and highlights.
A second content provider 24 might provide a different kind of
content, for example business news.
[0049] Traditionally, if a user (such as the one using the first
user terminal 12) wished to access the content provided by the
first content provider 22, the terminal 12 would query the first
content provider 22 directly. A request message would propagate
from the terminal 12, across the Internet 10, to the content
provider 22. The content provider 22 would send the desired data
across the Internet 10 back to the terminal 12.
[0050] Several delivery, or "mirror" sites are shown connected to
the Internet 10 in FIG. 1. A first delivery site 26 might be
located a small number of "hops" from the first user terminal 12. A
second delivery site 28 might be located further away from the
first user terminal 12, but close to the third user terminal 20. A
third delivery site 30 might be as close to the third user terminal
20 as the second delivery site 28 is. As previously noted, a user
and a provider or delivery site that are "geographically" near each
other might not be "electronically" near each other on the
Internet. By decreasing the "electronic" distance between the user
and the provider or delivery site, the number of network
connections and routers over which data must travel can be
decreased.
[0051] As discussed above, the Smart Mirroring system acts to
improve network performance by decreasing the incidence of the
foregoing network problems. Packet loss and delay problems are
generally decreased by reducing the number of network connections
over which data must travel, although in some cases, the network
testing procedure of the invention shows that some longer paths
provide better throughput than some shorter paths. Very little
packet loss, and essentially no delay, occurs in network cable; it
typically is caused by overloaded network storage and routing
devices. Because the Smart Mirror sites of the invention are
located electronically near each user, packet losses and delays are
reduced. The problem of excessive server utilization is reduced
because multiple delivery sites share the load that typically would
have been handled by a single server. The relatively low capacity
of the network infrastructure becomes less of a problem, because
data retrieved from parallel delivery sites in different locations
generally need not travel over the same network links.
[0052] For the purposes of describing this invention, a delivery
site is a "node" on the network which may store data or other
files, such as software code, for delivery. The term can also
include a site which is responsible for data delivery, including
mirror sites, content providers, and servers for broadcast video
streams or Web sites.
[0053] In the system, a mirror service provider (MSP) 32 is
connected to the Internet 10. The MSP 32, which exercises a
management function over the distribution of delivery sites 26, 28,
and 30, and over the allocation of requests to the original and
delivery sites from user terminals 12, 16, and 20, includes a
database capable of transmitting and receiving data over the
Internet 10.
[0054] This management function is facilitated by the use of a
configuration utility 34 and a client program 36 run within a
storage medium (i.e. random access memory) on the user terminal 12.
Although the configuration utility 34 and the client program 36 are
shown in FIG. 1 as a part of only the first user terminal 12, it
should be recognized that any user terminal, such as terminals 16
and 20, participating in the system will use such software. A user
desiring to participate in the system can obtain the software
comprising the configuration utility 34 and client program 36
directly from the MSP 32, or through traditional retail or other
channels (such as being part of the browser or operating system of
the computer). It should be noted that the functions performed by
the configuration utility 34 in the described embodiment of the
invention can be integrated into general Internet application
software, such as a browser or other network application; a
stand-alone program is not necessary.
[0055] In a preferred embodiment, the configuration utility 34 must
be run by the user, either by command or automatically, before the
user terminal 12 will have access to the system. The operation of
the configuration utility 34 is shown in detail in FIG. 2.
[0056] The configuration utility 34, when first run on the user
terminal 12, retrieves a delivery site file (step 40) from the MSP
32 (FIG. 1). If the user already has a delivery site file (e.g., it
was received with the configuration utility 34), and that delivery
site file is sufficiently new, the delivery site file can be
retrieved from the local hard disk of the user terminal 12. This
delivery site file contains a list of all available delivery sites
(such as delivery sites 26, 28, and 30) and a list of network tests
to be run at the user terminal 12. In the context of the invention,
there can be as few as two delivery sites, or if the number of
users justifies it, as many as several thousand. The number of
sites in principal is unlimited, with each available delivery site
represented in the delivery site file.
[0057] The delivery site file is generated by the database from
within the MSP's computer system. The database application uses
information about the user to dynamically determine the optimum
tests to run. Consequently, the delivery site file need not contain
entries for every delivery site in existence; the list can be
tailored to include only those sites which appear appropriate or
feasible.
[0058] Initially, the magnitude of run-time variation in test
configurations for the delivery system users is low; that is, the
first group of users all run essentially the same tests. As the
delivery service grows, however, the intensity of each user's
testing is reduced in order to compensate for the increased
magnitude of testing network-wide. The scope of testing and the
number of delivery sites tested both can be narrowed to further
reduce the aggregate load of network testing.
[0059] In one embodiment, the delivery site file will have a format
generally as follows:
[0060] 1. File Revision Number and Message. The file includes this
field to determine whether a new version of the configuration
utility 34 is available. If the revision number in the delivery
site file is higher than the version number for the configuration
utility, configuration is not allowed. Instead, the user would be
prompted to acquire a newer version of the configuration utility
34. File revision verification as described herein ensures that the
most up-to-date delivery site selection algorithms are applied to
the test data generated by the configuration utility 34.
[0061] 2. A list of available Smart Mirror delivery sites.
[0062] For each available delivery site, the following information
is provided:
[0063] a. Host name. In the known Internet format of
"www.server.com."
[0064] b. IP Address. A numerical Internet address in the known
format. The address is presently a 32-bit number of the form
w.x.y.z., where w, x, y, and z are each in the range of 0 to
255.
[0065] c. Alternate Name. An informal name such as "The First
Mirror Site."
[0066] d. A list of tests to be executed. For each test, the
following information is provided:
[0067] i. Test ID. Each type of test has a unique identifier known
to the configuration utility 34.
[0068] ii. Weighting factor. Each test will be weighted by a
specified percentage.
[0069] iii. Frequency. Each test is not necessarily run every time.
This field specifies a probability, determining how often a
particular test will be run.
[0070] iv. Additional Information (optional).
[0071] For certain tests, additional information may be needed.
[0072] e. Site Preference Level. Each site can be given a
weighting, or preference level, between, for example, 1 and 100. As
discussed below, aggregate data in the MSP's database is used to
perform network usage analysis not possible with only the single
user's instantaneous end to end testing. The weighting factor
provided here is used to incorporate the test results received from
the service provider's database. This weighting factor is also used
to limit assignment of new users to a delivery site once a
predetermined maximum usage level has been reached.
[0073] f. Test Site Flag. If this flag is enabled, the foregoing
tests will be run, but the site will not be assigned as a delivery
site even if it yields the best performance.
[0074] g. Content Provider Groups. Each site can belong to one or
more content provider groups, thereby mirroring only certain
content. If a user is not interested in the types of data hosted by
a particular delivery site, then it does not need to be tested.
[0075] The configuration utility 34 then queries the user (step 42)
for various items of information needed in the configuration
process, for example, the user's name, e-mail address, password,
modem speed, and information related to access control (e.g. what
levels of various attributes are viewable by the user). The access
control mechanism will be discussed in further detail below. In one
embodiment of the invention, the information received from the user
is encrypted and stored in a configuration file on the user
terminal 12.
[0076] The configuration utility 34 then determines whether the
user terminal 12 is connected to the Internet (step 42). If not, it
will initiate a connection (step 44) or prompt the user to do
so.
[0077] A series of network tests is then performed (step 46). One
or more tests can be performed for each available site listed in
the delivery site file; not all sites in the file need to be
tested.
[0078] The following test types are presently considered to provide
useful data:
[0079] 1. Ping. Provides information on whether a remote server is
reachable, and if so, how long it takes for a low-priority message
to travel round trip from the user terminal 12 to the remote server
and back. Ping is a simple test useful in deciding whether a site
is available for further evaluation. Excessive times returned by
the ping application can be used to eliminate delivery systems
which are far too "slow" for effective information delivery. This
test is used by the terminal to reduce the number of delivery sites
tested.
[0080] 2. Traceroute. Provides information on what route is taken
by a message from the user terminal 12 to a remote server,
including what systems are used along the way, and how long each
hop takes. Traceroute is used by the configuration program 34 to
document the path of information transmission. Several traces with
differing results might indicate that the stability of the route
from a particular user to a specific server is not acceptable.
Previously aggregated data on particular routes, from the service
provider's system database, may also influence the decision to
choose a particular delivery site for a specific user. Route
stability is the primary consideration.
[0081] 3. Reverse Traceroute. Provides information on what route is
taken by a message from a remote server to the user terminal,
including what systems are used along the way, and how long each
hop takes. Reverse Traceroute is used by the configuration program
to document the path of information receipt. Several traces with
differing results might indicate that the stability of the route
from a particular server to a specific user is not acceptable.
Previously aggregated data on particular routes, from the service
provider's system database, may also influence the decision to
choose a particular delivery site for a specific user. Again, route
stability is the primary consideration.
[0082] 4. Dynamic Traceroute. Similar to traceroute or reverse
traceroute, but between any specified pair of computers on the
Internet. Dynamic Traceroute is used by the configuration program
to document a path of information transmission. Several traces with
differing results might indicate that the stability of the route
between two network locations is not acceptable. Previously
aggregated data on particular routes, from the service provider's
system database, may also influence the decision to choose a
particular delivery site for a specific user. As above, route
stability is the primary consideration.
[0083] 5. Name Server Resolution Delay. If the numeric Internet
address is unspecified, a name server lookup is performed to
determine what numeric address corresponds to the desired host
name. This process can take a substantial amount of time.
[0084] 6. Throughput. A sample file is downloaded, or partially
downloaded, from the remote server to determine the actual
throughput in bytes per second.
[0085] 7. Throughput variation. A sample file is downloaded, or
partially downloaded, from the remote server to determine if the
throughput is relatively constant or fluctuating.
[0086] 8. Error rate. A sample file is downloaded, or partially
downloaded, from the remote server to determine if the transmission
is subject to transmission errors. This information is obtained by
counting the number of error message packets returned to the user,
thereby learning of the error rate from the user to the server, and
by tracking the number of bytes received as a fraction of the
number of bytes transferred, thereby learning of the error rate
from the server to the user.
[0087] 9. Packet Fragmentation. A sample file is downloaded, or
partially downloaded, from the remote server to determine it the
transmission is subject to fragmentation or out-of-order packet
reception.
[0088] 10. Capacity Query. If the remote server is so enabled, the
configuration utility 34 queries the server to determine its
transmission capacity and its average load. This information is
collected via the Simple Network Management Protocol ("SNMP"),
which is supported by nearly all Internet servers.
[0089] 11. Macroscopic Network Analysis. The data accumulated by
the MSP database offers a global view of network behavior. This
information permits the Smart Mirror system user to have a
historical view of the performance of the available delivery sites.
The accumulated data is manipulated by the delivery system database
to analyze network performance, in order to emphasize usage in
high-capacity areas of the network, while deemphasizing usage in
areas already experiencing diminished performance.
[0090] Information on how each of the foregoing tests are performed
is well known in the art of network analysis. See, e.g., Bob Quinn
and Dave Shute, Windows Sockets Network Programming (Addison-Wesley
1996). In one embodiment of the invention, testing is accomplished
by performing a "ping" test to verify whether a server is
reachable, a series of small (e.g. 20K) downloads, a series of
large (e.g. 200K) downloads, and "traceroute" and "reverse
traceroute" tests to document delivery paths.
[0091] The traceroute information is used by the MSP 32 to
correlate test data to information in its database; in that way,
particularly bad network links and servers can be identified. Such
information is provided in the delivery site file discussed above;
if a particular link or server is known to be unreliable, based on
information obtained from other users, an individual user can be
routed away from it, even if a single test gives good results.
[0092] The short downloads are used to determine server capacity.
The name server resolution delay can be determined by such a test,
as well as the time it takes a server to begin sending data. The
later result is strongly related to server load, capacity, and
performance.
[0093] The long downloads allow the configuration utility 34 to
determine how packet loss, network congestion, and server
utilization affect file delivery. It is not ideal to determine
which of the foregoing factors is causing decreased performance
based on test results from a single user. However, such results in
the aggregate, as stored in the database maintained by the MSP 32,
indicate the root causes.
[0094] It should be noted that some of the test results may be used
in conjunction with other test results. For example, the load on a
delivery site as determined through a capacity query can be divided
by the results of a throughput test to derive an average expected
download time, given the load characteristics of the server.
[0095] After all specified tests are run, the results are collected
and processed (step 48). It is possible that certain tests were not
able to be successfully performed; in such cases, the results
should indicate an appropriate worst-case value (e.g. zero
throughput or extremely high delay).
[0096] It is important to note that not all possible tests will be
performed each time the configuration utility 34 is run. When a
large number of users are using the system, a substantial drain on
server and network capacity would be caused by the testing
procedure alone, increasing the downward spiral of network
performance previously discussed.
[0097] As noted above, a test frequency number is stored in the
delivery site file for the purpose of dynamically controlling the
number of users performing a test. The testing performed by the
configuration utility 34 is performed to achieve statistical
confidence in deciding which delivery site is best suited for data
delivery to a particular user. Statistical confidence is obtained
by testing a small sample of users sufficiently well and using that
data to influence the choice of a delivery site, or by having a
large number of users each "lightly" test several available sites
and using that data in the aggregate.
[0098] Accordingly, when the system is used initially, a relatively
small number of users are "enrolled" in the system. The delivery
site file maintained by the MSP 32 reflects those conditions, and
requires each user to test the network (through the configuration
utility 34) relatively heavily. As the number of users increases,
the delivery site file is modified to decrease the tests performed
by each user. By the time a very large number of users are using
the system, the configuration utility 34 may predominantly test for
delivery site reachability (via a "ping"-type test, as discussed
above), and rely primarily on test data provided by other users and
stored in the database maintained by the MSP 32. However, even when
many users are testing the system, a small number of users (e.g.
one in 5,000) may be selected to run a comprehensive set of
tests.
[0099] Preferably, testing should not contribute more than
approximately 5% of total server load. One way to reach this goal
is to lightly test a large number of servers, yielding a group of
delivery sites having adequate performance. This group of delivery
sites can then be used in rotation to retrieve data. Information on
multimedia clip actual download times for each of the delivery
sites in the group is accumulated as discussed below, and further
information on delivery site performance can then be furnished to
the MSP 32 transparently, without the need for further outright
testing.
[0100] Accordingly, on the basis of the collected test results, and
on information provided in the delivery site file by the MSP 32,
the configuration utility 34 determines which delivery site, or
group of delivery sites, is best for the user terminal 12 (step
50). This determination can be made numerically by weighting the
various tests performed and comparing the score for each site.
[0101] In a presently preferred embodiment, for use in a
low-traffic environment with a relatively small number of delivery
sites and users, the configuration utility 34 relies primarily on
ping and throughput tests for each available delivery site. An
initial ping test is performed to determine if a delivery site is
reachable. Short and long downloads are performed in the throughput
tests to determine the maximum and minimum throughputs from the
delivery site, and to determine whether throughput variation is
small enough to accommodate the transmission of video data.
Accordingly, those tests are all given high weights. Other tests,
such as traceroute, can be performed, and the results reported to
the MSP 32, without playing a role in the choice of delivery sites
(such other tests can be given weights of zero, or nearly zero, for
example). As the size of the system increases, and additional
delivery sites and users are enrolled, the site selection formula
can be altered, by changing the delivery site file contents, to
reflect changing network conditions.
[0102] In one embodiment of the invention, a proprietary graphical
interface is provided so that the location of the user and the
locations (both geographic and electronic) of each site tested can
be displayed on a monitor connected to the user terminal 12,
allowing a visual indication of the relative distances between
sites. In one embodiment, the display is shown in the form of a
"radar screen," upon which the user terminal 12 and delivery sites
are displayed as "blips" superimposed over a map of the pertinent
geographical region. In order to encourage the user to use the
application and to offer more network-wide data, the user interface
can allow the user to enter an "ad-hoc" test site for additional
performance testing. In this case, the configuration utility will
test either the default Web page file (e.g., "index.html") or a
specific file requested by the user. Analysis results from the
user-selected site are adjusted so that reasonable comparisons can
be made with results from other sites.
[0103] It should be noted that multiple sets of delivery sites can
be maintained by the invention, to accommodate several groups of
content providers. Each content provider might be mirrored only at
certain sites. Accordingly, for each content provider having a
unique set of delivery sites, a primary delivery site is selected
by the configuration utility 34. To accomplish this, the foregoing
tests can be run once, and then, in one embodiment, a numerical
weighting can be applied to each appropriate set of delivery sites.
A plurality of Smart Mirror sites is selected, one for each content
provider group. The content provider groups is specified in the
delivery site file; each possible delivery site is identified as
belonging to one or more content provider groups. When content
provider groups are used, there can be as few as two groups; the
maximum number is essentially unlimited.
[0104] It should also be noted that a prioritized ranking of
delivery sites can also be generated and maintained. If this is
done, failure of the primary Smart Mirror site to respond will
allow the system to fall back to the next-highest ranked Smart
Mirror site.
[0105] After a Smart Mirror site is selected, certain data will be
sent to the MSP 32 (step 52) via e-mail or other Internet
electronic protocol. The information received by querying the user,
the identity of the selected Smart Mirror site, and all raw test
data and results, including the time and date at which each test
was run, is compiled into a text file (which is encrypted in one
embodiment). Upon receipt by the MSP 32, the data is stored in a
database for use in managing and analyzing the system.
[0106] Finally, the configuration utility 34 saves the identity of
the selected Smart Mirror site for each set of delivery sites, or
the prioritized list, to the (encrypted) configuration file (step
54). The configuration utility may also save information on
relative performance for each tested delivery site. The client
program 36 uses the encrypted configuration file to download data
files (video clips or other content) from the appropriate Smart
Mirror site.
[0107] It should be noted that in the operation of the system, the
MSP 32 performs certain functions. The MSP 32 maintains the
delivery site list, adding and deleting sites as necessary. The MSP
32 also maintains the database of network performance, containing
information received via e-mail or other means from users running
the configuration utility 34. As large amounts of data are received
from numerous users, the database can provide valuable information
on the performance and other characteristics of the Internet and
portions thereof. Various data processing techniques are known to
derive such information.
[0108] The locations of the delivery sites used with the invention
are ultimately determined by a number of factors, including
marketing considerations and cost/benefit analyses. However, the
data stored in the MSP's database can confirm the utility of
placing a delivery site at a given location on the Internet or
other network. In one embodiment, servers are located on each major
backbone (portion of the Internet maintained by a single
corporation) and on other Internet lines serving large numbers of
users, such as the major lines operated by the Regional Bell
Operating Companies ("RBOCs"). In certain networks serving large
numbers of users or having heavy video delivery traffic, servers
can be placed at major Points of Presence ("POPs") for the network
to ensure that each user has access to a fast server.
[0109] Once the configuration utility 34 has been run, the user can
use the system to enable and facilitate the receipt of data files,
specifically video clips, audio clips, software programs, and other
content.
[0110] As time passes and the usage patterns of a user's region of
the Internet change, the user might become dissatisfied with the
performance of the Smart Mirror site associated with his user
terminal 12. If this happens, the user may re-run the configuration
utility 34. By that time, additional delivery sites might have been
placed into service, or a different pre-existing site might perform
better than the one previously assigned. Furthermore, if the player
program 36 determines that the selected Smart Mirror site is not
performing adequately (e.g., it has failed three times out of ten
attempts), the player program 36 can prompt the user to re-run the
configuration utility 34. In other embodiment of the invention the
testing and mirror assignment is run automatically with each
request for a file on the Smart Mirror service or at some
intermittent times such as after every other, every third, every
tenth or every one hundredth request.
[0111] In one embodiment of the invention, the Smart Mirror system
is used to locate a delivery site from which to download a video or
audio clip ("clip") referenced on a Web page. In this embodiment,
the client program can be referred to or considered a "player
program." The player program, in addition to carrying out the
functions of the client program 36, enables the retrieval and
playback of video data. Ordinarily, a browser program 38 is run on
the user terminal 12 to view Web content. Browser programs
typically used include NCSA Mosaic, Netscape Navigator, and
Microsoft Internet Explorer. The browser program 38 allows the user
to hotlink among various Web sites on the Internet.
[0112] The EMBED tag is used within HTML documents to indicate
which Web pages include content managed by the system. When the
browser program 38 receives a Web page containing an EMBED tag, a
download of the file referenced by the tag is commenced, and the
file type is analyzed. If the file is of a type handled by the
player program 36, e.g. MPEG, the browser program 38 initiates the
player program 36. The contents of the tag are then passed by the
browser program 38 to the player program 36.
[0113] The player program 36 (FIG. 1) provides the Smart Mirroring
services facilitated by the MSP 32. The operation of the player
program 36 is shown in detail in FIG. 3.
[0114] The player program first analyzes the EMBED tag to determine
if there is an "SM" (Smart Mirror) parameter (step 60); the
presence of such a parameter indicates that the embedded clip is
enabled for Smart Mirroring. Data associated with the "SM"
parameter specifies the particular content provider from which the
desired clip originated, as well as the group of mirror servers
that particular content provider uses.
[0115] If the player program 36 determines that the EMBED tag
references a video clip or other content handled by the system
(step 62), the transfer of the embedded clip from the content
provider 22 is stopped. The player program 36 then extracts access
control or rating information from the EMBED statement (step 64),
if any exists. This rating information is compared against the
reference levels stored in the configuration file stored at the
user terminal 12 (step 66). If rating information does not exist
for the clip, the configuration file is queried to determine
whether unrated clips, as defined below, may be played (step 68).
Based on the foregoing information, the player program 36 will
authorize or decline the viewing of the desired clip.
[0116] If playback is authorized, the player program 36 attempts to
find the referenced clip on the local computer belonging to the
user terminal 12 (Step 70). If it exists there, it is not
re-downloaded, and can be played directly on the computer (from the
disk or from RAM) (step 72). However, the time and date of creation
of the clip on the local computer is first verified against the
time and date for the clip available on the network, to determine
if the stored clip is the most recent version (step 74). If it is
not, the stored clip is discarded (step 76) and the download
proceeds as follows.
[0117] If the clip does not exist on the local computer, the player
creates a new URL (step 78) in the following form: "http://", plus
the IP address of the selected Smart Mirror site stored in the
configuration file, plus the path name to mirror files (e.g.
"/pub/mirror/"), plus the name of the content provider taken from
the "SM" parameter in the EMBED statement, plus the filename taken
from the EMBED statement. The constructed URL is used to retrieve
the selected clip from the appropriate Smart Mirror site selected
by the configuration utility 34 (step 80). If more than one set of
delivery sites exists for different content providers, the "SM"
parameter is further used by the player program 36 to determine
which Smart Mirror site in the configuration file is to be used in
the constructed URL (step 82). In one embodiment of the invention,
site selection is performed at least partially by a redirection
server. This embodiment will be described in detail below with
reference to FIG. 4.
[0118] If the clip corresponding to the constructed URL is not
found at the Smart Mirror site, or is unable to be accessed, then
the download proceeds from the next-highest ranked Smart Mirror
site in the configuration file (step 84), or the next-highest
ranked delivery site selected by the redirection server (see FIG.
4). If all delivery sites fail, the download proceeds from the
original content provider's site as specified directly by the EMBED
statement.
[0119] If playback is disallowed, the player prevents the clip from
being transferred (step 88) and displays a bitmap (step 90)
advising the user that the download is not be permitted.
[0120] If the player program 36 determines that the EMBED tag
references a video clip or other content not handled by the system,
the player will check whether the access control level set in the
configuration file allows the user to play these clips or other
files which are considered "unrated" (step 92). If so, the clip is
transferred from its original content provider 22 by traditional
means (step 94), and the player program 36 displays the downloaded
file (step 96). If not, the player prevents the clip from being
transferred (step 98) and displays a message (step 100) advising
the user that the download is not permitted.
[0121] Upon download, the data file representing the desired clip
is stored within a specified data area on the local computer,
usually on the hard disk, belonging to the user terminal 12 (step
102). In one embodiment, this data area can be managed on a
least-recently-used basis by the player program 36. That is, if no
room in the data area remains for a new clip, the
least-recently-used (or viewed) clip or clips can be discarded to
make room (step 104).
[0122] In one embodiment of the invention, the client program 36 is
capable of sending messages to the MSP 32 (step 106) to reflect
whether downloads were successful. This message contains the
Internet address of the user terminal 12, the identity of the
selected server set, the Internet address of the site used to
accomplish the download, the Internet addresses of all sites which
failed, the name of the file downloaded, and the time to download
the file. This information can also be used by the MSP 32 to track
file downloads and to determine, in real time, whether there are
any problems with any Smart Mirror sites.
[0123] Alternatively, the client program 36 can maintain a small
local database of file transfer performance. Each download would
then be timed. Specifically, information can be gathered on the
time it takes a server to begin sending the requested file, the
stability of the data transfer rate, and the error rate of the
transfer. At some interval (e.g. weekly or once every 100
downloads), a message containing the accumulated file transfer
performance information, as well as the user and server information
discussed above, would be sent (automatically or upon request) to
the MSP 32 (step 106) to update the MSP's database. This additional
information increases the MSP's "knowledge" of network performance
without incurring any additional testing overhead.
[0124] This data is especially valuable in ascertaining the
performance of delivery sites, for the purpose of assessing the
quality of service purchased from the delivery site provider, and
for documenting the quality of service to content providers, to
support the cost of the system. It is recognized, however, that
much of the same information can be obtained through new users
running the configuration utility 34.
[0125] In one embodiment of the invention, information derived from
the database of the MSP 32 can be used to predict an improved
delivery site for a given user without actually having to run the
configuration utility to test the network between that user and a
list of potential delivery sites. More specifically, the aggregate
network performance data contained in the MSP 32 database is
analyzed in terms of the performance differences between a given
Internet IP address and a number of different delivery sites. Based
on this analysis, a correlation can be drawn between a user's IP
address and a delivery site that offers better data delivery
performance. This correlated data is used to produce a look-up
table which can be utilized by the MSP 32 in the process of
delivery site selection.
[0126] In practice, a redirection server is included within the MSP
network. In one embodiment, functions of the redirection server are
implemented within and performed by the MSP 32 server. In
alternative embodiments, several redirection servers may be
employed at various locations throughout the network.
[0127] In operation, the redirection server will acquire the IP
address of the user when the user requests a file that is managed
by the MSP delivery system. A request is made of the redirection
server through an EMBED statement, as discussed above. The EMBED
statement can explicitly refer to a specific server IP address,
identifying a single redirection server (e.g. the MSP 32), or can
contain a script or executable program code (e.g. in JavaScript or
the Java programming language) specifying a plurality of
redirection servers, to which access can be attempted in sequence
or in a random order. The user's IP address is then determined by
the server through traditional means, as HTTP (HyperText Transport
Protocol) requests typically include information on the requester's
address. The redirection server then maps the user's IP address to
an optimum delivery site located in the look-up table and forwards
the delivery site address to the user. The user's client program 36
or the redirection server then redirects the file request so that
the file is delivered from the optimum delivery site.
[0128] An important factor in designing the look-up table derives
from the large number of addresses on the Internet. Every computer
connected to the Internet is assigned an address. In the
conventional Internet addressing scheme, An address is comprised of
a 4-byte value that, by convention, is expressed by converting each
byte into a decimal number (0-255) and separating the bytes with a
period. For example, an address for the "www.intervu.net" server is
192.215.147.185. With this addressing scheme, there are over four
billion possible addresses on the Internet. Given the current state
of the art, a look-up table including four billion addresses is too
large to be useful in the embodiment described herein, so a way was
sought to compress the table.
[0129] It has been found that the selection of an optimum delivery
site can often be correlated to the first byte of a user's IP
address. This correlation is such that, after running the
configuration utility 34, a statistically significant number of
users having the same first-byte address would select the same
delivery site, or another site from a small group of delivery
sites. It has been observed that these delivery sites, in
comparison to uncorrelated delivery sites, provide improved
performance for most users having the same first-byte address. The
correlation is significant enough that in one embodiment of the
invention, a compressed look-up table is formed comprising a list
of first-byte IP addresses numbering 0-255, and for each address, a
list of delivery sites providing improved performance for users
having corresponding IP addresses. In this way, one or more
delivery sites are mapped to each entry in the address list.
[0130] It should be noted that in certain circumstances, some of
the first-byte IP addresses in the look-up table might not be
mapped to a corresponding server. This would be the case when, for
example, few users have IP addresses corresponding to a particular
entry in the table, and not enough of them have run the
configuration utility 34 to generate statistically significant or
reliable results. In this case, one or more default servers can be
specified in the database for use when a specific server is not
identified in the look-up table.
[0131] In a preferred embodiment, the look-up list is stored at a
single redirection server, e.g. the MSP 32. However, the look-up
list and related programming could also be stored at a web page
server, a content provider 22 server or a combination of the
above.
[0132] The redirection server is accessed to select a delivery site
(step 82, FIG. 3) as follows, and as described in FIG. 4. The user,
via the user terminal browser, requests a file referenced on a web
page by clicking on a link having an EMBED statement for that file.
If the file request is for a file managed by the MSP's delivery
system, the file request is forwarded to the redirection server
(e.g. the MSP 32) using conventional HTML file request semantics,
i.e. server "GET" (step 120).
[0133] The redirection server examines the incoming request and
determines the user's network address (IP address) using the
"REMOTE_HOST" variable supplied by the web server (step 122). It
should be noted that the embodiment of the invention described in
FIG. 4 can be accomplished without special-purpose client program
(such as the client program 36) installed on the user terminal 12.
If no client program 36 is installed (step 124), and the user, when
queried by a script or downloaded program, does not want to install
a client program (step 126), then site selection will be performed
entirely by the redirection server.
[0134] The redirection server then analyzes the user's IP address
and examines the list of potential delivery sites on the look-up
table to determine what delivery site or sites are correlated with
the user's IP address (step 128). The redirection server then
chooses a delivery site address, if more than one address
corresponds to the user's look-up table entry (step 130). If a
single delivery site address is found, then an HTTP redirection
response is used to deliver the file from the selected delivery
site (step 132). According to the HTTP specification, a file
requested from a certain server can be redirected by that server to
another location without any user or client program intervention.
Site selection is then complete (step 134). To complete the
transaction, the client program requests a copy of the file from
the selected delivery site and the delivery site server retrieves
the file and delivers it to the user.
[0135] If the user wants to install the client program 36 (step
126), then the program will be downloaded and installed (step 136)
by traditional means. If the client program 36 was already
installed (step 124), or if installation has just completed, the
file request proceeds differently, and is able to utilize both
server-side and client-side processing to retrieve a file in the
most efficient manner possible.
[0136] First, the redirection server analyzes the user's IP address
and examines the list of potential delivery sites on the look-up
table to determine what delivery site or sites are correlated with
the user's IP address (step 138). In some cases, it is possible
that the redirection server storing the look-up table will generate
(step 140) and send (step 142) to the user terminal 12 a small file
including a sublist of delivery sites and rely on the client
program 36 to make the final delivery site selection (step 144).
There are a number of reasons this may occur.
[0137] First, as previously noted, an analysis of aggregate network
performance data may indicate that a number of delivery sites (as
opposed to a single delivery site) offer improved performance to
certain users having the same first-byte address range. This
occurs, for example, where a number of users, all having the same
first-byte address or range of addresses within a single first-byte
address, selected different delivery sites after running the
configuration utility. In this case, the client program 36 can take
the sublist downloaded by the redirection server and compare it to
a saved list of mirror sites which had been previously selected by
running the configuration utility (see FIG. 3, step 54). If a match
is found, the client program redirects the file request to the
matching delivery site (step 146). The client would also have the
option to ignore the selection make by the client program and make
a best-guess selection from among the delivery sites contained in
the look-up list, since one or more of these delivery sites may
offer improved performance over any delivery site previously
selected by the configuration utility, especially if the
configuration utility has not been run recently.
[0138] Second, a situation may also arise where the number of
delivery sites and IP addresses managed by the MSP has increased to
a point where the look-up table becomes too large to be practical,
i.e., the redirection server is delayed in responding to a new file
request because it is busy searching through the look-up tables on
behalf of a previous file request. If this is the case, the task of
searching through the look-up table is split between the
redirection server and the client program 36. Thus the user
terminal 12 is required to do some of the processing and also act
as a router by making the final delivery site selection.
[0139] In order to accomplish this, the redirection server
subdivides the look-up table into smaller sublists with a given
range of addresses. Thus, when the redirection server receives a
request for a file, the server will map the user's IP address (step
138) to the sublist with the corresponding address range, and then
generate (step 140) and download (step 142) to the user a small
file containing the sublist. The client program 36 then acts as a
router, selecting a delivery site (step 144) from among the
delivery sites in the sublist look-up table, by either mapping the
user's IP address to the proper correlated delivery site address on
the sublist, or by looking for a match between a delivery site on
the sublist and a delivery site on the prioritized list of sites
saved by the configuration utility 34 after previously running
network performance tests, as described above. Once the client
program has selected a delivery site, the client program redirects
the file request to the selected delivery site (step 146). By
splitting the work between the redirection server and the user
terminal 12, the file request can be processed quicker, thereby
reducing the delay between the time the user requests the file and
the time when the file is received by the user terminal 12.
[0140] Although the MSP 32 redirection look-up table will be
updated frequently in response to changes in network performance,
the sublists passed down to the user are expected to be
satisfactory for at least a few days. Thus, the client program 36
can reuse the list for a few days before acquiring a new sublist.
This function can be implemented, for example, by a script embedded
in the web page hosting the file request statement. The script can
query the client program 36 for an expiration date encoded in the
sublist stored at the user terminal 12. The expiration date and
sublist type can be passed back to the redirection server and if
necessary, the server will pass down a new sublist.
[0141] It is possible that a particular user may request a file
managed by the MSP delivery system, and the system will have no
knowledge of that user (i.e., no matches are found between the
user's IP address and delivery sites in the look-up table). In this
case, the redirection server will select a delivery site for the
user (steps 130 and 144) from a default list stored at the
redirection server. When the user downloads the requested file from
this delivery site, he may be prompted via an embedded script or
program to acquire the configuration utility file from the MSP 32
for the purpose of improving content delivery, or will be
temporarily assigned a server which is an approximation (e.g. has a
similar, but not identical, first-byte IP address) for improved
content delivery. If the user acquires and runs the configuration
utility, the user terminal 12 will begin providing the MSP 32 with
the results of various network tests, as described above, and this
information will ultimately become part of the MSP database of
network performance data. Thus, on the next file request from that
new user, the redirection server will be able to map the user's IP
address to a more appropriate server based on an analysis of the
additional network performance data.
[0142] By modifying the look-up table, the redirection server can
also perform load balancing and management with respect to file
requests. If the MSP 32 (or an individual controlling the MSP 32)
determines in advance that sections of the network will be down for
a period of time, or if certain delivery sites must be shut down
for a period of time, the look-up table can be modified so that the
redirection server will point users to alternative delivery sites.
Thus, it is possible that on two back-to-back requests for the same
file, a user may be directed to two different delivery sites.
[0143] It should be appreciated that the file comprising a sublist
of the look-up table can function as the delivery site file which
is used by the configuration utility 34 to run network tests. The
sublist represents delivery sites which have already been screened
for improved performance via aggregate network performance data
derived from a group of other users who have previously conducted
network tests. This sublist of delivery sites can be further
pared-down or prioritized by running the configuration utility 34
against the list and performing the sequence of network tests
retained from a previous delivery site file. Once the sublist is
prioritized, the configuration utility 34 saves the list to the
(encrypted) configuration file as described above.
[0144] In the following exemplary description, the Smart Mirror
system utilizes the look-up table to locate an improved delivery
site from which to download a video clip referenced on a Web page
advertising banner. When dealing with relatively unpopular content
such as advertising, it is important to deliver advertising content
to the intended customer as quickly as possible, so the potential
customer does not lose interest. With respect to the content in a
Web page advertising banner, the same is true: it is desirable to
be able to deliver the video to the customer as quickly as possible
without having to download a substantial amount of software in
advance. Therefore, as an alternative to utilizing the invention as
a premium service, a service provider can distribute advertising
banners on Web pages across the Internet. Each banner would
reference a video clip, and all of the clips would be stored at a
content provider's server established for that purpose.
[0145] In this example, the client program 36 is referred to as a
"player program," and it has the added functionality of retrieving
and playing back video data as previously described. A browser 38
(such as Netscape Navigator or Microsoft Internet Explorer) is used
to view Web content at the user terminal 12 and to communicate
between the user terminal 12 and other computers on the Internet
10.
[0146] When the client selects an advertising banner displayed on a
Web page, an EMBED tag encoded in the banner is examined by the
browser. The browser commences a download of the file referenced by
the EMBED tag and the file type is analyzed. If the file is of a
type handled by the player program, e.g. MPEG, the browser
initiates the player program by passing the tag to the player
program. The player program examines the EMBED tag for the file
name of the video clip and attempts to find the clip on the local
computer belonging to the user terminal. If it exists there, it is
not re-downloaded, and can be played directly on the computer (from
the disk or from RAM). If the video clip is not on the local
computer, the player program analyzes the EMBED tag to determine if
there is an "SM" (Smart Mirror) parameter; the presence of such a
parameter indicates that the embedded clip is enabled for Smart
Mirroring. The SM parameter further specifies the address of the
redirection server, and as discussed above, the particular content
provider from which the desired clip originated, as well as the
group of mirror servers that particular content provider uses.
[0147] If the player program recognizes a parameter specifying a
redirection server, the player program will invoke the browser to
request the referenced ad banner file from the redirection server
via conventional HTML file request techniques. The redirection
server examines the incoming request and determine the IP address
of the client. The redirection server maps the client's IP address
to the look-up table and retrieve a delivery site address or a
sublist. The delivery site address (or a sublist of delivery sites
and IP addresses) is returned to the player program by the
redirection server. If a sublist is returned, the player program
selects a single delivery site from among those listed, as
previously described. Once a single delivery site is determined,
the player program creates a new URL in the following form:
"http://", plus the IP address of the selected delivery site, plus
the path name to mirror files (e.g. "/pub/mirror/"), plus the name
of the content provider taken from the "SM" parameter in the EMBED
statement, plus the filename taken from the EMBED statement. The
constructed URL is used to retrieve the selected clip from the
delivery site selected from the look-up table.
[0148] If the SM parameters in the EMBED tag do not specify a
redirection server, or if the redirection server is unavailable and
does not return a response, the player program will select an IP
address from the prioritized list of Smart Mirror sites stored in
the configuration utility file and substitute this address in the
URL. If the player program does not detect the presence of the
prioritized list of smart mirror sites (for example, if the user
never downloaded the configuration utility 34), then the player
program will request the video using the address of the original
content provider's server, as specified directly by the EMBED
statement.
[0149] In applications not specifically targeted to the delivery of
advertising content, the provision of download information to the
MSP facilitates the use of the invention as a premium
subscription-based service. As successful downloads are tracked in
a database, each user can have an associated "account" to track
charges. The user can be charged for use of the Smart Mirror system
by the file, by the megabyte, by the month, or by other known
means. In one embodiment, the EMBED tag associated with a file
contains billing information, or a "price" for the file. The
invention's tracking of download performance allows discounts or
credits to be issued if downloads are found to be unduly difficult
or slow.
[0150] To ensure that files stored on Smart Mirror delivery sites
are used only by authorized users of the invention (e.g. those
users having paid accounts), the files stored at the delivery sites
can optionally be in encrypted form, and the downloading step
described above can include a decryption step. Such encryption and
decryption can be performed by well known means.
[0151] As discussed above, the clips managed by the invention can
have content rating information associated therewith. This is
accomplished by providing a "PG" parameter in the EMBED statement
corresponding to the clip. In one embodiment, four characteristics
are rated: nudity, sexuality, profanity, and violence. Accordingly,
the PG parameter can be specified by a four-digit argument. Each
characteristic is rated on a scale of one to three. One corresponds
to no filtering (i.e. all content is allowable), two corresponds to
some filtering (e.g. equal to levels typically allowed in broadcast
television), and three corresponds to the most extensive filtering
(e.g. for children). The ratings levels contained in the EMBED
statement for a file are compared to the ratings filter levels
contained in the configuration file stored at the user terminal 12
in the foregoing authorization process, and only authorized files
are transferred.
[0152] In view of the above, it will be appreciated that
embodiments of the invention may be employed in many different
applications to permit the acquisition and analysis of performance
data for networks between a given user and content provider or
delivery site. Thus, although the described embodiment illustrates
the system operating within the context of the Internet, and with
an Internet-type addressing scheme, it is recognized that such a
system could prove to be useful in other network environments,
including but not limited to corporate "intranets."
[0153] Moreover, although the illustrative embodiments are
described primarily for use in a video delivery system, it should
be recognized that a system according to the invention can be used
to distribute various other kinds of computer data (e.g.
application programs, database files and other business
information, virtual reality files, multimedia such as Macromedia
Shockwave files, and large text files such as books) as well. Such
other types of data can be managed by the invention in different
content provider groups as discussed in detail above; a different
type of program (rather than the player program 36) typically would
be invoked at the user terminal 12 to view or use other types of
data.
[0154] It should also be noted that certain functionality described
as performed at the user terminal 12 (specifically, certain
functions performed by the configuration utility 34, or
client/player program 36) can be implemented as a standalone
program, as a "plug-in" or "helper application" to run within a
browser program, or as a Java applet downloaded from a delivery
site to run within a browser environment. For user terminals
capable of running the Microsoft Windows operating system, an
environment known as Microsoft ActiveX is also useful.
[0155] While certain exemplary structures and operations have been
described, the invention is not so limited, and its scope is to be
determined according to the claims set forth below.
* * * * *
References