U.S. patent application number 09/896562 was filed with the patent office on 2002-05-16 for content propagation in interactive television.
This patent application is currently assigned to SeaChange International, Inc., a Delaware corporation. Invention is credited to Sanders, Mark.
Application Number | 20020059394 09/896562 |
Document ID | / |
Family ID | 24184771 |
Filed Date | 2002-05-16 |
United States Patent
Application |
20020059394 |
Kind Code |
A1 |
Sanders, Mark |
May 16, 2002 |
Content propagation in interactive television
Abstract
A process of propagates viewing assets on a system of video
storages. The process includes copying a missing portion of a
replica of a selected viewing asset onto a target video server. The
act of copying is responsive to determining that a priority to
propagate the selected asset to the target server is higher than a
retention value of a replica of one or more viewing assets stored
on the target server.
Inventors: |
Sanders, Mark; (Carlisle,
MA) |
Correspondence
Address: |
FAUSTINO A. LICHAUCO
Fish & Richardson P.C.
225 Franklin Street
Boston
MA
02110-2804
US
|
Assignee: |
SeaChange International, Inc., a
Delaware corporation
|
Family ID: |
24184771 |
Appl. No.: |
09/896562 |
Filed: |
June 29, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09896562 |
Jun 29, 2001 |
|
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09547474 |
Apr 12, 2000 |
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Current U.S.
Class: |
709/217 ;
348/E7.073 |
Current CPC
Class: |
H04N 21/23103 20130101;
H04N 7/17336 20130101; H04N 21/40 20130101; H04N 21/23113 20130101;
H04L 65/612 20220501; H04N 21/23106 20130101 |
Class at
Publication: |
709/217 |
International
Class: |
G06F 015/16 |
Claims
What is claimed is:
1. A process of propagating viewing assets to a system of video
servers, comprising: copying a missing portion of a replica of a
selected viewing asset to a target video server in response to
determining that a priority to propagate the selected asset to the
target server is higher than a retention value of a replica of one
or more viewing assets stored on the target server.
2. The process of claim 1, wherein the copying writes the missing
portion of the replica of the selected asset onto a storage region
of the target video server previously storing a portion of the
replica of one or more viewing assets.
3. The process of claim 1, further comprising: selecting a portion
of the replica of one or more viewing assets in response to the
replica of one or more viewing assets having a data size at least
as large as a data size of the missing portion of the selected
asset.
4. The process of claim 1, wherein the copying the missing portion
of the replica of a selected asset includes copying the missing
portion from one or more video servers.
5. The process of claim 1, further comprising: assigning propagate
priorities of a plurality of viewing assets; ranking the viewing
assets according to the assigned priorities; and selecting the
selected asset in response to the selected asset having more than a
preselected minimum rank.
6. The process of claim 5, wherein the assigning includes
determining the propagation priorities based at least in part on
global priorities to propagate associated ones of the assets to
target video servers.
7. The process of claim 5, wherein the assigning includes
determining local priorities to have replicas of associated assets
on particular video servers, the local priorities depending on the
states of the particular video servers.
8. The process of claim 5, wherein the portion of replica of one or
more viewing assets consists of replicas of asset elements
belonging to one or more ELists.
9. The process of claim 3, further comprising: updating retention
values of replicas of viewing assets remaining on the target server
in response to the copying.
10. The process of claim 1, wherein the viewing assets include
video files for at least one of movies, news emissions, and
shopping emissions.
11. The process of claim 1, wherein the replica of one or more
viewing assets includes a replica of an asset element shared by
replicas of two assets on the target server.
12. A process for propagating digital viewing assets to video
servers, comprising: assigning to each of a plurality of digital
viewing assets a priority to propagate the asset onto video
servers; ranking the assets based on the assigned priorities; and
propagating one of the assets to one or more selected video servers
in response to the one of the assets having a preselected minimum
ranking.
13. The process of claim 12, wherein the assigning includes:
assigning a viewing asset to a usage class, the usage class
providing a portion of an initial value for priorities to propagate
assets assigned to the class.
14. The process of claim 13, further comprising: accumulating usage
data on individual assets stored on the video servers; and updating
the priorities to propagate the assets based on the usage data.
15. The process of claim 13, wherein the viewing assets include one
of encoded digital video assets and encoded digital audio
assets.
16. The process of claim 14, wherein the usage data includes
numbers of viewer requests during predetermined periods and
differences between numbers of viewer requests during earlier and
later predetermined periods.
17. The process of claim 14, further comprising: updating the
priority to propagate a particular asset in the usage class based
on a difference between the usage level of the usage class and a
usage level of the particular asset determined from the accumulated
usage data.
18. The process of claim 13, further comprising: calculating the
priority to propagate the one of the assets onto a particular video
server from a global priority to propagate the one of the assets
and a local priority to propagate a replica of the asset on the one
of the selected video servers.
19. The process of claim 13, further comprising: streaming a
replica of the copied one of the assets from the particular video
server to a television of a viewer in response to receiving a
request to view the asset from the viewer.
20. A process of propagating viewing assets to a video storage,
comprising: assigning propagation priorities to viewing assets;
constructing a table of element deletion lists for a target video
storage; selecting a group of element deletion lists from the
table, the group having a data size at least as large as a data
size of a portion of a replica of another asset not stored on the
target storage; and copying the portion of the replica of the
another asset onto the target video storage in response to the
propagation priority of the another asset being larger than a
retention value of the group.
21. The process of claim 20, wherein the copying writes the portion
onto a region of the target video storage previously storing the
group.
22. The process of claim 20, wherein the selecting a group includes
constructing a table listing sets of element deletion lists with
lower retention value than the propagation priority of the another
asset.
23. The process of claim 22, wherein the selecting includes picking
one of the lists having a data size at least as large as the
portion of the replica of the another asset.
24. The process of claim 20, further comprising: updating the table
of element deletion lists in response to performing the
copying.
25. The process of claim 20, wherein each element deletion list
includes a set of replicas of asset elements that are shared by the
same assets.
26. A process of distributing viewing assets to viewers,
comprising: assigning priorities to assets, the priorities
indicating priorities for distributing the associated assets to
video servers accessible to viewers; selecting a video server; and
copying one of the assets onto the video server in response to
determining that the priority associated with the one of the assets
is greater than a retention value associated with a set replicas of
viewing assets stored on the video server, the replicas occupying
enough space to store the one of the assets.
27. The process of claim 26, wherein the copying includes searching
for one or more sets of replicas of asset elements to delete from a
table of element deletion lists.
28. The process of claim 26, further comprising: updating the
retention values in response to anticipated changes in viewer
request levels for assets.
29. The process of claim 28, further comprising: accumulating data
on usage of individual ones of the assets, the updating based at
least in part on the accumulated data.
30. An interactive television system, comprising: one of a network
and a bus; a plurality of video servers to store digital replicas
of viewing assets for viewers, the video servers being connected by
the one of a network and a bus; and a control unit connected to the
video servers and configured to control copying of a missing
portion of a replica of a selected asset to one of the video
servers in response to a priority to propagate the selected asset
onto the target server being higher than a value of retaining a
replica of one or more other assets already stored on the one of
the servers.
31. The system of claim 30, wherein the control unit is further
configured to record usage data for the assets stored on each of
the local video storages.
32. The system of claim 30, further comprising: a plurality of
distribution networks to provide channels for delivering viewing
assets to viewer televisions, each distribution network connected
to portion of the video servers.
33. The system of claim 30, wherein the control unit is configured
to accumulate usage data on viewing assets from the video
servers.
34. A program storage media storing computer executable
instructions for propagating viewing assets onto video storages,
the instructions to cause the computer to: order copying of a
missing portion of a replica of a selected viewing asset to a
target video server in response to determining that a priority to
propagate the selected asset to the target server is higher than a
retention value of a replica of one or more viewing assets stored
on the target server.
35. The media of claim 34, the instructions further causing the
computer to: select a portion of the replica of one or more viewing
assets in response to the replica of one or more viewing assets
having a data size at least as large as a data size of the missing
portion of the selected asset.
36. The media of claim 34, wherein the instructions to order
copying of the missing portion of the replica of a selected asset
cause the computer to control copying of the missing portion from
one or more video servers.
37. The media of claim 34, the instructions further causing the
computer to: assign priorities to propagate to a plurality of
viewing assets; rank the viewing assets according to the assigned
priorities; and select the selected asset in response to the
selected asset having more than a preselected minimum rank.
38. The media of claim 37, wherein the instructions to assign cause
the computer to: determine the propagation priorities based at
least in part on global priorities to propagate associated ones of
the assets to target video servers.
39. The media of claim 37, wherein the portion of replica of one or
more viewing assets consists of replicas of asset elements
belonging to one or more ELists.
40. The media of claim 35, the instructions further causing the
computer to: update retention values of replicas of viewing assets
remaining on the target server in response to the copying.
41. A program storage media storing executable instructions for
propagating digital viewing assets onto video servers, the
instructions causing a computer to: assign to each of a plurality
of digital viewing assets a priority to propagate the asset onto
video servers; rank the assets based on the assigned priorities;
and order propagation of one of the assets to one or more selected
video servers in response to the one of the assets having a
preselected minimum ranking.
42. The media of claim 41, wherein the instructions to assign cause
the computer to: assign a viewing asset to a usage class, the usage
class providing a portion of an initial value for priorities to
propagate assets assigned to the class.
43. The media of claim 42, the instructions further causing the
computer to: accumulate usage data on individual assets stored on
the video servers; and update the priorities to propagate the
assets based on the usage data.
44. The media of claim 43, wherein the usage data includes numbers
of viewer requests during predetermined periods and differences
between numbers of viewer requests during earlier and later
predetermined periods.
45. The media of claim 43, the instructions further causing the
computer to: update the priority to propagate a particular asset in
the usage class based on a difference between the usage level of
the usage class and a usage level of the particular asset
determined from the accumulated usage data.
46. The media of claim 42, the instructions further causing the
computer to: calculate the priority to propagate the one of the
assets onto a particular video server from a global priority to
propagate the one of the assets and a local priority to propagate a
replica of the asset on the one of the selected video servers.
47. A program storage media storing executable instructions for
propagating viewing assets to a video storage, the instructions
causing a computer to: assign propagation priorities to viewing
assets; construct a table of element deletion lists for a target
video storage; select a group of element deletion lists from the
table, the group having a data size at least as large as a data
size of a portion of a replica of another asset not stored on the
target storage; and order copying of the portion of the replica of
the another asset onto the target video storage in response to the
propagation priority of the another asset being larger than a
retention value of the group.
48. The media of claim 47, wherein the instructions to select a
group cause the computer to construct a table listing sets of
element deletion lists with lower retention value than the
propagation priority of the another asset.
49. The media of claim 48, wherein the instructions to select cause
the computer to pick one of the lists having a data size at least
as large as the portion of the replica of the another asset.
50. The media of claim 47, wherein each element deletion list
includes a set of replicas of asset elements that are shared by the
same assets.
51. A process for propagating digital viewing assets to video
servers, comprising: propagating a plurality of viewing assets to
video servers based on priorities to propagate, the priorities
providing a ranking of the assets; accumulating usage data on
individual ones of the assets stored on the video servers; and
updating the priorities based on the usage data.
52. The process of claim 51, further comprising: assigning a
viewing asset to a usage class, the usage class providing a portion
of an initial value for the priorities to propagate for the assets
assigned to the class.
53. The process of claim 52, further comprising: calculating the
priority to propagate a selected one of the assets onto one of the
video servers from a global priority to propagate the selected one
of the assets and a local priority to propagate a replica of the
selected one of the assets onto the one of the video servers.
54. The process of claim 53, wherein the global priority is based
in part on a counter value, the counter value measuring usage of
the selected one of the assets.
55. The process of claim 53, wherein the local priority is based in
part on a bandwidth for streaming the selected one of the assets
from the one of the video servers to a set of viewers.
Description
TECHNICAL FIELD
[0001] This invention relates to interactive television.
BACKGROUND
[0002] Interactive television systems provide viewers with network
access to video servers that offer a large plurality of viewing
selections. To make a viewing selection, a viewer looks at a menu
transmitted by the system and selects a viewing asset. The viewer
issues a request for the selected asset through a network that
connects his or her television to the interactive television
system. In response to receiving the viewer's request, the
interactive television system uses the network to stream the
requested asset from one of the video servers to the viewer's
television. The collection of video data objects and related data
objects such as posters, descriptions, and preview objects, may
together form a complete viewing asset.
[0003] In an interactive television system, the selection of
available viewing assets is preferably large. Furthermore, the
viewing assets themselves often include large video data objects.
The desire to offer large selections to viewers means that such
systems need very substantial data storage resources for viewing
assets.
[0004] An interactive television system may store a large amount of
asset data on an array of servers. Typically, only a subset of the
servers is accessible to a single viewer, because one server cannot
server every viewer. In such a system, an individual asset may have
to reside on several servers so that different viewers can access
the asset.
[0005] The collection of accessible assets may also change over
time. Changes to the collection of assets may respond to asset
popularity shifts and/or viewing population changes.
SUMMARY
[0006] In one aspect, the invention features a process of
propagating viewing assets on a system of video storages.
[0007] The process includes copying a missing portion of a replica
of a selected viewing asset onto a target video server. The act of
copying is responsive to determining that a priority to propagate
the selected asset to the target server is higher than a retention
value of a replica of one or more viewing assets stored on the
target server.
[0008] In some embodiments, the act of copying includes writing the
missing portion of the replica of the selected asset onto a storage
region of the target video server that previously stored a portion
of the replica of one or more viewing assets. The copying may
include reading the missing portion from video servers that serve
viewers.
[0009] In some embodiments, the act of selecting a portion of the
replica of one or more viewing assets is responsive to the replica
of one or more viewing assets having a data size at least as large
as a data size of the missing portion of the selected asset.
[0010] In some embodiments, the process also includes assigning
priorities to propagate to a plurality of viewing assets, ranking
the viewing assets according to the assigned priorities, and
choosing the selected asset for copying in response to the selected
asset being ranked above a preselected minimum rank.
[0011] In a second aspect, the invention features a process for
propagating digital viewing assets to video servers. The process
includes assigning to each of a plurality of digital viewing assets
a priority to propagate the asset onto video servers, ranking the
assets based on the assigned priorities; and propagating one of the
assets to one or more selected video servers. The act of
propagating is responsive to the one of the assets having a
preselected minimum ranking.
[0012] In some embodiments, the act of assigning includes assigning
a viewing asset to a usage class. The usage class provides a
contribution to initial values of the priorities to propagate
assets assigned to the class.
[0013] In some embodiments, the process further includes
accumulating usage data on individual assets stored on the video
servers and updating the priorities to propagate based on the usage
data. The usage data may include numbers of viewer requests during
predetermined time periods and differences between numbers of
viewer requests during earlier and later predetermined periods.
[0014] In a third aspect, the invention features a process for
propagating viewing assets onto a video storage. The process
includes assigning propagation priorities to viewing assets,
constructing a table of element deletion lists for a target video
storage, and selecting a group of element deletion lists from the
table. The group has a data size at least as large as a data size
of a portion of a replica of another asset not stored on the target
storage. The process also includes copying the portion of a replica
of the other asset onto the target video storage in response to the
propagation priority of the other asset being larger than a
retention value of the group.
[0015] In some embodiments, the act of copying includes writing the
portion onto a region of the target video storage previously
storing the group.
[0016] In some embodiments, the act of selecting a group includes
constructing a table listing sets of element deletion lists with
lower retention value than the priority of the other asset. The act
of selecting includes picking one of the lists having a data size
at least as large as the portion of the replica of the other
asset.
[0017] In a fourth aspect, the invention features a process of
distributing viewing assets to viewers. The process includes
assigning priorities to assets, selecting a video server, and
copying one of the assets onto the video server. The priorities are
priorities for distributing the associated assets to video servers
accessible to viewers. The act of copying is responsive to
determining that the priority associated with the one of the assets
is greater than a retention value associated with a set of viewing
assets having replicas on the video server. The replicas occupy
enough space to store the one of the assets.
[0018] In some embodiments, the copying includes searching for one
or more sets of replicas of asset elements to delete on a table of
element deletion lists.
[0019] In some embodiments, the process further includes
accumulating data on usage of individual ones of the assets. Then,
the act of updating is based at least in part on the accumulated
data.
[0020] In a fifth aspect, the invention features an interactive
television system. The system includes a network or bus, a
plurality of video servers to store digital replicas of viewing
assets for viewers, and a control unit connected to the video
servers. The video servers are connected by the network or bus. The
control unit orders copying of a missing portion of a replica of a
selected asset to one of the video servers if a priority to
propagate the selected asset onto the one of servers is higher than
a value of retaining a replica of one or more other assets already
stored on the target server.
[0021] In some embodiments, the system also includes a plurality of
distribution networks to provide channels for delivering viewing
assets to viewer televisions. Each distribution network connects to
portion of the video servers.
[0022] In a sixth aspect, the invention features a process for
propagating digital viewing assets onto video servers. The process
includes propagating a plurality of viewing assets onto video
servers based on priorities to propagate, accumulating usage data
on individual assets stored on the video servers, and updating the
priorities based on the usage data. The priorities provide a
ranking of the assets.
[0023] In some embodiments, the process includes assigning a
viewing asset to a usage class that provides a portion of an
initial value for the priorities to propagate the assets assigned
to the class. The process may also include calculating the priority
to propagate a selected one of the assets onto one of the video
servers. The calculation may be based on a global priority to
propagate the selected one of the assets and a local priority to
propagate a replica of the selected one of the assets onto the one
of the video servers. The global priority may be based in part on a
counter value that measures usage of the selected one of the
assets. The local priority may be based in part on a bandwidth for
streaming the selected one of assets from the one of the video
servers to a set of viewers.
[0024] In various aspects, the invention features a data storage
media storing a computer executable program of instructions for
performing one or more of the above-mentioned processes.
[0025] Other features, objects, and advantages of the invention
will be apparent from the description and drawings, and from the
claims.
DESCRIPTION OF DRAWINGS
[0026] FIG. 1 is a block diagram of an interactive television
system;
[0027] FIG. 2 illustrates asset delivery pathways of the media
clusters shown in FIG. 1;
[0028] FIG. 3 is a high-level block diagram of software processes
that manage and control the interactive television system of FIG.
1;
[0029] FIG. 4 illustrates interactions between a propagation
service process and other processes of FIG. 3;
[0030] FIG. 5A is a flow chart for a process that ranks viewing
assets and evaluates retention values of replicas of asset elements
and entries in element deletion lists;
[0031] FIG. 5B is a flow chart for a process that decides whether
to propagate a replica of an asset to a media cluster;
[0032] FIG. 6 is a flow chart illustrating a process that
calculates total propagation priorities of replicas of assets;
[0033] FIG. 7 is a flow chart illustrating a process that
determines whether to copy a replica of a viewing asset onto a
media cluster;
[0034] FIG. 8A illustrates relations between replicas of viewing
assets and replicas of asset elements stored on a media
cluster;
[0035] FIG. 8B illustrates ELists for the replicas of viewing
assets and asset elements shown in FIG. 8A;
[0036] FIG. 8C illustrates replicas of assets, replicas of asset
elements, and ELists that remain on the media cluster of FIG. 8A
after deletion of the asset elements of one EList;
[0037] FIG. 8D is a table enumerating the ELists remaining in FIG.
8C;
[0038] FIG. 9A is a table showing the ELists shown in FIG. 8B;
[0039] FIG. 9B is a table that enumerates "combinations of ELists"
from FIG. 9A with retention values below 50;
[0040] FIG. 10 is a flow chart illustrating a process that uses
ELists to free space for propagating replicas of new assets;
and
[0041] FIG. 11 is a flow chart illustrating a process that
initially defines and subsequently updates a new asset's global
propagation priority;
[0042] Like reference symbols in the drawings indicate like
elements.
DETAILED DESCRIPTION
[0043] Interactive Television System
[0044] FIG. 1 shows a networked system 10 that provides interactive
television to subscribing viewers. The system 10 includes a set of
control units 16. The control units 16 connect to each other
through a multi-channel communications bus 12. In some embodiments,
the bus 12 may be a network. The bus 12 also couples a plurality of
media clusters 40, 40', 40", which store replicas of viewing assets
for viewers. The media clusters 40, 40', 40" couple to node groups
of local viewers 20, 20', 20", 20"' through hybrid fiber coaxial
(HFC) networks 22, which function as broadband or multi-channel
broadcast networks for the local node groups 20, 20', 20", 20"'.
The HFC networks 22 carry viewing assets from the media clusters
40, 40', 40" to interactive viewer televisions 24 and carry viewing
status data and viewing requests from the televisions 24 up to the
media clusters 40, 40', 40" and control units 16.
[0045] The arrangement of control units 16 and media clusters 40,
40', 40" may serve a large number of viewers. For example, each
media cluster 40, 40', 40" may serve between about ten to fifty
thousand local viewers. The connectivity between individual media
clusters 40, 40', 40" and individual node groups 20, 20', 20", 20"'
may differ from cluster to cluster. For example, the media cluster
40 couples to node groups 20 and 20' while the media cluster 40"
couples to node groups 20" and 20"'. Thus, different viewers may be
served by different subsets of the media clusters 40, 40', 40".
[0046] Each interactive viewer television 24 includes a set top box
26 that connects a normal television 25 to the local HFC network 22
and provides an interface for communicating with a portion of the
media clusters 40, 40', 40" and control units 16. The set top boxes
26 receive viewing assets from the associated HFC networks 22,
decode the received assets, and display the decoded assets on a
normal television 25. In some embodiments, the set top boxes 26 may
be integrated into the televisions 25. The set top boxes 26 also
receive menus of available viewing assets, display the menus on the
normal televisions 25, and transmit viewer requests for viewing
assets and streaming-control commands to the control units 16. The
streaming-control commands implemented by the set top boxes 26 may
include stop, pause, fast-forward, and reverse.
[0047] The viewing assets are sequences of encoded digital files
for video, text, audio, graphic, and/or interactive control
applications. Each file of the sequence, for a viewing asset, will
be referred to as an asset element. The displayed viewing assets
may, for example, be movies, newscasts, shopping emissions or
interfaces, posters, or audio presentations.
[0048] Each control unit 16 includes a computer 28, a data storage
media 30, e.g., a hard drive or compact disk, for storing software
processes executable by the computer. The control units 16 manage
viewing assets on the media clusters 40, 40', 40" and control
delivery of these assets to viewers. The management of assets
includes propagating assets among the media clusters 40, 40', 40"
and accumulating asset usage data to insure that the propagation of
assets to the media clusters 40, 40', 40" anticipates viewer
demand. The controlling asset delivery includes receiving, viewing
requests from individual interactive televisions 24 and assigning
asset delivery pathways from the media clusters 40 to the node
groups 20, 20', 20", 20"' corresponding to requesting viewers.
[0049] Each media cluster 40, 40', 40" stores replicas of viewing
assets that are currently available to the node groups 20, 20',
20", 20"' connected to the media cluster 40, 40', 40". The
selection of viewing assets varies from media cluster to media
cluster 40, 40', 40". The media clusters 40, 40', 40" stream
viewing assets to associated local node groups 20, 20', 20", 20"'
in response to control commands received from the control units 16.
The control units 16 send such control commands in response to
receiving requests for viewing assets from the various node groups
20, 20', 20", 20"'.
[0050] Each media cluster 40, 40', 40" has space for storing a
limited number of replicas of viewing assets. The media clusters
40, 40', 40" store assets for meeting present and near-future
viewing demands. To handle changing viewing demands, the control
units 16 regularly update the asset selection on the media clusters
40, 40', 40" by copying replicas of new viewing assets to the media
clusters 40, 40', 40" and/or by copying viewing assets between
different media clusters 40", 40, 40'. To propagate an asset, a
control unit 16 first copies a replica of a new asset to a
preselected one of the media clusters 40, 40', 40" and then orders
cluster-to-cluster copying to propagate the asset to other clusters
40, 40', 40". The control units 16 update the viewing asset
selection on the media clusters 40, 40' 40" to maximize the
economic value that the entire asset collect provides to the system
10 as is explained below.
[0051] Though the system 10 of FIG. 1 is not hierarchical, other
embodiments may use hierarchical organizations of media clusters
and/or control units, e.g., in master-slave relationships. In those
embodiments, master servers control slave servers and provide for
larger video storages. Several hierarchical organizations of media
clusters or video servers are described in U.S. Pat. No. 5,862,312
and U.S. patent application Ser. No. 09/293,011, filed Apr. 16,
1999, which are both incorporated by reference herein.
[0052] FIG. 2 shows media clusters 40, 40', 40" in more detail.
Each media cluster 40, 40', 40" has several video data servers 42,
42', 42" that locally interconnect through a network or bus 34,
34', 34". The servers 42, 42', 42" of the same cluster 40, 40', 40"
share a data storage 36, 36', 36", which may be physically lumped
or spread over the individual local servers 42, 42', 42". The
servers 42, 42', 42" delivery viewing assets from the cluster video
storages 36, 36', 36" to node groups 20, 20', 20", 20"' connected
to the associated media cluster 40, 40', 40". The video data
storages 36, 36', 36" store replicas of the viewing assets, which
the media cluster 40, 40' can deliver to local node groups 20, 20',
20", 20"'. The selection of replicas of assets stored on different
clusters 40, 40', 40" may differ so that different media clusters
40, 40', 40" do not generally provide identical viewing selections
to the locally connected node groups 20, 20', 20", 20"'.
[0053] FIG. 2 also shows some of the delivery pathways between
various media clusters 40, 40', 40" and local node groups 20, 20',
20", 20"'. Each delivery pathway includes one of the servers 42,
42', 42", an output card of the server, a quadrature amplitude
modulator (QAMs) 50, a combiner 52, 52', 52", 52"' and an HFC 22
that connects the destination node group 20, 20', 20", 20"'. The
servers 42, 42', 42" have one or more output cards, which produce
streams of digital data packets for transporting viewing assets to
the node groups 20, 20', 20", 20"'. The output streams are received
by QAMs 50 that connect to the output cards. Each QAM 50 reads
headers of received packets and retransmits the packets towards the
node group 20, 20', 20", 20"' served by the QAM 50 if that node
group 20, 20', 20", 20".' is a destination of the packet. The
retransmitted packets are received by combiners 52, 52', 52", 52"',
which send broadband transmissions from several QAMs 50 to the
associated node groups 20, 20', 20", 20"' via the associated HFC
22.
[0054] Referring again to FIG. 1, the different media clusters 40,
40', 40" may have different delivery pathways to the node groups
20, 20', 20", 20"'. The control of delivery of viewing content over
these delivery pathways and the management of replicas of assets
stored on the media clusters 40, 40', 40" are both performed by the
control units 16. The control units 16 execute processes that
perform these functions and are able to manage in excess of ten
thousand assets and a variety of control application types. An
individual control unit 16 may perform the above-functions for some
or all of the media clusters 40, 40', 40".
[0055] Processes Controlling Assets
[0056] Assets are the smallest viewable objects that can be
requested by or streamed to viewers. Replicas of assets can be
activated or deactivated on the media clusters 40, 40', 40". An
asset may include several elements, e.g., consecutive portions of a
movie, a movie poster, and a movie trailer. The elements of an
asset are individual files and are the smallest data objects that
can be copied to or deleted from a media cluster 40, 40', 40".
Physical copies of assets and asset elements on particular media
cluster 40, 40', 40" are referred to as replicas of assets and
replicas of asset elements, respectively.
[0057] FIG. 3 is a block diagram showing software processes
executed by the computers 28 of the control units 16 to manage and
control viewing assets and asset usage in the interactive
television system 10 shown in FIG. 1. On each control unit 16, the
processes include modules 62, 64, 66, 68, 70, 72, 74, 76, which
perform asset management, directory service, propagation services,
connection management, streaming services, movies-on-demand (MOD)
control application services, MOD billing services, and program
guide services. In some embodiments, other processes may provide
control application services and billing services for content
types, such as news-on-demand (NOD), interactive shopping, and
interactive games (not shown). On each media clusters 40, 40', 40",
resident processes include an instance of a media cluster agent 78.
On the set top boxes 26, resident processes include one or more
application agents 80, e.g., a MOD application agent.
[0058] FIG. 4 illustrates functional relationships between the
software process modules 62, 64, 66, 68, 70, 78 that manage and
control assets. These relationships are further described
below.
[0059] The asset management module 62 provides an interface for
receiving new viewing assets into the control unit 16. The
interface may, e.g., support automated downloads of viewing assets
from a distribution cable (not shown) and/or manual uploads of
viewing assets under control of a user operating a graphical user
interface. For each newly received asset, the asset management
module 62 creates an automated work queue 63 that controls the life
cycle of the associated asset. The work queues 63 control the life
cycle transitions performed by the propagation service (PS) module
66. An asset's life cycle may include states such as received;
encoded; stored on some media clusters 40, 40', 40"; activated;
deactivated; and deleted.
[0060] The asset management module 62 accepts several types of data
objects including encoded data files, e.g., encoded according to
the Movie Picture Experts Group (MPEG) standards, nonencoded data
files, executable applications, and metadata associated with other
assets. The received data assets may be for video, audio, text,
graphics, or interactive applications.
[0061] The directory service module 64 provides assets with
filenames arranged in hierarchical namespaces. The directory
service module 64 keeps information about the element composition
of assets and metadata associated with assets.
[0062] In various embodiments, the control applications may include
movies on demand (MOD), television on demand (TVOD), news on demand
(NOV), interactive shopping and others.
[0063] The propagation service module 66 controls copying of assets
to and deleting of assets from individual media clusters 40, 40',
40". A media cluster 40, 40', 40" needs a replica of each element
of an asset to be able to play the asset to viewers. But, replicas
of different assets may share replicas of some asset elements
stored on the same media cluster 40, 40', 40".
[0064] The propagation service module 66 orders copying of new
assets to a preselected one of the media clusters, e.g., cluster
40. The propagation service module 66 also orders copying of the
asset replica to other ones of the media clusters, e.g., clusters
40', 40", to meet anticipated user demand for the assets, e.g.,
demands that are upcoming in the next few hours. The propagation
service module 66 also provides location information on active
replicas of assets to the other process modules 64, 68, 70.
[0065] The connection manager module 68 selects pathways for
streaming viewing assets from media clusters 40, 40', 40" storing
replicas of the viewing assets to viewers requesting the viewing
assets. To optimize streaming, the connection manager module 68
uses an abstract representation of each potential delivery pathway.
The representations indicate throughputs and bottlenecks along each
pathway. The connection manager module 68 selects pathways with the
highest available throughputs, i.e. the least restrictive
bottlenecks, as the pathways for delivering assets to requesting
viewers.
[0066] The connection manager module 68 also provides the abstract
representation of delivery pathways for the propagation service
module 66. This representation indicates available total bandwidths
for delivering various viewing assets to local node groups 20. The
propagation server module 66 uses this representation to determine
when the available bandwidth for delivering an asset to viewers is
so diminished that an additional replica of the asset is needed on
another media cluster 40, 40', 40". The connection manager module
68 provides the representations of delivery pathways between media
clusters 40, 40', 40" and node groups 20, 20', 20", 20"' to other
ones of the software modules.
[0067] The connection manager module 68 is also an interface that
receives requests for assets from viewer televisions 24 and set top
boxes 26.
[0068] The streaming service module 70 provides
application-independent streaming services to the connection
management module 68, control application service modules 72, and
media cluster agents 78. The provided services include stream
creation, operation, and tear down of delivery pathways. The
streaming service module 70 also has interfaces for controlling
media cluster agents 78 that reside on the individual media
clusters 40, 40', 40".
[0069] The media cluster agents 78 copy new replicas of asset
elements to and delete old replicas of asset elements from the
associated media clusters 40, 40', 40" in response to commands or
orders from the propagation service module 66.
[0070] The MOD application service module 72 resides on the control
unit 16 and controls processing of viewer requests to purchase
movies and other on-demand video assets. The MOD application server
module 72 interacts with an application database 82 and the MOD
billing service module 74 to check viewer credit status and to bill
virtual video rentals. The MOD application service module 72 can
suspend or resume asset streaming to viewers, monitors viewing
progress, and records viewer activities in the database 82.
[0071] The MOD application client 80 resides on each set top box 26
and provides a viewer with system navigation interface for
requesting a programming guide and requesting assets for viewing.
The interface transmits a viewer's requests to one of the control
units 16.
[0072] The program guide service module 76 provides program guide
files to set top boxes 26, which in turn displays a program guide
on the attached normal television 25. Viewers can request assets in
the program guide for viewing.
[0073] For each media cluster 40, 40', 40" serviced, the
propagation service module 66 generates and regularly updates a
table of element deletion lists (ELists). In the table, each EList
is identified by a "selected element" belonging to the EList. Each
EList indicates a set of replicas of elements that can also be
deleted if the identified selected element is deleted without
incurring addition loss of retention value (RV) from the media
cluster 40, 40', 40" storing the replicas.
[0074] Management of Replicas of Assets on Media Clusters
[0075] The propagation service module 66 controls propagations of
viewing assets to and among the media clusters 40, 40', 40". The
propagation service module 66 propagates assets to increase the
economic value of the entire collection of assets available to
viewers. The economic value of propagating a particular asset to a
particular media cluster 40, 40', 40" is rated by a total
propagation priority (TPP). TPPs enable comparisons of the economic
values of potential propagations of assets to particular media
clusters 40, 40', 40" of the interactive television system 10.
[0076] The asset propagation process includes a process 100 that
ranks potential propagations and a process 110 that selects which
asset propagations to perform.
[0077] Referring to FIG. 5A, a flow chart for the ranking process
100 is shown. The process 100 evaluates the TPP of potential asset
propagations (step 102). A potential asset propagation identifies
an asset and a target media cluster 40, 40', 40" to which the
identified asset can be propagated. The target cluster 40, 40', 40"
does not already store a replica of the asset. Using the TPPs, the
process 100 ranks the set of potential asset propagation in a list
(step 104). Potential asset propagations with higher TPPs are
ranked higher and correspond to propagations predicted to provide
larger increases the economic value of the entire collection of
replicas of assets stored on media clusters 40, 40', 40".
[0078] The ranking process 100 also assigns a retention value (RV)
to each replica of an asset (step 106). The assigned RVs depend
both on the asset and on the media cluster 40, 40', 40". The
retention value, RV, indicates the value to the entire system 10 of
keeping the associated replica of the asset on the associated media
cluster 40, 40', 40". From the RVs of replicas of assets, the
process 100 calculates the RVs of element deletion lists (step
108). Element deletion lists, which are described below, are groups
of replicas of asset elements that can be deleted together. The
ranking process 100 is repeated at regular intervals.
[0079] Referring to FIG. 5B, a flow chart for a propagation
selection process 110 is shown. The process 110 selects the highest
ranked potential asset propagation that remains on the ranking list
(step 112). The selected potential propagation has the largest TPP
among potential asset propagations, which have not already been
processed. The process determines whether the associated target
media cluster 40, 40', 40" of the selected potential asset
propagation has a suitable storage region for a replica the asset
(step 114). A suitable storage area is storage space that is large
enough to store a replica of any elements of the asset not already
on the target media cluster 40, 40', 40", i.e., any missing
elements, and that has a total RV that is smaller than the TPP of
the selected asset. If a suitable storage area exists, the process
110 selects the most appropriate region; orders copying of replicas
of the missing elements of the selected asset from another media
cluster 40, 40', 40" onto the most appropriate region; and then
updates RVs, ELists, and combinations of ELists of the target
cluster 40, 40', 40" (step 1I16). The most appropriate region has
the smallest total RV value and among such regions the smallest
size. The copying replaces existing replicas of the most
appropriate region with missing replicas of the asset being
propagated. After considering the selected propagation, the process
110 loops back 118 to select the remaining asset propagation on the
ranking list having the next highest TPP.
[0080] FIG. 6 is a flow chart for a process 120 that calculates
TPPs of potential asset propagations. The propagation service
module 66 determines a global propagation priority (GPP) for a
viewing asset, which is available for copying onto the media
clusters 40, 40', 40" (step 122). The GPP is a time-dependent
number, e.g., in the range of 0 to 100, that expresses the economic
value of malting a new replica of the associated asset available to
viewers. The process 120 also determines a local propagation
priority (LPP) for copying a replica of the asset onto a particular
target media cluster 40, 40', 40" (step 122). The determination of
an LPP is performed separately for each target media cluster on
which the asset is not already stored. Finally, the process 120
adds the GPP and LPP to obtain the TPP associated with the asset
and the particular target media cluster 40, 40', 40" (step
126).
[0081] Replication of an asset to a media cluster 40, 40', 40"
involves copying replicas of the elements of the asset, which are
not already present, onto the cluster's video data storage 36, 36',
36". On the same media cluster 40, 40', 40", replicas of different
assets can share replicas of the asset elements. Thus, replicas of
asset elements already on a media cluster are not recopied onto the
cluster during propagation of the asset to the cluster. Copying
entails pulling elements of the asset, which are not already on the
cluster, from the video data storage 36, 36', 36" of another media
cluster 40, 40', 40" and writing the pulled elements to the video
data storage 36, 36', 36" of the target media cluster 40, 40', 40".
After deciding to propagate an asset to a media cluster 40, 40',
40", the propagation service module 66 updates RVs of the replicas
of assets and asset elements on the target cluster 40, 40',
40".
[0082] Referring to FIG. 7, a process 140 for determining whether
to propagate a selected asset to a target media cluster 40, 40',
40" is shown. The propagation service module 66 calculates a TPP
for a replica of the selected asset on the target media cluster 40,
40', 40" (step 142). The TPP is the sum of the asset's GPP for
propagating a new replica of the asset on the system 10 and the LPP
for having a replica of the selected asset on the particular media
cluster 40, 40', 40".
[0083] The propagation service module 66 selects a list of regions,
e.g., combinations of ELists, of the target media cluster 40, 40',
40" that have smaller RVs than the TPP for the selected asset (step
144). The propagation service module 66 determines whether any
regions on the list have a size sufficient to store replicas of the
elements of the selected asset that are not already stored on the
media cluster 40, 40', 40", i.e., replicas of the missing elements
(step 146). If at least one such region exists, the propagation
service module selects the most appropriate one of such regions
(step 147). The most appropriate region is a region with the
smallest RV and among regions with the smallest RV, the most
appropriate region has the smallest size. The propagation service
module 66 replaces data in the selected region by replicas of the
missing elements of the selected asset (step 148). The target
region for the copying is the region from the list with the
smallest RV and sufficient size to store the elements. During
copying of the missing asset elements to the target cluster 40,
40', 40", the propagation service module 66 protects both source
and destination replicas from deletion.
[0084] To copy the asset elements, the propagation service module
66 identifies a video data storage 36, 36', 36" of another media
cluster 40, 40', 40" to act as a source for the elements being
copied. The propagation service module 66 also fixes a minimum
transfer rate for the elements being copied and protects the source
and target from being overwritten during copying.
[0085] After ordering the replication of the selected asset, the
propagation service module 66 also updates the RVs of replicas of
asset elements remaining on the target media cluster 40, 40', 40"
(step 150). Any replicas of asset elements not belonging to a full
replica of an asset are updated to have RVs with low values, e.g.,
the value zero. Replicas of these asset elements will be the first
elements removed to provide space for new replicas of assets.
[0086] If none of the listed regions has sufficient size to store
the replicas of missing elements of the selected asset, the
propagation service module 66 does not copy replicas of the missing
asset elements to the target media cluster 40 (step 152).
[0087] Element Deletion Lists
[0088] FIG. 8A is a snapshot showing relationships between data
objects stored on the video data storage 36 of one media cluster 40
shown in FIG. 1. The data objects include replicas of asset
elements A-H and replicas of assets 1-5, which are composed of the
replicas of elements A-H. Each replica of an asset 1-4 has an
associated RV, i.e., a number determining the asset replicas value
with respect to being deleted. Each replica of an element A-H has
an associated data size and an RV inherited from the assets to
which the element belongs.
[0089] The replicas of elements A-H that belong to an asset are
streamed from the media cluster 36 to a viewer in response to a
viewing request. Thus, the absence of a replica of an element A-H
belonging to the replica of the requested asset results in the
asset being not streamable and thus, unusable for viewers. The
deletion of the replica of any element A-H results in each replica
of an asset 1-5, to which the deleted replica of the element A-H
belonged, ceasing to exist. For this reason, the RV of a replica of
an element is itself equal to a preselected combination of the RVs
of the replicas of assets 1-5 to which the element A-H belongs,
e.g., a sum of the RVs of replicas of such assets. For example, the
shared element I has an RV of 30, which is the sum of the RVs of
the replicas of assets 1 and 2 to which replica of element I
belongs.
[0090] To free space on the video data storage 36, a replica of a
selected element A-H can be deleted or overwritten. Each replica of
an element A-H also defines an element deletion list (EList). An
EList includes the additional replicas of elements A-H that can be
deleted along with the selected replica of an element A-H without
making additional replicas of assets of the media cluster 40
disappear. The EList of a selected asset includes replicas of all
elements A-H that belong "only" to assets to which the selected
replica of an element A-H belongs. For example, the EList for
selected replica of an element H includes the replicas of elements
H and G. The replica of element G belongs to this EList, because it
belongs only to the replicas of assets 4, 5 to which the selected
replica of element H also belongs. Deletion of all replicas of
elements A-H of an EList does not produce more loss of RV for the
media cluster 40 than the RV loss produced by only deleting the
selected replica of element A-H defining the EList. On the other
hand, deleting all the replicas of assets in the EList of a
selected replica of an asset often liberates more space for writing
new replicas of assets to the media cluster 40.
[0091] FIG. 8B illustrates the ELists 1'-6' for the replicas of
elements A-H and replicas of assets 1-5 shown in FIG. 8A. For each
EList 1'-6', an RV and a size can be defined. FIG. 8B shows RV and
size of each EList by labels RV/size. The RV of an EList 1'-6' is
the preselected combination of the RVs of the replicas of assets
1-5 to which the ELists 1'-6' selected replica of an element AH
belongs. The size of an EList 1'-6' is a sum of the data sizes of
the replicas of elements A-H that belong to the EList 1'-6'.
[0092] FIG. 9A is a table 160 whose entries characterize the ELists
1'-6' of the video data storage 36, shown in FIGS. 8A-8B. Each
entry of table 160 provides an RV, size, and a list of replicas of
elements A-I for one of the ELists 1'-6'. The last column 162 of
the table 160 indicates which replicas of assets 1-5 will cease to
exist on the associated media cluster 40 if the EList 1'-6'
associated with the entry is deleted.
[0093] FIG. 8C shows the data objects remaining on the video data
storage 36 after deletion of EList 3', shown in table 160. After
the deletion, remaining ELists 2", 3" have forms that differ from
the forms of any ELists 1'-6' prior to the deletion. Table 160' of
FIG. 8D characterizes the ELists 1', 2", 3", 4' that remain after
the above-described deletion.
[0094] Elements from several ELists can be deleted together to free
regions of the video data storage for replicas of new asset
elements. FIG. 9B shows a table 160" that provides region economic
values, i.e., total RVs, and sizes of "combinations of ELists",
which are formed from the ELists 1'-6' shown in FIG. 8B. The region
values and sizes are found by combining RVs, e.g., by summing, and
summing sizes, respectively, for the ELists 1'-6' belonging to the
combinations. The table 160" lists the "combinations of ELists" in
order of increasing replacement value up to a value of 50 where 50
is the largest TPP of assets currently under consideration for
propagation.
[0095] From the ELists, the propagation service module 66 produces
a table listing "combinations of ELists" for the media cluster 40.
The table lists "combinations of ELists" whose total RVs are
smaller than the maximum TPP of any asset being currently
considered for propagation to the target cluster 40. To create the
table, the propagation service module 66 searches the media
cluster's table of ELists for combinations of ELists whose combined
RVs are smaller than the maximum TPP of any asset considered for
propagation to the target media cluster 40. Limiting searches to
this upper bound on RVs reduces the number of "combinations of
ELists" for which the propagation service module 66 needs to
determine a total RV or region economic value.
[0096] FIG. 10 is a flow chart for a process 168 that decides
whether a target media cluster 40, 40', 40" has space for a replica
of a new selected asset not presently on the cluster 40, 40', 40".
From the table listing "combinations of ELists", the process 168
selects the entries whose RVs are smaller than the TPP of the new
selected asset (step 170). From these entries, the propagation
service module 66 searches for a "combination of ELists" that that
occupy space large enough to store the replicas of elements of the
selected new asset, which are not already on the media cluster
(step 172). If several one or more such combinations exist, the
propagation service module 66 selects the "combination of ELists"
whose RV is smallest. Among the combinations of ELists with
smallest RVs, the propagation service module 66 selects the
combination having the smallest data size, i.e., this combination
of ELists defines the most appropriate storage region to delete.
The data size must be sufficient to store replicas of elements of
the selected new asset not already on the target media cluster 40,
40', 40". If the sought "combination of ELists" exists, the
propagation service module 66 replaces elements of the new selected
asset, not already on the media cluster, to the region previously
occupied by the sought combination of ELists (step 174). After
performing the copying, the propagation service module 66 updates
RV of replicas of elements and asset elements on the media cluster
40, 40', 40" and the table of ELists (step 176). If the sought
combination of ELists does not exist, the propagation service
module 66 does not copy missing elements of the new selected asset
to the target media cluster 40, 40', 40" (step 178).
[0097] Global and Local Propagation Priorities
[0098] The TPP for replicating an asset is a sum of a global
propagation priority (GPP) and a local propagation priority. The
GPP is independent of target media cluster 40, 40', 40". The LPP
depends on the target media cluster 40, 40', 40".
[0099] Each GPP is a sum of several components, which may take
values from 0 to 100. Each component may separately vary in time
thereby changing the probability of propagating a replica of the
asset to new media clusters 40, 40', 40".
[0100] FIG. 11 shows a flow chart for a process 180 that initially
defines and subsequently updates the GPP of a new asset. When a new
asset first becomes active in the system 10, the process 180
assigns the new asset to a usage class of similar assets (step
182). Membership to usage classes may be based on an asset's genre,
e.g., a subject classification such as newly released movies or
sports events, or may be based on other criteria such as
anticipated popularity. The process 180 assigns an initial GPP to
the new asset based, in part, on the usage class of which the asset
is a member (step 184).
[0101] After being assigned a GPP, replicas of the new asset may be
propagated to new media clusters 40, 40', 40" based on the TPP,
i.e., the TPP=GPP+LPP (step 186). While the asset is available to
viewers, the associated GPP is updated over time to match the
actual viewer usage (step 188). Media clusters 40, 40', 40" having
replicas of assets report usage data to the connection management
module 68, which reports the data to propagation service module 66.
Using the data, the propagation service module 66 recalculates the
GPP of the asset.
[0102] Since the updated GPP partially determines to which media
clusters 40, 40', 40" an asset propagates, the distribution of the
asset on the media clusters 40, 40', 40" changes in response to
usage data fed back to the propagation service module 66.
Gradually, the GPP is adjusted to reflect, in part, relative viewer
requests for the asset as compared to viewer requests for other
assets.
[0103] The propagation service module 66 uses usage data to update
the value of the usage pattern of the usage class to which the
asset is a member (step 190).
[0104] The viewer usage data may be determined from values of
counters 162, shown in FIG. 3, associated with individual assets.
The counters 162 record demands for individual ones of the assets.
The usage data accumulated by these counters 162 is described
below.
[0105] One of the counters 162 measures use of each asset during
specific times of week. A set of accumulators is maintained to
actually indicate use of each asset during every 2 hour interval of
the week. For example, one of these counters may store data
indicating that the Tuesday night news is most requested on
Wednesday morning. The accumulator corresponding to the current
time of week is one of the counters 162. The usage data for a usage
class, as described above, for a new asset is maintained by an
analogous set of counters and accumulators.
[0106] Usage data is accumulated on short-term viewer demand,
medium-term viewer demand, total number of viewer requests, and
last-request-time for each asset. The counters 162 (FIG. 3)
accumulate usage data, which are associated with individual
replicas of assets on media clusters 40, 40', 40".
[0107] Another of the counters 162 measures the "short-term demand"
for an associated asset by counting each viewer request for the
asset. The propagation service module 66 may decrement this counter
162 by a fixed amount every few hours or perform another counter
correction to make the counter's total count indicative of the
number of "recent" requests. The count is never decremented to
negative values. If the accumulated count is high, the propagation
priority, i.e., value of putting another replica of the asset onto
a media cluster 40 is high, and the propagation service module 66
increases the asset's TPP.
[0108] The medium-term demand for each asset is measured by seven
of the counters 162, which accumulate numbers of demands for the
asset over weeklong periods. The period of each counter ends on
different day. For each counter, the count from the present week is
compared to the count from the same counter for the last week. A
decrease in this count indicates a declining interest for the
asset, and the propagation service module 66 reduces the GPP of the
asset in response to such decreases.
[0109] Other counters 162 measure the total number of requests and
time of the last request for each asset. These counts track
popularities of assets. The total number of requests may be used to
update the GPP of the asset to generally reflect its popularity.
The lengths of time since last request for different assets are
compared to determine relative asset popularities.
[0110] The GPP of an asset may depend on other components. One
component measures whether an asset is a rapid mover, e.g., an
asset whose usage changes suddenly. Another component raises the
GPP of assets for which only one replica exists. This favorizes
generation of a second replica, which is valuable to the system to
avoid failures. Another component raises the GPP of assets whose
one or more replicas are only accessible through heavily loaded
delivery networks. This favors adding a second replica, which can
offset unavailability of the asset caused by other video streaming
traffic.
[0111] The LPP assigned to a replica of an asset is also a sum of
several components, but the components depend on properties of a
server's local environment. Each of the components may take a value
in a preselected range, e.g., 0 to 100. The components contributing
to LPP cause the propagation service module 66 to distribute
replicas of assets to media clusters 40 a manner that accounts, in
part, for local viewing preferences.
[0112] One component of LPPs depends on the classification of an
asset, e.g., genre and language. This component causes
distributions of replica of assets to accord with local preferences
of viewers and may be updated by historical viewing data. Counters
162 of the propagation service module 66 accumulate numbers of
viewer requests for various classes of assets for use in
determining the value of this component.
[0113] Another component of LPPs depends on whether multiple
replicas of the asset are stored on the set of media clusters 40,
40', 40". This component is high for clusters 40, 40', 40" not
storing a replica of the asset if a replica of the asset is only on
one cluster 40, 40', 40". This component stimulates the propagation
service module 66 to replicate each asset present on one media
cluster 40, 40', 40" onto a second media cluster 40, 40', 40". The
second replica helps to avoid delivery failures caused by hardware
failures.
[0114] Another component to LPPs depends on activity levels of
media clusters 40 increasing the LPP for replicas of new assets
only located on other media clusters 40, 40', 40" that are heavily
loaded. The component causes the propagation service module 66 to
copy a replica of the asset to a less busy media cluster 40, 40',
40" if current replicas of the asset are on media clusters 40
operating at near capacity. The propagation service module 66 uses
delivery pathway data from the connection manager 68 to determine
whether media clusters 40, 40', 40" are operating at near
capacity.
[0115] Another component to LPPs depends on activity levels of
delivery pathways. This component causes the propagation service
module 66 to copy a replica of an asset onto a media cluster 40
that is connected to a node group 20, 20', 20", 20"' by less
burdened delivery pathway if the presently usable delivery pathways
are near capacity. The loading of each delivery pathway is
determined by the connection manager 68, which provides an
abstracted view of the deliver pathways to the propagation service
module 66.
[0116] Another component to LPPs causes the propagation service
module 66 to copy a replica of an asset to a new media cluster 40,
40', 40" if present replicas are inaccessible to some users. The
inaccessibility may result from the absence of delivery pathways
from the clusters 40, 40', 40" presently storing a replica of the
asset and the node groups 20, 20', 20", 20"' without access.
[0117] In various embodiments, other historical usage data is used
to set the values of the GPPs and LPPs of potential propagations.
The propagation of viewing assets to media clusters 40, 40', 40' is
calculated to increase the total economic value of the assets to
the system 10, e.g., by increasing viewer payments for movie
rentals. As viewer demands change, the propagation priorities
assigned to replicas of assets are updated to follow the changing
demands. Asset propagation evolves the distribution of replicas of
the assets on the media clusters 40, 40', 40" in response to the
updates to GPP and LPP. Thus, changes in viewing preferences
automatically induce an evolution in the distribution of viewing
assets and, at least partially, follows the viewing
preferences.
[0118] The retention values (RVs) assigned to replicas of assets
and to replicas of asset elements, which are both stored on the
media clusters 40, 40', 40", are calculated and updated through
processes analogous to the processes used to determine the TPP. The
RV may be a sum of a global value and a local value. The global
value indicates an economic value associated with retaining the
present set of replicas of the asset on the entire collection of
media clusters 40, 40', 40". The local value indicates an economic
value associated with retaining the replica of the asset on a
particular associated media cluster 40, 40', 40". Both the local
and global values may be sums of components of the same types as
the components contributing to LPP and GPP, but coefficients may
vary. The global and local values may depend on collected usage
data and be assigned to usage classes that contribute to defining
initial values.
[0119] Other additions, subtractions, and modifications of the
described embodiments may be apparent to one practiced in this
field.
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