PCT
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`25 May 2000 (25.05.00)
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`PCT/US99/27325|(81) Designated States: AE, AL, AM, AT, AU, AZ, BA, BB, BG,
`(21) International Application Number:
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`BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, EE,
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`ES, FI, GB, GD, GE, GH, GM, HR, HU,ID,IL,IN,IS, JP,
`(22) International Filing Date:
`17 November 1999 (17.11.99)
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`KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA,
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`MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU,
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`SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG,
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`UZ, VN, YU, ZA, ZW, ARIPO patent (GH, GM, KE,LS,
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`MW,SD, SL, SZ, TZ, UG, ZW), Eurasian patent (AM, AZ,
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`BY, KG, KZ, MD, RU, TJ, TM), European patent (AT, BE,
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`CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC,
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`NL, PT, SE), OAPI patent (BF, BJ, CF, CG, CI, CM, GA,
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`GN, GW, ML, MR,NE, SN, TD, TG).
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`(30) Priority Data:
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`60/108,855
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`09/440,975
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`18 November 1998 (18.11.98)
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`16 November 1999 (16.11.99)
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`US
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`US
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`(71) Applicant:
`INFOLIBRIA,
`[US/US]; Suite 323, 411
`INC.
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`Waverly Oaks Road, Waltham, MA 02454 (US).
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`(72) Inventors: LEWIS, Kevin, T.; 100 Fulton Street, No 4T,
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`Boston, MA 02109 (US). HOEY, David, L.; 102 Concord
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`Road, Wayland, MA 01778 (US).
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`(74) Agents: THIBODEAU,David, J., Jr. et al.; Hamilton, Brook,
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`Smith & Reynolds, P.C., Two Militia Drive, Lexington, MA
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`02421 (US).
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`Published
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`With international search report.
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`Before the expiration of the time limit for amending the
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`claims and to be republished in the event of the receipt of
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`amendments,
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`WORLD INTELLECTUAL PROPERTY ORGANIZATION
`International Bureau
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`INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
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`(51) International Patent Classification 7 :
`WO 00/29990
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`(11) International Publication Number:
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`GO06F 17/30, H0O4L 29/08
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`(43) International Publication Date:
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`CACHE
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`(54) Title: EFFICIENT CONTENT SERVER USING REQUEST REDIRECTION
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`(57) Abstract
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`A technique for optimizing delivery of specialized content
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`files such as multimediafiles in a computer network. A multimedia
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`file cache is
`located at a point of presence,
`such as at an
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`Internet Service Provider (ISP), gateway, or other place close to
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`user connection points into the network. A redirection function
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`intercepts media redirection file requests sent to or from the media
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`server and rewrites such requests so that they point to the local
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`media file cache.
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`USER REQUESTS
`MEDIA STREAM
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`AT BROWSER
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`BROWSER REQUESTS
`MRF FROM
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`WEB SERVER
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`WEB SERVER
`SENDS MRF
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`REDIRECTOR
`INTERCEPTS
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`MRF
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`CONTENT
`HIT IN
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`REDIRECTOR
`CHANGES MRF
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`TO MEDIA
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`SERVER
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`SEND REQUEST TO
`MEDIA SERVER, ROUTE
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`CONTENTTO MEDIA CACHE
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`116
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`BROWSER OPENS
`MEDIA PLAYER
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`CONTENT STREAMED
`FROM MEDIA
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`Unified Patents Exhibit 1004
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`Unified Patents Exhibit 1004
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`

`

`Zimbabwe
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`FOR THE PURPOSES OF INFORMATION ONLY
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`Codesused to identify States party to the PCT on the front pages of pamphlets publishing international applications under the PCT.
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`SI
`ES
`Albania
`Spain
`SK
`FI
`Armenia
`Finland
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`SN
`FR
`France
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`Austria
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`SZ
`GA
`Australia
`Gabon
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`TD
`GB
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`United Kingdom
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`Azerbaijan
`TG
`GE
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`Georgia
`Bosnia and Herzegovina
`TJ
`Barbados
`GH
`Ghana
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`Guinea
`GN
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`Belgium
`Greece
`GR
`Burkina Faso
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`HU
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`Hungary
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`Bulgaria
`IE
`Treland
`Benin
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`IL
`Israel
`Brazil
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`Is
`Belarus
`Iceland
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`IT
`Canada
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`Italy
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`JP
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`Japan
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`Central African Republic
`KE
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`Kenya
`Congo
`KG
`Switzerland
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`Kyrgyzstan
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`KP
`Céte d'Ivoire
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`Democratic People’s
`Cameroon
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`Republic of Korea
`KR
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`China
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`Republic of Korea
`KZ
`Kazakstan
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`Cuba
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`Saint Lucia
`LC
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`Czech Republic
`LI
`Liechtenstein
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`Germany
`LK
`Sri Lanka
`Denmark
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`LR
`Liberia
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`Estonia
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`Slovenia
`Slovakia
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`Senegal
`Swaziland
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`Chad
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`Togo
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`Tajikistan
`Turkmenistan
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`Turkey
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`Trinidad and Tobago
`Ukraine
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`Uganda
`United States of America
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`Uzbekistan
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`Viet Nam
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`Yugoslavia
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`LS
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`LU
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`LV
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`MC
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`MD
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`MG
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`MK
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`ML
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`MR
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`MW
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`Mx
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`NE
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`NL
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`NO
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`NZ
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`PL
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`PT
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`RO
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`RU
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`SD
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`SE
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`SG
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`Lesotho
`Lithuania
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`Luxembourg
`Latvia
`Monaco
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`Republic of Moldova
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`Madagascar
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`The former Yugoslav
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`Republic of Macedonia
`Mali
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`Mongolia
`Mauritania
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`Malawi
`Mexico
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`Niger
`Netherlands
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`Norway
`New Zealand
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`Poland
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`Portugal
`Romania
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`Russian Federation
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`Sudan
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`Sweden
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`Singapore
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`R
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`TT
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`UA
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`UG
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`us
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`UZ
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`VN
`YU
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`ZW
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`

`

`WO 00/29990
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`PCT/US99/27325
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`EFFICIENT CONTENT SERVER USING REQUEST REDIRECTION
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`FIELD OF THE INVENTION
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`This invention relates generally to content
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`delivery in computer networks and in particular to a
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`technique for selectively redirecting media content
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`requests to local caches.
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`BACKGROUND
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`During the twentieth century, continuous media
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`services such as broadcast and cable television have
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`become an ubiquitous vehicle for distributing
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`entertainment, education, advertising, and other
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`programs to the public.
`Emerging standards define new
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`formats for television broadcast distribution in
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`digital form.
`In addition, devices such as cable
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`modems and Digital Subscriber Line (xDSL) modems are
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`beginning to become available to the public.
`These
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`products promise to provide a mix of access to
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`television programming and high speed telecommunication
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`services such as the Internet, which are increasingly
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`looked to as vehicles which will augment traditional
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`television broadcasts.
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`these two content delivery systems,
`Indeed,
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`optimized for television broadcast and those optimized
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`for distribution of data content are merging.
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`example, standards such as the Motion Picture Experts
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`Group (MPEG) -2 standard and other encoding schemes
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`specify how video signals may be digitized for
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`efficient transfer. Other efforts such as the Internet
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`Engineering Task Force (IETF) audio/video transport
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`(AVT) working group are developing specifications for
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`realtime transmission of video over User Datagram
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`For
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`those
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`15
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`20
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`25
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`30
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`

`

`WO 00/29990
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`PCT/US99/27325
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`type layered
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`(UDP) and Internet Protocol
`Protocol
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`networks such as the Internet.
`The vision is that in
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`the future it will not be necessary to have an analog
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`television within the home or at another cable
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`subscriber site.
`In particular, video programs will
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`routinely be broadcast in digital form as packetized
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`data using UDP/IP or other data protocols.
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`In addition, with the growth of the Web and other
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`activities on the Internet, it is increasingly
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`to find ways to efficiently manage a mix of
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`text, graphics, and video data such as is associated
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`with typical Web browsing activities.
`New techniques
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`for specifying, handling, and distributing multimedia
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`content such as contained in video clips are therefore
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`In the context of the Internet and with the
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`communication protocol known as Hypertext Transfer
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`Protocol, a content file is typically specified by an
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`alpha numeric string known as a Uniform Resource
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`Locator
`(URL).
`The URL includes an address portion
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`which indicates a network address of a home server from
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`which to obtain the desired information.
`The URL also
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`includes a local
`information text stream that
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`identifies the requested information which may,
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`example, be a file name, a search request, or other
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`identification.
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`important
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`needed.
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`for
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`After the user specifies a URL to the client
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`browser computer,
`the address portion of the URL is
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`sent over the network. Once the connection with the
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`server is established,
`the client can then retrieve a
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`desired document by passing the local
`information text
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`stream over the network to the home server.
`The home
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`server then retrieves the document from its local disk
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`WO 00/29990
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`PCT/US99/27325
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`or memory storage and transmits the document over the
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`network down to the client.
`The network connection
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`between the home server and the client is then
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`terminated.
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`However, an additional step is typically required
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`in the context of streaming media files.
`For example,
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`Microsoft has a set of multimedia technology tools for
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`assisting with the creation of Web streaming media
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`content. This tool set is an open, extensible platform
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`that allows one to define a streaming media format file
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`which makes it possible to combine a multitude of data
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`types, such as audio, video, still images, URLs, etc.
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`into an integrated data stream.
`One of the tools is a
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`Microsoft Media Player tool that augments the
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`capabilities of a Web browser to display multimedia
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`content. Companies such as Apple Computer,
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`RealNetworks, and Xing Technologies also provide
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`standardized media players and streaming media file
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`formats.
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`the user of a Web browser
`In the typical scenario,
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`requests that a media stream file be downloaded, such
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`as sending,
`in particular,
`the URL of a media
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`redirection file from a Web server.
`The media
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`redirection file (MRF)
`is a type of specialized
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`Hypertext Markup Language (HTML) file that contains
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`instructions for how to locate the multimedia file and
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`in what format
`the multimedia file is in.
`The Web
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`server returns the MRF file to the user’s browser
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`program.
`The browser program then reads the MRF file
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`to determine the location of the media server
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`containing one or more multimedia content files.
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`browser then launches the associated media player
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`application program and passes the MRF file to it.
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`The
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`The
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`

`

`WO 00/29990
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`PCT/US99/27325
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`media player reads the MRF file to obtain the
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`information needed to open a connection to a media
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`server, such as a URL, and the required protocol
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`information, depending upon the type of medial content
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`is in the file.
`The streaming media content file is
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`then routed from the media server down to the user.
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`the
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`SUMMARY OF THE INVENTION
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`The problem with standard techniques for handling
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`media redirection files is that the media server must
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`have a connection open to it for each browser which
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`needs access to the streaming media content.
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`The present
`invention avoids this difficulty by
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`deploying a multimedia cache and a cache redirector
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`functionality within the network.
`In particular,
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`invention locates a multimedia cache at a point of
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`presence, such as at an Internet Service Provider
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`(ISP), at an intranet gateway, or at other places close
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`to the edge of the network near the user.
`A redirector
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`function allows requests for a multimedia program
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`to be redirected to the local media cache
`content
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`server instead of routing them up through the network.
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`This rerouting is transparent to the operation of the
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`media server as well as being transparent to the user's
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`browser and media player programs.
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`in a preferred embodiment,
`Now more particularly,
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`a user's browser program first requests a media
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`redirection file (MRF)
`from an origin Web server.
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`Web server then returns the MRF file to the user’s
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`browser program. As in the prior art,
`the MRF file
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`contains instructions for telling the browser where to
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`locate the streaming media content file and what
`type
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`of player program will be needed to view it. However,
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`The
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`

`

`WO 00/29990
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`PCT/US99/27325
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`as the MRF file is returned from the media server,
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`cache redirector intercepts the MRF file before it is
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`actually forwarded to the browser.
`The cache
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`redirector examines the MRF file to determine if the
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`requested multimedia content file is available in the
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`local media cache.
`If so,
`then the designation in the
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`MRF file is changed by the cache redirector to indicate
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`the local media cache as the location of the requested
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`media content.
`On a local cache miss operation, a
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`request for the media file is launched to the indicated
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`media server.
`In either event,
`the browser then opens
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`the media player and the media player obtains the
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`stream from the local media cache.
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`the cache
`In the aforementioned arrangement,
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`redirector should maintain, or at least have access to,
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`information concerning the contents of the local media
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`In particular,
`the cache redirector at a
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`minimum has access to information as to what is
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`contained in the media cache so that it can determine
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`whether or not the media file being requested is
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`already resident
`in the local media cache.
`The cache
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`redirector may preferably also manage the media cache,
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`telling it what content files to store and what to
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`The media cache typically uses the same type of
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`computing equipment as the media server, i.e., a high
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`speed computer processor with high speed disk storage
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`capable of managing connections to various network
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`layers for a number of users.
`The media cache may
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`support any number of different file formats such as
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`Microsoft Media Technologies, Apple Computer,
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`RealNetworks, Xing Technologies, or other types of
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`streaming file formats.
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`10
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`15
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`20
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`25
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`30
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`cache.
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`delete.
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`the
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`

`

`WO 00/29990
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`PCT/US99/27325
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`The cache redirector can be a small network server
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`(appliance) whose only function is media file
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`redirection.
`The cache redirector watches packet
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`traffic arriving at the point of presence, rewrites MRF
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`files as needed, and keeps track of what is contained
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`in the media cache. However,
`the cache redirector may
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`also itself contain cache memory for caching other
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`types of content such as text files and the like.
`
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`the cache
`In another embodiment of the invention,
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`redirector does not need to keep track of what is in
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`the media cache itself.
`In this instance,
`the cache
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`redirector communicates in some way with the media
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`cache in order to be able to query it as to the media
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`cache.
`In this scenario,
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`intelligent about storing streaming media content
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`files.
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`especially realized in environments where high speed
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`modem equipment, such as Digital Subscriber Line (xDSL)
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`or cable modem equipment,
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`can run at speeds of 500 kilobits per second or more,
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`kilobits per second or even less per user connection.
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`Thus, by placing the media cache with the media file
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`redirection protocol at the edge of the network closest
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`to the user, such as at a point of presence, streaming
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`media files can be presented to users at the highest
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`available data rates provided by their high speed
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`interface equipment, without having to tolerate delays
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`through the Internet.
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`Many types of specialized content files such as
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`banner ads, streaming video clips, and the like can
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`benefit from the deployment of a cache redirector and
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`local cache server.
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`the media
`In an alternative embodiment,
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`redirection file can instead be modified by the origin
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`In this embodiment,
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`server.
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`access to information concerning the address of media
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`caches located at points of presence in the network.
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`The net effect is that the cache redirector
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`functionality is instead resident at the origin server,
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`which modifies the MRF before it is passed to the user.
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`In yet another embodiment, a Directory Name
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`Service (DNS) can be used to implement
`the cache
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`redirection functionality. This embodiment may be
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`preferred for networks where it is not possible to
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`intercept traffic or modify origin servers.
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`Specifically, a DNS for the network zone in question
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`may be queried by the user when attempting to locate
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`the MRF file or even the media file itself.
`In this
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`embodiment,
`the DNS returns the address of the local
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`media cache to the user.
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`It is also possible to pre-position media file
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`content at the media cache servers. This helps
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`expedite even the initial service of media files to
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`users in a network zone for a given media cache.
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`The foregoing and other objects, features and
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`advantages of the invention will be apparent from the
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`following more particular description of preferred
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`embodiments of the invention, as illustrated in the
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`accompanying drawings in which like reference
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`characters refer to the same parts throughout the
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`different views.
`The drawings are not necessarily to
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`scale, emphasis instead being placed upon illustrating
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`the principles of the invention.
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`1 is a system diagram of a computer network
`Fig.
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`in which media request file redirection may be
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`implemented according to the invention.
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`2 is an example of a media request file in
`Fig.
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`which a redirection takes place.
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`Fig.
`3 is a flow diagram of the steps performed by
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`various components of the network.
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`Fig.
`4 is a modified system diagram showing media
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`caches distributed throughout
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`Fig.
`5 is a modified series of steps performed in
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`the environment of Fig. 4.
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`DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
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`Turning attention now to the drawings more
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`particularly, Fig.
`1 is a system level diagram of a
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`computer network in which media file requests are
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`served according to the invention. As is typical in
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`computer networks such as the Internet, a home or
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`origin location 10 contains a number of computers. At
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`certain points of presence (POPs) 30 in the network,
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`additional computing and communications equipment
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`the establishment of connections over the
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`Internet 20 to other computers (known as clients) ata
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`user site 40.
`The computers at the origin location 10
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`are typically referred to as servers.
`In the context
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`of the Web,
`for example, one type of computer may be a
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`Web server 12 that serves documents in the well known
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`Hypertext Markup Language (HTML), or other formats.
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`this environment,
`the clients 40 run software that is
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`enabled to interpret and display HTML files such as Web
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`[In
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`permit
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`browsers like Netscape Navigator, or Microsoft Internet
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`Explorer.
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`In the illustrated scenario, a media server 14
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`contains multimedia documents such as streaming audio
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`5 or streaming video files that are associated with the
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`Web server 12.
`The media server 14 is typically
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`implemented with an architecture especially optimized
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`for supporting the high speed presentation of such
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`video and audio files. Both the Web server 12 and
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`10 media server 14 make connections through a router 16 to
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`provide such media files to client computers 40
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`connected to the Internet 20. Although the Web server
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`12 and media server 14 are shown as being co-located at
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`the same site, it should be understood that they may be
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`15 physically located at different sites.
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`the point of presence 30, computing and
`At
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`communications equipment include a router 32, a link
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`34, a cache redirector 36, a media cache 38, anda
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`local area network 39.
`The point of presence 30 may,
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`for example, be an intranet gateway or an Internet
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`the end
`service provider (ISP).
`In the former case,
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`nodes 42 may be directly connected to the local area
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`network 39.
`In the latter case, a Remote Access Server
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`(RAS) device 45 provides communication connections
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`through another network 50 such as the Public Switch
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`Telephone Network (PSTN)
`to subscribers units 52
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`located, for example, within homes or businesses that
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`make connections through a dial up network.
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`The remote access server 45 preferably makes use
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`30 of high speed subscriber interconnection equipment such
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`as Digital Subscriber Line (xDSL), cable modems, or
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`other high speed interconnectivity devices.
`The remote
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`access server 45 may,
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`-10-
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`Tl converter, or
`multiplexer, cable modem head end,
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`other such equipment which concentrates Internet
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`protocol
`(IP)
`type traffic and forwards it over
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`connections such as the public switch telephone network
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`or cable distribution network.
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`In accordance with the invention, also located at
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`the point of presence 30 is a media cache 38. Media
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`cache 38 is populated with media files that are most
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`popularly requested by the users of the client
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`computers 42 and 52.
`In general,
`the idea behind the
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`present invention is that when a streaming media file
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`request is made by one of the clients 42 or 52, steps
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`are taken to ensure that the request is served from the
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`media cache 38 located at the point of presence 30, as
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`opposed to having to retrieve the requested streaming
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`media file from the media server 14 on the other side
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`of the Internet 20.
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`invention in particular operates in an
`The present
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`environment where requests for media files are made in
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`the form of redirection objects generated by the
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`browser programs located at the clients 42, 52.
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`particular,
`the browser programs 54 located at the
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`clients 42, 52 are typically not capable of directly
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`displaying or playing streaming media files.
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`particular,
`the browser needs to open or "launch" an
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`associated application such as a media player program.
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`One example of such a media player program which is
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`well known in the art is the RealPlayer™ software
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`available from RealNetworks of Seattle, Washington, or
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`the Media Player™ software available from Microsoft
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`Corporation of Redmond, Washington.
`Thus, when a media
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`file is presented to the browser,
`the browser, strictly
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`speaking, does not hand