Clouding IP LLC v. Oracle Corporation

Filing 1

COMPLAINT FOR PATENET INFRINGEMENT filed with Jury Demand against Oracle Corporation - Magistrate Consent Notice to Pltf. ( Filing fee $ 350, receipt number 311-1078455.) - filed by STEC IP LLC. (Attachments: # 1 Exhibit A Part 1 of 2, # 2 Exhibit A Part 2 of 2, # 3 Exhibit B, # 4 Exhibit C, # 5 Exhibit D, # 6 Exhibit E, # 7 Exhibit F Part 1 of 2, # 8 Exhibit F Part 2 of 2, # 9 Exhibit G Part 1 of 2, # 10 Exhibit G Part 2 of 2, # 11 Exhibit H, # 12 Exhibit I, # 13 Civil Cover Sheet)(dmp, )

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EXHIBIT C United States Patent (10) Dickenson (12) (45) METHODS AND APPARATUSES FOR FILE SYNCHRONIZATION AND UPDATING USING A SIGNATURE LIST Inventor: Patent NO.: US 6,738,799 B2 Date of Patent: *May 18,2004 5,794,258 A 5,819,274 A 811998 Ishikawa et al. ............ 3451751 1011998 Jackson, Jr. ................. 707110 (List continued on next page.) Peter Dickenson, Williamsburg, VA FOREIGN PATENT DOCUMENTS (US) Assignee: Symantec Corporation, Cupertino, CA (US) Notice: OTHER PUBLICATIONS Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days. Schneier, B., "One-Way Hash Functions," Dr. Dobb's Journal, vol. 16, No. 9, pp. 148-151 (Sept. 1991). This patent is subject to a terminal disclaimer. Primary Examineraharat Barot (74) Attorney, Agent, or Firmqliesler Meyer LLP Jun. 2, 2003 Prior Publication Data US 200310200207 A1 Oct. 23, 2003 Related U.S. Application Data Continuation of application No. 091303,958, filed on May 3, 1999, now Pat. No. 6,574,657. Int. CL7 ................................................ G06F 15/16 U.S. C1. ....................... 7091203; 7091217; 7091219; 7091229; 70711; 7071203 Field of Search ................................. 7091200-203, 7091216-219, 229, 231-232, 235-237; 717110-12; 71416-7; 70711, 8-10, 2 0 e 2 0 4 References Cited (56) U.S. PATENT DOCUMENTS 5,008,853 5,694,596 5,729,735 5,752,039 5,787,247 A A A A A 411991 1211997 311998 511998 711998 ABSTRACT (57) Appl. No.: 101452,156 Filed: (List continued on next page.) B ~ et al. ................... 3451751 Y Campbell ................... 7091215 Meyering .................... 707110 Tanimura ..................... 717111 Norin et al. ................ 7091220 __ A server generates an update file for transmission to a client that permits the client to generate a copy of a current version of a subscription file from a copy of an earlier version of the subscription file. For each segment of the current version of the subscription file, the server searches an earlier version of a signature list for an old segment signature which matches a new segment signature corresponding to the segment. When a match is detected, the server writes a command in the update file for the client to copy an old segment of the client's copy of the earlier version of the subscription file into the client's copy of the current version of the subscription file, where the old segment corresponds to the segment for which a match was detected. When no match is detected, the server writes a command into the update file for the client to insert a new segment of the current version of the subscription file into the client's copy of the current version of the-subscription file, where the new segment of the current version of the subscrivtion file is written into the update file. The update file is only generated when the server determines the subscription file has changed. The server periodically monitors the subscription file to determine if it has been altered before generating an update file. 46 Claims, 12 Drawing Sheets WRITE COMMAND IN UPDATE FILE TO COPY OLD SEGMENT KJA IN OLD SIGNATURE LIST? L/ WRITE COMMAND IN UPDATE FILE TO INSERT NEW SEGMENT 1006 US 6,738,799 B2 Page 2 U.S. PATENT DOCUMENTS 5,835,911 5,864,837 5,890,164 5,913,032 6,012,087 6,014,135 6,058,428 6,073,007 6,101,507 6,151,708 6,161,125 6,327,617 6,574,657 A A A A A A A A A A A B1 B1 1111998 111999 311999 611999 112000 112000 512000 612000 812000 1112000 1212000 * 1212001 * 612003 Nakagawa et al. ......... 7071203 Maimone ....................... 70711 Nielsen ...................... 7071201 Schwartz et al. ........... 7091213 Freivald et al. ............. 7091218 Fernandes ................... 7091203 Wang et al. ................ 7091232 Doyle ........................ 7091203 Cane et al. ................. 7071204 Pedrizetti et al. ............. 717111 Traversat et al. ........... 7091203 Fawcett ...................... 7091219 Dickinson ................... 7091203 OTHER PUBLICATIONS Diem, D., "Wireless Data and Minimum Airtime Software," Dr. Dobb's Journal, pp. 1-14 (Dec. 1993). Coppieters, K., "Across-Platform Binary Diff," Dr. Dobb's Journal, pp. 1-7 (May 1995). "Keeping Road Warriors on Track," Mind Your Own Business, Market Place Publishing, UK, vol. 21, No. 6, p. 49 (Jun. 1998). Freed, Les "Symantec Mobile Update," First Looks section of PC Magazine Online, http://www.zdnet.com/pcmag/firstlooks/9806/f980610a.htm (Jun. 10, 1998). * cited by examiner U.S. Patent May 18,2004 Sheet 1 of 12 /;4 1 I 102 \ DATA ADDRESS CONTROL 106 41 RAM o \ 41 DISPLAY MONITOR 0 4) 4b J \ 41 1 0 3 ~ ROM 41 4 b 1 4I 4 P L - - A 41 MICRO PROCESSOR 41 0 -- 4I MODEM 4I I l f 4b 4b 4b 41 105 J ' - KEYBOARD 0 104 (I07 HARD DISK 1 FIG. 1 4) 4b NETWORK INTERFACE I '.S. Patent May 18,2004 Sheet 2 of 12 U.S. Patent May 18,2004 Sheet 3 of 12 41 1 412 413 414 41 5 c 416 SEGMENT LOCATION A1 A2 A3 A4 A5 A6 LOC(A1) , SIZE(A1) / I / SIZE(A2) 1 ) SIZE(A3) I / , SIZE(A4) 1 SIZE(A5) I SIZE (A6) 1 /I \, -,\ \ ,\\\ LOC(A2) LOC(A3) LOC(A4) LOC(A5) LOC(A6)\, I ,\\I I SEGMENT SIGNATURE SEGMENT SIZE /I 401 402 403 404 405 406 ' FIG. 4 SIG(A1) S IG (A2) SIG(A3) S IG (A4) SIG(A5) SIG(A6) / 311 / -,312 -+-- 313 --314 - - - 315 316 U.S. Patent May 18,2004 Sheet 5 of 12 READ SUBSCRIPTION FlLE FROM NETWORK DRIVE / \ NO NEW SUBSCRIPTION FILE? / \ DETERMINE MOST EFFICIENT SEGMENT 7~ 505 RETRIEVE DELIMITER v SCAN FlLE FOR DELIMITER OR END OF FlLE TO DETERMINE NEXT SEGMENT F 506 7 COMPUTE SIGNATURE FOR SEGMENT S 8 ADD SIGNATURE TO SIGNATURE LIST v SEGMENT ENDS WITH DELIMITER? \' FIG. 5 DONE U.S. Patent May 18,2004 Sheet 6 of 12 U.S. Patent May 18,2004 Sheet 7 of 12 U.S. Patent May 18,2004 Sheet 8 of 12 U.S. Patent May 18,2004 Sheet 9 of 12 U.S. Patent May 18,2004 Sheet 11 of 12 UPDATE FILE FOR <FILENAME> - COPY INSERT COPY INSERT INSERT COPY COPY LOC(A1) SIZE(A1) <CONTENTS OF B2> LOC(A3) SIZE(A3) <CONTENTS OF B4> <CONTENTS OF B5> LOC(A5) SIZE(A5) LOC(A6) SIZE(A6) FIG. 11 - - U.S. Patent May 18,2004 Sheet 12 of 12 US 6,738,799 B2 1 2 METHODS AND APPARATUSES FOR FILE SYNCHRONIZATION AND UPDATING USING A SIGNATURE LIST into the corporate world. For IS Managers, "push-based technologies" were seen as an uncontrollable avenue for terabytes of graphics and HTML to come through the corporate firewall and network, filling local hard drives. Microsoft and Netscape entered the fray with their own "push" clients &mdash; IE 4.0 Active Desktop and Communicator's Netcaster, respectively. Rather than spurring the growth of content delivery, however, the effect of the push entries has been to call into question the value of delivering Web content to user hard drives. The value is questioned not only in terms of relevance, but also its effects and load on corporate networks. The automated information flow becomes a flood through the Internet gate-ways of corporations threatening the stability and reliability of the network infrastructure itself. Within the corporate world, the future of content push remains in limbo. Uncertainty over standards and overall value have caused the market to trip on the initial momentum and slow to a crawl. However, what is questioned here is not the value of automating delivery or "push," but rather the value of what is being pushed. Software Push is another important objective. Microsoft and Marimba, among others, have recognized the importance and potential of "Electronic Software Distribution" (ESL) or "software push" as a way of addressing the need to seamlessly deliver software updates across the network with the goal of directly impacting the total cost of ownership. The reauirements for software distribution are dramatically different from content distribution. For one, the "content" in software delivery is, by its very nature, deemed critical. To reduce the impact of supporting multiple versions of products across the corporate network, near-simultaneous deployment is imperative. Companies that do not use some form of software push technologies require dedicated individuals to make the rounds updating software by reinstalling or applying patches for each personal computer and laptop. ~~~h~~ than aggregating and displaying information, software push transparently delivers one specific piece of information and applies it to user systems or applications. Files tend to be very large and the delivery of these files must be well-managed, Incremental downloading becomes important t~ reduce frustration and bandwidth associated with broken and lost connections. Management of software updating also needs to be centralized and MIS-controlled. In addition, the primary value of the application is to IS personnel and only indirectly to for the end-users. A good example of software push is Marimba's Castanet, which allows Java applications to be distributed and updated seamlessly and automatically without user intervention, hi^ same approach to Java programming can be, and is being, applied to C-language programs as well. The case of content push vs. software push makes it clear that the importance lies in the distinction between the data being delivered &rndash; and not the delivery mechanism itself. The Next Phase is Electronic Document Delivery. The final frontier in digital push is "electronic document delivery"or EDD. It deals with delivering changes or "updates" to the same physical files (like software push), but the files themselves are highly personalized (like content push). Different from content push, these files exist in the form of sales presentations (Powerpoint), spreadsheets (Excel and Lotus 1,2,3), and reports and plans (Word or Wordperfect). These are the types of documents for which companies currently invest millions of dollars in file servers and intranet technologies in order to share among respective workgroups. The important distinction here between content and PRIORITY CLAIMS 5 This application is a continuation of U,S, patent application Ser. No. 09/303,958, filed May 3, 1999 (now U.S. Pat. No. 6,574,657). CROSS-REFERENCE TO RELATED APPLICATION 10 This Application is related to the following application, which is incorporated herein by reference: U.S. patent application Ser. No. 091304,295, entitled "Methods and Apparatuses for Single Connection File Synchronization and Workgroup File Update", filed May 3, 1999 (now U.S. Pat. No. 6,654,746). BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of personal computers which access files on network drives and which utilize electronic mail systems. Specifically, the present invention involves the synchronization of the local copies of files on user's client computer hard disk to the current versions of the files on a network drive. 2. Discussion of the Related Art As more and more business information moves from analog to digital formats, the relatively newfound ability to create, amend, and revise information spontaneously and frequently has brought with it challenges for corporate users. Revenue results can now be easily aggregated and updated in near real time, sales presentations can be amended regularly, and changes made to business documents. However, causing these changes to effectively trickle down through the organization without causing a digital flood is a challenge. Companies have responded to the threat by carefully creating structures for organizing, storing, and sharing these electronic files. Organizations have moved from file servers to intranet sites to combinations of both to meet the need of the corporate user. While these structures are clearly effective means of storing, sharing, and organizing information, they do not address the fact that users have very individual information needs. They also do not resolve the obstacle users face who do not have the time to spend looking for changes. An effective paradigm for addressing the problem of individual needs and delivering changes to documents can be found in the emerging category of ''Push techno log^." As its simplest definition, push is the process of automatically delivering user-requested information electronically. It is not an application, but merely a function or feature in a product. There are clear distinctions between the three different categories of push-based application: content, software, and document. Content push is the first mover. Conventional products focus on delivering breaking news and information to user desktops automatically. Instead of the user constantly surfing multiple Web sites for stock quotes, news, weather, etc., conventional products aggregate and broadcast information automatically according to individual user preferences. Many companies incorporate "push" functionality into their products. Following acceptance by hundreds of thousands of early adopters, many push-based applications started the move 30 35 40 45 55 60 65 US 6,738,799 B2 3 4 document push is the fact that EDD delivers data that was detected. The command need only specify the location within the earlier version of the file where the old segment currently exists in its native format within corporations and is stored, rather than the actual data that is stored at this whose value is clearly understood by the company, MIS, and position. This information is found in the signature list in the the end-user, With the recognized features, the willingness to 5 beginning location and size fields. The beginning location invest in infrastructure is more likely. field is preferably expressed as a number of bytes from the Within conventional environments, users have access to beginning of the file. At the client computer, when this and can Or them whenever location information is combined with the offset of the they are aware that the network file document changes. File beginning of the client computer,s copy of the earlier servers and intranet servers act as document repositories version of the subscription file, the correct old segment can waiting passively to be accessed. The reality is that these 10 be copied into the client computer~scopy of the current files change erratically and the user can never really know version of the subscription file, The size of the copy cornwhen a file has changed. As a result, those who need to have mand is negligible in comparison to the size of the segment to which it pertains, This savings reduces the size of the the most current documents are required to perform hit-andmiss network browsing and checking which is timeupdate file, and thus reduces the connection time in cornconsuming, unproductive, and frustrating. Even if the 15 rnUnicating the update file to the client computer, changes are scheduled, the user is still required to manually When no match is detected in the earlier version of the access, retrieve and manage those changes. signature list, the server computer writes a command into the For mobile users, the problem of knowing about and update file for the client computer to insert a new segment accessing changes to network-based files is compounded by of the current version of the subscription file into the client infrequent access to the corporate network. In addition, 20 computer's copy of the current version of the subscription file, where the new segment of the current version of the when remote from the ofice, users need to establish connections to the networkvia dial-up networking technologies, subscription file is written into the update file. Because the then search and browse the network over an often slow, new segment of the current version of the subscription file contains the actual data of the new segment, the new unreliable connection. The productivity losses and fmstrations are simply multiplied. 25 segment of the current version of the subscription file may As is apparent from the above discussion, a need exists for be compressed to reduce the size, encrypted for security, or both, by the server computer before being written into the an and effective mechanism for allowing a cornupdate file. puter user to have copies of the current versions of network When the update file is completed, the server computer files on his client computer. 30 transmits the update file to the client computer as an executSUMMARY OF THE INVENTION able attachment via electronic mail. The update file is only generated when the server computer determines that the Conventionally, those who need to have the most current subscription file has changed. The server computer periodiversions of computer files are required to perform hit-andmiss network browsing and checking which is time- 35 cally monitors the subscription file to determine if it has been altered before generating an update file. The user consuming, unproductive, and frustrating. An object of the present invention is to provide a mechanism by which a user determines the periodicity of the checks to determine if the can be automatically provided with a current version of a file file has been altered, and if so, to generate the update file and to which he subscribes. Another object of the present invensend it as an electronic mail. tion is to communicate the current version of the file in an 40 These and other features of the present invention are efficient manner. According to the present invention, a server apparent from the Drawings which are described in narrative form in the Detailed Description of the Invention. computer monitors network files and folders stored on the network for changes and then sends the user email notifiBRIEF DESCRIPTION OF THE DRAWINGS cations and updates when monitored items change. FIG. 1illustrates a general purpose computer architecture According to the present invention, a server computer 45 suitable for implementing the methods according to the generates an update file for transmission to a client computer present invention. that permits the client computer to generate a copy of a FIG. 2 illustrates a network of computers suitable for current version of a subscription file from a copy of an the the present invenearlier version of the subscription file, The server computer periodically reads the subscription file from the network so tion. FIG. 3 illustrates an earlier version of a subscription file drive and divides the subscription file into variable-length broken into six segments and the signatures corresponding segments based upon a segment delimiter, The server cornthe six segments for use with the methods puter computes a signature for each segment and stores the according the present segment signature along with the beginning position and FIG. 4 illustrates an earlier version of a signature list length of each segment in a current version of the signature 55 according to the Present invention corresponding to the list. The server computer also maintains the earlier version earlier version of the subscription file shown in FIG. 3. of the signature list. FIG. 5 is a flow chart illustrating a method according to For each segment of the current version of the subscripthe present invention of building a signature list correspondtion file, the server computer searches an earlier version of a signature list for an old segment signature which matches 60 ing to a subscription file. FIG. 6 illustrates a current version of the subscription file a new segment signature corresponding to the segment. shown in FIG. 3 broken into seven segments and the When a match is detected, the server computer writes a signatures corresponding to the seven segments suitable for command in the update file for the client computer to copy use with the methods according to the present invention. an old segment of the client computer's copy of the earlier FIG. 7 illustrates a current version of a signature list version of the subscription file into the client computer's 65 copy of the current version of the subscription file, where the according to the present invention corresponding to the old segment corresponds to the segment for which a match current version of the subscription file shown in FIG. 6. US 6,738,799 B2 5 6 variety of information sources is very compelling to both FIG. 8 illustrates the correspondence of the current version of the subscription file to the earlier version of the users and corporations, with the caveat that the files being sent must not impede the network, the mail server, or the subscription file and the segments which are communicated end-user's experience. This means, for truly effective docuto the client computer from the server computer in an update s ment push, file size has to be addressed, first and foremost. file according to the present invention. FIG. 9 illustrates the creation of a current copy on the Electronic Document Delivery involves more than just the client computer of the current subscription file from a copy physical process of sending out documents automatically. The indiscriminate sending or downloading of full-size files of the earlier version of the subscription file on the client computer using the update file. places a heavy burden on network bandwidth, IS, and the FIG. 10 is a flow chart illustrating a method according to 10 mobile professional. Intelligence needs to be built into the entire process of delivery to be truly effective and valuable the present invention of generating an update file from the to both MIS and users. current version of the subscription file and the current and earlier versions of the signature list. For truly effective Document Delivery, server-based intelligence is required. It is needed for detecting and sending FIG. 11 illustrates an update file generated by the method changed files, but also as well as for detecting what changes according to the present invention illustrated in FIG. 10 have been made and packaging only those changes as applied to the earlier and current versions of the signature efficiently as possible. If only 50 cells of 5000 have changed list illustrated in FIGS. 4 and 7, respectively. in a spread-sheet, it does not make sense to send the entire FIG, 12 illustrates a large and diverse network of file again. If only a single slide in a 50-slide presentation puters suitable for implementing the methods according to 20 changes, it does not make sense to re-send the entire 2 MB the present invention. file. The Figures are more thoroughly described in narrative Symantec Mobile UpdateTM (Symantec Mobile Update is form in the Detailed Description of the Invention. a trademark of Symantec Corporation and its subsidiaries) DETAILED DESCRIPTION OF THE according to the present invention, through a combination of INVENTION 25 server-based "delta technology" and client-based "update agent technology", adds "intelligence" to document delivery ~ l ~ intranets are growing in popularity, they are not h ~ ~ ~ h likely to replace file servers any time soon. File servers are a way receiving changes to corporate documents. he next section discusses one of the primary ways to store and share data on corporate according to the used networks due to their sheer simplicity for posting and 30 the present invention to bring "intelligence" to document delivretrieving files, usershave grown accustomed to working ery. with network drives, even to the extent where in which data Mobile Update according to the present invention is is actually stored directly on the network, rather than on their designed primarily to serve the mobile professional as the own hard drives. The intranet, on the other hand, requires that documents be "posted" or "uploaded" to a web server, 35 target user, who relies on copies of the most up-to-date usually by a select group of individuals, Thus, making documents to be effective, but who is not always connected to the network to access changes. In addition, the mobile documents available to others goes from the simple task of user is challenged with both slow connection speeds to the copying a file onto a network directory to submitting a file network (typically 28.8 Kblsec modem), as well as the to be processed by others. On the recipient end, it involves activating a browser, going to the appropriate URL or IP 40 hassles of getting and staying connected. The Mobile Update solution according to the present invention is comprised of address, finding the document on a page and downloading it a server portion (for tracking files on the network and (as opposed to a simple drag-and-drop file copy to the hard processing changes) and a client portion (for managing drive). document "subscriptions" and for incorporating changes spite of the varying degrees of complexity, there is value in both methods of file sharing. Since virtually all 45 into existing The Mobile Update Client portion is used to create and Intranet documents are converted forms of some other type manage subscriptions to network documents. The process of of document file, the most current information is often found selecting files to be monitored is referred to as "subscribin native files on the LAN, rather than information posted to ing". Users browse to the network directory where the a web page. In addition, not all changing files used in the day-to-day life of the mobile professional are found on the so desired files are stored and select either individual files or folders (excluding sub-folders). Once selected, the user then intranet, whereas all intranet-based files can typically be found on the network. Thus, browser-access alone is not determines the polling or monitoring interval for the server to check for changes and also what to do when changes always adequate to serve the needs of document delivery. According to research, the most popular method of conO C , i.e.9 package and send file changes or simple notifiCU ' netting to the corporate network is through electronic mail. 5s cation. Once the subscription is set up, the information is in its database. Not surprisingly, electronic mail is treated as a mission passed to the server and The Mobile Update Server according to the present invencritical application. For remote or mobile professionals, it is tion acts as an "electronic assistant" on the network, tracking the one connection they do make to the network on a documents for changes. It polls files or subfolders at either recurrent basis. This familiar, reliable system is well-suited for electronic document delivery (EDD). So well-suited, in 60 user-defined intervals for any changes to date, time stamps. fact, that many departments and users currently rely on When it detects a change, it checks the integrity of the file, electronic mail as a primary way to send documents to other then decides whether it needs to deliver the actual changes or simply notify send notice of a file change. users. Even with existing network and Intranet infrastructures, a typical response to the suggestion, "It's FIG. 1 illustrates a general purpose computer system 100 now posted on the site, you can download it" is "I know, but 65 suitable for implementing the methods according to the could you send it to me by email? It's easier". The simplicity present invention. The general purpose computer system 100 includes at least a microprocessor 104. The general of using electronic mail as a single connection to a wide US 6,738,799 B2 7 8 purpose computer may also include random access memory most efficient "delimiter" or "dividing point" to break the 102, ROM memory 103, a keyboard 107, and a modem 108. file into segments as shown in FIG. 3. Adigital 'snapshot' is All of the elements of the general purpose computer 100 are comprised of a series of segments which define the overall optionally tied together by a common bus 101 for transportcontents and structure of a file. A file can be segmented into ing data between the various elements. The bus 101 typically 5 hundreds, if not thousands, of segments depending on the includes data, address, and control signals. Although the file size and type. general purpose computer 100 illustrated in FIG. 1includes FIG. 3 illustrates an earlier version of a subscription file a single data bus 101 which ties together all of the elements broken into six segments and the signatures corresponding of the general purpose computer 100, there is no requirement to the six segments suitable for use with the methods that there be a single communication bus 101 which con- lo according to the present invention. SegmentsAl throughA6 nects the various elements of the general purpose computer represent variable length portions of the earlier version of the subscription file. The ends of each of the segments (A1 100. For example, the microprocessor 104, RAM 102, and ROM 103, are alternatively tied together with a data bus through A6) are determined by segment delimiters 301 while the hard disk 105, modem 108, keyboard 107, display through 306. The segment delimiters 301 through 306 are specific portions of data, perhaps bytes, that are statistically monitor 106, and network interface 109 are connected together with a second data bus (not shown). In this case, the determined to be an optimal, or at least acceptable, division point for the variable length segments A1 throughA6 for the first data bus 101 and the second data bus (not shown) are linked by a bidirectional bus interface (not shown). earlier version of the subscription file. Signatures 311 Alternatively, some of the elements, such as the microprothrough 316 are fixed length values derived from the varicessor 102 and RAM 102 are connected to both the first data 20 able length segments A1 through A6. The signatures 311 bus 101 and the second data bus (not shown), and commuthrough 316 may be determined by any one of a variety of hashing methods or signature algorithms. In the presently nication between the first and second data bus occurs preferred embodiment, the signatures A1 through A6 are through the microprocessor 102 and RAM 102. The network interface 109 provides communication capability to a local computed using the cyclic redundancy check (CRC). area network LAN using an ethernet connection, for 2s However, any signature algorithms may be used according example. The modem 108 allows the computer 100 to to the present invention. For example, MD5 can be used to communicate through the telephone system. The methods of derive a fixed length digital signature from the variable the present invention are executable on any general purpose length segments. computer system such as the 100 illustrated in FIG. 1, but FIG. 4 illustrates an earlier version of a signature list there is clearly no limitation that this computer system is the 30 according to the present invention corresponding to the only one which can execute the methods of the Present earlier version of the subscription file shown in FIG. 3. The invention. signature list 400 shown in FIG. 4 further includes the FIG. 2 illustrates a network of computers suitable for starting locations 401 through 406 of each of the segments A1 through A6 shown in FIG. 3. The starting locations 401 implementing the methods according to the present invention. A client computer 201 is connected to a network drive 35 through 406 are preferably represented as byte address 202 through link 205. Aserver computer 203 is connected to locations relative to the beginning of the earlier version of a network drive 202 through a link 206. The client computer the subscription file. Thus, an offset representing the loca201 and server computer 203 are logically connected by a tion of the beginning of the earlier version of the subscriplink 207 for communication between them. The server tion list is combined with each of the segment location computer 203 is logically connected to an electronic mail 40 values 401 through 406 to determine the address of the beginning of each of the segments within the address space facility 204 through link 209. Client computer 201 is logically connected to the electronic mail facility 204 through within which the segments A1 through A6 are stored. The link 208. The logical connections 207,208, and 209 are not signature list 400 also includes a segment size field which necessarily physical connections. For example, the client stores the size of each of the variable length segments A1 computer 201 is alternatively a remote computer which 45 through A6 as a number of bytes within the variable length periodically connects to the network drive 202 through a segment to which it corresponds. The segment location and modem. In this event, the modem (not shown) provides the segment size allow the addresses of all of the data within the physical connection through which the logical connections segment to be computed. However, it should be noted that 205, 207, and 208 are implemented. the information necessary to compute the addresses of the FIG. 2 illustrates the interaction between client, server, so pieces of data within each segment could be represented in and network according to the present invention. The user some alternative manner. For example, instead of attaching browses the network through link 205 from his client the segment size within the signature list, the ending location computer 201 to determine the files to which he wishes to of each segment could alternatively be stored according to subscribe. The client computer 201 sends the subscription the present invention. information to the server computer 203 through logical link ss FIG. 5 is a flowchart illustrating a method according to the 207. The server computer 203 polls the network 202 through present invention of building a signature list corresponding link 206 for changes to the subscription files. The server to a subscription file. The method starts at step 501. At step sends update files to the client computer 201 through the 502, the subscription file is read from the network drive 202. email facility 204 through logical link 209. The client If the subscription file read from the network drive is a new computer receives update files through the logical link 208. 60 subscription file, test 503 delivers the method to step 504 Symantec's Delta Technology according to the present where the most efficient segment delimiter is determined for invention has been optimized to detect and process changes that new subscription file. Thus, the byte value which quickly and efficiently, while concurrently maintaining the represents the segment delimiters 301 through 306 shown in integrity of the file. When a user first "subscribes" to a file, FIG. 3 are computed at step 504 the first time that the the server takes a "digital snapshot" that forms the basis for 65 subscription file is read. If the subscription file read from the determining changes made to the file in the future. The network drive in step 502 is not a new subscription file, then server reads the file from the network and determines the the task 503 delivers the message to step 505, where the US 6,738,799 B2 9 10 delimiter corresponding to the subscription file is retrieved file according to the present invention. As discussed above, the earlier version of the subscription file shown in FIG. 3 from a table (not shown) which stores the values of the and the current version of the subscription file shown in FIG. segment delimiters which correspond to each of the sub6 pertain to the same file name. They are different versions scription files that the server computer 203 monitors. After the segment delimiter corresponding to the subscription file s of the same file. FIG. 8 shows the current version of the subscription file. FIG. 8 is annotated to show which segis retrieved at step 505, the method scans the file from the ments within the current version of the subscription file are beginning for the delimiter in order to determine the first the same or identical to a segment within the earlier version variable length segment corresponding to that subscription of the subscription file. As shown in FIG. 8, each of the file. If the end of the file is reached before the delimiter is found, then step 506 marks that as a segment, and that will 10 Segments B1, B6, and B7 are the same as a ing segment within the earlier version of the subscription file be the last segment corresponding to the subscription file, Thus, the segment delimiter 306, which pertains to the last as segments A1 in 3. Segments B2, and B5 are each different from any of the segment A6, is the last byte in the file, and is not necessarily the same value as the other segment delimiters 301 through Segments A1 in 3. According to the Present invention, the new or changed 305. At step 507, the signature for the variable length IS Segments B2, B4 and B5 are extracted from the current segment is computed. At step 508, the signature is added to version of the subscription file stored on the network drive the signature list along with the beginning location and 202 by the server computer 203, and are packaged in an segment size corresponding to the segment. Test 509 deterupdate file 801 for transmission to the client computer 201 mines whether or not the segment ends with the delimiter, ~f the segment ends with the delimiter, then it is not the last 20 shown in FIG. 2 so that the client computer 201 can build a C P of the current version of the subscription file from its OY segment in the subscription file, and therefore the test 509 returns the message to step 506 so that the next variable C P of the earlier version of the subscription file. OY FIG. 9 illustrates the creation of a current copy on the length segment can be determined. If the segment does not client computer of the current subscription file from a copy end with the delimiter, then it is assumed that it is the end of the file, and the method 500 is completed. At this point, 25 of the earlier version of the subscription file on the client the signature list corresponding to the subscription file has computer using the update file 801 shown in FIG. 8. FIG. 9 shows the copy of the earlier version of the subscription file been computed and stored. when the server 203 polls the subscription file at a future 901 as well as the data contents of the update file 902 as it ~0"es~o"ds to the client computer's copy of the current time and detects a change, a second "snapshot" is generated using the same process as the first snapshot as shown in FIG, 30 version of the subscription file 903. FIG. 9 shows arrows 910 through 913 which indicate segments which the client 7, shown in FIG, 8, the new or changed segments are accompanied by unchanged segments, depending on the 201 can its the subscription file into the current version of the subscription number and severity of the changes made to the file, ~h~ Delta Engine according to the present invention then cornfile. Specifically, segment A1 is illustrated by arrow 910 as segment C1 the the current pares the two sets of segments to determine which segments 35 being version. Similarly, segment A3 may be copied into segment have been altered, which ones are new and which ones have C3, segment A5 may be copied into segment C6 and remained unchanged, as illustrated in FIG. 8. segment A6 may be copied into segment C7. Arrows 920 FIG. 6 illustrates a current version of the subscription file through 922 show segments which are inserted from the shown in FIG. 3 broken into seven segments and the 40 update file 902 into the copy of the current version of the signatures corresponding to the seven segments suitable for subscription file 903. Specifically, segment B2 is inserted use with the methods according to the present invention. from the update file 902 into the copy of the current version Segment delimiters 601 through 607 represent byte codes of the subscription file at segment C2. Segment B4 is which were determined for this subscription file to indicate inserted from the update file 902 into the copy of the current the end of each of the segments B1 through B7. Signatures 45 version 903 at segment C4. Segment B5 is inserted from the 611 through 617 represent fixed length signatures computed update file 902 into the copy of the current version 903 at from each of the seven segments B1 through B7. segment C5. Dotted rectangle 950 illustrates data that is FIG. 7 illustrates a current version of a signature list resident on the client computer 201, update file 902 is according to the Present invention corresponding to the communicated to the client computer 201 through an eleccurrent version of the subscription file shown in FIG. 6. The h the ~ update file 902 must be ~ , tronic mail facility 204, ~ signature list 700 includes the segment signatures 701 transmitted to the client computer 201 through whatever 707 the length segments communication link the client computer 201 uses to access B1 B7 in and the its electronic mail 204. This link 208 shown in FIG. 2 may segment locations 721 through 727 representing the beginbe a modem, an ethernet connection, or some other cornning position each the segments B1 B7 as 5 s munication device. A is illustrated in FIG. 9, the present s as the segment sizes 711 through 717 corresponding to each invention maximizes the information already stored on the of the segments B1 through B7. client computer 201 and minimizes the information needed The engine according to the present invention extracts to be transmitted to the client computer 201 in order to create new or changed segments and bundles these into a file, the copy of the current version of the subscription file. called an Update File. This file is then optionally corn- 60 Specifically because segments Al, A3, AS, and A6 are identical to corresponding segments in the current version of pressed to reduce its size even further. At its simplest, an the subscription file, they need not be transmitted to the Update File contains just the changes made to a file, in a compressed state, as shown in FIG. 8. client computer 201 through the electronic mail facility 204. FIG. 8 illustrates the correspondence of the current verOnly the changes B2, B4, and B5 are communicated to the sion of the subscription file to the earlier version of the 65 client computer 201. subscription file and the segments which are communicated FIG. 10 is a flowchart illustrating a method according to to the client computer from the server computer in an update the present invention of generating an update file from the B33 B43 US 6,738,799 B2 11 12 current version of the subscription field and the current and the copying of segmentA3 into segment C3 shown by arrow earlier versions of the signature list. The method starts at 911 in FIG. 9. The command 1104 implements the copying step 1001. At step 1002, the method compares the new of segment B4 into segment C4 illustrated by arrow 921 segment signature to an old segment signature. Here, the shown in FIG. 9. The command 1105 implements the new segment refers to segments within the current version of 5 copying of segment B5 into segment C5 illustrated by the arrow 922 shown in FIG. 9. The command 1106 implements the subscription file; the old segment signature refers to the copying of the segment A5 into segment C6 illustrated segment signatures within the earlier version of the subby arrow 912 shown in FIG. 9. The COPY command 1107 scription file. For example, each of the segment signatures implements the copying of segment A6 into segment C7 311 through 316 shown in FIGS. 3 and 4 are old segment signatures, while each of the signatures 701 through 707 lo illustrated by arrow 913 in FIG. 9. Each of the copy shown in FIG. 7 represent new segment signatures. Step commands 1101,1103,1106, and 1107 must specify for the 1002 begins with the first new segment signature in the client computer 201 where the segments to which they current version of the subscription file. For example, step pertain are actually stored on the client computer. 1002 begins with the segment signature 701 pertaining to Because the client computer does not store the signature segment B1. Step 1002 compares the new segment signature lists or have any knowledge of the fact that the subscription to the old segment signature. Step 1002 begins with the first files are broken into segments by the server computer, the old segment signature, for example the segment signature update file must include address information necessary to 311 corresponding to segment A 1 shown in FIG. 4. effectuate the copying of the correct bytes into the copy of If step 1002 determines that there is a match between the the current version of the subscription file. Thus, the location new segment signature and the old segment signature, then 20 and size of each segment are included as arguments to each the method 1000 writes a command in the update file to copy of the copy commands so that the client computer can the old segment into the client computer's copy of the compute the address of the correct bytes. The client comcurrent version of the subscription file at step 1003. Then puter stores the copies of the subscription files as standard step 1007 determines if the last new segment signature in the files within its operating system and only knows the beginnew signature list has been processed and if so, the method 25 ning location and size of the entire file. The location and size is done at step 1009. For example, when the method gets to information included in each copy command by the server the new segment signature 707 corresponding to segment computer 203 is combined with the file offset value at the client computer in order for the client computer to calculate B7, step 1007 will indicate that the method is done. However, if there are more new segment signatures to be the range of addresses to be copied. In addition, the server processed, step 1007 delivers the message to step 1008 30 computer 203 has no way of knowing where exactly on the client computer's hard disk that the client computer stored which retrieves the next new segment signature, and then the earlier version of the subscription file. The insert comreturns the method to step 1002. If there is not a match mands 1102, 1104, and 1105 include the actual contents of between the new segment signature and the old segment the segments B2, B4, and B5, respectively. Although the signature, then step 1002 delivers the method to step 1004, where it is determined whether or not the last old segment 35 segment size is variable, the inclusion of the actual contents of the new or changed segments B2, B4, and B5 represent signature in the old signature list has been compared to the the vast bulk of the update file 1100. In other words, the copy new segment signature. If test 1004 determines that there are commands 1101,1103,1106, and 1107 are negligible in size no more old segment signatures in the old signature list, for in comparison to the contents of the actual new or changed example the segment signature 316 corresponding to segmentA6 shown in FIG. 4, then test 1004 delivers the method 40 segments which must be transmitted. In fact, in FIG. 9, the update file 902 and in FIG. 8, the update file 801, are to step 1006 where the server computer writes a command in the update file to insert the new segment into the client illustrated solely by the contents of the segments B2, B4, and B5 and omit illustrating the actual copy and insert comcomputer's copy of the current version of the subscription file. In other words, if step 1006 is reached, then there were mands because they are negligible in size to the actual no matches for the new segment signature in the old segment 45 content of the transmitted segments. Because the segments are transmitted via electronic mail, they may be further signature list. Then the method reverts to test 1007. If test compressed to reduce their size and thereby minimize con1004 determines that there are more old segment signatures nection time in receiving the electronic mail. Because the in the old signature list, then the next old segment signature update file is often transmitted over an insecure communiis considered at step 1006 and the method reverts to step 1002 for comparison of the new segment signature to the old so cation medium, such as the internet, the update file 902 is optionally encrypted for security purposes according to the segment signature. Present invention. FIG. 1 shows the update file which is communicated to 1 Once a delta or Update File has been generated, the server the client computer 202 via electronic mail. Although the creates an email message and sends the Update File as a preferred embodiment of the present invention involves electronic mail transmission of the update file to the client 5s simple binary attachment to the user. The user then receives updates through the user's standard email client. computer 201, there is no requirement that an electronic mail 1 For mobile professionals, this means making one connecfacility be used. FIG. 1 illustrates an update file generated by the method according to the present invention illustrated tion to the network to receive all messages and document in FIG. 10 applied to the earlier and current versions of the updates. It also means that the size of the attachment is a signature list illustrated in FIGS. 4 and 7, respectively. The 60 fraction of the full file, containing only the changes to be update file 1100 shown in FIG. 1 is preferable an execut1 applied. In other words, the user performs the standard task able attachment to an electronic mail that is received by the of checking email &mdash; i.e. a task that is familiar, secure, client computer 201. The command 1101 implements the and, for the most part, reliable. Once an Update Message copy of segment A 1 into segment C1 illustrated by the arrow arrives, the user simply launches or opens the attachment 910 shown in FIG. 9. The insert command 1102 implements 65 (again, in a way they are most familiar with) and the Mobile the insertion of the segment B2 into segment C2 by arrow Update Agent processes the changes automatically. It does 920 shown in FIG. 9. The copy command 1103 implements this by substituting the new and modified segments in the US 6,738,799 B2 13 14 Update File with the segments in the existing file, as sages are then sent when the user logs on to check or send e-mail. The messages are then received by the server's mail illustrated in FIG. 9. and parsed and processed The As shown in FIG. 9, segment B2 is a replacement segment Update Server according to the present invention can access for A2 in the current file, A2 is removed and B2 takes its any WAN-based server, providing it has the Ilecplace, Segment B4 is a brand new segment that fits in after 5 essary network access rights, as illustrated in FIG. 12. A3, and the files to the right of it (i.e., A4, AS, and A6) are 'ymantec according to the present moved over by one segment, Finally, segment B5 replaces invention is the first solution in the document delivery or A4 as it is the modified segment for A4, The last two "push" category in which currently existing data like segments in the and A6) are reused' The lo reports, spreadsheets, presentations, etc., are delivered to the updated file on the hard drive now has an identical "binary desk-top 'intelligently,, It does this by watching the network profile" Or the taken the files of folders for changes, delivering "just the changes" or server. For the next change, the server take yet notifies of changes, uses one familiar and reliable connecand it against the latest tion to deliver those changes (email), and provides seamless and so on. functionality, thereby leveraging the way users currently The Mobile Update Server according to the present invenwork (in email), tion preferably runs as a service under NT 4.0 Document push, like software push, is only compelling if (Workstation or Server) and can run across virtually any it can deliver clear value to end-users and corporate IS. network 'peratink? 'ystem that supports Windows NT. Mobile Update according to the present invention offers two However, it should be noted that the server according to the tiers of benefits to corporations, F~~ the mobile user, it present is as under any O receives updates anywhere, anytime (location-independent), ' operating system. The server according to the Present invenit stays up-to-date on changes to key documents, it reduces tion requires its own mail client (account) that is capable of download time for email attachments, and it reduces the sending and receiving email messages the hassle of accessing changes to key documents. For MIS mail server. The server uses the mail client to receive and 25 personnel, it easily and effectively keeps mobile employees process email-based subscription changes and requests autoconnected to corporate, L A N - files, it reduces the ~ ~ ~ ~ ~ matically generated by clients when they are in off-line length of connection times (quicker email downloads), it (i.e., the It uses the reduces the number of connections made (leverages email mail client to create and send notification and update connection), and it reduce the size of email attachments requests to its users. In addition, the server requires a (delta technology), network account with access rights that encompass those of 30 Although the present invention has been described with its users, i.e. it should at least share the same profile as its respect to its preferred embodiment, that embodiment is users. This allows the server to access network files on the offered by way of example, not by way of limitation, It is to user's behalf to check for changes. be understood that various additions and modifications can When installing the server, the administrator specifies 35 be made without departing from the spirit and scope of the where client install files should be located on the network for present invention,~ ~ ~ all such additions ~ modi~ ~ d i and ~ l easy install access by users. Once the server is set UP, the fications are deemed to lie with the spirit and scope of the user installs the client from the network drive. Each client is present invention as set out in the appended claims, registered with the server and writes its user name, email What is claimed is: address, etc., to the server's database. The client can now 40 1. Amethod for a first computer to generate an update for subscribe to any network-based files located on a shared transmission to a second computer that permits the second directory. computer to generate a copy of a current version of a file FIG. 12 illustrates a large and diverse network of corncomprised of a first plurality of file segments from a copy of puters suitable for implementing the methods according to an earlier version of the file comprised of a second plurality the present invention. Specifically, the server computer 1201 45 of file segments, such that each file segment corresponds to accesses subscription files stored on any of the file servers a portion of its respective file, the method comprising the 1202 through 1209. The personal computers 1210 through steps of: 1212 are connected to local area network 1216. Remote for each segment of the current version of the file, personal computers 1213 through 1215 dial in to modems (a) searching an earlier version of a signature list 1218 through 1220 respectively in order to receive their corresponding to an earlier version of the file for an electronic mail from the electronic mail facility 1221 and old segment signature which matches a new segment receive update files corresponding to the subscription files to signature corresponding to the segment; which they subscribe. (b) if step (a) results in a match, writing a command in FIG. 12 illustrates a sample deployment for Mobile the update for the second computer to copy an old Update according to the present invention. The clients runs 55 segment of the second computer's copy of the earlier in both on-line mode and off-line mode. The client runs in version of the file into the second computer's copy of on-line mode when it is on the network where it can the current version of the file, wherein the old communicate directly with the server's database. The client segment corresponds to the segment for which a runs in off-line mode when the user is mobile and not match was detected in step (a); and connected to the network. (c) if step (a) results in no match, writing a command 60 in the update for the second computer to insert a new In the off-line mode according to the present invention, segment of the current version of the file into the the user communicates with the server through email messecond computer's copy of the current version of the saging. If changes are made to the properties of a file; subscription, such as a change in polling frequency or a wherein the new segment of the current version of the re-sync request is made, the Mobile Update client automati- 65 cally generates an email message to the server which is then file is written into the update and the unchanged segment is excluded from the update; and placed in the outbox of the user's mail client. These mes- ~ , wherein steps (a) through (c) are performed by the first computer, without interaction with the second computer, in response to the first computer detecting a change between the current version of the file and the earlier version of the file. 2. The method of claim 1, wherein the new segment of the current version of the file is compressed. 3. The method of claim 1, wherein the new segment of the current version of the file is encrypted. 4. The method of claim 1, wherein the new segment of the current version of the file is retrieved by the first computer from a network drive. 5. The method of claim 1. further comarisinn: a (d) transmitting the update to the second computer as an executable attachment by electronic mail, wherein the executable attachment will cause the second computer to generate a copy of the current version of the file from the copy of the earlier version of the file, in response to the second computer executing the attachment. 6. The method of claim 5, further comprising: prior to step (a), performing a check on the current version of the file to determine if the file has been altered since a previous check and continuing to perform the remaining steps only if the check determines that the current version of the file has been altered. 7. The method of claim 6, wherein the step of performing a check is performed at periodic intervals. 8. The method of claim 6, wherein the step of performing a check on the current version of the file comprises checking a current time stamp of the current version of the file to determine whether it differs from an earlier time stamp of the file. 9. The method of claim 1, wherein the update comprises a software update. 10. The method of claim 1, wherein the update comprises a document update. 11. The method of claim 1, wherein the update comprises a content uadate. 12. A computer readable storage medium, comprising computer readable program code embodied on said computer readable storage medium, said computer readable program code for programming a first computer to generate an update for transmission to a second computer that permits the second computer to generate a copy of a current version of a file comprised of a first plurality of file segments from a copy of an earlier version of the file comprised of a second plurality of file segments, such that each file segment corresponds to a portion of its respective file, the computer readable program code causing the first computer to perform the following steps: for each segment of the current version of the file, (a) searching an earlier version of a signature list corresponding to an earlier version of the file for an old segment signature which matches a new segment signature corresponding to the segment; (b) if step (a) results in a match, writing a command in the update for the second computer to copy an old segment of the second computer's copy of the earlier version of the file into the second computer's copy of the current version of the file, wherein the old segment corresponds to the segment for which a match was detected in step (a); and (c) if step (a) results in no match, writing a command in the update for the second computer to insert a new segment of the current version of the file into the second computer's copy of the current version of the file; s lo L 2s 30 35 wherein the new segment of the current version of the file is written into the update and the unchanged segment is excluded from the update; and wherein steps (a) through (c) are performed by the first computer, without interaction with the second computer, in response to the first computer detecting a change between the current version of the file and the earlier version of the file. 13. The computer readable storage medium of claim 12, wherein the new segment of the current version of the file is compressed. 14. The computer readable storage medium of claim 12, wherein the new segment of the current version of the file is encrypted. 15. The computer readable storage medium of claim 12, wherein the new segment of the current version of the file is retrieved by the first computer from a network drive. 16. The computer readable storage medium of claim 12, further comprising computer readable program code causing the first computer to perform the following step: (d) transmitting the update to the second computer as an executable attachment by electronic mail, wherein the executable attachment will cause the second comauter to generate a copy of the current version of the file from the copy of the earlier version of the file, in response to the second computer executing the attachment. 17. The computer readable storage medium of claim 16, further comprising computer readable program code causing the first computer to perform the following step: prior to step (a), performing a check on the current version of the file to determine if the file has been altered since a previous check and continuing to perform the remaining steps only if the check determines that the current version of the file has been altered. 18. The computer readable storage medium of 17, wherein the step of performing a check is performed at periodic intervals. 19. The computer readable storage medium of claim 17, wherein the stea of aerforminn a check on the current a version of the file comprises checking a current time stamp of the current version of the file to determine whether it differs from an earlier time stamp of the file. 20. The computer readable storage medium of claim 12, wherein the update comprises a software update. 21. The computer readable storage medium of claim 12, wherein the update comprises a document update. 22. The computer readable storage medium of claim 12, wherein the update comprises a content update. 23. Amethod for a first computer to generate an update for transmission to a second computer that permits the second computer to generate a copy of a current version of a file comprised of a first plurality of file segments from a copy of an earlier version of the file comprised of a second plurality of file segments, such that each file segment corresponds to a portion of its respective file, the method comprising the steps of: for each segment of the current version of the file, (a) searching an earlier version of a signature list corresponding to an earlier version of the file for an old segment signature which matches a new segment signature corresponding to the segment; (b) if step (a) results in a match, writing a command in the update for the second computer to copy an old segment of the second computer's copy of the earlier version of the file into the second computer's copy of the current version of the file, wherein the old segment corresponds to the segment for which a match was detected in step (a); and L 40 45 so 5s 60 65 L US 6,738,799 B2 17 (c) if step (a) results in no match, writing a command in the update for the second computer to insert a new segment of the current version of the file into the second computer's copy of the current version of the file; wherein steps (a) through (c) are performed by the first computer, without interaction with the second computer, in response to the first computer detecting a change between the current version of the file and the earlier version of the file. 24. The method of claim 23, wherein the new segment of the current version of the file is written into the update and the unchanged segment is excluded from the update. 25. The method of claim 23, further comprising: (d) transmitting the update to the second computer as an executable attachment by electronic mail, wherein the executable attachment will cause the second computer to generate a copy of the current version of the file from the copy of the earlier version of the file, in response to the second computer executing the attachment. 26. The method of claim 25, further comprising: prior to step (a), performing a check on the current version of the file to determine if the file has been altered since a previous check and continuing to perform the remaining steps only if the check determines that the current version of the file has been altered. 27. The method of claim 23, wherein the update comprises a software update. 28, ~h~ method of claim 23, wherein the update prises a document update. 29. The method of claim 23, wherein the update comprises a content update. 30. A computer readable storage medium, comprising computer readable program code embodied on said computer readable storage medium, said computer readable program code for programming a first computer to generate an update for transmission to a second computer that permits the second computer to generate a copy of a current version of a file comprised of a first plurality of file segments from a copy of an earlier version of the file comprised of a second plurality of file segments, such that each file segment corresponds to a portion of its respective file, the computer readable Program code causing the first computer to perform the following steps: for each segment of the current version of the file, (a) searching an earlier version of a signature list corresponding to an earlier version of the file for an old segment signature which matches a new segment signature corresponding to the segment; (b) if step (a) results in a match, writing a command in the update for the second computer to copy an old segment of the second computer's copy of the earlier version of the file into the second computer's copy of the current version of the file, wherein the old segment corresponds to the segment for which a match was detected in step (a); and (c) if step (a) results in no match, writing a command in the update for the second computer to insert a new segment of the current version of the file into the second computer's copy of the current version of the file; wherein steps (a) through (c) are performed by the first computer, without interaction with the second computer, in response to the first computer detecting a change between the current version of the file and the earlier version of the file. 18 31. The computer readable storage medium of claim 30, wherein the new segment of the current version of the file is written into the update and the unchanged segment is excluded from the update. s 32. The computer readable storage medium of claim 30, further comprising computer readable Program code causing the first computer to perform the following step: (d) transmitting the update to the second computer as an executable attachment by electronic mail, wherein the 10 executable attachment will cause the second computer to generate a copy of the current version of the file from the copy of the earlier version of the file, in response to the second computer executing the attachment. 33. The computer readable storage medium of claim 32, further comprising computer readable Program code causing the first computer to perform the following step: prior to step (a), performing a check on the current version of the file to determine if the file has been altered since a previous check and continuing to perform the remain20 ing steps only if the check determines that the current version of the file has been altered. 34. The computer readable storage medium of claim 30, wherein the update comprises a software update. 3 5 The computer readable storage medium of claim 30, 25 wherein the update comprises a document update. 36. The computer readable storage medium of claim 30, wherein the update comprises a content update. 37. A method for a first computer to provide updates for transmission to a second computer that permits the second 30 computer to obtain most recent versions of files, the method comprising the steps of: (a) determining whether the second computer has a latest version of a file, wherein said determining is performed by the first computer without interaction with the 35 second computer; (b) generating an update, if the second computer does not have a latest version of the file, wherein said generating is performed by the first computer without interaction 40 with the second computer; and (c) transmitting the update from the first computer to the second computer. 38, me method of claim 37, wherein step (c) comprises transmitting the update from the first computer to the second 45 computer as an executable attachment by electronic mail, wherein the executable attachment will cause the second computer to generate a copy of the current version of the file from the copy of the earlier version of the file, in response to the second computer executing the attachment. 39. The method of claim 37, wherein the update comso prises a software update. 40. The method of claim 37, wherein the update comprises a document update. 41. The method of claim 37, wherein the update com55 prises a content update. 42. A computer readable storage medium, comprising computer readable program code embodied on said computer readable storage medium, said computer readable program code for programming a first computer to provide 60 updates for transmission to a second computer that permits the second computer to obtain most recent versions of files, the computer readable program code causing the first computer to perform the following steps: (a) determining whether the second computer has a latest 65 version of a file, wherein said determining is performed by the first computer without interaction with the second computer; US 6,738,799 B2 19 20 (b) generating an update, if the second computer does not copy of the current version of the file from the copy of the have a latest version of the file, wherein said generating earlier version of the file, in response to the second computer is performed by the first computer without interaction executing the attachment. with the second computer; and 44. The computer readable storage medium of claim 42, (c) transmitting the update from the first computer to the 5 wherein the update comprises a software update. 45. The computer readable storage medium of claim 42, second computer. 43. The computer readable storage medium of claim 42, wherein the update comprises a document update. 46. The computer readable storage medium of claim 42, wherein step (c) comprises transmitting the update from the first computer to the second computer as an executable wherein the update comprises a content update. attachment by electronic mail, wherein the executable 10 * * * * * attachment will cause the second computer to generate a UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. APPLICATION NO. DATED INVENTOR(S) : 6,738,799 B2 : 101452156 : May 18,2004 : Peter Dickinson Page 1 of 1 It is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below: On the Title page, at Item (12), change the inventor name "Dickenson" to --Dickinson--; On the Title page, at Item ( 7 3 , change the inventor name "Dickenson" to --Dickinson--; Signed and Sealed this Tenth Day of February, 2009 yAaa JOHN DOLL Acting Director of the United States Patent and Trademark Ofice

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