PTAB

IPR2012-00026

Microsoft Corp v. Proxyconn Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: System And Method For Data Access
  • Brief Description: The ’717 patent discloses a method for reducing redundant data transmission over a network. The system works by having a sender computer create and transmit a "digital digest" (a fingerprint or hash) of data to a receiver, which checks if it already possesses data with an identical digest, thereby avoiding re-transmittal of the full data set if a match is found.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 1, 3, 10-12, 14, and 22-24 under 35 U.S.C. §102 by Perlman

  • Prior Art Relied Upon: Perlman (Patent 5,742,820).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Perlman discloses every element of the challenged claims. Perlman teaches a mechanism for efficiently synchronizing the contents of databases stored on different nodes of a computer network. It describes generating a "database identifier" (equivalent to the ’717 patent’s "digital digest") that uniquely represents the database contents. This identifier is distributed to receiving nodes, which compare it to their own identifier to determine if their databases are synchronized. If not, the receiving node requests the updated data, directly mapping to the method claimed in the ’717 patent.
    • Key Aspects: Petitioner contended that Perlman’s disclosure of using a 128-bit message digest or CRC hash as the database identifier directly reads on the "digital digest" limitation. Furthermore, Perlman’s description of a distributing node (sender) and receiving nodes (receivers) communicating over a packet-based network meets the claimed system architecture.

Ground 2: Obviousness of Claims 1, 3, 10-12, 14, and 22-24 under 35 U.S.C. §103 over Perlman in view of Yohe

  • Prior Art Relied Upon: Perlman (Patent 5,742,820) and Yohe (Patent 5,835,943).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner argued that the combination of Perlman and Yohe renders all challenged claims obvious. While Perlman’s illustrative embodiment describes storing digests in volatile RAM, certain claims (e.g., claim 10 and 23) require storing and searching for digests in the receiver’s permanent memory. Yohe explicitly teaches an apparatus for increased data access in a network file caching system where the cache is stored on a disk or other permanent-storage device. Therefore, Yohe supplies the permanent memory cache limitation arguably not present in Perlman's primary example. Conversely, Petitioner argued Perlman discloses bundling multiple digests in a single message (as required by claim 24), a feature not expressly disclosed in Yohe.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Perlman and Yohe for several reasons. Both references address the identical problem of reducing redundant network data transmissions by validating cached data. They also propose the same algorithmic solution: comparing digital fingerprints and requesting full data only upon a mismatch. Perlman expressly teaches that its mechanism is not limited to network routers but applies to "any type" of distributed system, which would naturally lead a POSITA to apply its teachings to a system like Yohe’s that uses permanent storage for its cache.
    • Expectation of Success: The combination would have yielded predictable results. The choice between volatile and persistent memory for a cache was a well-known design trade-off in 1998-99, balancing access speed against storage capacity and data persistence. Applying Perlman’s synchronization method to a system with a permanent memory cache as taught by Yohe was a simple substitution of one known element for another to obtain predictable results.

  • Additional Grounds: Petitioner asserted additional challenges, including anticipation of various claims by Yohe, Santos (a 1998 USENIX technical conference paper), and Baber (Patent 6,279,041). Further obviousness grounds were asserted based on the combination of Perlman, Yohe, and admitted prior art from the ’717 patent specification.

4. Key Claim Construction Positions

  • "digital digest": Petitioner argued that under the Broadest Reasonable Interpretation (BRI), this term encompasses known fixed-size digital fingerprints such as MD5 or CRC hashes, as disclosed in the prior art. Petitioner contended that the ’717 patent’s contradictory statements suggesting a "similarity check property" should be disregarded, as the patent fails to describe any algorithm with such a property, and the core disclosure relies on identity checks consistent with standard hashing algorithms.
  • "sender/computer": Petitioner contested the Patent Owner’s narrow interpretation that a sender must originate the data it sends. Petitioner proposed a broader BRI where a "sender/computer" is any device capable of sending information, including an intermediary device. This broader construction was necessary to map the claims onto prior art systems where data processing and transmission functions were distributed.
  • "network cache memory": Petitioner argued this term should be construed simply as a logical portion of a computer's memory (either permanent or volatile) used to store data received from a network. Petitioner asserted the term implies no special structure or capability beyond standard memory, allowing it to be read on the conventional cache and database storage disclosed in Perlman and Yohe.

5. Relief Requested

  • Petitioner requested the institution of an inter partes review and the cancellation of claims 1, 3, 10-12, 14, and 22-24 of the ’717 patent as unpatentable.