PTAB

IPR2021-00361

Unified Patents LLC v. DataCloud Technologies LLC

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1. Case Identification

2. Patent Overview

  • Title: Disambiguating File Descriptors
  • Brief Description: The ’613 patent discloses methods for distinguishing between different types of files (e.g., files stored on media vs. communication channels) within an operating system. The system intercepts standard system calls, stores an indicator associated with a file descriptor to mark its file type, and later examines this indicator to apply different rules or functions based on that type.

3. Grounds for Unpatentability

Ground 1: Anticipation by Dukach - Claims 1, 2, 5, 7, 14, and 17 are anticipated by Dukach under 35 U.S.C. §102(e).

  • Prior Art Relied Upon: Dukach (Patent 6,609,159).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Dukach discloses every limitation of the challenged claims. Dukach describes a client-server architecture where an "interposer library" intercepts system calls to extend functionality. Petitioner contended this library performs the claimed method of disambiguating file descriptors by distinguishing between network services to be handled by a front-end server and those that are not.
      • The library intercepts system calls like bind(), accept(), and dup2() to "establish" file descriptors.
      • It then "stores" an indicator of file type by adding the file descriptor's number to a "list of monitored file descriptors" if it corresponds to a service handled by the front-end server. The presence of the descriptor's number on this list serves as the claimed "indicator."
      • Dukach’s library also intercepts calls that create copies of file descriptors, such as dup() and fork(). When dup() is intercepted, the number of the newly created "alias file descriptor" is recorded (stored) in the monitored list. When fork() is called, the entire list of monitored descriptors is copied to the new child process.
      • Finally, upon an attempt to access a file via subsequent intercepted calls like listen() or accept(), Dukach "examines" the stored indicator by testing if the file descriptor's number is on the monitored list to determine how to route the service request.
    • Key Aspects: Petitioner’s argument centered on equating Dukach’s "list of monitored file descriptors" with the ’613 patent's "indicator table," and the presence or absence of a descriptor on that list with the claimed "indicator."

Ground 2: Obviousness over Dukach in view of Dunsmuir - Claims 1, 2, 5, 7, 14, and 17 are obvious over Dukach in view of Dunsmuir under 35 U.S.C. §103.

  • Prior Art Relied Upon: Dukach (Patent 6,609,159) and Dunsmuir (a 1985 book titled "Programming the UNIX™ System").

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground asserted that even if Dukach does not explicitly disclose every detail, the combination with Dunsmuir renders the claims obvious. Dukach relies on well-known UNIX system calls like dup(), dup2(), and fork() but does not fully detail their operation. Dunsmuir, a standard programming guide, provides these missing details. For instance, Dunsmuir explains that dup() creates a copy of a file descriptor and dup2() establishes a new file descriptor, directly teaching limitations that Petitioner argued are at least implicitly present in Dukach.
    • Motivation to Combine: A POSITA implementing the system described in Dukach would be motivated to consult a standard reference like Dunsmuir to understand the precise, well-known functionality of the UNIX system calls (dup(), dup2(), fork()) that Dukach explicitly utilizes.
    • Expectation of Success: A POSITA would have a high expectation of success in applying Dunsmuir's teachings, as it merely provides standard, foundational knowledge about the very tools Dukach's system is built upon. The combination would involve no modification, only a deeper understanding of existing components.

  • Additional Grounds: Petitioner also asserted that claims 1, 2, 5, 7, 14, and 17 are obvious over Dukach alone, relying on the same teachings presented for anticipation but under the lower obviousness standard.

4. Key Claim Construction Positions

  • Petitioner argued that the term "file" should be construed as "any entity that is accessed via a file descriptor associated with the entity."
  • This construction was asserted to be critical because it is not limited to traditional files stored on media. It encompasses other entities treated as files by an operating system, such as the communication channels and control pipes described in Dukach. This broad interpretation, supported by the ’613 patent's own specification, allows Dukach’s method of distinguishing between network service types to be mapped to the claims’ requirement of disambiguating "file types."

5. Arguments Regarding Discretionary Denial

  • Petitioner argued against discretionary denial under 35 U.S.C. §325(d), asserting that the petition raises new issues of patentability. The primary prior art reference, Dukach, was not cited or considered during the original prosecution of the ’613 patent. Therefore, Petitioner contended that the Examiner never had the opportunity to evaluate the patentability of the claims in light of this highly material reference.

6. Relief Requested

  • Petitioner requested the institution of an inter partes review and the cancellation of claims 1, 2, 5, 7, 14, and 17 of the ’613 patent as unpatentable.