DCT
5:18-cv-06612
PersonalWeb Tech LLC v. Popsugar Inc
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: PersonalWeb Technologies, LLC (Texas) and Level 3 Communications, LLC (Delaware)
- Defendant: Popsugar Inc. (Delaware)
- Plaintiff’s Counsel: Stubbs, Alderton & Markiles, LLP
- Case Identification: 5:18-cv-06612, N.D. Cal., 10/30/2018
- Venue Allegations: Venue is alleged to be proper in the Northern District of California because the Defendant, Popsugar Inc., maintains a regular and established place of business within the district.
- Core Dispute: Plaintiff alleges that Defendant’s website content delivery system infringes patents related to using content-based identifiers to manage, distribute, and control access to data across computer networks.
- Technical Context: The technology involves generating unique identifiers for data files based on their content (e.g., via cryptographic hashing), a foundational concept for modern content delivery networks (CDNs) and cloud computing that enhances efficiency and data integrity.
- Key Procedural History: The complaint notes that the patents-in-suit have been successfully enforced against other parties, resulting in settlements and non-exclusive licenses. It also states that the last of the patents-in-suit has expired, indicating the action is for past damages only.
Case Timeline
| Date | Event |
|---|---|
| 1995-04-11 | Priority Date for ’442, ’310, and ’420 Patents |
| 2005-08-09 | U.S. Patent No. 6,928,442 Issued |
| 2010-09-21 | U.S. Patent No. 7,802,310 Issued |
| 2012-01-17 | U.S. Patent No. 8,099,420 Issued |
| 2018-10-30 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 6,928,442 - "Enforcement and Policing of Licensed Content Using Content-Based Identifiers" (Issued Aug. 9, 2005)
The Invention Explained
- Problem Addressed: The patent's background describes the limitations of conventional data identification methods in computer networks, where file names are context-dependent and have no direct relationship to the data itself, leading to data duplication, difficulties in verifying data integrity, and inefficient caching (U.S. Patent No. 6,928,442, col. 2:13-25).
- The Patented Solution: The invention proposes a system using a "substantially unique identifier," called a "True Name," which is generated by applying a function (such as a message digest or hash function) to the actual content of a data item. This content-based identifier allows a data item to be uniquely identified, managed, and accessed independent of its location or user-assigned name, thereby enabling more efficient and reliable data management in a distributed system (’442 Patent, col. 4:24-34; Abstract).
- Technical Importance: This approach of content-addressable storage provided a method for reducing redundant data transfer and storage, a technique foundational to the efficiency of modern CDNs and distributed file systems (Compl. ¶11, ¶14).
Key Claims at a Glance
- The complaint asserts infringement of at least claims 10 and 11 (Compl. ¶49). Independent claim 10 includes the following essential elements:
- A method in a system with files distributed across multiple computers.
- Obtaining a name for a data file based at least in part on a function of the file's contents.
- Using that name to determine whether a copy of the data file is present on at least one of the computers.
- Determining whether a present copy of the data file is an "unauthorized copy or an unlicensed copy."
U.S. Patent No. 7,802,310 - "Controlling Access to Data in a Data Processing System" (Issued Sep. 21, 2010)
The Invention Explained
- Problem Addressed: The patent addresses the same problems as the ’442 Patent regarding context-dependent file naming and the resulting inefficiencies in distributed data processing systems (U.S. Patent No. 7,802,310, col. 1:44-50).
- The Patented Solution: The invention describes a method for controlling content distribution between computers using a content-dependent name. A first computer receives a request from a second computer that includes a content-dependent name for a piece of data. The first computer then uses this name to determine if the content is "unauthorized or unlicensed" and, based on this determination, either permits or denies the second computer access to the content (’310 Patent, col. 4:25-35; Abstract).
- Technical Importance: This method provides a mechanism for managing access rights and content validity in a distributed network by tying authorization directly to the data's intrinsic content, rather than its location or filename (Compl. ¶17).
Key Claims at a Glance
- The complaint asserts infringement of at least claim 20 (Compl. ¶57). Independent claim 20 includes the following essential elements:
- A computer-implemented method in a system of multiple computers.
- Controlling content distribution from a first computer to another in response to a request from a second device.
- The request includes a "content-dependent name" of a data item, where the name is based on a hash or message digest function of the data's content.
- Based on the content-dependent name, the first device permits access if the content is not determined to be unauthorized or unlicensed, and otherwise does not permit access.
U.S. Patent No. 8,099,420 - "Accessing Data in a Data Processing System" (Issued Jan. 17, 2012)
Technology Synopsis
This patent describes a system comprising hardware and software for accessing data using content-dependent identifiers. The system determines one or more digital identifiers for a data item based on a function of its content and then selectively permits the data item to be accessed based on whether its identifier corresponds to an entry in one or more databases, thereby preventing unauthorized access (Compl. ¶67-68; ’420 Patent, Abstract).
Asserted Claims
Independent claim 166 and dependent claims 25, 26, 27, 29, 30, 32, and 34-36 are asserted (Compl. ¶64).
Accused Features
The complaint accuses Defendant's system of using content-based ETags and associated URIs, stored in databases on web servers, to control access to webpage asset files in response to conditional GET requests from downstream caches (Compl. ¶65-69).
III. The Accused Instrumentality
Product Identification
The accused instrumentality is the "popsugar.com" website and its associated system and method for distributing webpage content (Compl. ¶29).
Functionality and Market Context
- The system delivers webpages, which consist of base files (e.g., HTML) and asset files (e.g., images, scripts), to end-user browsers and intermediate cache servers (Compl. ¶34). It utilizes the standard HTTP protocol to manage content requests and responses (Compl. ¶31).
- A core technical feature is the use of "ETag" values associated with asset files. The complaint alleges these ETags are content-based identifiers ("CBI ETag") generated by applying a hash function to the "sequence of bits" comprising the file's content (Compl. ¶35).
- The system uses these ETags to manage caching. When a browser or intermediate cache requests a file it already has stored, it sends a conditional GET request including the file's ETag in an "If-None-Match" header (Compl. ¶31, ¶41).
- An upstream server compares the received ETag with its own ETag for the requested file. A match results in an HTTP 304 (Not Modified) response, authorizing the use of the cached copy. A mismatch results in an HTTP 200 response with the new file and a new ETag, invalidating the old copy (Compl. ¶43-44). The complaint alleges this system reduces bandwidth and ensures that only "authorized webpage content" is served (Compl. ¶33, ¶46).
- The complaint states that Defendant uses Amazon's S3 system to store and serve some assets, and that the S3 system generates content-based ETags on Defendant's behalf (Compl. ¶36).
- No probative visual evidence provided in complaint.
IV. Analysis of Infringement Allegations
U.S. Patent No. 6,928,442 Infringement Allegations
| Claim Element (from Independent Claim 10) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| obtaining a name for a data file, the name being based at least in part on a given function of the data... | Defendant's system generates or obtains ETags for its asset files by applying a hash function to the contents of the files. | ¶51 | col. 13:15-21 |
| determining, using at least the name, whether a copy of the data file is present on at least one of said computers. | An origin or intermediate cache server receives a conditional GET request with an ETag and determines if it has a file present for the corresponding URI with a matching ETag. | ¶52 | col. 7:40-44 |
| determining whether a copy of the data file that is present... is an unauthorized copy or an unlicensed copy of the data file. | If the received ETag matches the server's ETag, the cached copy is determined to be authorized; if it does not match, the cached copy is determined to be unauthorized (i.e., stale and outdated). | ¶53 | col. 40:45-56 |
U.S. Patent No. 7,802,310 Infringement Allegations
| Claim Element (from Independent Claim 20) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| controlling distribution of content from a first computer to at least one other computer, in response to a request...the request including at least a content-dependent name of a particular data item... | An upstream server (first computer) receives a conditional GET request from a downstream browser or cache (second computer), which includes a content-dependent ETag. | ¶59 | col. 20:39-49 |
| based at least in part on said content-dependent name...the first device (A) permitting the content to be provided to or accessed...if it is not determined that the content is unauthorized or unlicensed, otherwise, (B)...not permitting... | The upstream server compares the received ETag with its stored ETag. If they match, it permits access to the cached content by sending an HTTP 304 response. If they do not match, it does not permit use of the old content. | ¶60 | col. 20:50-62 |
Identified Points of Contention
- Scope Questions: A central dispute may concern whether an HTTP "ETag," a value used for cache validation within a specific protocol, constitutes a "name for a data file" as that term is used in the patents, which describe a more general, system-wide file identification architecture.
- Technical Questions: The infringement theory hinges on equating a stale or outdated cached file (identified by an ETag mismatch) with an "unauthorized or unlicensed copy" as required by the claims. The case may turn on whether the function of cache coherency (ensuring the latest version is used) is legally and technically equivalent to the function of policing licensed content and access rights as described in the patent specifications.
V. Key Claim Terms for Construction
The Term: "name for a data file" / "content-dependent name"
- Context and Importance: The definition of this term is critical, as infringement depends on whether an HTTP ETag falls within its scope. Practitioners may focus on this term because the patent describes a comprehensive "True Name" system, whereas the accused instrumentality uses ETags within the narrower context of the HTTP protocol.
- Intrinsic Evidence for a Broader Interpretation: The patent specification states that a "True Name" is a "substantially unique data identifier" generated from a "function, MD, which reduces a data block B of arbitrary length to a relatively small, fixed size identifier" (’442 Patent, col. 10:58-63). This broad, functional definition could be argued to read on any content-based hash, including an ETag.
- Intrinsic Evidence for a Narrower Interpretation: The specification describes the invention as a file system that augments or replaces traditional operating system file management, where the "True Name" is used to reference data items independent of "name, origin, location, address, or other information" (’442 Patent, col. 3:32-36). This could support an interpretation that the "name" must be part of a complete, location-agnostic file management system, not just a header value for cache validation like an ETag.
The Term: "unauthorized copy or an unlicensed copy"
- Context and Importance: This term is the lynchpin of the "policing" and "controlling access" limitations. The dispute will likely focus on whether an ETag mismatch, which indicates that a cached file is out-of-date, renders that file "unauthorized."
- Intrinsic Evidence for a Broader Interpretation: The complaint alleges that when content changes, the previously cached version is "no longer the correct and authorized content" (Compl. ¶27). This suggests that "authorized" can mean "the currently valid version as specified by the content owner."
- Intrinsic Evidence for a Narrower Interpretation: The patent's title and abstract frame the invention in terms of "Enforcement and Policing of Licensed Content" and ensuring a "copy of a requested file is only provided to licensed (or authorized) parties" (’442 Patent, Abstract). The specification also discusses tracking files for "licensing purposes" (col. 8:52-56), suggesting "unauthorized" or "unlicensed" refers to a violation of usage rights, not merely using a technically stale version of a file.
VI. Other Allegations
- Indirect Infringement: The complaint does not explicitly plead counts for induced or contributory infringement. It alleges direct infringement by Defendant for "controlling the distribution of its webpage content" (Compl. ¶49, ¶57) and for "causing" various servers in the system to perform the claimed steps (Compl. ¶51, ¶52). The complaint does not provide sufficient detail for analysis of the specific knowledge and intent elements required for indirect infringement.
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of definitional scope: can the term "unauthorized or unlicensed copy," which is described in the patent specification primarily in the context of enforcing content licenses and usage rights, be construed to cover a technically stale web asset in a browser's cache?
- A key technical question will be one of functional purpose: does the accused system's use of HTTP ETags for cache-coherency management perform the same function as the patented method of using a content-based "True Name" to police and control access to licensed content, or is there a fundamental mismatch between the technical purpose of a caching mechanism and that of a content authorization system?