US 10701173

US patent 10701173, titled "Caching in a content delivery framework," was issued on June 30, 2020. The application for this patent, US15/588,935, was filed on May 8, 2017. The inventors are Christopher Newton and William Crowder. While Level 3 Communications LLC was the original assignee, the current assignee is Sandpiper Cdn LLC as of a 2024-07-09 assignment.

Abstract:
The patent describes a computer-implemented method for caching within a content delivery network (CDN) that utilizes "late binding" of caching policies. When a caching node in the CDN receives a request for content, it first determines if that content is already cached locally. If it is, the node then determines the current cache policy associated with the content. Based on this policy, the node decides whether the locally cached version is acceptable to serve. If it's not acceptable, a new version of the content is obtained and served. Otherwise, if the locally cached version is acceptable, it is served. [cite: US10701173B2]

Plain-language overview of Independent Claims:

• Independent Claim 1 (Computer-Implemented Method):
  This claim describes a method for a node within a Content Delivery Network (CDN) to handle content requests.

  1. When a request for content is received, the node checks if it has a local copy of that content.
  2. If the content is cached locally, the node then determines the most up-to-date caching policy for that content, specifically identifying how long the content should be considered valid in the cache.
  3. Using this current cache policy, the node decides if it's okay to deliver the locally cached content.
  4. If the locally cached content is not acceptable based on the current policy (e.g., it's stale), the node gets and serves a new version of the content.
  5. If the locally cached content is acceptable, the node serves that local version. [cite: US10701173B2]

• Independent Claim 8 (Computer Program Product):
  This claim covers a computer program product, essentially software instructions stored on a non-transitory computer-readable medium. These instructions, when run on a device with hardware (like memory and a processor) within a CDN, implement the exact same method described in Claim 1. That is:

  1. In response to a content request, a CDN node determines if the content is locally cached.
  2. If locally cached, the node determines the current cache policy, including the content's expiration time.
  3. Based on this policy, the node decides if the locally cached content can be served.
  4. If not acceptable, a new version is obtained and served.
  5. If acceptable, the locally cached version is served. [cite: US10701173B2]

Litigation Status:
The patent family is involved in litigation. A PTAB case, IPR2026-00180, has been filed and is currently pending. Additionally, a US case has been filed in the Texas Eastern District Court (case 2:25-cv-00664). [cite: US10701173B2]

As of April 26, 2026, there is known litigation involving US patent 10701173.

Here are the details of the known litigation:

• Case Number: IPR2026-00180

• Plaintiff(s): Petitioner (details not explicitly stated but Unified Patents typically files these petitions)

• Defendant(s): Sandpiper Cdn LLC (current assignee of US10701173)

• Jurisdiction: Patent Trial and Appeal Board (PTAB)

• Filing Date: Not explicitly stated, but the case is listed as "Pending". Given the case number IPR2026-00180, it was likely filed in late 2025 or early 2026.

• Outcome/Current Status: Pending.

• Case Number: 2:25-cv-00664

• Plaintiff(s): Not explicitly stated

• Defendant(s): Not explicitly stated

• Jurisdiction: Texas Eastern District Court

• Filing Date: Not explicitly stated. Given the case number, it was likely filed in 2025.

• Outcome/Current Status: The case has been filed.

Proceedings overview

There is one AIA trial proceeding on file for US patent 10701173: IPR2026-00180. This proceeding is currently Pending, with no final decision on the patentability of claims. This early stage means the patent's claims remain untested by the PTAB for now.

IPR2026-00180 — Microsoft Corporation v. Sandpiper CDN LLC

• Type: Inter Partes Review
• Filed: 2025-12-24
• Status: Pending. This IPR is in the initial stages, awaiting an institution decision from the USPTO Director.
• Judge panel: The judge panel for the trial phase would only be assigned if the IPR is instituted. Institution decisions are now made solely by the USPTO Director.
• Petition grounds: Microsoft Corporation, the petitioner, challenged all 14 claims of US10701173B2 (claims 1-14) on grounds of obviousness under 35 U.S.C. § 103.
  • Ground 1: Claims 1 and 8 are obvious over O'Rourke (U.S. Pat. No. 7,912,921). Petitioner argued that O'Rourke teaches a cache server in a CDN that uses flexible, user-determined cache policies, including a process of checking if content is local and then using policies to determine if the cached version is acceptable. The ability to add/remove "policy plug-ins" was asserted to teach the "late-binding" concept of determining a "current cache policy" upon request.
  • Ground 1A: Claims 2 and 9 are obvious over O'Rourke and Blumofe.
  • Ground 1B: Claims 4-6 and 11-13 are obvious over O'Rourke and MS-MSSO (Media Streaming Server System Overview, Microsoft Corporation, 2009).
  • Ground 1C: Claims 7 and 14 are obvious over O'Rourke and Blumofe. This ground targeted claims 7 and 14, which require the cache policy to relate to caching content both within the CDN and outside the CDN. Blumofe was cited for teaching a "CDN Extender" operating outside the CDN but controlled by the main CDN.
  • Ground 2: Claims 3 and 10 are obvious over O'Rourke and MS-MSSO. This ground addressed claims 3 and 10, which specify that the content request is an HTTP request and the content comprises one or more resources.
  • Ground 2A: Claims 1-2, 4-6, 8-9, and 11-13 are obvious over Middleton (U.S. Pat. No. 6,185,598) alone. Middleton was cited for teaching an extensible CDN platform where an edge server uses cache policies like Time-To-Live (TTL) values.
  • Ground 2B: Claims 3 and 10 are obvious over Middleton and MS-MSSO.
  • Ground 2C: Claims 7 and 14 are obvious over Middleton and Blumofe.
  • Prior Art Relied Upon: O'Rourke (U.S. Pat. No. 7,912,921), MS-MSSO (Media Streaming Server System Overview, Microsoft Corporation, 2009), Middleton (U.S. Pat. No. 6,185,598), and Blumofe (U.S. Published Patent Application No. 2004/0073663).
• Institution decision: Not yet issued. The institution decision is due approximately 6 months from the filing date (December 24, 2025), which would be around June 24, 2026. As of October 20, 2025, the USPTO Director is solely responsible for deciding whether to institute IPR trials. Recent policy changes also require the Director to consider factors such as U.S. manufacturing activity when making institution decisions.
• Final Written Decision (if issued): Not applicable, as the IPR is still pending an institution decision.
• Settlement / termination: Not applicable, as the IPR is still pending an institution decision.
• Appeal: Not applicable.
• Defensive value: This proceeding indicates that Microsoft Corporation believes all 14 claims of US10701173B2 are vulnerable to obviousness challenges based on the cited prior art. If the IPR is instituted and claims are invalidated, it would significantly weaken the patent. However, as it is still pending institution, the claims currently remain intact.

Strategic summary

US patent 10701173 currently has all 14 of its claims (claims 1-14) untested by any PTAB Final Written Decision. The sole IPR proceeding, IPR2026-00180, filed by Microsoft Corporation, challenges all of these claims based on various obviousness grounds, primarily citing O'Rourke, MS-MSSO, Middleton, and Blumofe. This IPR is still in its early stages, awaiting a decision on whether to institute a trial.

The estoppel landscape has not yet been formed by this proceeding. If IPR2026-00180 is instituted and proceeds to a Final Written Decision, 35 U.S.C. § 315(e)(2) would bar Microsoft (and its privies) from asserting in future district court litigation or other USPTO proceedings any ground of invalidity that it raised or reasonably could have raised during the IPR. Until then, all prior-art grounds remain available to other potential challengers. Given the recent policy shifts at the USPTO, where the Director now solely decides on institution and may consider factors like U.S. manufacturing footprint, the outcome of the institution decision for IPR2026-00180 is subject to these new discretionary considerations.

There isn't a clear pattern signal yet from this single, pending IPR. However, the petitioner being Microsoft Corporation suggests a significant defendant is actively challenging the patent. There is also a related district court case, Sandpiper CDN, LLC v. Microsoft Corporation (2:25-cv-00664) in the Eastern District of Texas, filed on 2025-06-26, alleging infringement of this and other patents. This IPR is likely a defensive maneuver in response to that litigation.

Recommended next steps

• Monitor the status of IPR2026-00180 closely. The institution decision is expected around June 24, 2026. A favorable decision for Microsoft would indicate that the PTAB Director believes there is a reasonable likelihood that at least one of the challenged claims is unpatentable, opening the door for trial. A denial of institution would strengthen the patent owner's position against future IPR challenges by Microsoft on these grounds.
• Review the IPR petition and any Patent Owner Preliminary Response (if filed) for IPR2026-00180 on the USPTO PTAB E2E portal (searchable via https://www.uspto.gov/patents/ptab) to understand Microsoft's full invalidity arguments and Sandpiper CDN LLC's responses.
• Given the concurrent district court litigation (2:25-cv-00664 in E.D. Texas), understanding the interplay between the IPR and the court proceedings is crucial, especially regarding potential stays of litigation if the IPR is instituted.## Proceedings overview

There is one AIA trial proceeding on file for US patent 107011173: IPR2026-00180. This proceeding is currently Pending, with no final decision on the patentability of claims, meaning the patent's claims remain untested by the PTAB for now.

IPR2026-00180 — Microsoft Corporation v. Sandpiper CDN LLC

• Type: Inter Partes Review
• Filed: 2025-12-24
• Status: Pending. This IPR is in the initial stages, awaiting an institution decision from the USPTO Director.
• Judge panel: The judge panel for the trial phase would only be assigned if the IPR is instituted. Institution decisions are now made solely by the USPTO Director.
• Petition grounds: Microsoft Corporation, the petitioner, challenged all 14 claims of US10701173B2 (claims 1-14) on grounds of obviousness under 35 U.S.C. § 103.
  • Ground 1: Claims 1 and 8 are obvious over O'Rourke (U.S. Pat. No. 7,912,921). Petitioner argued that O'Rourke teaches a cache server in a CDN that uses flexible, user-determined cache policies, including a process of checking if content is local and then using policies to determine if the cached version is acceptable. The ability to add/remove "policy plug-ins" was asserted to teach the "late-binding" concept of determining a "current cache policy" upon request.
  • Ground 1A: Claims 2 and 9 are obvious over O'Rourke and Blumofe (U.S. Published Patent Application No. 2004/0073663).
  • Ground 1B: Claims 4-6 and 11-13 are obvious over O'Rourke and MS-MSSO (Media Streaming Server System Overview, Microsoft Corporation, 2009).
  • Ground 1C: Claims 7 and 14 are obvious over O'Rourke and Blumofe. This ground targeted claims 7 and 14, which require the cache policy to relate to caching content both within the CDN and outside the CDN. Blumofe was cited for teaching a "CDN Extender" operating outside the CDN but controlled by the main CDN.
  • Ground 2: Claims 3 and 10 are obvious over O'Rourke and MS-MSSO. This ground addressed claims 3 and 10, which specify that the content request is an HTTP request and the content comprises one or more resources.
  • Ground 2A: Claims 1-2, 4-6, 8-9, and 11-13 are obvious over Middleton (U.S. Pat. No. 6,185,598) alone. Middleton was cited for teaching an extensible CDN platform where an edge server uses cache policies like Time-To-Live (TTL) values.
  • Ground 2B: Claims 3 and 10 are obvious over Middleton and MS-MSSO.
  • Ground 2C: Claims 7 and 14 are obvious over Middleton and Blumofe.
  • Prior Art Relied Upon: O'Rourke (U.S. Pat. No. 7,912,921), MS-MSSO (Media Streaming Server System Overview, Microsoft Corporation, 2009), Middleton (U.S. Pat. No. 6,185,598), and Blumofe (U.S. Published Patent Application No. 2004/0073663).
• Institution decision: Not yet issued. The institution decision is due approximately 6 months from the filing date (December 24, 2025), which would be around June 24, 2026. As of October 20, 2025, the USPTO Director is solely responsible for deciding whether to institute IPR trials. Recent policy changes also require the Director to consider factors such as U.S. manufacturing activity when making institution decisions.
• Final Written Decision (if issued): Not applicable, as the IPR is still pending an institution decision.
• Settlement / termination: Not applicable, as the IPR is still pending an institution decision.
• Appeal: Not applicable.
• Defensive value: This proceeding indicates that Microsoft Corporation believes all 14 claims of US10701173B2 are vulnerable to obviousness challenges based on the cited prior art. If the IPR is instituted and claims are invalidated, it would significantly weaken the patent. However, as it is still pending institution, the claims currently remain intact.

Strategic summary

US patent 10701173 currently has all 14 of its claims (claims 1-14) untested by any PTAB Final Written Decision. The sole IPR proceeding, IPR2026-00180, filed by Microsoft Corporation, challenges all of these claims based on various obviousness grounds, primarily citing O'Rourke, MS-MSSO, Middleton, and Blumofe. This IPR is still in its early stages, awaiting a decision on whether to institute a trial.

The estoppel landscape has not yet been formed by this proceeding. If IPR2026-00180 is instituted and proceeds to a Final Written Decision, 35 U.S.C. § 315(e)(2) would bar Microsoft (and its privies) from asserting in future district court litigation or other USPTO proceedings any ground of invalidity that it raised or reasonably could have raised during the IPR. Until then, all prior-art grounds remain available to other potential challengers. Given the recent policy shifts at the USPTO, where the Director now solely decides on institution and may consider factors like U.S. manufacturing footprint, the outcome of the institution decision for IPR2026-00180 is subject to these new discretionary considerations.

There isn't a clear pattern signal yet from this single, pending IPR. However, the petitioner being Microsoft Corporation suggests a significant defendant is actively challenging the patent. There is also a related district court case, Sandpiper CDN, LLC v. Microsoft Corporation (2:25-cv-00664) in the Eastern District of Texas, filed on 2025-06-26, alleging infringement of this and other patents. This IPR is likely a defensive maneuver in response to that litigation.

Recommended next steps

• Monitor the status of IPR2026-00180 closely. The institution decision is expected around June 24, 2026. A favorable decision for Microsoft would indicate that the PTAB Director believes there is a reasonable likelihood that at least one of the challenged claims is unpatentable, opening the door for trial. A denial of institution would strengthen the patent owner's position against future IPR challenges by Microsoft on these grounds.
• Review the IPR petition and any Patent Owner Preliminary Response (if filed) for IPR2026-00180 on the USPTO PTAB E2E portal (searchable via https://www.uspto.gov/patents/ptab) to understand Microsoft's full invalidity arguments and Sandpiper CDN LLC's responses.
• Given the concurrent district court litigation (2:25-cv-00664 in E.D. Texas), understanding the interplay between the IPR and the court proceedings is crucial, especially regarding potential stays of litigation if the IPR is instituted.

Inventors

Christopher Newton and William Crowder were the named inventors. They were employed by Level 3 Communications LLC at the time of filing.

Original assignee

The original assignee on the issued patent is Level 3 Communications LLC. Level 3 Communications LLC was an American multinational telecommunications and internet service provider. They operated a Tier 1 network and provided core transport, IP, voice, video, and content delivery services for large internet carriers and businesses. They offered a range of products including internet, security services, VoIP, Ethernet services, optical transport networks, and cloud connect solutions.

Level 3 Communications LLC was acquired by CenturyLink (now Lumen Technologies) on November 1, 2017. Prior to this, Level 3 Communications Inc. had acquired several companies and their assets, including Sandpiper Networks' CDN business in January 2007. Level 3 Communications LLC is now a subsidiary of Lumen Technologies, Inc., and continues to provide telecommunications and network services, including to the U.S. federal government.

Assignment timeline

• 2017-05-17 (executed) / recorded 2017-05-17 — Reel 042415/0361
  • Conveyance: Assignment
  • Assignor: NEWTON, CHRISTOPHER
  • Assignee: LEVEL 3 COMMUNICATIONS, LLC, COLORADO
  • Correspondent: NOT RECORDED
  • Context: Internal transfer from inventor to employer
• 2017-05-17 (executed) / recorded 2017-05-17 — Reel 042415/0404
  • Conveyance: Assignment
  • Assignor: CROWDER, WILLIAM
  • Assignee: LEVEL 3 COMMUNICATIONS, LLC, COLORADO
  • Correspondent: NOT RECORDED
  • Context: Internal transfer from inventor to employer
• 2024-05-31 (executed) / recorded 2024-07-09 — Reel 068256/0091
  • Conveyance: Assignment
  • Assignor: LEVEL 3 COMMUNICATIONS, LLC
  • Assignee: SANDPIPER CDN, LLC, DELAWARE
  • Correspondent: Andrew D. Skale, Paradigm Counsel, LLP, 1680 Civic Center Dr. Ste. 100, Santa Clara, CA 95050. This correspondent also appears as counsel for other Sandpiper CDN entities in litigation records.
  • Context: Divestiture of CDN patent portfolio

Timeline diagram

timeline
    title Ownership of US 10701173
    2017 : Inventors to Level 3 Communications
    2020 : Patent issued
    2024 : Assigned to Sandpiper CDN LLC

NPE / troll-pattern signals

1. Shell-entity transfer — present. On 2024-05-31 (recorded 2024-07-09), Level 3 Communications LLC assigned the patent to Sandpiper CDN, LLC. Sandpiper CDN, LLC is a Delaware plaintiff that has launched litigation against major tech companies. Their website states they manage an extensive patent portfolio related to CDN technology and software. Their privacy policy notes that they collect general location information to identify where their audience views their site from, and that they may share information with data processors and partners, including Google Cloud Platform for secure cloud hosting, suggesting a focus on leveraging their IP for business operations rather than solely product development. Sandpiper CDN, LLC has also disclosed Theseus LF Asset Holdings, LLC as its parent corporation, which was formed in Delaware in August 2023. This structure indicates a licensing-focused entity.
2. Known asserter in the chain — present. Sandpiper CDN, LLC is a recently formed Delaware plaintiff that has initiated patent litigation against companies like Alphabet (Google) and Microsoft, asserting patents generally related to content delivery networks. This activity aligns with the behavior of a patent assertion entity (PAE) or NPE. RPX Insight has identified Sandpiper CDN, LLC as an entity that has launched litigation with patents received from Level 3 Communications.
3. Repeat correspondent across the chain — present. Andrew D. Skale of Paradigm Counsel, LLP is listed as the correspondent for the 2024-07-09 assignment to Sandpiper CDN, LLC (Reel 068256/0091). Publicly available information from RPX shows Andrew D. Skale as counsel for Sandpiper CDN, LLC in patent litigation campaigns.
4. Cascading transfers — not present. There is one main assignment from Level 3 Communications to Sandpiper CDN, LLC.
5. Pre-litigation transfer — unclear. The patent was assigned to Sandpiper CDN, LLC on 2024-05-31, and litigation by Sandpiper CDN, LLC was reported in May 2024 against Google and June 2025 against Microsoft. While the assignment date is close to reported litigation, the exact filing date of the first suit specifically naming this patent is not precisely six months before the assignment date based on the information available.
6. Bankruptcy fire-sale — not present. Level 3 Communications was acquired by CenturyLink (now Lumen Technologies) in 2017, not dissolved or in bankruptcy.
7. Privateering — unclear. While Level 3 Communications (which became part of Lumen Technologies) divested its CDN business and related patents to Sandpiper CDN, LLC, there is no explicit information to definitively state that Level 3 or Lumen Technologies is sponsoring Sandpiper CDN's assertion activities against competitors. However, RPX notes that this transfer is not Level 3's first to an NPE.
8. Defensive aggregator (anti-NPE) — not present. The chain terminates with Sandpiper CDN, LLC, which is identified as a patent assertion entity.

Verdict

NPE — high confidence

The transfer from Level 3 Communications LLC to Sandpiper CDN, LLC, a recently formed Delaware LLC specializing in managing an extensive patent portfolio and initiating litigation against major tech companies, strongly indicates an NPE. This is further supported by the identification of Sandpiper CDN, LLC as a plaintiff by RPX and the recurrence of the correspondent attorney, Andrew D. Skale, known for NPE representation. The fact that Level 3 Communications decided to exit the CDN market and sell off its CDN assets, including these patents, to an entity that then immediately began asserting them, points to a strategic transfer to enable assertion.

USPTO Assignment Center search page: https://assignmentcenter.uspto.gov/

To identify the most relevant prior art for US Patent 10701173 and assess potential anticipation under 35 U.S.C. § 102, I have analyzed the "Citations" section of the patent document, focusing on references marked as "* Cited by examiner" that are not part of the patent's own family (i.e., not a parent application or continuation).

The core inventive concept of US10701173, as described in its claims (Claims 1-14), revolves around a computer-implemented method and computer program product for caching in a content delivery network (CDN) that utilizes "late binding of caching policies." Specifically, upon receiving a request for content at a CDN node, the node first determines if the content is locally cached. If it is, the node then determines a current cache policy (including an expiration time) for that content from a potentially distinct source (e.g., a database). Based on this current policy, the node decides whether to serve the locally cached version or obtain and serve a new version. This contrasts with applying a policy at the time content is initially cached ("fill time").

Here are the most relevant prior art patents cited by the examiner, along with their details and a brief analysis of potential anticipation:

Identified Prior Art References:

1. US20030188009A1

   • Full Citation: US20030188009A1, "Method and system for caching fragments while avoiding parsing of pages that do not contain fragments"
   • Publication/Filing Date: Publication: 2003-10-02; Filing: 2001-12-19
   • Brief Description: This patent application describes a system and method for caching fragments of web pages. It focuses on efficiently caching fragments by identifying pages that contain fragments and then storing/retrieving those fragments separately. This approach aims to avoid parsing entire pages that do not contain fragments, thereby improving performance. The caching strategy is primarily focused on the granular management of page components (fragments) rather than the dynamic determination of a current global content caching policy at request time.
   • Potential Anticipation (35 U.S.C. § 102): Less likely to directly anticipate the "late binding" of a current cache policy based on an external rulebase at request time for an entire content item's expiration. While it discusses caching and policy (e.g., for fragments), it doesn't clearly teach the dynamic determination of a current overall content expiration policy from a separate source after content is locally cached, and using that current policy to decide serving. However, elements of "determining if content is cached locally" (Claim 1(A), 8(A)) and "serving the content" (Claim 1(B)(3)(ii), 8(B)(3)(ii)) are fundamental to caching systems.

2. US20080065273A1

   • Full Citation: US20080065273A1, "Method and device for adaptive control"
   • Publication/Filing Date: Publication: 2008-03-13; Filing: 2006-08-28
   • Brief Description: This patent application describes methods and devices for adaptive control, particularly in networked systems. The abstract suggests dynamic adjustment of system behavior based on various parameters. While "adaptive control" might involve policy adjustments, the application's focus appears to be broad and not specifically on the "late binding" of content caching expiration policies in a CDN context as described in US10701173.
   • Potential Anticipation (35 U.S.C. § 102): Unlikely to anticipate the specific method of US10701173. Its broad "adaptive control" doesn't directly disclose determining a current cache policy (specifically an expiration time for locally cached content) from a distinct source at request time to decide whether to serve or refresh.

3. US7987239B2

   • Full Citation: US7987239B2, "Method and system for caching role-specific fragments"
   • Publication/Filing Date: Publication: 2011-07-26; Filing: 2001-12-19
   • Brief Description: This patent describes caching fragments of web pages based on user roles. Different versions of a fragment might be cached depending on the authenticated user's role. This involves managing multiple cached versions and applying policies based on user attributes. Like US20030188009A1, it deals with fragment caching and policy, but the policy is tied to user roles for varying content versions rather than a dynamic global expiration policy for a single content item determined at request time from an external source.
   • Potential Anticipation (35 U.S.C. § 102): Similar to US20030188009A1, this patent details specific caching strategies but doesn't explicitly describe the "late binding" of an up-to-date expiration policy from a distinct source to validate locally cached content at the time of request, which is central to US10701173.

4. US8032586B2

   • Full Citation: US8032586B2, "Method and system for caching message fragments using an expansion attribute in a fragment link tag"
   • Publication/Filing Date: Publication: 2011-10-04; Filing: 2001-12-19
   • Brief Description: This patent focuses on caching fragments of messages or web pages, using an expansion attribute to determine how fragments are linked and cached. It's another example of granular caching for web page components. The mechanisms described are related to fragment assembly and caching, not the dynamic evaluation of a content's expiration policy from an external source at the moment a request for that content is received.
   • Potential Anticipation (35 U.S.C. § 102): The claims of US10701173 are directed to the determination of a current cache policy (including expiration) at request time to decide serving locally cached content. US8032586B2, while describing caching, does not appear to teach this specific "late binding" mechanism for content expiration.

5. US20140129779A1

   • Full Citation: US20140129779A1, "Cache replacement policy for data with strong temporal locality"
   • Publication/Filing Date: Publication: 2014-05-08; Filing: 2012-11-06
   • Brief Description: This application discusses cache replacement policies, specifically for data exhibiting strong temporal locality (i.e., data that is likely to be requested again soon after its last access). It describes methods for determining which items to retain or evict from a cache based on predicted future access. While it deals with "cache policy," its focus is on replacement rather than the expiration or freshness of an item based on a dynamically retrieved current policy at request time.
   • Potential Anticipation (35 U.S.C. § 102): This patent application is relevant to general caching policies but does not appear to anticipate the specific steps of US10701173, particularly "determining a current cache policy associated with the content, wherein determining the current cache policy comprises determining a time period for expiration of content in the cache" (Claim 1(B)(1), 8(B)(1)) and using this current policy to validate the freshness of an already cached item at request time.

6. US20140215802A1

   • Full Citation: US20140215802A1, "Three piece floor mat retention system"
   • Publication/Filing Date: Publication: 2014-08-07; Filing: 2008-11-14
   • Brief Description: This patent application describes a system for retaining a floor mat, particularly a three-piece floor mat, within a vehicle. This is clearly unrelated to content delivery networks or caching.
   • Potential Anticipation (35 U.S.C. § 102): This patent does not anticipate any claims of US10701173 as it pertains to an entirely different field of invention. This appears to be an erroneous citation by the examiner, or it was cited for a very tangential, non-substantive reason.

7. US8812695B2

   • Full Citation: US8812695B2, "Method and system for management of a virtual network connection without heartbeat messages"
   • Publication/Filing Date: Publication: 2014-08-19; Filing: 2012-04-09
   • Brief Description: This patent describes managing virtual network connections more efficiently by avoiding periodic heartbeat messages. It focuses on network communication protocols and efficiency, not content caching policies or their dynamic application in a CDN.
   • Potential Anticipation (35 U.S.C. § 102): This patent does not appear to anticipate any claims of US10701173, as its subject matter is distinct.

8. US20140245359A1

   • Full Citation: US20140245359A1, "Content Delivery Network Interconnection (CDNI) Mechanism"
   • Publication/Filing Date: Publication: 2014-08-28; Filing: 2011-06-01
   • Brief Description: This application relates to mechanisms for interconnecting different CDNs (CDNI). It describes how content requests and content delivery might traverse multiple CDN boundaries. While it is in the CDN domain, its focus is on inter-CDN communication and routing, not the internal caching policy determination logic within a single CDN node, especially not the "late binding" expiration policy.
   • Potential Anticipation (35 U.S.C. § 102): This reference is relevant to CDNs but does not appear to teach the specific elements of US10701173 regarding dynamically retrieving and applying a current cache expiration policy at request time to a locally cached item.

9. US20140365683A1

   • Full Citation: US20140365683A1, "Domain name system bypass in user applications"
   • Publication/Filing Date: Publication: 2014-12-11; Filing: 2013-06-07
   • Brief Description: This application describes techniques for user applications to bypass the standard Domain Name System (DNS) resolution process to improve content access, potentially by directly connecting to known content servers. This relates to content access mechanisms but not to the internal caching policy logic of a CDN node.
   • Potential Anticipation (35 U.S.C. § 102): Unlikely to anticipate the core claims of US10701173. The focus on DNS bypass is distinct from determining and applying a current cache expiration policy at request time.

10. US8984166B2

    • Full Citation: US8984166B2, "Method and apparatus for reducing network resource transmission size using delta compression"
    • Publication/Filing Date: Publication: 2015-03-17; Filing: 2012-04-05
    • Brief Description: This patent describes methods and apparatus for reducing the size of network resources transmitted over a network using delta compression techniques. While it aims to improve network efficiency, it's focused on data compression, not the management or "late binding" of content caching expiration policies within a CDN.
    • Potential Anticipation (35 U.S.C. § 102): This patent is unrelated to the core aspects of US10701173.

11. US20150333930A1

    • Full Citation: US20150333930A1, "Dynamic service function chaining"
    • Publication/Filing Date: Publication: 2015-11-19; Filing: 2014-05-15
    • Brief Description: This application describes dynamic service function chaining, where network services (like firewalls, load balancers, etc.) are chained together dynamically based on traffic flows or policy. This is about orchestrating network functions, which is different from managing content caching expiration policies.
    • Potential Anticipation (35 U.S.C. § 102): While "dynamic" and "policy" are keywords, this patent is about chaining services and not specifically about the late binding of content caching expiration policies for locally stored content in a CDN.

12. US20150347248A1

    • Full Citation: US20150347248A1, "Communication continuation during content node failover"
    • Publication/Filing Date: Publication: 2015-12-03; Filing: 2014-05-30
    • Brief Description: This application describes mechanisms to ensure continuous communication when a content node in a CDN fails over to another node. It focuses on fault tolerance and session continuity, rather than the determination of content caching policies.
    • Potential Anticipation (35 U.S.C. § 102): This patent is related to CDN operations but does not teach the specific "late binding" of caching expiration policies at request time as defined in US10701173.

13. US20180129613A1

    • Full Citation: US20180129613A1, "Cache memory architecture and policies for accelerating graph algorithms"
    • Publication/Filing Date: Publication: 2018-05-10; Filing: 2016-11-10
    • Brief Description: This application describes cache memory architectures and policies specifically designed to accelerate graph algorithms. The caching policies are tailored for the unique access patterns of graph processing, which is a different domain than general content delivery or web caching.
    • Potential Anticipation (35 U.S.C. § 102): Although it discusses "cache memory architecture and policies," the context is highly specialized for graph algorithms, making it unlikely to directly anticipate the generic CDN caching method of US10701173. The focus on algorithm acceleration differs significantly from managing content expiration for web resources.

14. US10417134B2

    • Full Citation: US10417134B2, "Cache memory architecture and policies for accelerating graph algorithms"
    • Publication/Filing Date: Publication: 2019-09-17; Filing: 2016-11-10
    • Brief Description: This is a granted patent stemming from the same application as US20180129613A1. Its description and relevance are identical.
    • Potential Anticipation (35 U.S.C. § 102): Same as US20180129613A1, unlikely to anticipate the generic CDN caching method of US10701173.

Summary of Potential Anticipation:

Most of the cited prior art patents describe various caching techniques or CDN-related functionalities. However, the unique aspect of US10701173, as defined in its claims, is the "late binding" of a current cache expiration policy, obtained from a potentially distinct source (like a RuleBase), and dynamically applying this policy at request time to determine whether a locally cached version of content is still acceptable to serve. Many of the prior art references discuss general caching, replacement policies, or fragment-specific caching, but none explicitly teach or fully anticipate all elements of Claim 1, particularly the combination of:

• Determining a current cache policy (specifically for expiration) after content is locally cached.
• Obtaining this policy from a location distinct from the node (e.g., a database).
• Using this current policy to determine if the locally cached version is acceptable to serve.
• Performing this determination at request time to avoid invalidations.

Therefore, while these prior art references demonstrate the existence of caching, policies, and CDN operations, they do not appear to fully anticipate the specific late-binding expiration policy determination claimed in US10701173 under 35 U.S.C. § 102. The most relevant ones (e.g., US20030188009A1, US7987239B2, US20140129779A1) pertain to general caching or fragment caching policies, but not the "late binding" of a dynamically updatable expiration policy from an external source to validate cached content at the point of serving.

Obviousness Analysis of US Patent 10701173 under 35 U.S.C. § 103

This analysis identifies combinations of prior art references that would render the claims of US Patent 10701173 obvious to a person having ordinary skill in the art (POSA). The core innovation of US10701173 resides in the "late binding" of caching policies, where the caching policy is determined at request time rather than at fill time, to ensure the latest policy is applied without forcing invalidations.

Prior Art References

The patent US10701173 itself lists the following as prior art:

• U.S. Published Patent Applications Nos. US 2013-0159472 and US 2013-0159473, both filed Dec. 12, 2012; and No. US 2014-0344399 A1, filed Jun. 17, 2014; and U.S. Pat. No. 6,185,598, filed Feb. 10, 1998.

Combinations and Motivation for Combination

A POSA in content delivery networks would possess knowledge of existing caching mechanisms, content delivery strategies, and methods for managing content policies. The motivation to combine references would stem from a desire to improve efficiency, ensure content freshness, and reduce operational overhead in CDNs.

Combination 1: US 6,185,598 in view of general knowledge of dynamic content and policy management

• US 6,185,598 (Farber et al.): This patent describes a computer network with origin servers and repeaters (caches). It explicitly states that when a repeater gets a client's request, it responds by returning the requested resource. If the repeater has a local copy, it returns that copy; otherwise, it forwards the request to the origin server to get the resource and saves a local copy. This demonstrates a fundamental caching mechanism within a network. The patent also mentions that "static" and "dynamic" are relative terms, and "static resources may change at some regular, albeit long, interval."

• Obviousness Argument: A POSA, aware of the teachings of US 6,185,598 regarding caching and the dynamic nature of content, would be motivated to ensure that cached content remains fresh and adheres to current policies. While US 6,185,598 describes a basic caching process where a repeater serves a local copy if available, it doesn't explicitly detail how caching policies are dynamically applied at request time to account for potential updates.

  The motivation for a POSA to combine this with general knowledge of dynamic policy management would be to address the problem of stale content and inefficient invalidation mechanisms. If a caching policy (e.g., TTL) for a resource changes, simply relying on the initial fill time (as implied by US 6,185,598's description of serving a local copy) could lead to serving outdated content. A POSA would understand the need to re-evaluate the caching validity more frequently or dynamically. Therefore, a POSA would be motivated to introduce a mechanism to check the current caching policy at the time of a request to determine if the locally cached content is still valid. This would inherently lead to the concept of "late binding" of caching policies to avoid serving stale content without immediately resorting to expensive invalidations across the entire CDN.

Combination 2: US 2013-0159472 / US 2013-0159473 / US 2014-0344399 A1 in view of US 6,185,598 and existing CDN architectures.

• US 2013-0159472, US 2013-0159473, US 2014-0344399 A1: While the full text of these applications is not provided in the prompt, US10701173 itself states that "Exemplary CDNs are described in U.S. Published Patent Applications Nos. US 2013-0159472 and US 2013-0159473... and No. US 2014-0344399 A1". This indicates that these documents describe established CDN architectures and services, which would inherently include aspects of content delivery, request handling, and potentially content caching, even if the specifics of dynamic policy application are not detailed.

• Obviousness Argument: Assuming these references disclose conventional CDN operations, including the use of caching nodes and handling of content requests, a POSA would look to optimize their performance and content freshness. Combining the general CDN frameworks described in these applications with the basic caching principles of US 6,185,598 would be a natural step.

  The explicit problem addressed by US10701173 is the challenge of "invalidating cached content... every time a caching policy for that content is set" and instead determining "the caching policy of requested content at request time rather than at fill time." This problem-solution approach, in the context of known CDN architectures (from the 2013 and 2014 applications) and basic caching (from US 6,185,598), suggests an obvious modification. A POSA encountering the inefficiencies of widespread invalidation in a complex CDN would naturally seek a more granular and dynamic way to manage caching. The idea of "late binding" the policy at the time of request is a logical step to achieve this, allowing for immediate reflection of policy changes without the overhead of full invalidations. This would involve storing policies separately (e.g., in a database as described in US10701173) and querying them at request time, which is a common approach for dynamic configurations in distributed systems.

Conclusion

The core inventive step of US10701173—determining the current cache policy at request time (late binding) to avoid frequent invalidations—appears to be an obvious combination of existing caching techniques (as shown in US 6,185,598) and general knowledge of dynamic content management within the context of Content Delivery Networks (as broadly described by the other cited prior art applications). A person having ordinary skill in the art would be motivated to improve the efficiency and content freshness of CDNs by implementing a dynamic policy evaluation mechanism at the point of content delivery, rather than relying solely on static or fill-time policies. The separate storage and retrieval of policies (e.g., from a database/RuleBase as described in US10701173) is a conventional method for managing dynamic configurations in distributed systems and would be readily adopted by a POSA to implement late binding.

To detail the patent term adjustments (PTA), patent term extensions (PTE), continuation applications, divisional applications, related family members, and the projected expiration date for US patent 10701173, I will use information available from the USPTO.

A US utility patent generally expires 20 years from the earliest filing date of the application. However, this term can be adjusted by Patent Term Adjustment (PTA) or Patent Term Extension (PTE).

Patent Term Adjustment (PTA):
PTA is granted to compensate patentees for certain delays caused by the USPTO during the prosecution of a patent application. These delays can include the USPTO failing to:

• Issue a first office action within 14 months of filing.
• Respond to an applicant's reply within four months.
• Issue a patent within four months of payment of the issue fee.
• Issue a patent within three years from the actual filing date (with some exceptions).

The USPTO calculates PTA at the time the patent issues and includes it in the Issue Notification Letter. While the provided patent document for US10701173 does not explicitly state the PTA amount, the Google Patents interface indicates an "Anticipated expiration" date of 2034-12-15. This date suggests that PTA has been applied, as the original priority date is 2014-12-15, which would typically lead to a 2034-12-15 expiration without adjustment. However, given the filing date of 2017-05-08 for US15/588,935 and a publication date of 2020-06-30, delays in prosecution might have occurred. Without the specific PTA calculation from the USPTO file wrapper, the exact amount cannot be determined, but the provided expiration date implies a calculation has been made.

Patent Term Extension (PTE):
PTE is a different mechanism available for patents on certain products (like human drugs, medical devices, food or color additives, and veterinary biological products) to restore patent term lost due to premarket government approval processes. US10701173 relates to "caching in a content delivery framework," which is a software and telecommunications-related invention, not a product requiring regulatory approval from agencies like the FDA. Therefore, it is highly unlikely that US10701173 would be eligible for PTE.

Continuation Applications, Divisional Applications, and Related Family Members:

• Continuation Applications: A continuation application allows an applicant to pursue new claims based on the same specification and drawings as a previously filed "parent" application, sharing the same priority date.
• Divisional Applications: A divisional application is filed when the USPTO determines that an application contains claims to more than one invention. The applicant then "divides" the claims into separate applications.

The patent document for US10701173 explicitly lists its relationship to other applications. It states, "This application is a continuation of and claims the benefit of priority from U.S. patent application Ser. No. 14/570,512, entitled 'CACHING IN A CONTENT DELIVERY FRAMEWORK,' filed Dec. 15, 2014." This identifies US14/570,512 as the parent application. [cite: US10701173B2]

The "Priority Applications" section of US10701173 lists the following applications that claim priority from the original filing date of 2014-12-15:

• US15/588,935 (US10701173B2 itself) [cite: US10701173B2]
• US16/909,245 (US11425223B2) [cite: US10701173B2]
• US17/891,675 (US11818229B2) [cite: US10701173B2]
• US18/388,844 (US20240080373A1) [cite: US10701173B2]

The "Related Parent Applications" section confirms that US14/570,512 (US9648127B2) is a parent application. [cite: US10701173B2]

The "Related Child Applications" section lists US16/909,245 (US11425223B2) as a continuation. [cite: US10701173B2]

The "Family Applications" section, which represents the patent family, includes:

• US14/570,512 (US9648127B2) [cite: US10701173B2]
• US15/588,935 (US10701173B2) [cite: US10701173B2]
• US16/909,245 (US11425223B2) [cite: US10701173B2]
• US17/891,675 (US11818229B2) [cite: US10701173B2]
• US18/388,844 (US20240080373A1) [cite: US10701173B2]
• US19/263,989 (US20260006107A1) [cite: US10701173B2]

These indicate a series of continuation applications originating from the priority date of US14/570,512 (December 15, 2014). No explicit divisional applications are mentioned in the provided patent text, but continuation applications are clearly present.

Projected Expiration Date:
For utility patents filed on or after June 8, 1995, the patent term generally expires 20 years from the earliest filing date of the application, subject to any patent term adjustments or extensions.

The earliest priority date for US10701173 is December 15, 2014, from U.S. patent application Ser. No. 14/570,512. [cite: US10701173B2]
Therefore, the base 20-year patent term would extend to December 15, 2034.

The "Anticipated expiration" listed on the Google Patents page for US10701173B2 is 2034-12-15. [cite: US10701173B2] This date aligns with the 20-year term from the earliest priority date and suggests that any PTA awarded did not extend the term beyond this date, or that any applicant delay negated USPTO delay. Without access to the specific PTA calculation from the USPTO file history for US10701173, it is not possible to confirm the exact PTA amount or factors.