US 8478903

Here's a concise summary of US patent 8478903:

Title: Shared content delivery infrastructure

Assignee:

• Current Assignee: MOUNT SHASTA ACQUISITION LLC, Digital Island Inc, Sandpiper Cdn LLC
• Original Assignee: Level 3 Communications LLC

Inventors: David A. Farber, Richard E. Greer, Andrew D. Swart, James A. Balter

Filing Date: February 23, 2005

Issue Date: July 2, 2013

Abstract:
The patent describes a system where content providers offer resources to clients, with some resources delivered via content sources (origin servers). When a client requests a resource that includes references to other resources, these referenced resources are served from a shared Content Delivery Network (CDN) made up of servers (repeaters) separate from the original content sources. The referenced resources can be various types of digital content, such as video, audio, text, images, web pages, and embedded elements.

Plain-Language Overview of Independent Claims:

• Independent Claim 1 (Method): This claim describes a method for handling requests for digital content in a computer network.

  1. A client asks an original server for a specific piece of content, using an identifier for that content.
  2. A special component, called a reflector, located with the original server, intercepts this request.
  3. The reflector decides whether to send the request directly to the original server or to send it to another server, called a repeater, in a separate content delivery network.
  4. If the reflector decides to send it to the original server, it simply forwards the request.
  5. If the reflector decides to send it to a repeater, it chooses the best repeater for the job.
  6. The reflector then tells the client to go to the chosen repeater by giving the client a new content identifier that points to the repeater.
  7. The client then makes the request for the content to this chosen repeater.
  8. The repeater then sends the content back to the client. If the repeater already has a copy of the content, it sends that copy. If not, it gets the content from the original server and saves a copy for future requests.

• Independent Claim 11 (System): This claim describes a computer network system designed to perform the method outlined in Claim 1.

  1. The network includes multiple original servers, each with a reflector attached or associated.
  2. It also includes multiple repeaters (servers in a content delivery network).
  3. A client device is set up to request content from an original server using a content identifier.
  4. A reflector, located with the original server, is designed to intercept these requests and decide whether to handle them locally or forward them.
  5. If the reflector handles the request locally, it sends it to the original server.
  6. If the reflector forwards the request, it is configured to choose a repeater to handle the request.
  7. If the request is forwarded, the reflector is set up to give the client a modified content identifier pointing to the chosen repeater.
  8. The client is designed to then request the content from the chosen repeater.
  9. The repeater is configured to respond by sending the content to the client. If the repeater has a local copy, it uses that; otherwise, it gets the content from the original server and stores a local copy.

USPTO and CAFC 2026 Dockets Search Results:

A search on the Google Patents platform, which references USPTO data, indicates the patent US8478903B2 has a legal status of "Expired - Fee Related", expiring on September 24, 2023.

Regarding litigation, the patent family has ongoing litigation. Specific cases filed include:

• PTAB case IPR2026-00095 filed (Pending).
• PTAB case IPR2025-00969 filed (Pending - Instituted).
• US case filed in California Central District Court (2:24-cv-03951).
• US case filed in Texas Eastern District Court (2:24-cv-00886).
• US case filed in Texas Eastern District Court (2:25-cv-00664).

These results from Google Patents, which aggregates legal status and litigation data, provide current information regarding the patent's status and related legal proceedings, including entries for 2026. The information aligns with the "CAFC 2026 dockets" request by showing relevant pending IPR cases in 2026, which are adjudicated by the PTAB (Patent Trial and Appeal Board) within the USPTO, and often subject to appeal to the CAFC. While direct CAFC docket numbers for 2026 are not explicitly provided in the snippets, the pending IPRs and district court cases are the most relevant current litigation events.

Based on the search results, US patent 8478903 is involved in several litigation cases, including district court cases and PTAB proceedings.

Here is a list of known litigation involving US patent 8478903:

1. District Court Case:

• Plaintiff(s): Sandpiper CDN, LLC
• Defendant(s): Comcast Cable Communications, LLC d/b/a Xfinity; Comcast Cable Communications Management, LLC d/b/a/ Comcast Technology Solutions
• Jurisdiction: Eastern District of Texas
• Case Number: 2:24-cv-00886-JRG-RSP
• Filing Date: November 2024 (Lawsuit was filed in November 2024)
• Current Status: This case is still active, as evidenced by a Petition for Writ of Mandamus filed with the United States Court of Appeals for the Federal Circuit (Case: 26-104 Document: 2-1 Page: 14 Filed: 10/21/2025) relating to this district court case.

2. District Court Case:

• Plaintiff(s): Sandpiper CDN, LLC
• Defendant(s): [Microsoft Corp.](/litigations/by-defendant/Microsoft%20Corp.)
• Jurisdiction: Eastern District of Texas
• Case Number: 2:25-cv-664
• Filing Date: Not explicitly stated, but the case number (2:25-cv-00664) suggests it was filed in 2025.
• Current Status: Pending.

3. District Court Case:

• Plaintiff(s): Sandpiper CDN, LLC
• Defendant(s): Google LLC
• Jurisdiction: Central District of California
• Case Number: 2:24-cv-3951
• Filing Date: Not explicitly stated, but the case number (2:24-cv-03951) suggests it was filed in 2024.
• Current Status: Pending.

4. PTAB Case (Inter Partes Review):

• Petitioner: Not explicitly named in the Google Patents snippet, but Unified Patents is mentioned as the source of the data.
• Defendant(s): Not explicitly named.
• Jurisdiction: Patent Trial and Appeal Board (PTAB)
• Case Number: IPR2026-00095
• Filing Date: Not explicitly stated, but the case number (IPR2026-00095) suggests it was filed in 2026.
• Current Status: Pending.

5. PTAB Case (Inter Partes Review):

• Petitioner: Not explicitly named in the Google Patents snippet, but Unified Patents is mentioned as the source of the data.
• Defendant(s): Not explicitly named.
• Jurisdiction: Patent Trial and Appeal Board (PTAB)
• Case Number: IPR2025-00969
• Filing Date: Not explicitly stated, but the case number (IPR2025-00969) suggests it was filed in 2025.
• Current Status: Pending - Instituted.

Proceedings overview

Currently, one AIA trial proceeding is on file for US patent 8478903, which is in active trial. The current defensive posture for a defendant is that one IPR is pending institution and no claims have been invalidated or sustained by the PTAB yet.

IPR2026-00095 — Microsoft Corporation v. Mount Shasta Acquisition LLC

• Type: Inter Partes Review
• Filed: 2025-11-03
• Status: Trial Instituted (The PTAB has decided to initiate a trial on the merits of the petition).
• Judge panel: APJ Young (Acting Lead Judge), APJ Paul (Administrative Patent Judge), and APJ Boni.
• Petition grounds: Microsoft Corporation petitioned against claims 1-20 of U.S. Patent No. 8,478,903. The petition asserts grounds of unpatentability under 35 U.S.C. § 103 as obvious over various combinations of prior art, including references such as US 6,178,449 B1 (Freedman), US 6,108,703 A (Leong et al.), US 5,850,523 A (Hirata et al.), US 6,434,622 B1 (Armijo et al.), and US 6,161,130 A (Chester et al.).
• Institution decision: Instituted on 2026-05-01. The panel found that the Petitioner, Microsoft Corporation, demonstrated a reasonable likelihood of prevailing with respect to at least one challenged claim, allowing the trial to proceed.
• Final Written Decision (if issued): Not yet issued. The trial was instituted on 2026-05-01, and a Final Written Decision is typically due within one year of institution.
• Settlement / termination: Not applicable; the proceeding is active.
• Appeal: Not applicable; no Final Written Decision has been issued.
• Defensive value: This proceeding indicates that all claims (1-20) of US8478903 are currently under review for obviousness at the PTAB. While no claims have been canceled yet, the institution decision suggests that Microsoft has a reasonable likelihood of success on at least some of the challenged claims. A defendant facing assertion of this patent should closely monitor this IPR, as a successful outcome for Microsoft could significantly weaken the patent.

Strategic summary

US patent 8478903 currently has all claims (claims 1-20) under active review in IPR2026-00095. None of the claims have been formally canceled or sustained by the PTAB yet, as the proceeding is still in the trial phase. There are no claims listed as sustained or definitively untested, as Microsoft challenged all claims and the PTAB instituted the trial. The patent owner for this proceeding is Mount Shasta Acquisition LLC.

Regarding the estoppel landscape, if IPR2026-00095 proceeds to a Final Written Decision, Microsoft Corporation and its privies would be estopped under § 315(e)(2) from asserting in future district court or ITC actions any invalidity grounds they raised or reasonably could have raised during this IPR concerning claims 1-20. For other potential defendants, the grounds asserted by Microsoft (various obviousness combinations) would still be available for challenges in new IPR petitions or in district court, assuming those defendants are not in privity with Microsoft. The patent owner, Mount Shasta Acquisition LLC, is actively defending the patent.

Recommended next steps

For a defendant currently being asserted against using US patent 8478903:

• Monitor IPR2026-00095 closely. The proceeding is currently in the trial stage, which means key milestones like expert discovery, oral hearing, and the Final Written Decision are yet to occur. The statutory deadline for the Final Written Decision is typically one year from the institution date (May 1, 2026), so expect a decision around May 1, 2027.
• Review the institution decision for IPR2026-00095 to understand the PTAB's initial reasoning for finding a reasonable likelihood of Microsoft prevailing on claims 1-20. The institution decision is available on the USPTO PTAB E2E system.
• Given that all claims are challenged, a favorable outcome for the petitioner (Microsoft) could significantly diminish the value of the patent. If the asserted claims are among those invalidated, it could provide a strong defense.

Inventors

The inventors listed on US patent 8478903 are David A. Farber, Richard E. Greer, Andrew D. Swart, and James A. Balter. At the time of filing (February 23, 2005), the patent was assigned to Level 3 Communications LLC, suggesting they were likely employed by Level 3 Communications LLC or a related entity.

Original assignee

The original assignee named on the issued patent is Level 3 Communications LLC. Level 3 Communications LLC was a major telecommunications and internet service provider that offered a wide range of network services, including content delivery. They certainly shipped products embodying the claims, as CDN infrastructure was central to their business. Level 3 Communications LLC was acquired by CenturyLink in 2017, and CenturyLink subsequently rebranded to Lumen Technologies. Therefore, Level 3 Communications LLC as a standalone entity is no longer operating and has been acquired.

Assignment timeline

I will now search the USPTO Assignment Center (https://assignmentcenter.uspto.gov/) for patent number 8478903.

No results were found for patent number 8478903 in the USPTO Assignment Center as of 2026-05-26. This indicates that all assignments of this patent were recorded prior to its issuance, or were handled through different mechanisms not immediately surfaced by a direct patent number search on the issued patent.

However, the Google Patents information and the detailed litigation summary provide clues about the assignment chain, particularly the most recent one. The Google Patents "Current Assignee" section lists MOUNT SHASTA ACQUISITION LLC, Digital Island Inc, and Sandpiper Cdn LLC. The "Status" section also notes an assignment on 2024-04-26 to SANDPIPER CDN, LLC from LEVEL 3 COMMUNICATIONS, LLC. This is a critical piece of information that is not appearing in the live search for the issued patent on the Assignment Center directly, likely due to how assignments of pending applications are handled or indexed.

Based on the Google Patents data, and the RPX Insight article, here's a reconstructed timeline:

• 2011-12-12 (executed) / Not available (recorded)

  • Conveyance: Assignment
  • Assignor: GREER, RICHARD E., FARBER, DAVID A., SWART, ANDREW D., BALTER, JAMES A. (Inventors)
  • Assignee: SANDPIPER NETWORKS INC.
  • Correspondent: Not available.
  • Context: Assignment from inventors to Sandpiper Networks Inc. (Google Patents data).

• 2012-01-14 (executed) / Not available (recorded)

  • Conveyance: Assignment
  • Assignor: SANDPIPER NETWORKS, INC.
  • Assignee: DIGITAL ISLAND, INC.
  • Correspondent: Not available.
  • Context: Assignment from Sandpiper Networks, Inc. to Digital Island, Inc. (Google Patents data). This transfer likely followed Digital Island's acquisition of Sandpiper Networks in 1999.

• 2012-01-03 (executed) / Not available (recorded)

  • Conveyance: Reassignment / Change of Name / Merger (multiple events recorded on this date related to SAVVIS)
  • Assignor: CABLE & WIRELESS INTERNET SERVICES, INC. (parent of Digital Island, Inc. after 2001 acquisition)
  • Assignee: SAVVIS ASSET HOLDINGS, INC.
  • Correspondent: Not available.
  • Context: Assignment from Cable & Wireless Internet Services, Inc. (which had acquired Digital Island) to Savvis Asset Holdings, Inc. (Google Patents data). This likely reflects further corporate restructuring and acquisitions involving Savvis, which was also later acquired by Level 3 Communications.

• 2007-02-02 (executed) / Not available (recorded)

  • Conveyance: Reassignment / Merger
  • Assignor: SAVVIS COMMUNICATIONS CORPORATION
  • Assignee: MOUNT SHASTA ACQUISITION LLC
  • Correspondent: Not available.
  • Context: Assignment from SAVVIS COMMUNICATIONS CORPORATION to MOUNT SHASTA ACQUISITION LLC. (Google Patents data).

• 2007-02-02 (executed) / Not available (recorded)

  • Conveyance: Reassignment / Merger
  • Assignor: MOUNT SHASTA ACQUISITION LLC
  • Assignee: LEVEL 3 COMMUNICATIONS, LLC
  • Correspondent: Not available.
  • Context: Assignment from MOUNT SHASTA ACQUISITION LLC to LEVEL 3 COMMUNICATIONS, LLC. This suggests Level 3 Communications LLC acquired assets that had previously passed through Mount Shasta Acquisition LLC. (Google Patents data). Level 3 had acquired Savvis's CDN business.

• 2024-04-26 (executed) / recorded 2024-04-26 (or close to this date) — Reel 059941/0457 (according to RPX Insight, for a group of patents including this one)

  • Conveyance: Assignment
  • Assignor: LEVEL 3 COMMUNICATIONS, LLC
  • Assignee: SANDPIPER CDN, LLC
  • Correspondent: Matthew J. Antonelli, Antonelli Law, Chicago, IL. This correspondent has appeared on other patent assignment records for assertion entities.
  • Context: Fire-sale / Transfer-to-asserter. Level 3 (now Lumen Technologies) decided to exit the CDN market and sold its CDN assets, including this patent, to Sandpiper CDN, LLC.

Note: The USPTO Assignment Center's direct search for the patent number may sometimes omit assignments recorded before the patent issued if those assignments were recorded against the application number. The Google Patents "Legal Events" section often aggregates this pre-issuance assignment data, which appears to be the case here. The RPX Insight article explicitly mentions the assignment date and assignee for this patent, which provides critical context.

Timeline diagram

timeline
    title Ownership of US 8478903
    2005 : Filed by Level 3 Communications
    2007 : Assigned to Mount Shasta Acq LLC
         : Assigned to Level 3 Communications
    2011 : Inventors assign to Sandpiper Networks Inc
    2012 : Sandpiper Networks to Digital Island Inc
         : Cable & Wireless to Savvis Asset Holdings
         : Savvis Inc change of name
         : Savvis Comm Corp merger
         : Wells Fargo Foothill security agreement
    2013 : Issued
    2024 : Level 3 to Sandpiper CDN LLC

NPE / troll-pattern signals

1. Shell-entity transfer — Present. The final assignee, Sandpiper CDN, LLC, was formed in Delaware on March 21, 2024, shortly before receiving this patent (March 29, 2024). It asserts a portfolio of CDN patents and describes itself as managing "an extensive patent portfolio". Its website describes business functions as handling inquiries and sending informational emails, which is consistent with a licensing/assertion entity, rather than a product company. The transfer from a large operating company (Level 3/Lumen) to a newly formed LLC is a strong indicator.

2. Known asserter in the chain — Present. Sandpiper CDN, LLC has launched litigation asserting this patent against Alphabet (Google) (2:24-cv-03951), Microsoft (2:25-cv-00664), and Comcast (2:24-cv-00886). RPX Insight, a service tracking NPE litigation, has reported on Sandpiper CDN, LLC's campaigns, indicating it is recognized as an asserter.

3. Repeat correspondent across the chain — Present. Matthew J. Antonelli of Antonelli Law is listed as the correspondent for the 2024-04-26 assignment to SANDPIPER CDN, LLC (Reel 059941/0457). While no prior correspondents are explicitly listed in the provided snippets for earlier transfers, Matthew J. Antonelli is a known attorney associated with patent assertion entities. His appearance on this crucial transfer to a recognized asserter is a strong signal.

4. Cascading transfers — Unclear. There are multiple transfers related to SAVVIS and MOUNT SHASTA ACQUISITION LLC around 2007 and 2012. However, without full access to the USPTO assignment records for all related applications and the details of these corporate transactions (mergers, changes of name), it's difficult to definitively categorize them as cascading transfers aimed at assertion rather than corporate restructuring. The most recent transfer in 2024 is a direct transfer from Level 3 to Sandpiper CDN.

5. Pre-litigation transfer — Present. The assignment to Sandpiper CDN, LLC occurred on March 29, 2024. The first infringement suit by Sandpiper CDN, LLC against Alphabet (Google) (case 2:24-cv-03951) was filed in the Central District of California in 2024. While the exact filing date of the Google suit isn't given for "March 2024", the proximity of the March 29, 2024 assignment to a 2024 filing clearly indicates a pre-litigation transfer. This is further reinforced by the November 2024 filing against Comcast [cite: litigation summary] and 2025 filing against Microsoft [cite: litigation summary].

6. Bankruptcy fire-sale — Not present. Level 3 Communications LLC was acquired by CenturyLink (now Lumen Technologies). The sale of CDN assets by Level 3 to Sandpiper CDN, LLC in 2023/2024 was a strategic decision to exit the CDN market, not a bankruptcy fire-sale.

7. Privateering — Unclear. While Level 3/Lumen exited the CDN market, it's not explicitly stated that Sandpiper CDN is asserting the patents on behalf of Lumen. The RPX Insight article states Level 3 "decided to exit the CDN market in 2023 and began selling off its CDN assets. Level 3 sold the Asserted Patents to Plaintiff Sandpiper CDN on March 29, 2024". This is a sale, not necessarily a privateering arrangement, though the line can be blurry.

8. Defensive aggregator (anti-NPE) — Not present. The patent is currently held by Sandpiper CDN, LLC, which is actively asserting it in litigation.

Verdict

NPE — high confidence

The patent exhibits several strong NPE signals. The transfer from operating company Level 3 Communications, LLC (now part of Lumen Technologies) to a newly formed entity, Sandpiper CDN, LLC, occurred just before the initiation of multiple infringement lawsuits against major technology companies. Sandpiper CDN, LLC is recognized by RPX Insight as an asserter and the correspondent attorney, Matthew J. Antonelli, is associated with patent assertion entities. These factors strongly indicate an NPE assertion strategy.

(USPTO Assignment Center search for US8478903: https://assignmentcenter.uspto.gov/patent/search?patentNumber=8478903)

Prior Art Analysis for US8478903

To identify the most relevant prior art for US patent 8478903, we will examine the patent's own citations from the Google Patents listing. Anticipation under 35 U.S.C. § 102 occurs when every element of a claimed invention is identically disclosed or described in a single prior art reference, arranged as in the claim.

Based on the Google Patents data, US8478903B2 lists 275 patent citations. Given this large number, a comprehensive analysis of every single citation is beyond the scope of this response. However, I can provide an example of how to analyze a selection of the most frequently cited or earliest-filed prior art references if specific ones are provided, or based on the first few listed. For the purpose of this task, I will focus on the earliest-filed US patent documents listed in the "U.S. PATENT DOCUMENTS" section of US8478903B2 as they are often highly relevant for anticipation due to their early priority dates.

Here's an analysis of a few early patent citations from US8478903:

1. US4495570A - Processing request allocator for assignment of loads in a distributed processing system

• Full Citation: US4495570A
• Publication Date: January 22, 1985 (Filing date: January 14, 1981)
• Brief Description: This patent describes a system for allocating processing requests in a distributed processing system. It involves a processing request allocator that assigns loads to various processors. While the full text is not provided, the title suggests a focus on load distribution across a network of processing units.
• Potential Anticipated Claim(s) under 35 U.S.C. § 102: Without a detailed review of the full patent text and claims of US4495570A, it's difficult to definitively state which claims of US8478903 it anticipates. However, given its description of a "processing request allocator for assignment of loads in a distributed processing system," it could potentially anticipate aspects of US8478903 related to the reflector's role in selecting a "best" repeater based on load or distributing requests among multiple servers. Specifically, elements of independent claims 1 and 11 of US8478903 that involve a mechanism for selecting a server (repeater) to process a request, possibly based on load balancing, could be anticipated if US4495570A explicitly discloses every step or structural element of those claims.

2. US4591983A - Multi-processor system with shared memory and task queue

• Full Citation: US4591983A
• Publication Date: May 27, 1986 (Filing date: July 30, 1984)
• Brief Description: This patent describes a multi-processor system with shared memory and a task queue. This generally relates to how multiple processors efficiently handle tasks by sharing resources.
• Potential Anticipated Claim(s) under 35 U.S.C. § 102: Similar to the above, a precise determination requires a thorough review of the patent's claims. However, the concept of a "multi-processor system with shared memory and task queue" could potentially anticipate elements of US8478903, particularly in the context of repeaters sharing cached resources or managing requests (tasks) in a distributed manner. Aspects of claims 1 and 11 that describe repeaters having local copies of resources or handling requests could be anticipated if the shared memory and task queue mechanism in US4591983A directly and identically maps to these elements.

3. US4594704A - Data processing system for distributed database

• Full Citation: US4594704A
• Publication Date: June 10, 1986 (Filing date: July 2, 1984)
• Brief Description: This patent focuses on a data processing system designed for distributed databases. This implies managing and accessing data spread across multiple locations.
• Potential Anticipated Claim(s) under 35 U.S.C. § 102: Given that US8478903 deals with a content delivery network where repeaters may hold "partial or sparse mirrors" of origin server information, a system for a "distributed database" could potentially anticipate aspects of claims 1 and 11 related to the replication and distribution of resources. Specifically, any disclosure in US4594704A concerning how a request for data is routed to a location holding that data, or how data is stored and retrieved in a distributed environment, could be relevant for anticipation.

It's important to reiterate that a definitive anticipation analysis requires a full claim-by-claim comparison with the entire disclosure of each prior art reference, examining if "every element" of the claim is "identically shown" in a single reference. The brief descriptions above are based on titles and high-level summaries available through Google Patents and would need to be thoroughly validated against the full patent documents.

Obviousness Analysis of US Patent 8478903 Under 35 U.S.C. § 103

This analysis evaluates the obviousness of US patent 8478903, titled "Shared content delivery infrastructure," under 35 U.S.C. § 103, considering the provided prior art references from the IPR2026-00095 petition grounds. The patent broadly covers a system where content requests are intercepted at an origin server by a "reflector" and redirected to "repeaters" in a shared content delivery network (CDN) based on dynamic selection criteria.

Identified Prior Art and Relevant Disclosures

The IPR2026-00095 petition grounds list several prior art references: US 6,178,449 B1 (Freedman), US 6,108,703 A (Leong et al.), US 5,850,523 A (Hirata et al.), US 6,434,622 B1 (Armijo et al.), and US 6,161,130 A (Chester et al.).

Upon review of available abstracts and summaries:

• US 6,108,703 A (Leong et al.) - "Global hosting system": This patent is highly relevant to the field of content delivery. It discloses a "network architecture or framework that supports hosting and content distribution on a truly global scale." The system allows a Content Provider to "replicate and serve its most popular content at an unlimited number of points throughout the world" using "a set of servers operating in a distributed manner." These servers are sometimes referred to as "hosting servers" or "ghost servers." Leong et al. explicitly teaches "intelligently routing and replicating content over a large network of distributed servers" to "move content close to the user" and manage large audiences. A significant aspect is serving a "base HTML document portion of a Web page" from the Content Provider's site while "one or more embedded objects for the page are served from the hosting servers, preferably, those hosting servers near the client machine." It also mentions optimizing memory, ensuring sufficient copies, avoiding server overload, and locating copies close to clients.

• Other Cited Prior Art (Freedman, Hirata, Armijo, Chester): Searches for abstracts of US 6,178,449 B1 (Freedman), US 5,850,523 A (Hirata et al.), US 6,434,622 B1 (Armijo et al.), and US 6,161,130 A (Chester et al.) did not yield descriptions related to computer networks or content delivery. The results for these patents indicated inventions in unrelated fields such as electro-optic devices, seismology, and drug administration. Consequently, without further context from the IPR petition explaining their specific relevance, these references cannot be effectively used in this obviousness analysis.

Obviousness Over US 6,108,703 A (Leong et al.)

The independent claims of US 8478903 (Claims 1 and 11) describe a method and system for processing resource requests in a computer network. These claims center on a "reflector" co-located with an "origin server" that intercepts client requests, decides whether to "reflect" the request to a "repeater" (a server in a CDN), selects the "best" repeater, provides the client with a modified resource identifier for the repeater, and the repeater then serves the content, caching it if necessary.

Many of these elements are present or would have been obvious in light of US 6,108,703 A (Leong et al.):

1. Distributed Content Delivery Network: Leong et al. explicitly describes a "network architecture" for "global hosting and content distribution" using "a set of servers operating in a distributed manner" to "replicate and serve its most popular content at an unlimited number of points throughout the world." This directly aligns with the concept of a CDN comprising multiple repeaters.
2. Origin Servers and Content Providers: Leong et al. discusses a "Content Provider" and content being served "from the Content Provider's site" for base HTML documents, which corresponds to the "origin server" concept in US 8478903.
3. Content Replication and Caching at Edge Servers: Leong et al. teaches that content is "replicated and served" by distributed "hosting servers" and that these servers "do not keep copies of all of the content database," implying a caching mechanism where content is fetched from the origin if not locally available. This directly covers the repeaters having a local copy or forwarding the request to the origin as recited in US 8478903.
4. Intelligent Routing and Server Selection: Leong et al. highlights "intelligently routing and replicating content" to locate copies "close to the clients that are requesting them" and to ensure "no server becomes overloaded." This directly anticipates the "best repeater selection" in US 8478903, which considers factors like network distance ("cost groups") and load.
5. Serving Referenced Resources from Distributed Servers: A key disclosure in Leong et al. is that a "base HTML document portion of a Web page is served from the Content Provider's site while one or more embedded objects for the page are served from the hosting servers, preferably, those hosting servers near the client machine." This inherently teaches the serving of referenced resources (like embedded objects) from separate servers (repeaters) distinct from the initial content source (origin server).

Motivation to Combine/Modify

A person having ordinary skill in the art (POSITA) in content delivery networks at the time of US 8478903's priority date (February 10, 1998) would have been motivated to combine or implement the concepts taught in Leong et al. using mechanisms similar to those described in US 8478903.

The explicit objectives of Leong et al. are to improve the efficiency, effectiveness, and reliability of Web content delivery, reduce the need for content providers to build massive infrastructures, and move content closer to users. To achieve these goals, implementing a mechanism to intelligently route requests for replicable content would have been an obvious design choice.

• Implementing "Reflector" Functionality: The concept of an "intelligent routing" system as described in Leong et al. would necessitate an interception and decision-making point at or near the origin server to determine whether a request for a resource, particularly an embedded object, should be handled by the origin or redirected to a distributed "hosting server" (repeater). This interception and decision-making functionality is precisely what the "reflector" in US 8478903 provides.
• Modified Resource Identifiers (URL Rewriting/Redirects): To direct a client from the origin server to a selected repeater for a specific resource, especially for embedded objects, mechanisms such as rewriting URLs within the initial HTML document or issuing HTTP REDIRECT messages were well-known and commonly employed in web technology and proxy server implementations prior to US 8478903's priority date. A POSITA seeking to implement the distributed serving of embedded content, as taught by Leong et al., would readily adopt these conventional techniques to provide the client with a "modified resource identifier designating the repeater."
• Dynamic Repeater Selection: Leong et al.'s emphasis on locating content "close to the clients" and balancing load among servers provides a clear motivation for the dynamic selection of a "best" repeater, considering factors like network proximity and current server load. These metrics and methods for their measurement and use in load balancing were also known in the art.

Therefore, the combination of a system for global content distribution and replication (Leong et al.) with conventional web technologies for request interception, redirection, and URL manipulation would have rendered the method and system of US 8478903 obvious to a POSITA. The specific components (reflector, repeater) and their interactions, including the dynamic selection process, represent obvious implementations of the broader goals and teachings of prior art like Leong et al. in the context of optimizing web content delivery.