Request Router Root Manifest Encapsulation for CDN Redirection
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Solution Overview
Problem
HTTP redirection methods in content delivery networks (CDNs) using HTTP Dynamic Streaming (HDS) result in excessive redirections when content manifests contain relative URLs, leading to inefficiencies and content provider objections to manifest re-writing.
Innovation Solution
Implementing a request router that encapsulates a content manifest within a root manifest with a base URL pointing to the delivery node and a media link, allowing the media playback device to request content directly from the delivery node, thereby reducing the need for multiple HTTP redirects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HTTP redirection is used with relative URLs in content manifests, then the content delivery network can route requests to appropriate delivery nodes, but the number of redirection requests increases significantly
Solution Approach 1:
The patent applies preliminary action by performing manifest rewriting at the request router before content delivery. The request router intercepts the initial manifest request, rewrites the relative URLs to absolute URLs with the target delivery node's domain, and returns the modified manifest. This preliminary transformation eliminates the need for subsequent redirection requests, as all media fragment requests can be directly resolved to the correct delivery node through the absolute URLs already embedded in the manifest.
Solution Approach 2:
The request router serves as an intermediary between the content consumer and the content delivery network. It captures the initial manifest request, determines the appropriate delivery node, rewrites the URLs in the manifest to point directly to that delivery node, and returns the modified manifest to the content consumer. This intermediary action transforms the relative URL-based manifest into an absolute URL-based manifest, enabling direct communication between the content consumer and the selected delivery node without requiring further redirection.
2Productivity
If manifest re-writing is used to provide absolute URLs, then the number of redirection requests is reduced, but content providers object to revision of their manifest files
Solution Approach 1:
The patent applies local quality by performing URL rewriting only in the specific context where it is needed - in the manifest file served through the CDN - while leaving the original manifest files stored at the content provider's origin server unchanged. The request router intercepts requests for manifests with relative URLs, rewrites only those specific instances to absolute URLs with the appropriate delivery node domain, and returns the modified version. This localized transformation maintains content provider control over their original files while achieving the productivity benefits of absolute URLs in the delivery path.
3Reliability
If temporary redirection is used, then the content consumer can fetch the content manifest from the delivery node, but future requests for media content are redirected to the load balancing node resulting in excessive redirections
Solution Approach 1:
The patent applies preliminary action by transforming the manifest URLs from relative to absolute format before returning them to the content consumer. The request router intercepts the initial manifest request, rewrites the URLs to include the target delivery node's domain, and returns the modified manifest. This preliminary URL transformation ensures that all subsequent media fragment requests contain absolute URLs that directly resolve to the correct delivery node, eliminating the need for temporary redirection and preventing the accumulation of redirection overhead.
Data Source
AI summary
A method of HTTP redirection is provided for scenarios where a manifest file for media content contains a relative URL. A request router or other network device encapsulates the content manifest file within a root manifest file. The root manifest file contains a base URL that points to the location of the content and a media link that points to the requested content manifest.