Understanding Open Caching

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Understanding Open Caching

An Open Architecture for Content Delivery

Open Caching is ultimately about flexibility. By standardizing how requests for content are handled, content delivery gets decoupled from proprietary solutions enabling discrete networks involved in delivering content to act as a single network. This, in turn, improves management of the content delivery infrastructure (for content owners) while better involving eyeball network operators (ISPs) in the delivery chain. This, in turn, creates an “overlay” network called an Open Caching Network. Because the interfaces for managing this overlay network are APIs adhering to industry standards, new, programmatic workflows can be used to manage content delivery end-to-end.

Key Terms

Open Caching has its own lexicon. Understanding the terms will improve your understanding of how it works and the various components required for operation. Note that these terms are pulled from the SVTA Streaming Video Wiki.

Specifications and Documents

The following specifications and other documents can help you better understand the fundamentals of an Open Caching Network, architecture, APIs, and implementation.

SVTA1013: Optimizing Video Delivery With The Open Caching Network

Delivering a great video experience requires content to be served as close to the end-user as possible. In this whitepaper, we illustrate how network operators can implement Open Caching nodes at the edge of their network, while adhering to specifications created by the Open Caching Working Group of the Streaming Video Alliance. These nodes can mitigate delivery latency and provide an improved viewer experience when hosted by the ISP and connected to the CDN/Content Provider nodes outside of the operator network, to create an Open Caching Network.

SVTA2007-1: Open Cache Request Routing Functional Specification (Version 2.0)

High-level functional specification of open caching request routing and the required interfaces to enable request routing to be performed from an upstream CDN to an open cache system.

SVTA2026: Home Storage Functional Specification

The Home Storage Open Caching Node (HS-OCN) project adds functionality to the open caching system to further improve quality of experience (QoE) on networks with last mile challenges including speed limits (e.g. low speed DSL), usage limits (e.g. wireless), and last mile congestion (e.g. COVID quarantine). In the United States, almost 20 million households still have DSL or wireless Internet service. This number is larger worldwide. By leveraging storage in the home, end-users can have experiences with fewer rebuffer events, faster start times, and higher visual quality including UHD. At the same time as the QoE is improved, the amount of content which can be viewed is increased because the operator can reduce the peak period usage.

SVTA2028-1: Configuration Interface Part 1: Overview and Architecture

This is the first part in a set of documents that specify the Streaming Video Technology Alliance (SVTA) Configuration Interface, defining both the metadata model and Application Programming Interfaces (APIs) for entities to publish and retrieve configuration metadata. This document specifies the motivational drivers, use cases, and standards to facilitate interoperability within the content delivery network (CDN) and Open Caching ecosystems. The full document set presents a layered architecture that extends the Internet Engineering Task Force (IETF) CDN Interconnect (CDNI) Metadata and Capabilities Models and adds publishing APIs to provide configuration management capabilities required by the CDN and Open Caching industries.

SVTA2045: Open Caching API Footprint and Capabilities

This document describes the Application Programming Interface (API) methods and data model related to the Footprint and Capabilities Interface. The API has been entirely designed by the SVTA Open Caching group whereas the data model is based on the IETF Content Delivery Network Interconnection (CDNi) work. and on extensions specified by the SVTA Open Caching group.

SVTA2048: Open Caching Request Routing Interface

Content delivery delegation in open caching can be realized through two modes of request redirection, iterative and recursive.

Open caching previously supported the iterative mode only. This document describes the data model and architecture changes required to enable the recursive mode of delegation as well.

SVTA2049: Open Caching Capacity Insight Interface

This document describes the Capacity Insights Interface that allows content providers (CPs), service providers (SPs), and content delivery networks (CDNs) to exchange information to facilitate an integrated and informed end-to-end traffic steering workflow. The goal is to enable real-time traffic steering based on available capacity in an effort to keep key performance indicators (KPIs) at acceptable levels. Mechanisms such as reservations and service level agreements (SLAs) are considered out of scope for the purpose of this interface.

SVTA2050: Open Caching Logging Specification

This document describes extensions to the Open Caching Configuration API and the Content Delivery Networks Interconnection (CDNI) Footprint & Capabilities Interface [RFC8008] to support configuration and advertisement of logging capabilities, along with examples and best practices to support logging,log record transformation and transmission between participants within an Open Caching environment. The extensions are based on the Internet Engineering Task Force (IETF) CDNI Request for Comments (RFCs) and extensions proposed by this Streaming Video Technology Alliance (SVTA) group.

SVTA5044: Open Caching API Implementation Guidelines

The Streaming Video Technology Alliance Open Caching Application Programming Interfaces (APIs) are described in several documents, each related to a particular interface. This document is the starting point for anyone implementing these APIs. It describes the Open Caching model and includes modes of operations necessary for implementation.