What is Open Caching?

A New Approach for Streaming:

Many Caches, All Connected

Since the beginning of streaming video, caches have been largely proprietary. Even when developed using open source technologies, like Squid, companies often made unique enhancements and developed their own approaches to hierarchies, session windows, and even the OS TCP stack. Now, with most streaming operators employing multiple CDNs, managing all of the caches across the different networks from a single interface is extremely complex. Open Caching is an attempt to level the paying field so content rights holders, network operators, and CDNs all have visibility into the caching network.

Specifications

Open Caching is defined by a library of documentation which specify the requirements, functions, and programming layer (APIs) of different elements of the Open Caching Network: Nodes, Request Routing, and Control Plane.

Code

In addition to the documentation, the Open Caching work at the Streaming Video Alliance has also produced reference code. These public repos provide a starting point for companies looking to implement Open Caching technologies.

Collaboration

The Open Caching specifications and code weren't developed by a single company. They were the result of a combined effort from dozens of companies since the Alliance's inception.

Functional Components

Click on a box to get more detail about the Open Caching component.

Enabling Caching Interoperability

Three key components make up an Open Caching Network.

Caching Nodes

An Open Caching Node represents a caching server, within a content delivery architecture, that complies with Open Caching specifications. The cache can either be built using the specifications (such as for an ISP implementing Open Caching at the edge of their network), or Open Caching functionality can be added through plugins or other means (such as for a Content Delivery Network caches or OTT Platform origins).

Request Router

The Request Router handles the inbound request for content and forwards this request to the appropriate caching node within an environment. The Open Caching specifications identify three methods of routing: DNS, HTTP, and Manifest.

Control Plane

The Control Plane handles all communication related to management of configurations, content purging and pre-positioning, logging, and security. While the Request workflow is focused on the end user’s ability to retrieve content, the Control Plane is focused on how the different members of the video distribution chain are empowered to partake in the delivery process.

The Industry is Beginning to Notice

Open Caching Implementations

ISPs
CDNs
Content Owners
Commercial Providers

Document Spotlight

(DRAFT) SVTA5069: Content Steering with Open Caching

This document will focus primarily on how the Content Steering server(s) make decisions about what information to provide the user agent. The protocol used to communicate between the Content Steering server and the user agent, and the semantics of those instructions are the focus of other initiatives. The primary exceptions to this are the 302 Request Routing mechanism, which by its nature is exposed directly to the User Agent, and the client probing mechanism, which is a new User Agent behavior described below.