File Prefetch

1 Feature Intro

1.1 Brief Introduction

When a file is requested by users for the first time, the file will be obtained from the origin and cached on CDN PoPs for subsequent file access requests. By using file prefetch, CDN helps improve the first-time file access efficiency, greatly reduce the response time and address the problem of long response time in the first-time access.

1.2 Applicable Product Lines

• Content Acceleration
• Dynamic Web Acceleration
• Media Acceleration

1.3 Application Scenarios

This feature is applicable to customers who have large files which consumes large amounts of bandwidth, and file prefetch will effectively reduce the back-to-origin requests and traffic for the customers.

2 Feature Detail

2.1 Feature Description

CDNetworks provides interface on the webpage and API interface, where the prefetch command will be sent to CDNetworks edge PoP or second-level caching PoP (normally the relay PoP) by submitting prefetch URL on the webpage or through API interface. By doing this, the corresponding PoP will obtain the file from the origin in advance and cache it. Thus, the cached file in the PoP will be returned to users directly when it is requested, without fetching it from the origin.
There are 2 types of prefetch:

1. Conditional Prefetch:
   The file is prefetched and cached on the PoP regardless of whether the PoP has a file to be prefetched. That is, only when the file to be prefetched does not exist on the CDN PoP or the cache has expired, the CDN PoP will go back to origin to obtain the file.
2. Compulsory Prefetch:
   First clean up the cached files on the PoP, and then prefetch the files to the PoP. That is, the CDN PoP will go back to origin to obtain the files, regardless of whether the files to be prefetched have been cached on the CDN PoP or have expired or not.

2.2 Instruction

To facilitate customer usage, CDNetworks file prefetch can be realized in the following two ways:

1. File Prefetch via Webpage
   Customer creates a file prefetch task and submits the prefetch URL in the content management system. The URL must be a specific URL starting with http://, and Regex and directory are not supported. Customer can also check the real-time status of the prefetch task in the content management system. A single customer can submit at most 500 pieces of URLs at a time.
2. File Prefetch via API interface
   CDNetworks File Prefetch is a set of API interface provided as an auxiliary for CDNetworks customers service platform. Through this interface, customers can send the file prefetch demand to CDNetworks PoPs, so the corresponding PoPs will obtain file from origin in advance and cache it, greatly improving the hit ratio and reducing the back-to-origin amount and bandwidth.

3 Notice

Email application is required if the number of items to be prefetched excesses 20,000 or 200G, but the service is still free.

4 Key Benefit

File prefetch improves the first-time file access efficiency and addresses the issue of long back-to-origin time when accessing a file for the first time.