A Content Delivery Network (CDN) is one of the most important tools that assists in enhancing the efficiency, velocity, and dependability of delivering content on the web. They operate under the principle that to allow users to access data from any server, the content should be replicated geographically. There are two main ways of disseminating content using CDNs as mentioned below Pull CDNs and Push CDNs. This article aims to help understand the differences between Pull and Push CDNs.
Important Topics for Pull CDN vs. Push CDN
What is Pull CDN?
A Pull CDN is also referred to as an “Origin Pull” CDN, which simply means that it only requests the content from the origin server when a particular user initially requests it. Once it is the first request, the content is stored at the server of CDN and successively served from the cache until its expiry or further update is made.
How it works?
- User Request: When a user enters a URL of your website and requests for contents such as an image, or a video, the request is forwarded to the nearest CDN edge server.
- Cache Miss: When there is cache miss that is when the CDN edge server does not have the content, it requests the origin server for the content.
- Cache Store: The CDN edge server then stores this content on the local cache of the CDN edge server system.
- Serving Content: This is based on the content delivered to the user. Subsequent requests to the same content simply reference this cache reducing the burden on the origin server and benefitting end-users with response time.t.
What is Push CDN?
In regards to the Push CDN, also referred to as the “Origin Push” CDN, the content owner has to initiate the uploading process by delivering content into the CDN platform. The content is then cached at the multiple edge servers covering the CDN network, so it is always available to serve to the user once requested.
How it works?
- Upload Content: Files are published on the CDN from the content owner’s site to the servers for storage.
- Distribution: The CDN delivers content to the edge servers in compliance with the specified distribution or algorithms.
- User Request: Specifically, when a user is requesting the content, it is delivered from the nearest edge server that has prior distribution of the content.
- Content Management: The challenge with this approach is that when there is a change or an update to the content, someone has to physically update the CDN servers so as to get the updates reflected on the site.
Differences Between Pull CDN and Push CDN
Below are the differences between the Pull CDN and Push CDN:
Feature | Pull CDN | Push CDN |
|---|---|---|
Content Fetching | Automatically pulls from origin server on request | Manually uploaded to CDN servers by the content owner |
Cache Management | CDN manages caching automatically | Content owner manages the upload and distribution |
Ease of Setup | Easy to set up with minimal configuration | Requires more initial setup and maintenance |
Dynamic Content | Handles dynamic content well | Best for static content |
Latency | Initial request may have higher latency due to fetching from origin | Lower latency as content is pre-distributed |
Bandwidth Usage | Bandwidth usage is based on actual user demand | Bandwidth usage can be higher due to pre-distribution |
Cost Structure | Typically pay-as-you-go based on usage | May have higher costs due to storage and distribution overhead |
Real-world examples of Pull CDN
- Cloudflare:
- Cloudflare works as a pull model CDN, which means that it actively retrieves content from the origin server and stores it at Cloudflare edge nodes.
- As mentioned, this service is commonly employed for sites and applications that entail fast content trafficking with little to no configuration.
- Cloudflare offers convenient features that allow purging cache automatically and caching dynamic content while offering powerful analytics.
- Amazon CloudFront:
- Amazon CloudFront can work as a pull CDN where popular contents and files are requested from the AWS S3 and other origins for the first time and then cached in edge locations. CloudFront is known to be easily integrated into all other services that are offered under AWS making it popular for websites and apps under AWS.
Real-world examples of Push CDN
- Akamai:
- Akamai has traditional push CDN services where content is frontline loaded into the CDN’s server stores.
- This is often applied by large or massive enterprises that contain huge amounts of static content.
- Akamai has claimed to have a wide coverage, it operates from numerous points hence it can provide a high service availability and low latency especially for large files such as the software downloads and the multimedia content.
- Rackspace CDN:
- Rackspace offers a push CDN ability where users are able to upload their content directly to the CDN store and be assured that copies are available at the edge servers.
- Rackspace CDN is an excellent example of the CDN services, which are characterized by high performance and reliability, so that it fits the needs of companies with high demand to content delivery speed and performance.
Conclusion
Recognizing key differences between the Pull CDN and the Push CDN is imperative to identify an optimal CDN approach. It is most suitable for supporting dynamic content and give convenience to application because it handles its own caching and getter from the origin server by default. Push CDNs on the other hand are more useful for managed content delivery and more reliable for content which is static in nature, as they may be pre-cached at the edge server, however, they need manual management of content.