HTTP/2 and CDNs

The SPDY technology introduced by Google in 2014 seemed to be revolutionary at those times, but today, specialists have understood it has already reached the dead end. However, it laid foundation for the next significant protocol change: it’s time to switch from SPDY to HTTP2. Let’s find out which limitations HTTP2 eliminates, and how else this technology can be useful for you.

What Is HTTP/2?

Also known as “HTTP2.0”, HTTP/2 protocol is the new version of HTTP. It was partially developed and approved by the Internet Engineering Task Force (IETF). Today, 5% of traffic in Google is delivered with the help of HTTP/2, and recently, all of widespread browsers started supporting it.

Some twenty years ago, websites were much simpler: they contained texts mostly with a few images and external files. CSS and JavaScript files were among a few external resources. Styling was made with the help of tables and background images, and JavaScript was typically cut-and-paste in the content. HTML code of web-pages was dreadful, but it didn’t require much resources of the web-server, because the code was self-contained.

Web-pages today are different: they are coded well, but have a lot of external files. Web-developers started separating the layers of design, markup and behavior into multiple file, which simplified maintenance, but caused overhead when pages are loaded. Huge CSS frameworks and JavaScript libraries are now considered to be normal. Web-applications can consist of big files that control the appearance and behavior of web-pages.

Why HTTP 1.1 is outdated?

Today, HTTP 1.1 puts limitations on web-page performance and slows its down because of the overhead. This is why it should be replaced, and one of such replacements was SPDY protocol created by Google team. SPDY gained support from the major web-browsers and web-servers – some are still using it to boost the delivery of website resources to their clients.

SPDY helps to increase website speed by up to 55%: it most cases, it makes up for improvement of at least 27%, even on websites that have already been optimized for speed. HTTP/2 is based on SPDY, and some of its advances make it even quicker and more secure.

Does Using HTTP/2 Matter?

The main benefit of using HTTP/2 is the increased speed and reduction of additional RTT (round trip times). Therefore, your website can become much faster without extra optimization. The same applied to SPDY itself, but it has some limits:

1. It’s not widely supported: although SPDY is an open-source solution, it’s not a web standard. O the opposite, HTTP/2 is a full web standard introduced by IETF, and browsers and servers have to comply with it.
2. It required all assets to be transferred via a secure HTTP connection. Although it’s not a problem for huge eCommerce companies, it was problematic for smaller websites, because there are many basic hosting accounts that don’t have an SSL certificates.
3. While SPDY supports single-host multiplexing, HTTP/2 supports multi-host multiplexing, which is beneficial for RTT.

With HTTP/2, these limitations aren’t a problem anymore, which is why Google started adopting this standard and preferring it to SPDY.

Drawbacks of HTTP/1.1

• Huge HTTP request headers, headers aren’t compressed.
• Visitors have to use domain sharing and concatenation to keep up.
• Browsers have to exploit 4-8 connections, and more are required.
• One client-server request per TCP connection.

Performance Rules

It’s crucial to have modern websites optimized. When it comes to mobile devices, HTTP causes difficulties connected with 3G networks: many requests to the same server face time penalty. HTTP/2 was designed to solve this issue, so you can witness a serious boost of performance of your website on tablets and smartphones.

Users require fast loading of pages, which is why performance optimization is crucial as never before. Since the most popular websites have become much faster, less optimized projects aren’t favored at all. Google has started taking speed into consideration as a ranking factor: they opt for results that please customers, and people definitely don’t like slow websites.

HTTP/2 – What Does it Mean for a CDN?

Offering content delivery networks, SpaceCDN does everything to accelerate the delivery of assets over the web. We strive to boost the delivery of every data package to its destination by caching content closer to the end users. HTTP 1.1 puts limitations on CDNs that are very hard to avoid.

With HTTP/2, we’ve made a huge step forward. It allows us offering faster experience to the end-users and clients without need to make any changes at their end. HTTP/2 also eases job for web-developers making some optimization methods less important.

Since CDN serves multiple visitors, it’s crucial to protect our servers against attacks: HTTP/2 is more secure than SPDY, because it applies a fixed Huffman code-based algorithm (HPACK) to compress HTTP headers. In this case, less reliable stream-based compression is replaced by other technologies, which makes our infrastructure a more secure place. With HTTP/2, resources can be “pushed” to the browser, and the files can be anticipated before the browser even requests them.

Web users enjoy a significant boost in performance in websites supporting HTTP/2, which is why SpaceCDN implements this protocol. We’ve launched HTTP/2 support for our customers that can be enabled on the dashboard in one click.