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Web Performance and the Impact of SPDY, HTTP/2 & QUIC - Part 5

Jean Tunis

This blog is the final installment in a 5-part series on APMdigest where I discuss web application performance and how new protocols like SPDY, HTTP/2, and QUIC will hopefully improve it so we can have happy website users.

Start with Web Performance 101: The Bandwidth Myth

Start with Web Performance 101: 4 Recommendations to Improve Web Performance

Start with Web Performance and the Impact of SPDY, HTTP/2 & QUIC - Part 1

Start with Web Performance and the Impact of SPDY, HTTP/2 & QUIC - Part 2

Start with Web Performance and the Impact of SPDY, HTTP/2 & QUIC - Part 3

Start with Web Performance and the Impact of SPDY, HTTP/2 & QUIC - Part 4

HTTP/2 Implementations

It has been almost a year since HTTP/2 has been a ratified standard. I talked about how widely support it is - only 4% of the top 2 million Alexa sites truly support it.

Does your website support it? What about your web host provider?

One place to check is the Google Chrome browser itself by going to Chrome Web Tools.


You can also check by doing a packet capture with Wireshark. Or go to tools.keycdn.com/http2-test.

By now, most web browsers support the new version of HTTP. The top five, Chrome, Firefox, IE/Edge, Opera and Safari all support HTTP/2, at least partially. The top two widely used web servers, Apache and Nginx, support it as well.

Previously, I mentioned a number of workarounds that developers used to make their websites faster with HTTP/1.1. Now with HTTP/2, some of these workarounds can actually degrade performance with HTTP/2 implementation.

The Unsharding

With only one connection per host that is allowed with HTTP/2, domain sharding can hurt a developer's attempt to improve performance. So if there was used previously, an upgrade to HTTP/2 means that the domains must be unsharded.

The Uncombine

Combining Javascript and CSS files into one file helped to reduce the amount of connections on HTTP/1.1. This is no longer needed with only one connection.

However, care must be taken with this. Doing this must be tested on a case-by-case basis. Some large files are able to compress better than smaller files. So it may not be to your advantage to uncombine the files if you have a lot of smaller files.

The Uninlining

Inlining scripts directly into the HTML was another way to reduce the number of connections and round-trips to the server. With HTTP/2, this is no longer needed with only one TCP connection.

HTTP/2 Pros & Cons

There are number of advantages of using HTTP/2, including:

■ Substantially and measurably improve end-user perceived latency over HTTP/1.1 using TCP

■ Address the head of line blocking problem in HTTP

■ Not require multiple connections to a server to enable parallelism, thus improving its use of TCP

■ Retain the semantics of HTTP/1.1, like header fields, status codes, etc.

■ Clearly define how HTTP/2.0 interacts with HTTP/1.x via new Upgrade header field

But, despite these advantages, there are still some disadvantages that the new protocol version has not addressed.

Some disadvantages are:

■ Unable to get around TCP head of line blocking, particularly during packet loss

■ TCP's congestion avoidance algorithm increases serialization delay

■ TLS connection setup still takes time

■ Binary format (for people like me) makes troubleshooting a bit more difficult, not being able to see plaintext, without TLS encryption keys

We Need to Be QUIC

So we see that we still have a number of limitations even with HTTP/2. Although, I have to admit, the last one is somewhat selfish.

One big limitation is the TCP protocol. Due to its connection-oriented nature, there's no getting around the head of line blocking and the time it takes to open and close the connection.

Google wanted a way around this, and in 2012 set out to develop a protocol that runs on top of UDP, which is connectionless protocol. The protocol is called Quick UDP Internet Connections, or QUIC. Another clever name by Google?

Clever or not, Google needed a protocol with quicker connection setup time and quicker retransmissions. Unlike TCP, UDP would allow for this. They wanted to take some of the benefits of the work done with SPDY, that ultimately went into the HTTP/2 standard, such as multiplexed HTTP communication, but running over UDP rather than TCP.

The main goal? To reduce overall latency across the Internet for a user's interactions.

QUIC implements various TCP features, but without the limitations, such as the round-trip time for connection setup, flow control, and congestion avoidance. With UDP's connectionless orientation, RTT is zero since UDP just starts sending data when it needs to rather than talking to the other side to ensure it's available to talk.

Where is QUIC?

The most common place I've come across QUIC being used is on YouTube.

Have you ever compared the speed of a YouTube video compared to some of the other providers like Wistia and Vimeo? Where I live, I'll be lucky to get 3Mbps from my ISP. Watching a video on YouTube rarely buffers. I can almost always count on buffering when watching a video hosted on Wistia or Vimeo. As you can see in the screenshot below, the protocol being used on YouTube is a mix of QUIC and SPDY.


Contrast that to the screenshot I took from Wistia's site, below.


They are still largely using HTTP/1.1. They're not even on HTTP/2 yet. I'm sure they are doing a number of other things to make their web properties faster, but that explains to me why I rarely get any buffering on YouTube compared to Wistia.

Conclusion

If the speed with which SPDY was tested and went into the HTTP/2 standard, which took about three years from SPDY draft release to HTTP/2 draft release, is it possible that we could have a replacement for the TCP protocol on the web in the next couple of years? This should be interesting and exciting!

Jean Tunis is Senior Consultant and Founder of RootPerformance.

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Web Performance and the Impact of SPDY, HTTP/2 & QUIC - Part 5

Jean Tunis

This blog is the final installment in a 5-part series on APMdigest where I discuss web application performance and how new protocols like SPDY, HTTP/2, and QUIC will hopefully improve it so we can have happy website users.

Start with Web Performance 101: The Bandwidth Myth

Start with Web Performance 101: 4 Recommendations to Improve Web Performance

Start with Web Performance and the Impact of SPDY, HTTP/2 & QUIC - Part 1

Start with Web Performance and the Impact of SPDY, HTTP/2 & QUIC - Part 2

Start with Web Performance and the Impact of SPDY, HTTP/2 & QUIC - Part 3

Start with Web Performance and the Impact of SPDY, HTTP/2 & QUIC - Part 4

HTTP/2 Implementations

It has been almost a year since HTTP/2 has been a ratified standard. I talked about how widely support it is - only 4% of the top 2 million Alexa sites truly support it.

Does your website support it? What about your web host provider?

One place to check is the Google Chrome browser itself by going to Chrome Web Tools.


You can also check by doing a packet capture with Wireshark. Or go to tools.keycdn.com/http2-test.

By now, most web browsers support the new version of HTTP. The top five, Chrome, Firefox, IE/Edge, Opera and Safari all support HTTP/2, at least partially. The top two widely used web servers, Apache and Nginx, support it as well.

Previously, I mentioned a number of workarounds that developers used to make their websites faster with HTTP/1.1. Now with HTTP/2, some of these workarounds can actually degrade performance with HTTP/2 implementation.

The Unsharding

With only one connection per host that is allowed with HTTP/2, domain sharding can hurt a developer's attempt to improve performance. So if there was used previously, an upgrade to HTTP/2 means that the domains must be unsharded.

The Uncombine

Combining Javascript and CSS files into one file helped to reduce the amount of connections on HTTP/1.1. This is no longer needed with only one connection.

However, care must be taken with this. Doing this must be tested on a case-by-case basis. Some large files are able to compress better than smaller files. So it may not be to your advantage to uncombine the files if you have a lot of smaller files.

The Uninlining

Inlining scripts directly into the HTML was another way to reduce the number of connections and round-trips to the server. With HTTP/2, this is no longer needed with only one TCP connection.

HTTP/2 Pros & Cons

There are number of advantages of using HTTP/2, including:

■ Substantially and measurably improve end-user perceived latency over HTTP/1.1 using TCP

■ Address the head of line blocking problem in HTTP

■ Not require multiple connections to a server to enable parallelism, thus improving its use of TCP

■ Retain the semantics of HTTP/1.1, like header fields, status codes, etc.

■ Clearly define how HTTP/2.0 interacts with HTTP/1.x via new Upgrade header field

But, despite these advantages, there are still some disadvantages that the new protocol version has not addressed.

Some disadvantages are:

■ Unable to get around TCP head of line blocking, particularly during packet loss

■ TCP's congestion avoidance algorithm increases serialization delay

■ TLS connection setup still takes time

■ Binary format (for people like me) makes troubleshooting a bit more difficult, not being able to see plaintext, without TLS encryption keys

We Need to Be QUIC

So we see that we still have a number of limitations even with HTTP/2. Although, I have to admit, the last one is somewhat selfish.

One big limitation is the TCP protocol. Due to its connection-oriented nature, there's no getting around the head of line blocking and the time it takes to open and close the connection.

Google wanted a way around this, and in 2012 set out to develop a protocol that runs on top of UDP, which is connectionless protocol. The protocol is called Quick UDP Internet Connections, or QUIC. Another clever name by Google?

Clever or not, Google needed a protocol with quicker connection setup time and quicker retransmissions. Unlike TCP, UDP would allow for this. They wanted to take some of the benefits of the work done with SPDY, that ultimately went into the HTTP/2 standard, such as multiplexed HTTP communication, but running over UDP rather than TCP.

The main goal? To reduce overall latency across the Internet for a user's interactions.

QUIC implements various TCP features, but without the limitations, such as the round-trip time for connection setup, flow control, and congestion avoidance. With UDP's connectionless orientation, RTT is zero since UDP just starts sending data when it needs to rather than talking to the other side to ensure it's available to talk.

Where is QUIC?

The most common place I've come across QUIC being used is on YouTube.

Have you ever compared the speed of a YouTube video compared to some of the other providers like Wistia and Vimeo? Where I live, I'll be lucky to get 3Mbps from my ISP. Watching a video on YouTube rarely buffers. I can almost always count on buffering when watching a video hosted on Wistia or Vimeo. As you can see in the screenshot below, the protocol being used on YouTube is a mix of QUIC and SPDY.


Contrast that to the screenshot I took from Wistia's site, below.


They are still largely using HTTP/1.1. They're not even on HTTP/2 yet. I'm sure they are doing a number of other things to make their web properties faster, but that explains to me why I rarely get any buffering on YouTube compared to Wistia.

Conclusion

If the speed with which SPDY was tested and went into the HTTP/2 standard, which took about three years from SPDY draft release to HTTP/2 draft release, is it possible that we could have a replacement for the TCP protocol on the web in the next couple of years? This should be interesting and exciting!

Jean Tunis is Senior Consultant and Founder of RootPerformance.

Hot Topics

The Latest

AI is the catalyst for significant investment in data teams as enterprises require higher-quality data to power their AI applications, according to the State of Analytics Engineering Report from dbt Labs ...

Misaligned architecture can lead to business consequences, with 93% of respondents reporting negative outcomes such as service disruptions, high operational costs and security challenges ...

A Gartner analyst recently suggested that GenAI tools could create 25% time savings for network operational teams. Where might these time savings come from? How are GenAI tools helping NetOps teams today, and what other tasks might they take on in the future as models continue improving? In general, these savings come from automating or streamlining manual NetOps tasks ...

IT and line-of-business teams are increasingly aligned in their efforts to close the data gap and drive greater collaboration to alleviate IT bottlenecks and offload growing demands on IT teams, according to The 2025 Automation Benchmark Report: Insights from IT Leaders on Enterprise Automation & the Future of AI-Driven Businesses from Jitterbit ...

A large majority (86%) of data management and AI decision makers cite protecting data privacy as a top concern, with 76% of respondents citing ROI on data privacy and AI initiatives across their organization, according to a new Harris Poll from Collibra ...

According to Gartner, Inc. the following six trends will shape the future of cloud over the next four years, ultimately resulting in new ways of working that are digital in nature and transformative in impact ...

2020 was the equivalent of a wedding with a top-shelf open bar. As businesses scrambled to adjust to remote work, digital transformation accelerated at breakneck speed. New software categories emerged overnight. Tech stacks ballooned with all sorts of SaaS apps solving ALL the problems — often with little oversight or long-term integration planning, and yes frequently a lot of duplicated functionality ... But now the music's faded. The lights are on. Everyone from the CIO to the CFO is checking the bill. Welcome to the Great SaaS Hangover ...

Regardless of OpenShift being a scalable and flexible software, it can be a pain to monitor since complete visibility into the underlying operations is not guaranteed ... To effectively monitor an OpenShift environment, IT administrators should focus on these five key elements and their associated metrics ...

An overwhelming majority of IT leaders (95%) believe the upcoming wave of AI-powered digital transformation is set to be the most impactful and intensive seen thus far, according to The Science of Productivity: AI, Adoption, And Employee Experience, a new report from Nexthink ...

Overall outage frequency and the general level of reported severity continue to decline, according to the Outage Analysis 2025 from Uptime Institute. However, cyber security incidents are on the rise and often have severe, lasting impacts ...