Welcome!

Containers Expo Blog Authors: Pat Romanski, LeanTaaS Blog, Derek Weeks, Liz McMillan, Mehdi Daoudi

Related Topics: @DevOpsSummit, Linux Containers, Containers Expo Blog

@DevOpsSummit: Article

Using Prefetch | @DevOpsSummit @Catchpoint #DevOps #APM #AI #Monitoring

It is very important to proactively monitor webpages to ensure if this performance optimization technique is working or not

Using Prefetch as a Proactive Approach
By Ashish Kumar

Paul The Octopus was known as an animal oracle who could predict the result of a football match. He made accurate predictions for the matches played in the 2010 FIFA World Cup.

What if a browser could do the same thing? What if it anticipated the next page that the user was going to visit and downloaded it in advance? If that happened, it would help download critical resources ahead of time and significantly affect its performance.

One might say, ‘isn’t that what cache is for?’ Well yes, it is. Caching helps browsers avoid making expensive HTTP calls and delivers needed resources from the disk cache. However, it presents many challenges on modern websites and situations, where caching may not help:

  • First-time visitors: Cache only helps if the site is visited for a second or third time by a user. If you visit a site for the first time, caching would have not kicked in.
  • Expired cache: 69% of resources don’t have any cache headers or are cacheable for less than a day. If the user is visiting a page the second time and the cache has expired, then an HTTP request is needed to check for a fresh resource. Let’s assume that the web server states that the cache is valid, then network delays could factor in and make the pages load slowly.
  • Purged cache: If browser starts caching resources for every website, it’s possible that the browser will purge a website’s cache to make room for another.
  • Cleared cache: Cache gets cleared very frequently. It’s often done by the user, as well as some tools on your computer such as an antivirus program.

To address issues presented by caching, we need to do something more; this is where a pre-browsing or predictive browsing/prefetching, technique comes into play.

Prefetching defined
Websites today are driven by dynamic content and multimedia. A single webpage may load multiple images and videos from different sources which could result in long wait times and a poor user experience.

Modern browsers, such as Chrome, address this challenge by downloading the content in advanced. Different content, which will most likely be accessed by the user, gets downloaded in the background and becomes instantly available when the user needs to interact with it. This performance optimization technique is called pre-fetching, and it can help in reducing DNS lookup times, TCP connections, HTTPS handshakes, etc.

A few methods in practice today include:

  • DNS Prefetching
  • Link Prefetching
  • Prerendering

Types of prefetching
1. DNS Prefetching: Usually, a domain lookup takes anywhere between 1 milliseconds to several seconds, depending on caching done at different levels involved in DNS resolution process. DNS prefetching reduces domain lookup times by resolving different domains, such as Google Analytics or other social media domains a that need to load different resources on the webpage in advance.

Browsers such as Chrome, Firefox, etc., allow DNS prefetching by default; this allows a page to resolve different domains, which deliver content (such as eternal JS, images, etc.) on the page, in advance. Although modern browsers support DNS prefetch, it is still not available on mobile browsers and older IE versions. Also, if an external file has references to other domains, then the browser will not prefetch those until the external file has been downloaded and parsed. In such cases, we can explicitly ask the browser to do a DNS prefetch by specifying DNS-prefetch in your page’s <head> tag as shown below:

<link rel=’dns-prefetch’ href=’http://abc.com’>

Now, when the browser parses the page and comes across this HTML tag, it immediately performs DNS lookup in the background for the specified domain. When the resource from this domain is called, it only requires resource download and no more DNS lookup.

Let’s take an example of a user visiting Google Search and searching for “Flipkart iPhone 7.” It is very likely that the user will click on the link www.flipkart.com in the search results. In this case, Google can prefetch DNS for this domain which will help save DNS lookup time when the user visits www.flipkart.com.

The snapshot below illustrates DNS prefetch implemented on their pages:

2. Link Prefetching: It is a technique which downloads the entire resource including font, images, etc. If we are confident that the user will navigate to flipkart.com and we are aware of the site’s critical resources, then we can download these resources in advance using prefetch.

<link rel=’prefetch’ href=’http://www.flipkart.com/critical.js’>

Currently, its implementation is not consistent, and its specs are vague. So, you might see different implementation by different browsers such as:

  • Firefox downloads one prefetch at a time whenever it is idle. Chrome, on the other hand, downloads up to 10 resources in parallel.
  • Android browser, Firefox browser, and Firefox mobile browser starts prefetching after “window.onload” but Chrome does it immediately which impacts the page’s resource download as it utilizes current TCP connections.

It is best to prefetch only those resources that are critical to the page and cacheable.

3. Prerendering: This is a next level technique which downloads the entire webpage content and caches it in the background. With prerendering, the browser creates DOM tree, applies CSS, executes JS, etc.

In the same example that we considered above, if we are certain that the users next action would be to visit www.flipkart.com, then we can prerender the entire webpage like this:

<link rel=’prerender href=’http://www.flipkart.com/’>

When the browser encounters this, it will load the webpage and all the necessary resources in a hidden tab. If the user visits the specified URL, then the current tab is replaced with the new tab making the webpage visible instantly. Google Search has had this feature for years under the name Instant Pages. Microsoft recently announced they’re going to implement a similar feature for prerendering in Bing on IE11.

The following image illustrates the browser support for the pre-browsing techniques mentioned above:

It is very important to proactively monitor webpages to ensure if this performance optimization technique is working or not. Catchpoint’s digital experience intelligence platform helps you monitor it actively (synthetic monitoring) and passively (real user measurement).

The post Using Prefetch as a Proactive Approach appeared first on Catchpoint's Blog - Web Performance Monitoring.

More Stories By Mehdi Daoudi

Catchpoint radically transforms the way businesses manage, monitor, and test the performance of online applications. Truly understand and improve user experience with clear visibility into complex, distributed online systems.

Founded in 2008 by four DoubleClick / Google executives with a passion for speed, reliability and overall better online experiences, Catchpoint has now become the most innovative provider of web performance testing and monitoring solutions. We are a team with expertise in designing, building, operating, scaling and monitoring highly transactional Internet services used by thousands of companies and impacting the experience of millions of users. Catchpoint is funded by top-tier venture capital firm, Battery Ventures, which has invested in category leaders such as Akamai, Omniture (Adobe Systems), Optimizely, Tealium, BazaarVoice, Marketo and many more.

@ThingsExpo Stories
"Evatronix provides design services to companies that need to integrate the IoT technology in their products but they don't necessarily have the expertise, knowledge and design team to do so," explained Adam Morawiec, VP of Business Development at Evatronix, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Smart cities have the potential to change our lives at so many levels for citizens: less pollution, reduced parking obstacles, better health, education and more energy savings. Real-time data streaming and the Internet of Things (IoT) possess the power to turn this vision into a reality. However, most organizations today are building their data infrastructure to focus solely on addressing immediate business needs vs. a platform capable of quickly adapting emerging technologies to address future ...
In his Opening Keynote at 21st Cloud Expo, John Considine, General Manager of IBM Cloud Infrastructure, led attendees through the exciting evolution of the cloud. He looked at this major disruption from the perspective of technology, business models, and what this means for enterprises of all sizes. John Considine is General Manager of Cloud Infrastructure Services at IBM. In that role he is responsible for leading IBM’s public cloud infrastructure including strategy, development, and offering m...
Product connectivity goes hand and hand these days with increased use of personal data. New IoT devices are becoming more personalized than ever before. In his session at 22nd Cloud Expo | DXWorld Expo, Nicolas Fierro, CEO of MIMIR Blockchain Solutions, will discuss how in order to protect your data and privacy, IoT applications need to embrace Blockchain technology for a new level of product security never before seen - or needed.
The 22nd International Cloud Expo | 1st DXWorld Expo has announced that its Call for Papers is open. Cloud Expo | DXWorld Expo, to be held June 5-7, 2018, at the Javits Center in New York, NY, brings together Cloud Computing, Digital Transformation, Big Data, Internet of Things, DevOps, Machine Learning and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding busin...
SYS-CON Events announced today that Synametrics Technologies will exhibit at SYS-CON's 22nd International Cloud Expo®, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. Synametrics Technologies is a privately held company based in Plainsboro, New Jersey that has been providing solutions for the developer community since 1997. Based on the success of its initial product offerings such as WinSQL, Xeams, SynaMan and Syncrify, Synametrics continues to create and hone inn...
Digital Transformation (DX) is not a "one-size-fits all" strategy. Each organization needs to develop its own unique, long-term DX plan. It must do so by realizing that we now live in a data-driven age, and that technologies such as Cloud Computing, Big Data, the IoT, Cognitive Computing, and Blockchain are only tools. In her general session at 21st Cloud Expo, Rebecca Wanta explained how the strategy must focus on DX and include a commitment from top management to create great IT jobs, monitor ...
Cloud Expo | DXWorld Expo have announced the conference tracks for Cloud Expo 2018. Cloud Expo will be held June 5-7, 2018, at the Javits Center in New York City, and November 6-8, 2018, at the Santa Clara Convention Center, Santa Clara, CA. Digital Transformation (DX) is a major focus with the introduction of DX Expo within the program. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive ov...
A strange thing is happening along the way to the Internet of Things, namely far too many devices to work with and manage. It has become clear that we'll need much higher efficiency user experiences that can allow us to more easily and scalably work with the thousands of devices that will soon be in each of our lives. Enter the conversational interface revolution, combining bots we can literally talk with, gesture to, and even direct with our thoughts, with embedded artificial intelligence, whic...
Recently, REAN Cloud built a digital concierge for a North Carolina hospital that had observed that most patient call button questions were repetitive. In addition, the paper-based process used to measure patient health metrics was laborious, not in real-time and sometimes error-prone. In their session at 21st Cloud Expo, Sean Finnerty, Executive Director, Practice Lead, Health Care & Life Science at REAN Cloud, and Dr. S.P.T. Krishnan, Principal Architect at REAN Cloud, discussed how they built...
Recently, WebRTC has a lot of eyes from market. The use cases of WebRTC are expanding - video chat, online education, online health care etc. Not only for human-to-human communication, but also IoT use cases such as machine to human use cases can be seen recently. One of the typical use-case is remote camera monitoring. With WebRTC, people can have interoperability and flexibility for deploying monitoring service. However, the benefit of WebRTC for IoT is not only its convenience and interopera...
With tough new regulations coming to Europe on data privacy in May 2018, Calligo will explain why in reality the effect is global and transforms how you consider critical data. EU GDPR fundamentally rewrites the rules for cloud, Big Data and IoT. In his session at 21st Cloud Expo, Adam Ryan, Vice President and General Manager EMEA at Calligo, examined the regulations and provided insight on how it affects technology, challenges the established rules and will usher in new levels of diligence arou...
SYS-CON Events announced today that Evatronix will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Evatronix SA offers comprehensive solutions in the design and implementation of electronic systems, in CAD / CAM deployment, and also is a designer and manufacturer of advanced 3D scanners for professional applications.
To get the most out of their data, successful companies are not focusing on queries and data lakes, they are actively integrating analytics into their operations with a data-first application development approach. Real-time adjustments to improve revenues, reduce costs, or mitigate risk rely on applications that minimize latency on a variety of data sources. In his session at @BigDataExpo, Jack Norris, Senior Vice President, Data and Applications at MapR Technologies, reviewed best practices to ...
No hype cycles or predictions of a gazillion things here. IoT is here. You get it. You know your business and have great ideas for a business transformation strategy. What comes next? Time to make it happen. In his session at @ThingsExpo, Jay Mason, an Associate Partner of Analytics, IoT & Cybersecurity at M&S Consulting, presented a step-by-step plan to develop your technology implementation strategy. He also discussed the evaluation of communication standards and IoT messaging protocols, data...
In his session at 21st Cloud Expo, Raju Shreewastava, founder of Big Data Trunk, provided a fun and simple way to introduce Machine Leaning to anyone and everyone. He solved a machine learning problem and demonstrated an easy way to be able to do machine learning without even coding. Raju Shreewastava is the founder of Big Data Trunk (www.BigDataTrunk.com), a Big Data Training and consulting firm with offices in the United States. He previously led the data warehouse/business intelligence and B...
"Digital transformation - what we knew about it in the past has been redefined. Automation is going to play such a huge role in that because the culture, the technology, and the business operations are being shifted now," stated Brian Boeggeman, VP of Alliances & Partnerships at Ayehu, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Nordstrom is transforming the way that they do business and the cloud is the key to enabling speed and hyper personalized customer experiences. In his session at 21st Cloud Expo, Ken Schow, VP of Engineering at Nordstrom, discussed some of the key learnings and common pitfalls of large enterprises moving to the cloud. This includes strategies around choosing a cloud provider(s), architecture, and lessons learned. In addition, he covered some of the best practices for structured team migration an...
22nd International Cloud Expo, taking place June 5-7, 2018, at the Javits Center in New York City, NY, and co-located with the 1st DXWorld Expo will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud ...
22nd International Cloud Expo, taking place June 5-7, 2018, at the Javits Center in New York City, NY, and co-located with the 1st DXWorld Expo will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud ...