Welcome!

Linux Containers Authors: Liz McMillan, Jason Bloomberg, Zakia Bouachraoui, Yeshim Deniz, Elizabeth White

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

@DevOpsSummit: Article

Ops, APIs and Compression | @DevOpsSummit #API #APM #DevOps

I’ve been reading up on APIs. In particular I really enjoyed reading Best Practices for Designing a Pragmatic RESTful API

I've been reading up on APIs cause, coolness. And in particular I really enjoyed reading Best Practices for Designing a Pragmatic RESTful API because it had a lot of really good information and advice.

And then I got to the part about compressing your APIs.

Before we go too far let me first say I'm not saying you shouldn't compress your API or app responses. You probably should. What I am saying is that where you compress data and when are important considerations.

That's because generally speaking no one has put their web server (which is ultimately what tends to serve up responses, whether they're APIs or objects, XML or JSON) at the edge of the Internet. You know, where it's completely vulnerable. It's usually several devices back in the networking gauntlet that has be run before data gets from the edge of your network to the server.

wrong architecture

This is because there are myriad bad actors out salivating at the prospect of a return to an early aughts data center architecture in which firewalls, DDoS protection, and other app security services were not physically and logically located upstream from the apps they protect today.

Cause if you don't have to navigate the network, it's way easier to launch an attack on an app.

Today, we employ an average of 11 different services in the network, upstream from the app, to provide security, scale, and performance-enhancing services. Like compression.

better architecture

Now, you can enable compression on the web server. It's a standard thing in HTTP and it's little more than a bit to flip in the configuration. Easy peasy performance-enhancing change, right?

Except that today that's not always true.

The primary reason compression improves performance is because when it reduces the size of data it reduces the number of packets that must be transmitted. That reduces the potential for congestion that causes a Catch-22 where TCP retransmits increase congestion that increases packet loss that increases... well, you get the picture. This is particularly true when mobile clients are connecting via cellular networks, because latency is a real issue for them and the more round trips it takes, the worse the application experience.

Suffice to say that the primary reason compression improves performance is that it reduces the amount of data needing to be transmitted which means "faster" delivery to the client. Fewer packets = less time = happier users.

That's a good thing. Except when compression gets in the way or doesn't provide any real reduction that would improve performance.

What? How can that be, you ask.

Remember that we're looking for compression to reduce the number of packets transmitted, especially when it has to traverse a higher latency, lower capacity link between the data center and the client.

It turns out that sometimes compression doesn't really help with that.

Consider the aforementioned article and its section on compressing. The author ran some tests, and concluded that compression of text-based data produces some really awesome results:

Let's look at this with a real world example. I've pulled some data from GitHub's API, which uses pretty print by default. I'll also be doing some gzip comparisons:

$ curl https://api.github.com/users/veesahni > with-whitespace.txt $ ruby -r json -e 'puts JSON JSON.parse(STDIN.read)' < with-whitespace.txt > without-whitespace.txt
$ gzip -c with-whitespace.txt > with-whitespace.txt.gz
$ gzip -c without-whitespace.txt > without-whitespace.txt.gz

The output files have the following sizes:

  • without-whitespace.txt - 1252 bytes
  • with-whitespace.txt - 1369 bytes
  • without-whitespace.txt.gz - 496 bytes
  • with-whitespace.txt.gz - 509 bytes

In this example, the whitespace increased the output size by 8.5% when gzip is not in play and 2.6% when gzip is in play. On the other hand, the act of gzipping in itself provided over 60% in bandwidth savings. Since the cost of pretty printing is relatively small, it's best to pretty print by default and ensure gzip compression is supported!

To further hammer in this point, Twitter found that there was an 80% savings (in some cases)when enabling gzip compression on their Streaming API. Stack Exchange went as far as to never return a response that's not compressed!

Wow! I mean, from a purely mathematical perspective, that's some awesome results. And the author is correct in saying it will provide bandwidth savings.

What those results won't necessarily do is improve performance because the original size of the file was already less than the MSS for a single packet. Which means compressed or not, that data takes exactly one packet to transmit. That's it. I won't bore you with the mathematics, but the speed of light and networking says one packet takes the same amount of time to transit whether it's got 496 bytes of payload or 1396 bytes of payload. The typical MSS for Ethernet packets is 1460 bytes, which means compressing something smaller than that effectively nets you nothing in terms of performance. It's like a plane. It takes as long to fly from point A to point B whether there are 14 passengers or 140. Fuel efficiency (bandwidth) is impacted, but that doesn't really change performance, just the cost.

Furthermore, compressing the payload at the web server means that web app security services upstream have to decompress if they want to do their job, which is to say scan responses for sensitive or excessive data indicative of a breach of security policies. This is a big deal, kids. 42% of respondents in our annual security strategy to prevent data leaks. Which means they have to spend extra time to decompress the data to evaluate it and then recompress it, or perhaps they can't inspect it at all.

State of Application Delivery survey always scan responses as part of their overall attack-surfaces-soad-2016

Now, that said, bandwidth savings are a good thing. It's part of any comprehensive scaling strategy to consider the impact of increasing use of an app on bandwidth. And a clogged up network can impact performance negatively so compression is a good idea. But not necessarily at the web server. This is akin to carefully considering where you enforce SSL/TLS security measures, as there are similar impacts on security services upstream from the app / web server.

That's why the right place for compression and SSL/TLS is generally upstream, in the network, after security has checked out the response and it's actually ready to be delivered to the client. That's usually the load balancing service or the ADC, where compression can not only be applied most efficiently and without interfering with security services and offsetting the potential gains by forcing extra processing upstream.

As with rate limiting APIs, it's not always a matter of whether or not you should, it's a matter of where you should.

Architecture, not algorithms, are the key to scale and performance of modern applications.

Read the original blog entry...

More Stories By Lori MacVittie

Lori MacVittie is responsible for education and evangelism of application services available across F5’s entire product suite. Her role includes authorship of technical materials and participation in a number of community-based forums and industry standards organizations, among other efforts. MacVittie has extensive programming experience as an application architect, as well as network and systems development and administration expertise. Prior to joining F5, MacVittie was an award-winning Senior Technology Editor at Network Computing Magazine, where she conducted product research and evaluation focused on integration with application and network architectures, and authored articles on a variety of topics aimed at IT professionals. Her most recent area of focus included SOA-related products and architectures. She holds a B.S. in Information and Computing Science from the University of Wisconsin at Green Bay, and an M.S. in Computer Science from Nova Southeastern University.

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


IoT & Smart Cities Stories
The challenges of aggregating data from consumer-oriented devices, such as wearable technologies and smart thermostats, are fairly well-understood. However, there are a new set of challenges for IoT devices that generate megabytes or gigabytes of data per second. Certainly, the infrastructure will have to change, as those volumes of data will likely overwhelm the available bandwidth for aggregating the data into a central repository. Ochandarena discusses a whole new way to think about your next...
CloudEXPO | DevOpsSUMMIT | DXWorldEXPO are the world's most influential, independent events where Cloud Computing was coined and where technology buyers and vendors meet to experience and discuss the big picture of Digital Transformation and all of the strategies, tactics, and tools they need to realize their goals. Sponsors of DXWorldEXPO | CloudEXPO benefit from unmatched branding, profile building and lead generation opportunities.
All in Mobile is a place where we continually maximize their impact by fostering understanding, empathy, insights, creativity and joy. They believe that a truly useful and desirable mobile app doesn't need the brightest idea or the most advanced technology. A great product begins with understanding people. It's easy to think that customers will love your app, but can you justify it? They make sure your final app is something that users truly want and need. The only way to do this is by ...
Digital Transformation and Disruption, Amazon Style - What You Can Learn. Chris Kocher is a co-founder of Grey Heron, a management and strategic marketing consulting firm. He has 25+ years in both strategic and hands-on operating experience helping executives and investors build revenues and shareholder value. He has consulted with over 130 companies on innovating with new business models, product strategies and monetization. Chris has held management positions at HP and Symantec in addition to ...
DXWorldEXPO LLC announced today that Big Data Federation to Exhibit at the 22nd International CloudEXPO, colocated with DevOpsSUMMIT and DXWorldEXPO, November 12-13, 2018 in New York City. Big Data Federation, Inc. develops and applies artificial intelligence to predict financial and economic events that matter. The company uncovers patterns and precise drivers of performance and outcomes with the aid of machine-learning algorithms, big data, and fundamental analysis. Their products are deployed...
Dynatrace is an application performance management software company with products for the information technology departments and digital business owners of medium and large businesses. Building the Future of Monitoring with Artificial Intelligence. Today we can collect lots and lots of performance data. We build beautiful dashboards and even have fancy query languages to access and transform the data. Still performance data is a secret language only a couple of people understand. The more busine...
Cell networks have the advantage of long-range communications, reaching an estimated 90% of the world. But cell networks such as 2G, 3G and LTE consume lots of power and were designed for connecting people. They are not optimized for low- or battery-powered devices or for IoT applications with infrequently transmitted data. Cell IoT modules that support narrow-band IoT and 4G cell networks will enable cell connectivity, device management, and app enablement for low-power wide-area network IoT. B...
The hierarchical architecture that distributes "compute" within the network specially at the edge can enable new services by harnessing emerging technologies. But Edge-Compute comes at increased cost that needs to be managed and potentially augmented by creative architecture solutions as there will always a catching-up with the capacity demands. Processing power in smartphones has enhanced YoY and there is increasingly spare compute capacity that can be potentially pooled. Uber has successfully ...
SYS-CON Events announced today that CrowdReviews.com has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5–7, 2018, at the Javits Center in New York City, NY. CrowdReviews.com is a transparent online platform for determining which products and services are the best based on the opinion of the crowd. The crowd consists of Internet users that have experienced products and services first-hand and have an interest in letting other potential buye...
When talking IoT we often focus on the devices, the sensors, the hardware itself. The new smart appliances, the new smart or self-driving cars (which are amalgamations of many ‘things'). When we are looking at the world of IoT, we should take a step back, look at the big picture. What value are these devices providing. IoT is not about the devices, its about the data consumed and generated. The devices are tools, mechanisms, conduits. This paper discusses the considerations when dealing with the...