|By Steve Weisfeldt||
|February 11, 2013 05:00 PM EST||
Load testing, perhaps more than any other form of testing, is one of those activities that you either choose to do well or risk a result that leaves you worse off than not doing it at all. Half-hearted attempts at load testing yield "results," but too often those results are inaccurate, leading to a false sense of security for anyone who trusts them. This, in turn, leads to the release of applications that are not adequately tested and that experience performance problems soon after entering production.
I was reminded of this not long ago, when I worked with a customer who related an experience that may sound familiar to many of you. This customer was a test engineer for a bank that had recently merged with another bank, effectively doubling their customer base. He was part of a team responsible for load testing a new web application that would serve customers from both of the original banks. Before the application was rolled out, they performed load tests and confirmed that the application could handle the expected number of users with acceptable response times. When the system went live, however, it was slow as molasses - even under user loads less than what the team had tested.
The problem, as you may have guessed, was that the team had not accurately modeled the load. The virtual users used in the testing were a homogenous group that interacted with the system in roughly the same way, from roughly the same geographic locations, at the same network speed. In reality, the customers who came from Bank A tended to perform certain transactions much more frequently than those who came from Bank B. Most of Bank B's customers lived in a different part of the country than those from Bank A. More important, customers from both banks were accessing the application at widely differing connection speeds across a range of browsers. None of these factors were modeled accurately in the load tests the team had performed. In some cases it was because the team simply had not considered them, in others it was because the load testing tool they were using provided no way to handle these differences. In either case, the result was the same; the team had given the "go live" signal to an application that was not ready, basing their decision on inaccurate load test results.
Too often, organizations take a short cut to load testing. They are focused on a single number: how many concurrent users their application will support. As a result they put little effort into script development, and they end up with an unrealistic test - one of little value. I encourage all load testers to think beyond the concurrent users metric and take a closer look at other factors that go into creating a realistic load that will yield more accurate results, including:
- Modeling user activity
- Modeling different connection speeds
- Modeling different browsers and mobile devices
- Modeling geographically distributed users
Parameterizing Scripts to Better Model User Activity
Scripts that simply record a typical user's interaction with a web application and then play it back are not going to yield accurate performance data. As an example, a script that emulates a user logging into a site, searching for a product, placing it in the cart, and checking out does little to test the performance of other user activities such as checking product reviews, accessing detailed specifications, or comparing products.
More important, if the script always logs in as the same user and orders the same product, caching effects will often skew the performance measurements, making response times shorter than they would be under a real-world load. Caching on the web server, application server, and database server all come into play, compounding any caching that is done on the client side.
To minimize caching and similar effects, scripts must be parameterized. In my example above, the script would play back different users searching for different products, and purchasing them via different methods. Ideally the script would use randomization or data customization to fill in every user editable or selectable element on each form of the web application. This script parameterization, combined with creating multiple scripts to address a variety of user interactions, produces a much more realistic user load, and it's a good idea to have a load testing tool that simplifies these tasks.
Generating a Load with a Mixture of Connection Speeds and Network Characteristics
Many testing teams use the fastest available network connections when load testing a server. The belief is that if the application performs well under those connections, it will be guaranteed to work well in production when many real-world users will have slower connections. This is a faulty assumption that leads to performance problems when the application is subjected to real-world users accessing it at a variety of network bandwidths.
Testing with only high-speed connections can mask performance problems that occur only when lower speed connections are used. Slower data speeds will require connections to the server to stay open longer, and eventually the server may reach its limit for the maximum number of open connections.
Of course, testing with only low-speed connections is equally problematic. What's needed is a reasonable mixture of virtual users accessing the server at connection speeds representative of everything from 56K modems for dial-up users to T3 lines.
With more and more users accessing the web via mobile devices, it makes sense to include 3G and 4G connection rates in the mix as well. It's also important to take into account disparities in signal strength that can cause packet loss and increased network latency. Built-in support for incorporating these factors in performance testing is increasingly important, particularly for web applications that serve a high percentage of mobile users.
Emulating Different Browsers and Native Mobile Apps
Interestingly enough (and often surprising to some), not all browsers support the same number of concurrent HTTP connections. This obviously needs to be thought of as well - if a load test models the entire user population accessing a web application with a single browser that supports four connections per server, it neglects the effects of browsers that use twice that number.
This leads to a situation similar to the one that arises with inaccurate modeling of connection speeds - with more concurrent connections, it is not unusual to see slowdowns as a server reaches its limit for simultaneous connections. To minimize these effects, load tests should apply a variety of browser profiles during playback, so that the tests identify the traffic as originating from a realistic mixture of different browsers, including mobile browsers.
Mobile devices, in fact, present a new set of challenges for load testers (see Best Practices for Load Testing Mobile Applications, Part 1 and Best Practices for Load Testing Mobile Applications, Part 2), aside from the network connection issues I've already covered. Many companies now have a separate mobile version of their site, with content tailored specifically for mobile users. Again, to perform a valid load test on such sites, a test engineer must be able to override the browser identification during playback so that the virtual user appears to be using a mobile browser.
What about native mobile applications? There is no browser involved, so you'll need a testing solution that can record, parameterize, and play back the network traffic originating from the mobile device. For some cases this can be done via a proxy, but for some apps this is not an available option. These apps may call for a tunneling approach in which the testing tool acts as a DNS server. Even if you're not facing this situation today, you may want to see if your testing tool supports this feature so you're prepared when you do need it.
Generating a Geographically Distributed Load
Unless your end-user community is accessing your application from a single location, initiating tests solely from inside your datacenter is unlikely to represent a realistic load. Such tests fail to take into account the effects of third-party servers and content delivery networks that may sit between your users and your web application.
Using the cloud to generate load as part of your testing can better model a geographically distributed user base, one that may include users from around the world, enabling test engineers to generate realistic, large-scale tests across multiple regions. Cloud testing complements internal, lab-based tests and ideally test scripts from one domain are reused in the other. With separate performance metrics for each geographic region in hand, engineers can see where performance issues are likely to arise on a region-by-region basis.
If users are accessing your web site from all over the world, load testing from the cloud helps you model that reality. When this capability is combined with tests that incorporate parameterized scripts, browser differences, support for mobile apps, and a variety of connection speeds and network effects, you can trust the accuracy of your test results.
We are reaching the end of the beginning with WebRTC, and real systems using this technology have begun to appear. One challenge that faces every WebRTC deployment (in some form or another) is identity management. For example, if you have an existing service – possibly built on a variety of different PaaS/SaaS offerings – and you want to add real-time communications you are faced with a challenge relating to user management, authentication, authorization, and validation. Service providers will want to use their existing identities, but these will have credentials already that are (hopefully) i...
Nov. 27, 2014 04:00 AM EST Reads: 1,040
"Matrix is an ambitious open standard and implementation that's set up to break down the fragmentation problems that exist in IP messaging and VoIP communication," explained John Woolf, Technical Evangelist at Matrix, in this SYS-CON.tv interview at @ThingsExpo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Nov. 27, 2014 04:00 AM EST Reads: 992
Connected devices and the Internet of Things are getting significant momentum in 2014. In his session at Internet of @ThingsExpo, Jim Hunter, Chief Scientist & Technology Evangelist at Greenwave Systems, examined three key elements that together will drive mass adoption of the IoT before the end of 2015. The first element is the recent advent of robust open source protocols (like AllJoyn and WebRTC) that facilitate M2M communication. The second is broad availability of flexible, cost-effective storage designed to handle the massive surge in back-end data in a world where timely analytics is e...
Nov. 26, 2014 11:45 PM EST Reads: 1,129
How do APIs and IoT relate? The answer is not as simple as merely adding an API on top of a dumb device, but rather about understanding the architectural patterns for implementing an IoT fabric. There are typically two or three trends: Exposing the device to a management framework Exposing that management framework to a business centric logic Exposing that business layer and data to end users. This last trend is the IoT stack, which involves a new shift in the separation of what stuff happens, where data lives and where the interface lies. For instance, it's a mix of architectural styles ...
Nov. 26, 2014 11:30 PM EST Reads: 1,009
The Internet of Things will put IT to its ultimate test by creating infinite new opportunities to digitize products and services, generate and analyze new data to improve customer satisfaction, and discover new ways to gain a competitive advantage across nearly every industry. In order to help corporate business units to capitalize on the rapidly evolving IoT opportunities, IT must stand up to a new set of challenges. In his session at @ThingsExpo, Jeff Kaplan, Managing Director of THINKstrategies, will examine why IT must finally fulfill its role in support of its SBUs or face a new round of...
Nov. 26, 2014 09:00 PM EST Reads: 1,058
Cultural, regulatory, environmental, political and economic (CREPE) conditions over the past decade are creating cross-industry solution spaces that require processes and technologies from both the Internet of Things (IoT), and Data Management and Analytics (DMA). These solution spaces are evolving into Sensor Analytics Ecosystems (SAE) that represent significant new opportunities for organizations of all types. Public Utilities throughout the world, providing electricity, natural gas and water, are pursuing SmartGrid initiatives that represent one of the more mature examples of SAE. We have s...
Nov. 26, 2014 06:00 PM EST Reads: 1,053
The Internet of Things will greatly expand the opportunities for data collection and new business models driven off of that data. In her session at @ThingsExpo, Esmeralda Swartz, CMO of MetraTech, discussed how for this to be effective you not only need to have infrastructure and operational models capable of utilizing this new phenomenon, but increasingly service providers will need to convince a skeptical public to participate. Get ready to show them the money!
Nov. 26, 2014 04:00 PM EST Reads: 1,093
One of the biggest challenges when developing connected devices is identifying user value and delivering it through successful user experiences. In his session at Internet of @ThingsExpo, Mike Kuniavsky, Principal Scientist, Innovation Services at PARC, described an IoT-specific approach to user experience design that combines approaches from interaction design, industrial design and service design to create experiences that go beyond simple connected gadgets to create lasting, multi-device experiences grounded in people's real needs and desires.
Nov. 26, 2014 03:45 PM EST Reads: 1,041
P2P RTC will impact the landscape of communications, shifting from traditional telephony style communications models to OTT (Over-The-Top) cloud assisted & PaaS (Platform as a Service) communication services. The P2P shift will impact many areas of our lives, from mobile communication, human interactive web services, RTC and telephony infrastructure, user federation, security and privacy implications, business costs, and scalability. In his session at @ThingsExpo, Robin Raymond, Chief Architect at Hookflash, will walk through the shifting landscape of traditional telephone and voice services ...
Nov. 26, 2014 02:00 PM EST Reads: 1,506
Scott Jenson leads a project called The Physical Web within the Chrome team at Google. Project members are working to take the scalability and openness of the web and use it to talk to the exponentially exploding range of smart devices. Nearly every company today working on the IoT comes up with the same basic solution: use my server and you'll be fine. But if we really believe there will be trillions of these devices, that just can't scale. We need a system that is open a scalable and by using the URL as a basic building block, we open this up and get the same resilience that the web enjoys.
Nov. 25, 2014 09:30 PM EST Reads: 1,259
The Internet of Things is tied together with a thin strand that is known as time. Coincidentally, at the core of nearly all data analytics is a timestamp. When working with time series data there are a few core principles that everyone should consider, especially across datasets where time is the common boundary. In his session at Internet of @ThingsExpo, Jim Scott, Director of Enterprise Strategy & Architecture at MapR Technologies, discussed single-value, geo-spatial, and log time series data. By focusing on enterprise applications and the data center, he will use OpenTSDB as an example t...
Nov. 25, 2014 09:30 PM EST Reads: 1,318
The Domain Name Service (DNS) is one of the most important components in networking infrastructure, enabling users and services to access applications by translating URLs (names) into IP addresses (numbers). Because every icon and URL and all embedded content on a website requires a DNS lookup loading complex sites necessitates hundreds of DNS queries. In addition, as more internet-enabled ‘Things' get connected, people will rely on DNS to name and find their fridges, toasters and toilets. According to a recent IDG Research Services Survey this rate of traffic will only grow. What's driving t...
Nov. 25, 2014 07:00 PM EST Reads: 1,351
Enthusiasm for the Internet of Things has reached an all-time high. In 2013 alone, venture capitalists spent more than $1 billion dollars investing in the IoT space. With "smart" appliances and devices, IoT covers wearable smart devices, cloud services to hardware companies. Nest, a Google company, detects temperatures inside homes and automatically adjusts it by tracking its user's habit. These technologies are quickly developing and with it come challenges such as bridging infrastructure gaps, abiding by privacy concerns and making the concept a reality. These challenges can't be addressed w...
Nov. 25, 2014 04:30 PM EST Reads: 1,356
Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at Internet of @ThingsExpo, James Kirkland, Chief Architect for the Internet of Things and Intelligent Systems at Red Hat, described how to revolutioniz...
Nov. 24, 2014 07:00 PM EST Reads: 1,652
Bit6 today issued a challenge to the technology community implementing Web Real Time Communication (WebRTC). To leap beyond WebRTC’s significant limitations and fully leverage its underlying value to accelerate innovation, application developers need to consider the entire communications ecosystem.
Nov. 24, 2014 12:00 PM EST Reads: 1,540
The definition of IoT is not new, in fact it’s been around for over a decade. What has changed is the public's awareness that the technology we use on a daily basis has caught up on the vision of an always on, always connected world. If you look into the details of what comprises the IoT, you’ll see that it includes everything from cloud computing, Big Data analytics, “Things,” Web communication, applications, network, storage, etc. It is essentially including everything connected online from hardware to software, or as we like to say, it’s an Internet of many different things. The difference ...
Nov. 24, 2014 11:00 AM EST Reads: 1,675
Cloud Expo 2014 TV commercials will feature @ThingsExpo, which was launched in June, 2014 at New York City's Javits Center as the largest 'Internet of Things' event in the world.
Nov. 24, 2014 09:00 AM EST Reads: 1,697
SYS-CON Events announced today that Windstream, a leading provider of advanced network and cloud communications, has been named “Silver Sponsor” of SYS-CON's 16th International Cloud Expo®, which will take place on June 9–11, 2015, at the Javits Center in New York, NY. Windstream (Nasdaq: WIN), a FORTUNE 500 and S&P 500 company, is a leading provider of advanced network communications, including cloud computing and managed services, to businesses nationwide. The company also offers broadband, phone and digital TV services to consumers primarily in rural areas.
Nov. 23, 2014 07:30 PM EST Reads: 1,856
"There is a natural synchronization between the business models, the IoT is there to support ,” explained Brendan O'Brien, Co-founder and Chief Architect of Aria Systems, in this SYS-CON.tv interview at the 15th International Cloud Expo®, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Nov. 23, 2014 12:00 PM EST Reads: 1,806
The major cloud platforms defy a simple, side-by-side analysis. Each of the major IaaS public-cloud platforms offers their own unique strengths and functionality. Options for on-site private cloud are diverse as well, and must be designed and deployed while taking existing legacy architecture and infrastructure into account. Then the reality is that most enterprises are embarking on a hybrid cloud strategy and programs. In this Power Panel at 15th Cloud Expo (http://www.CloudComputingExpo.com), moderated by Ashar Baig, Research Director, Cloud, at Gigaom Research, Nate Gordon, Director of T...
Nov. 23, 2014 07:45 AM EST Reads: 1,844