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(Note: I'm the founder of a cloud-based load testing provider...) Well, there are a lot of reasons why cloud-based load testing makes sense beyond scripting. B

(Note: I'm the founder of a cloud-based load testing provider...) Well, there are a lot of reasons why cloud-based load testing makes sense beyond scripting. But specifically about scripting, I believe that the cloud actually _does_ make script creation MUCH easier and script playback MUCH more realistic. Here's why: Traditional load testing tools emulate HTTP traffic. Their recorders watch the protocol-level traffic a browser makes, and then poor engineers have to disassemble the traffic to make it appear as if thousands of users are coming from one machine. They end up writing regex expressions and other such logic which effectively emulates the more expensive parsing a browser does. Often times, especially with rich AJAX apps, they end up duplicate much of the same code written as JavaScript to run in the browser, but this time inside of their load tool. For an example, see my article on why load testing is hard when it comes to AJAX: http://ajaxian.com/archives/why-load-testing-ajax-is-hard http://ajaxian.com/archives/why-load-testing-ajax-is-hard With cloud-based scalability, a new opportunity is here: to ditch the old ways of load testing and actually use real browsers. Scripts become way simpler because you're no longer scripting complex protocol-level traffic, but instead scripting simpler user behavior. And the script playback becomes more authenticate because you are guaranteed not to have a bug in the protocol-level playback, error reporting can show you what the user actually saw with screenshots, and the traffic pattern is realistic (two connections per host, etc). Of course, not many providers are doing this (yet). My company, BrowserMob, is. Thanks to the cloud, instead of allocating 2GB and 2 CPU cores to a load test, we might allocate 2TB and 2000 CPU cores. But because it's elastic usage, our cost is still low, so our prices stay low too. All of the scripting is done with Selenium, an open source browser automation technology I am a contributor for. If you're interested in trying it out, we provide $100 worth of free trial credits: http://browsermob.com http://browsermob.com Besides the browser vs virtual user stuff, there are definitely plenty of other reasons why the cloud is a great way to do load testing, but I think those have already been touched in the comments.

moe 18y ago
Sorry, but this is exactly the nonsense that I falsely smelled in the original post. Emulating a full fledged browser for a load test is akin to killing a flea with a sledgehammer - a mindboggling waste of ressources. The webserver you are testing couldn't care less whether the requested pages are actually rendered or not. What I'd really want is a smart HTTP session recorder, smarter than Selenium and the ilk at least. The test-creator should perform a few average user-sessions in his browser and then be assisted with inserting smart tokens into the recorded HTTP traffic. The content that passes between browser and server is highly structured anyways, so things like "user clicked on first item" could even largely be auto-determined with a bit of pattern-analysis. I have constructed such tests in the past through ngrep and a bit of scripting magic - so I know it's possible and would merely need to be wrapped up in a shiny GUI. You make the "poor engineer" part sound harder than it has to be here. The place where it becomes really nasty is persistent connections via flash or comet. But plain old HTTP requests (AJAX or not) would be rather easy, if the existing tools didn't suck so hard.
- rlonn 18y ago
  Session recording is something we are very interested in. We currently have a session recorder that is run as a zero-configuration proxy. I.e. you don't need to install any plugin or anything, and you don't need to change your browser configuration. The recorder rewrites all URLs it sees to go through itself rather than directly to the destination. There are other similar proxies that do this - I think one is called phproxy or similar - but ours can also handle javascript, which is a bit unusual. Anyway, if there are people here with bright ideas they feel like sharing about how to construct the greatest recorder of all, don't hesitate to get in touch with us (Load Impact). We have some experience with this and are always interested in collaboration with others.
  - moe 18y ago
    Why did you not implement a real proxy instead of that rewriting hack? Zero-configuration doesn't sound like an argument to me in that context.
- Lightbody 18y ago
  Moe, Sorry, but you haven't convinced me. Yes, a very smart engineer with knowledge of all the internal workings of a web app can get by just fine. You seem to be one of those people. Congratulations to you! But not everyone is in the same boat you're in, so don't be so quick to write off new ideas, and certainly no need to impolite about it. I pasted a link about Ajax load testing which, if you read it, explains why your "smart token" idea often won't work and will fail at a growing rate as apps get more complex (ie: as Google evolves to include Google Suggest). I'd love to have a substantial discussion about how one could write a smart recorder (esp. since I'm 99.9% sure it's impossible - I've thought a REALLY long time about it). You say this approach is a "waste of ressources [sic]", but I disagree. If the cost is lower than traditional load testing services (thanks to the cloud), what's the harm in using a higher fidelity approach? To me, the "nonsense" would be avoiding such an approach! Your point about persistent connections is another reason why BrowserMob exists. Why spend hours or days working around an issue like that when you could be focussing on tuning the system performance? Again - if the cost is low enough, why should you care that terabytes of RAM are being used in the process? I appreciate your passion about this, but please understand that not everyone has the knowledge set you do, and not everyone tests the same apps you do. It's too bad you don't appreciate a unique approach to the problem even if it doesn't apply directly to you. Hopefully it doesn't turn off others from thinking outside the box! Patrick

moe 18y ago

Sorry, but this is exactly the nonsense that I falsely smelled in the original post. Emulating a full fledged browser for a load test is akin to killing a flea with a sledgehammer - a mindboggling waste of ressources. The webserver you are testing couldn't care less whether the requested pages are actually rendered or not. What I'd really want is a smart HTTP session recorder, smarter than Selenium and the ilk at least. The test-creator should perform a few average user-sessions in his browser and then be assisted with inserting smart tokens into the recorded HTTP traffic. The content that passes between browser and server is highly structured anyways, so things like "user clicked on first item" could even largely be auto-determined with a bit of pattern-analysis. I have constructed such tests in the past through ngrep and a bit of scripting magic - so I know it's possible and would merely need to be wrapped up in a shiny GUI. You make the "poor engineer" part sound harder than it has to be here. The place where it becomes really nasty is persistent connections via flash or comet. But plain old HTTP requests (AJAX or not) would be rather easy, if the existing tools didn't suck so hard.

rlonn 18y ago
Session recording is something we are very interested in. We currently have a session recorder that is run as a zero-configuration proxy. I.e. you don't need to install any plugin or anything, and you don't need to change your browser configuration. The recorder rewrites all URLs it sees to go through itself rather than directly to the destination. There are other similar proxies that do this - I think one is called phproxy or similar - but ours can also handle javascript, which is a bit unusual. Anyway, if there are people here with bright ideas they feel like sharing about how to construct the greatest recorder of all, don't hesitate to get in touch with us (Load Impact). We have some experience with this and are always interested in collaboration with others.
- moe 18y ago
  Why did you not implement a real proxy instead of that rewriting hack? Zero-configuration doesn't sound like an argument to me in that context.
Lightbody 18y ago
Moe, Sorry, but you haven't convinced me. Yes, a very smart engineer with knowledge of all the internal workings of a web app can get by just fine. You seem to be one of those people. Congratulations to you! But not everyone is in the same boat you're in, so don't be so quick to write off new ideas, and certainly no need to impolite about it. I pasted a link about Ajax load testing which, if you read it, explains why your "smart token" idea often won't work and will fail at a growing rate as apps get more complex (ie: as Google evolves to include Google Suggest). I'd love to have a substantial discussion about how one could write a smart recorder (esp. since I'm 99.9% sure it's impossible - I've thought a REALLY long time about it). You say this approach is a "waste of ressources [sic]", but I disagree. If the cost is lower than traditional load testing services (thanks to the cloud), what's the harm in using a higher fidelity approach? To me, the "nonsense" would be avoiding such an approach! Your point about persistent connections is another reason why BrowserMob exists. Why spend hours or days working around an issue like that when you could be focussing on tuning the system performance? Again - if the cost is low enough, why should you care that terabytes of RAM are being used in the process? I appreciate your passion about this, but please understand that not everyone has the knowledge set you do, and not everyone tests the same apps you do. It's too bad you don't appreciate a unique approach to the problem even if it doesn't apply directly to you. Hopefully it doesn't turn off others from thinking outside the box! Patrick