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  1. #1
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    Problems only seen when recording w/ LR? ...

    I'm trying to record some Web/http transactions using LR 11. It's a new Web system here and our first attempt to automate it.

    We have seen some strange authentication problems on and off and the developers are investigating. For example, at times soon after what appears to be a successful login, the Web site prompts a user to login again, they somehow become unauthenticated. Anyway it happens quite infrequently now.

    Here's the odd thing. When I try to record this site with LoadRunner 11's VuGen, I see the problem EVERY time! It's not a problem if I also have VUGen running, but it is a problem if VUGen is actively recording. It's pretty clear that it's not a coincidence. Has anyone seen anything like this before?

    I'm tinkering with some of the record options now.

    Thanks,
    Chris

  2. #2
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    Re: Problems only seen when recording w/ LR? ...

    Have you tried doing a network capture while you are recording to see what is going on? What type of authentication? What does your client traffic go through to get to the Web server? Do you have clustered servers?

    Sounds like your traffic may not be going back through the original authentication path. Like it is a persistence problem.

  3. #3
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    Re: Problems only seen when recording w/ LR? ...

    [caveat: i'm not a LR user, and have no clue about their underlying technology.. however...]

    > it is a problem if VUGen is actively recording

    interesting.
    most load test tools use a proxy-based recorder for capturing http requests. the side effect being, your requests are taking a slightly different path when in 'recording' mode. They are forwarded through a local proxy server, where some headers *may* be added/dropped/changed.
    my guess is that authentication headers are not the same when proxied by LR recorder as they are in a direct request to the server.
    Corey Goldberg
    Homepage: goldb.org
    Twitter: twitter.com/cgoldberg
    Google+: gplus.to/cgoldberg

  4. #4
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    Re: Problems only seen when recording w/ LR? ...

    [ QUOTE ]
    Have you tried doing a network capture while you are recording to see what is going on? What type of authentication? What does your client traffic go through to get to the Web server? Do you have clustered servers?
    Sounds like your traffic may not be going back through the original authentication path. Like it is a persistence problem.

    [/ QUOTE ]

    Thanks, Alan. Been trying to capture the traffic on another machine with Fiddler and working with Web developers. It does seem to be some kind of persistence problem, my best guess anyway. But why it happens 100% of the the time when LR is recording really has me scratching my head.

  5. #5
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    Re: Problems only seen when recording w/ LR? ...

    Thanks, Corey. That's definitely the concern. Though for what it's worth, in 10 years of LR work I've never seen a problem like this, in which the behavior of the system being tested was adversely affected by having VUGen running.

    [ QUOTE ]
    [caveat: i'm not a LR user, and have no clue about their underlying technology.. however...]
    > it is a problem if VUGen is actively recording
    interesting.
    most load test tools use a proxy-based recorder for capturing http requests. the side effect being, your requests are taking a slightly different path when in 'recording' mode. They are forwarded through a local proxy server, where some headers *may* be added/dropped/changed.
    my guess is that authentication headers are not the same when proxied by LR recorder as they are in a direct request to the server.

    [/ QUOTE ]

  6. #6
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    Re: Problems only seen when recording w/ LR? ...

    I've seen behaviour like this, where LR seems to be more susceptible to bugs compared to a browser. The problem is normally that if it is only an intermittent problem in the browser then the seriousness of the bug is not perceived to be that great - but for the load tester it's a nightmare!

    Typically, the best approach is to fix the original problem and that tends to solve LR's issues too. In your case it sounds like what others are saying: the state gets orphaned. I would guess it is something to do with load balancing or maybe caching?

  7. #7
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    Re: Problems only seen when recording w/ LR? ...

    This is interesting. I can't recall ever seeing a problem like this. On one occasion, however, I have had a need to route my traffic through vugen while recording on a separate machine. So I actually physically performed the actions on one box, routed the request through the vugen box's IP which then forwarded the requests to the AUT. I did this for some SSL related work.

    This type of thing *might* help you. Or at least narrow down your problem a bit.

    Unfortunately, I don't remember the changes I made to route the requests through my vugen box. I remember I had to make a registry change to the vugen box to put it in 'listen' mode (obv be careful with that) and employ a port forwarder to get the requests to the AUT and back to the box I was performing transactions on.

    Maybe you can try that route and see if you've got better luck? At least that way, you'll know for sure if you've got a loadrunner header issue. If you do try this, please update this thread, regardless of results. This is an interesting one.

  8. #8
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    Re: Problems only seen when recording w/ LR? ...

    Hey Chris,

    Did you resolve this issue yet? Was the problem that you weren't able to playback any scripts recorded using LR?

    I tested a web app previously that added some custom HTTP headers to each request, and LR doesn't know to add these unless you specifically add them to the recording options, so I'm wondering if it was something along those lines?

    I would have thought the following steps would have identified the issue?

    1) Use fiddler to capture logging into the app and going through a couple of pages
    2) Do the same recording in Vugen with Fiddler set as a proxy

    Anyway, interested to know how your investigations went.

    Cheers,
    Barry
    Barry Perez
    Melbourne, Australia

    My LinkedIn

 

 

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