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  1. #1
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    PayPal IPN Problem

    Pay Pal's IPN notifications are being delayed - while this post in another forum acknowledges problem, the statement that it's been fixed/caught up is not correct - still experiencing problem @ 7pm PDT 10-8-04....


    http://paypaldev.org/topic.asp?TOPIC_ID=7297

    Suggestion to PayPal: I don't think you should accept payments at all for IPN merchants when IPN isn't working or is being delayed. I = Instant. If you can't be instant, you're creating big problems for your merchants.
    AT LEAST ALLOW an option for members to elect not to allow payments to be made when your system isn't working correctly!!!!

  2. #2
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    Approximately 20% of PayPal IPN notifications either do not get sent out or worse yet, not received by the site in question.

    Do not forget one thing - there is not a DIRECT CONNECTION between your site and PayPal. At most, there could be 30 different computers (IP Addresses) between you and PayPal. All it would take is for one of those computers to have a hiccup and you don't receive your notification.

    Do a search on the Internet for TraceRoute or TraceRt. Some sites offer you to type in an IP Address or site name to see how many different computers are between their site and the site name you typed in.

    For example, between my home computer and PayPal, there are 19 different computers between us.

    A lot of people don't realize that the Internet is not direct connections but rather hops from computer to computer.

    PayPal now has the option of what's called AutoReturn in that once the customer has completed their payment, they are automatically returned to a predefined page on your web site without the customer having to push a button first. AutoReturn also allows transaction specific data to be returned as well. You could set up a special script that processes the AutoReturn the same way as IPN.

  3. #3
    SitePoint Enthusiast
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    Where did you pull that number from? I've had hundreds of payments go through the IPN, and in that time, only 1 payment was delayed (yesterday in fact) for a few hours. If PayPal cannot connect to your server, it should re-attempt later. Even so, if you experience that kind of failure rate, it sounds like a routing problem on your end.

    By that same logic, the average web surfer would only be able to access paypal 80% of the time. I dont think so...

    Added: I don't believe AutoReturn can replace the IPN, because you have no way to verify the information passed is correct.

  4. #4
    SitePoint Zealot ChrisCarter's Avatar
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    I would also question this "20%" figure. Perhaps you should brush yourself up on basic network functionality, Verilium, before posting misinformation. You may have 1000 hops between you and another person, but this only affects latency. If a packet cannot go through one route, it will choose another. HTTP (which IPN uses) runs atop TCP, rather than UDP, as well. This means that each packet is verified to have been received, and resent if it's not.

    Problems with IPN would stem from either your server being unavailable or PayPals. If there is an issue where the IPN broadcaster is too busy to broadcast, it resends later after traffic eases up. I've experienced this in several cases, and have never NOT received an IPN. I account for this in my code, and don't consider a transaction cleared until that final "Complete" message is received from PayPal.

  5. #5
    Follow Me On Twitter: @djg gold trophysilver trophybronze trophy Dan Grossman's Avatar
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    There were major problems with PayPal yesterday ranging from random error messages, inability to issue some refunds, inability to make merchant-initiated payments, and huge delays in IPN. Eventually they all did come in, which they almost always do. One or two a month don't make it to my IPN pages out of a few hundred.

    Needless to say, when IPN notices don't get sent instantly it does cause problems when you sell instant delivery items that don't get delivered instantly. I ended up giving away some freebies yesterday to appease customers until the notices showed up.

  6. #6
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    Smile

    My understanding ( and observation ) is that IPN sends a virtually instant message to your server then keeps repeating the message at ever increasing intervals. This is in the manual somewhere ( does somebody know where? ) Certainly this is very useful as if you don't get it the first time you will get it thenext time! I am just developing my application and during live testing I was able to keep debugging between each repeat. Which from my partially kept log were yesterday at:

    12.17pm
    12.28pm 11 mins later
    12.49pm 21 mins later
    13.32pm 43 mins later

    Any comments appreciated

  7. #7
    Follow Me On Twitter: @djg gold trophysilver trophybronze trophy Dan Grossman's Avatar
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    IPN does not make the post again if it was successful the first time. Perhaps there's an option to make it do so, but not by default at least.

  8. #8
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    There is useful info here:

    http://www.paypaldev.org/topic.asp?TOPIC_ID=5281

    from which I quote:

    "PayPal's IPN system re-posts to your script after 10 seconds, then 20 seconds, 40 seconds, 80 seconds, etc., (up to a 24 hour duration), until we receive a basic HTTP "200 OK" response from your web server or 4 days have passed since the initial post."

    and

    "The webserver handles sending back the HTTP 200...this should be done automatically when the script runs to completion. By chance, do you have your IPN url as the value of the return parameter in your button code?"

    ( I AM using the "IPN url as the value of the return parameter in your button code" during testing only)


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