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Old 08-28-2009, 06:11 PM
Alan Alan is offline
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Join Date: May 2009
Location: Vancouver
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Default BikePortland Bookstore: Partner ID (PID)

I just got turned on to the BikePortland.org "bookstore" by Todd B's comment in the "Woman arrested..." thread. I poked around a bit and found the book he mentioned, and then I started wondering about how Powells.com knows to credit BikePortland with the sale, and especially how they know to credit referrals for purchases which aren't linked directly from BikePortland's page. It turns out (unsurprisingly) that there is a code embedded in the URL which identifies BikePortland as the referring "partner." For BikePortland to get its credit, the URL of the Powells.com page where the buyer clicks "ADD TO CART" must contain that partner ID number (PID).

Now, apologies in advance that this gets a tiny bit geeky, or for explaining too much if you know it already, but I'd like BikePortland to get its due, so the easiest way for me to explain it is with an example. Here's the book I was looking for and its link as found on http://www.bikeportland.org/books:

Bicycling and the Law: Your Rights as a Cyclist by Bob Mionske
http://www.powells.com/partner/33501.../9781931382991

It turns out that "33501" is BikePortland's PID, and "9781931382991" is the ISBN13 number which identifies the book. Every book has an ISBN (well, almost every; close enough for this purpose). I have not checked how Powell's identify DVDs or other media, but I expect it's similar. Anyway, those are the two pieces of info you need to give a credit to BikePortland when add a book to your shopping cart and buy it.

Powells.com's webserver redirects that URL to the actual location of that book's description, here:

http://www.powells.com/biblio/9781931382991?&PID=33501

See those same two numbers, just rearranged. Adding that book to your shopping cart from that page will give a credit to BikePortland based on that PID code.

But then, if you start surfing around www.powells.com from there, using the Search function or various links provided by Powell's, maybe adding books into your shopping cart for purchase, note that the resulting description pages don't contain that "PID" code. I could be wrong but I doubt it, but when you follow the shopping cart link to purchase one of those other books, you aren't giving BikePortland credit for the sale. If you want to give BikePortland credit for the referral, then be sure to add this string to the end of of the book description URL, just before you click "ADD TO CART":

?&PID=33501

Copy that string and paste it on the end of the URL before you click "ADD TO CART". You can do that right in the address bar of your browser.

Let's take another example to illustrate that. I searched for "Dr. Seuss" in Powells.com main search form and it turned up a bunch of Dr. Seuss books. I clicked on the link for The Cat in the Hat and got to the description page at this URL:

http://www.powells.com/biblio/17-9780394800011-8

I can then add the PID and get this URL:

http://www.powells.com/biblio/17-978...1-8?&PID=33501

And then, when I buy The Cat in the Hat by clicking "ADD TO CART" from that page, BikePortland should get their partner's cut from my purchase.

If I'm wrong about how Powell's treats those PID URLs and referals (maybe they give credit for the entire order if any one of the books in the shopping cart contains the PID?) or if this is in some other way unhelpful, please feel free to correct me. Otherwise, render unto BP...
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