online stores and in stock quantity

blackhorse

We are building a online store that the in stock quantity is updated after every sale. We use 3rd party financial transaction site, such as authorizent, to handle the credit card payment. We don't handle the credit card payment on our site.

Our site take the address and orders information, check the "in stock availablity", and pass the order to authorizenet, authorizenet will take the credit card information and process the financial transaction and pass the results back to our site. Our site will update the in stock quantity after we get the results from authorizenet.

But there is a possible time gap.

Say client A, add the item#1 (in stock quantity is 1) to the cart, and Client B at the same time, add the item #1 to his cart too.

Client A's order is passed to authorizenet, and at this moment Client A is filling out his credit card information at the authorizenet. (So our site, the in stock quantity is still 1), then client B's order is ready to be passed to authorizenet. Our site checks the in stock quantity, still available, we pass the client B's order to authorizent.

Both orders passed to authorizenet, authorizenet take their credit cards payment and both payments is "AUTHORIZED". But the problem is we one have 1 item #1.

When authorizent pass back the transaction results to our sitem, and our site updates our in-stock quantity. At this moment we can find that Item #1 is double sold.

The solutions is: then the merchant have to refund the second client B and informed him.

Are there better solutions?

Will authorizenet or other financial transaction sites can also check with our site for the availability at the last step when they process the credit card transaction? For example after Client A or Client B fill out the credit card information at the authorizenet and submit, then authorizenet will have to check with us again to see if the quantity is still available at this moment, if yes, they will process, if no, they will not process.

etully

Think of it like a real life grocery store. You take the last bottle of Heintz ketchup off the shelf and you put it in your basket. Customer #2 comes along, there is nothing left on the shelf. Customer #1 wanders around the store, makes his purchase, and customer #2 never got his hopes up that he thinks he's going to get to buy it when he gets to the checkout.

With your model, Customer #1 puts it in his cart. Customer #2 puts it in his cart. And Customer #3 also puts it in her cart. Now it's a race to see who gets to the checkout first.

I'd be pissed if I saw the item, it said that there were still some in stock and then I got to the checkout and it was sold. Even worse, imagine if you got to the store, put the ketchup in your basket and thought, "Good, I was able to get ketchup. That means that I can buy the rest of the items for my picnic" and you spent another 20 minutes picking out hamburgers, hot dogs, chips, etc. only to find out that all your time was wasted because someone else bought the last ketchup while you thought you had one in your cart.

I would do it this way: As soon as Customer #1 puts the item into his cart, decrease the inventory in your store. Then have a cron job that checks once a minute to see if customer #1's session ID has hit any page on your site in the last 20 minutes. (This will tell you if he's still shopping). If 20 minutes go buy and his session id hasn't hit any page on your site, then take it out of his cart and increase the inventory. Then, let's say another 10 minutes go by and he does hit another page on your site (maybe he walked away from his computer or something). If he does hit a page on your site again, then check to see if all the items that WERE in his cart are still in stock... if so, simply replenish his cart. If not, then inform him that some or all of the items in his cart have sold out since he last hit the page.

It's not as hard as it sounds... but it will take some planning and good programming. But from a User Interface perspective, I think it makes the most sense and avoids pissed off customers. And with this model, you don't have to involve Authorize.Net at all (they weren't going to check your inventory anyway - they assume that when you want a CC authorized, that you have already made sure that you can sell him the product).

Stepdad

blackhorse wrote:
We are building a online store that the in stock quantity is updated after every sale. We use 3rd party financial transaction site, such as authorizent, to handle the credit card payment. We don't handle the credit card payment on our site.

Our site take the address and orders information, check the "in stock availablity", and pass the order to authorizenet, authorizenet will take the credit card information and process the financial transaction and pass the results back to our site. Our site will update the in stock quantity after we get the results from authorizenet.

But there is a possible time gap.

At the moment your code only considers two valid states for an inventory item, available and sold. What you need to do is add a third state, on hold. When your code passes the information to authorizenet, have it go in and update your database to remove the item in question from active inventory and place it on hold. This removes it from active inventory immediately, and will allow your salespeople to see that it is in stock, but is more or less spoken for already.

Once the transaction completes and authorizenet sends back the information, if the transaction was successful you can then remove the item from being on hold and mark it as sold. If the transaction is not successful you can remove the item from it's hold state and place it back in active inventory.

I think that would probably be the best solution overall. Hope that helps.

blackhorse

etully wrote:
you don't have to involve Authorize.Net at all (they weren't going to check your inventory anyway - they assume that when you want a CC authorized, that you have already made sure that you can sell him the product).

That is something I was considering about too. If one person put it into cart, it will be off the inventory. But still when the order goes to authorizenet, we still face the same issue, but the cron job checking cannot be applied to authorizenet from our site.

Here are some of the questions:

1) If this guy holds this item in his cart for too long, although, he may click the web pages every few minutes, later on, he take it off his cart, it will reduce the chances it might be sold for other clients. For example, if a client may only want 1 item, but he cannot make the decisions yet. He grabbed 10 different items into his cart so other people may not be able to grab the other items before he picks the one he wants- Although we can add another time checking there, such as a guy cannot hold the item (if it is the only one) for more than 10 minutes etc. or he cannot hold too many items. But it adds the difficulty and confustion for using this site. - I think we may just have to use your suggestion and assumes people will not abuse it.

2) this question is more serious. say, client A get his order to the authorizenet. He might drop the process when he is at authorizenet pages. So how should I decide when should I release the items Client A is ordering if I don't hear from Authorizenet of the results? 5 minutes? 10 minutes? If after 10 minutes, I release the product, but Client A may be still activated in the authorizenet and then at the 11th minute, he finishes his order at authorizenet? - I think we may have to assume that 10 minutes no response from authorizenet, the order is dead and then release the item for other people to add to cart. But if there is a way, authorizenet can double check with us to see if the item is still available, just in rare cases, at 11th minute, this guy finishes his order.

etully

I've never had an 11 minute wait from Authorize.Net. Eleven seconds is more like it. 30 seconds at the most in my experience but that's unusual.

blackhorse

etully wrote:
I've never had an 11 minute wait from Authorize.Net. Eleven seconds is more like it. 30 seconds at the most in my experience but that's unusual.

OK, then that might be working. If 1 in 1000 someone stays in authorizenet for too long, he will lose his order and the merchant can refund his money. (I can add a note in the site to remind the clients that it might happen if they waste too much time in authorizenet.)

etully

Oh, I didn't realize that you were talking about the Authorize.Net product where you send the customer over to the Authorize.Net site. In that case, you are right, it's very possible that they could spend 11 minutes there... and it's also possible that they could abandon their cart alltogether.

When I buy Concert tickets online, they tell me that I have 3 minutes to make my purchase or I lose the seats. You might have to do the same thing. Just warn people that when they go to Authorize.Net, they have 5 minutes to fill out the forms or something like that.