CasperVend 2/Event Vendor Script

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CasperVend2 is a very efficient vendor system, and as such has always been in popular use at events, many of which consisted of packed sims of 60+ avatars. Recently, though, there have been two reported instances of CasperVend vendors not working well at two particular events - Collabor88 and Uber.

While it has been very hard to diagnose these issues (none of our team have been able to gain access to the regions while the vendors were malfunctioning), we were able to get hold of some data from our side which has helped us identify the cause.

So, what's the problem?

It appears that the issue lies with HTTP-IN.

CasperVend is a very sophisticated system, which depends on complex algorithms and processes running on our servers. This is because there is simply not enough script space in the vendor itself to perform all the extensive functionality that CasperVend provides.

As part of this process, the server needs to "dial in" to the vendor - this is done to send notifications, or make payments. Unfortunately, it seems that once region load gets beyond a certain point, HTTP-IN just completely falls apart and can no longer be used, with every request failing with a message like so:

<lsl>Proxy Error

The proxy server received an invalid response from an upstream server. The proxy server could not handle the request POST http://10.9.4.70:13020/web/task/8f493d26-de0b-19f1-74c6-5d199f02a8df/script/b48999ce-5e27-5fe8-0c22-e0c03b34babc/http.

Reason: Error reading from remote server</lsl>

Once such an error has been encountered, the system automatically tries to "self-heal". This causes the vendor to reset and re-establish itself in the network. Unfortunately, in such a broken region, the vendor will take a long time to get back online.

I can't stress enough that this is an issue with Second Life and their architecture (notice the internal IP address, 10.9.4.70 is a machine on LL's internal network), and NOT a problem with CasperVend or our servers.

Why has this never been addressed before?

Quite frankly, it's never been an issue before. CasperVend has been used in huge events for many years, and while it's experienced some lag, there have never been such wide-scale issues before.

Our best bet is that something has changed recently in the LL server-side code which makes HTTP-IN more vulnerable to lag.

The CasperVend2 Event Vendor replacement script

We've now released a special "Event Vendor" replacement script.

This is a special version of the vendor which has all inbound communications ripped out and disabled. This means it's reliable enough to function in heavily overloaded/broken regions.

Caveats & Limitations

  1. Profit sharing works
  2. You must have at least one normal vendor rezzed elsewhere, on a non-overloaded region. If you don't, your transactions will stall and fail!
  3. If you make a change to the configuration on the website, the vendor will not automatically update. You have to touch it inworld and choose Reset to get it to pull the latest config.
  4. License notecards will be delivered, but we can't wait for them to be accepted - the transaction will just go through regardless.
  5. Same for gift deliveries - we can't wait for the customer to confirm their gift selection, it just goes through as a direct gift.
  6. The vendor won't automatically reload if the linkset changes. So if you link the vendor to something, be sure to touch -> reset.
  7. The event vendor script is no-transfer, because it can't be used in affiliate vendors - it can't transfer money

All these features depend on being able to communicate with the vendor, which is why they are not fully available with the Event Vendor replacement script.

To Use the Script

  1. Edit one of your existing vendors (regular vendors, NOT holovendors, quantity vendors, etc).
  2. Switch to the Contents tab
  3. Delete the "CasperVend2" script from the contents
  4. Drag the CasperVend2 Event Vendor replacement script into the contents of the vendor.
  5. Once the vendor boots, grant debit perms.
  6. Once again, MAKE SURE you have regular vendors rezzed elsewhere in Second Life. The more the merrier.
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