Plurchase is just a reverse HTTP proxy server looking for an application.

It's not too hard to do something similar in perl.

1) start off by downloading a copy of CGIProxy: http://www.jmarshall.com/tools/cgiproxy/

2) Setup an apache server running CGIProxy

3) Hack the interface box at the top of the screen to include: facebook integration, a meebo chat box, etc...

The problem is that this sort of thing tends to _really_ upset webmasters. So, you'll need to restrict proxy sessions to specific domains (zappos.com, etc...) from which you've received approval to run an open proxy against.

It's surprising how far you can take this with one server; what you want to do is to port CGIProxy so that it runs on a custom HTTP epoll server, instead of on Apache. Brad Fitzpatrick has some great perl code on CPAN that shows you how to do this.

Once you have CGIProxy running on epoll (with epoll enabled in the kernel config, of course) you can easily handle thousands of concurrent clients on a single Amazon EC2 (small) instance.

You can disable proxification for images and media to enhance throughput (and to cut down on your bandwidth usage).

This is basically all that Facebook platform is -- a glorified reverse HTTP proxy.

Reverse HTTP proxies are a neat hack. But, the excitement tends to wear off once you realize that's all they really are. The underlying websites against which you are proxifying retain all of the true value. Plus, you are beholden to their TOS (Terms of Service).

Some of the earliest applications of reverse HTTP proxies (back in the 90's) were for anonymizing web sessions. That tends not to work too well, because no one wants to assume all of that liability.

An obvious application of reverse HTTP proxies would be to create an "enhanced" Craigslist: facebook integration, chat windows, better site search, LSA-based suggestions, etc.... This sounds like a great idea until you realize that the Craigslist TOS prohibits this sort of thing -- as do most websites. Even if the TOS is vague about this, it's only a matter of time before you get shut down -- no one wants a middleman proxying traffic between their website and their customers.

Remember when an ISP in Texas was inserting ads into people's browsing sessions? They were using reverse HTTP proxies.

I haven't even discussed the security implications of this. It's trivial to setup an HTTPS reverse proxy. CGIProxy even works with an SSL-encrypted GMail session. Think about that: all of your username/password data is being handed to a 3rd party middleman in plain text.

Even if the middleman running the reverse HTTP proxy is the nicest guy in the whole world, the security of your data now depends on two different companies getting their security protocls correct: (1) the company running the HTTP proxy, (2) the back-end website.

I'm sure the intentions behind Plurchase are excellent. But, this is a _very_ bad idea.

The only way to fix this situation, would be to to license an "enterprisey" white-label reverse HTTP proxy to e-commerce sites for internal use behind their firewall. For instance, Plurchase could license a "reverse HTTP proxy social networking applicance" to Zappos as a way to retrofit "social networking" features onto the existing Zappos website. That would address many of these issues. But, it's an entirely different business. Plus, the "web accelerator appliance" model has never worked very well.

Eventually, all features get folded into the underlying platform.