A few quick notes in response to the above.
* FoxyBack probably shouldn’t be used by anybody at this point. It takes a LOT of work to get going and if you really need something that tightly integrated you’ll probably want to roll it yourself.
* The FoxyCart XML is no longer versioned independently from store versions, and every version has changes (mostly additions, not usually modifications or removals). So the latest XML is always going to be whatever the latest FoxyCart version is, and example XML will be on
the FoxyCart wiki (though the v0.7.0 sample isn’t up yet).
* We (FoxyCart) really don’t recommend using older versions. v0.4.0 is super old and has many issues that have been fixed in subsequent releases.
Ultimately though, the main reason you may want to or need to rebuild the paid webuser integration is that FoxyCart has rebuilt its subscription handling twice since v0.4.0. The latest version, v0.7.0, supports PayPal-based subscriptions and has a full subscription API. The old code relied on various cludgery and hacks to work around limitations but the latest FoxyCart release not only allows more flexibility but would radically simplify what this is doing. (I’d really, really like to write it up myself but I just don’t have the time, unfortunately. I’m more than happy to provide as much guidance as needed though, if anybody’s interested.)
Also, as far as user registrations go, you can handle that in two ways:
1) Force (using FoxyCart’s Single Sign On) a user to be registered and logged into MODx prior to allowing them to pay for the subscription.
2) Allow a checkout from an unauthenticated user, and automatically create the user in MODx from the FoxyCart XML datafeed (with synched MD5 password hash). Then either force user info updates through FoxyCart to modify the MODx user or make sure you sync changes to FoxyCart when they’re changed in MODx (via the FoxyCart API).
I hope that helps. Again, this snippet really should be rewritten because it’d just work a lot better and it’d allow for PayPal as well. I hope that helps, and I’m not just raining on the parade.