I had the opportunity, last year, to talk with the team behind AppJet. They’re building something quite cool: A simple platform for developing reusable server-side applications written completely in JavaScript.

They’ve come a long way since I originally wrote about them late last year. They now even provide a copy of their server-side software along with the full source. This, together with Aptana’s Jaxer, means that there is, at least, two high-powered, Open Source, JavaScript server platforms.

EtherPad is something new altogether. Building upon their existing platform, and adding in Comet streaming, they’ve constructed a completely real-time, multi-user, text and JavaScript editor.

I use two editors in my day-to-day work: vim and SubEthaEdit (in fact I’m writing this blog post in SubEthaEdit, at the moment) – and I can say pretty definitively that EtherPad is just like SubEthaEdit.

I had the opportunity to use it last week with four people all simultaneously editing a document. It has the characteristic SubEthaEdit feature: All changes, by any user, occur in near-real-time and are highlighted with that user’s chosen color.

Some may wonder how this is different from Google Docs. Let me just say that SubEthaEdit and EtherPad are in a completely different league from Google Docs: I’ve used all three pieces of software for multiple-editing a document and the responsiveness that you get from SubEthaEdit/EtherPad makes for an unparalleled experience. It’s really common to see users start chat discussions within a document simply because it’s so easy to see their response and get a discussion going.

EtherPad does have one major distinction from SubEthaEdit, though: The ability to save and restore page revisions. At any point you can hit a large ‘Save Now’ button on the page to tag a revision – and then go back and restore from it at any point. In many ways this makes the software more like a real-time, multi-user editable, Wiki.

The most exciting thing for me though, and a point which I think is unparalleled, the entire application is built using JavaScript from the bottom up. The server code is in JavaScript, the database is in JavaScript, and the frontend is in JavaScript – it’s a complete JavaScript stack. The AppJet team plans on releasing this new server-side software (similar to their previous release but with the addition of Comet functionality and other pieces) completely Open Source as well. I look forward to being able to give it a spin when the time comes.