Almost every software developer has used some sort of source code version control system. You’re probably familiar with the acronyms GIT, SVN or the now aging CVS. Here is a list of version control systems.

Version control is a form of concurrency control with the benefit of revisions. Todays major versioning systems work by creating a copy of a resource, and allowing a user to work on that copy. The user then checks their modified copy back to the central source code repository. If the copy at the repository has changed, then the user must merge the two changed copies together.

Since each user is working on a remote copy, there is no real time collaboration involved at all. Each user must edit their copy individually without input from the other users. The collaboration is somewhat chunked, instead of a smooth integration of two or more users inputs.

I’ve been waiting for the day when real time concurrency control is integrated with source code version control. Just lately Google launched Google Wave, which essentially implements real time concurrency control in document editing. A while before that, Appjet Launched their Etherpad product, which implemented real time concurrency control in document and JavaScript source code editing.

Neither of these currently implement source code version control. However, they are proofs that real time concurrency control can be achievable over the web (HTTP) using Operantional Transformation (OT).

Now the missing link is to tie together a real time concurrency control system, with a version control system. Imagine checking out a document with a number of colleges, editing it concurrently in real time, and checking it back into version control.

The model of source code versioning will change dramatically with integrated real-time concurrency control. Checking out a copy may be a thing of the past. You can just join a a group that is editing a live copy, and revisions can be saved automatically for individuals and/or the group as a whole.

Add your own thoughts here…

Appjet, a web based javascript application development platform, sent out an email to members today that they are closing down the service.

According to the email, they are closing their Appjet service because of the success of Etherpad - which is a real time document collaboration service that they built on Appjet. I think what they really mean is, appjet isn’t making any money and has become a liability. In that case, they just didn’t find a good way to capitalize on what they have, because it is quite awesome.

Appjet has been the only server side JavaScript development platform that offered a web based editor so you could create applications with just a connection to the internet, nothing else. There are many server side JavaScript alternatives, and many JavaScript Application development Platforms, none had the simplicity Appjet had. Nor is there a platform that encourages the sharing of libraries amongst developers like Appjet.

I have quite a few applications running on Appjet. One the fetches updates from freelance sites and posts it to a twitter account, freelance_jobs. Another pings websites and keeps a log of their uptime.Yet another acts as a proxy allowing RSS feeds to be fetched cross domain as a JSON callback. Theres even one that allows to to cheat at facebook’s wordtwist game by guessing all the possible combinations of words available for that round. There’s more then 10 of these apps I wrote and they were all hosted freely by Appjet. These were all developed in my spare time and at first I thought of them only as fun apps, but a few of them have become quite useful.

Now comes the porting of these apps to a new location. The great thing is that the appjet engine is available for download.

I’m considering installing this on my own server, or just rewriting everything in PHP.