Forum OpenACS Q&A: Response to AOLserver, aD, PG, ACS and OpenACS on Linux Journal, again
Let me give you a run-down of ACS 4.0's enhancements then:
* Complete Modularity
* Package Manager and Central Repository - You install just the ACS core and the packages you need from ArsDigita's central repository (ala Debian, but through a web interface).
* Improved Database API using bind variables - more secure and the programmer does not have to especifically grab and release db handles. Plus it's easier to port.
* Request Processor - takes care of all requests, filters. etc.
* Templated - complete separation of presentation and logic.
* Content Management package
* Easy to run several sites from one ACS 4 installation (almost impossible with 3.x)
* Several packages are already available, but not as many as there are in 3.x are available yet.
The Java version basically replaces Tcl with Java and it's currently in Alpha, with a beta release scheduled for next month and final in january.
I don't know if you are aware, but ArsDigita has a mod_aolserver for Apache that lets you run (Open)ACS in Apache, and an IIS dll that lets you run (Open)ACS on IIS.
Your columns have been great. I was kind of getting sick of only seeing MySQL and Python on LinuxJournal. It seemed to be all the magazine staff cared about.