We still use WO (but are slowly migrating to our own modern Swift-based framework). We have about 1.5M lines of WO code. It is rock solid (still).
Here one of the WO docs in PDF: https://developer.apple.com/library/archive/documentation/LegacyTechnologies/WebObjects/WebObjects_5/DeployingWebObjects/DeployingWOApps.pdf
@tuparev @_the_cloud My absolute favorite of Apple docs is this one:
https://leopard-adc.pepas.com/documentation/WebObjects/DesktopApplications/WODesktopApps.pdf
291 pages finest documentation of mostly forgotten tech.
I prefer the Objective-C version π
Both
In reality, very few production systems were deployed on non-Apple hardware/software. I was training many teams around the world, and 90%+ used some form of OpenStep. Java was more a marketing move.
BTW, after EOF 3.1 the Obj-C version were 3-tier too.