How to install, maintain, and use XOOPS, more from a developer's perspective than an end-user perspective. My docs assume you have basic XOOPS skillset. I've included information on the modules I've used in various installations along with changes made, if any, as I keep them all updated.

Now superceded by Installation, Update Info on 2.3.x series. I will no longer be maintaining this article.

Core

Install Latest XOOPS - 2.0.x (2.2.x is fork, considered not for production due to its incompatibilities with old modules, although many are using it as for awhile, it was the forward path).

Upgrading

Always read the release notes for each upgrade. Upgrades may require database changes, and if you've made any changes to the core files, you'll have to reconcile those together yourself. Here are some quick notes on specific updates:

• Patches beyond 2.0.16 (so far confirmed 2.0.17.1) are file copies only.
• 2.0.14/15 version to 2.0.16 and later requires a similar upgrade path.
• Updating to 2.0.13.x-to-2.0.14/15 requires an update
• Updating to 2.0.12a, you will have to update the system module in the admin area.
• Updating from 2.0.9.2 to 2.0.12 is just copying files

Before upgrading, you will want to:

• compare your current files to the old installed version, update new files as appropriate with these changes and save for later overwrite.
• remove from the new update (unless updated), mainfile.php, favicon.ico, .htaccess, and assuming you're using SmartProfile, edituser.php, register.php, user.php, userinfo.php, and pmlite.php if using the PM e-mail hack.
• use the AltSys Module to make sure you've saved any changes made to templates (also check your theme/modules area which overwrites these on the fly since 2.0.14)
• install the files, follow the upgrade instructions as appropriate, copy the changed files over existing.
• you should be done

Changed Files

Anytime an update is made, check to see if these files have been overwritten, and update as necessary.

Must Installs

These will overall enhance your installation and make it much easier for you to do your business.

System

• XOOPSeditors - FCKeditor - a number of WYSIWYG editors and my updated version of FCKeditor
• Frameworks - enhancements used for a number of modules including CBB
• SmartObjects - enhanced object framework used by SmartFactory modules, among others
• SmartProfiles - my bug-fixed/edited version of SmartProfiles; requires SmartObjects

Admin Modules

• Protector - prevents many security issues
• AltSys - admin module to manage blocks, templates and permissions
• XoopsInfo - provides information about XOOPS, server environment, etc.
• XoopsCare - helps automatically maintain your XOOPS site
• Backup & Restore - automatic backup of your database, other related
• Waiting Module - implements extensible block replacing core waiting contents block
• iStats - site usage module
• iSearch - search stats for your site
• MultiMenu - highly configurable menu system
• Avatar Manager
• Images - I suggest replacing the images in the /images folders with ones you like better -- especially the images/logo.gif (maybe symbolic link).

Used at one point, but not right now:

• Fastest Cache - faster caching hack for website (worked well when I last used it)

Modules

• XOOPS Module Repository (many of these are outdated, and there are many other places to get modules not listed here. Search the forums to read about more of them.
• Herve Thouzard's site (News, mydownload, shortcuts...)
• Panther Software Publishing (xProject, xAsset)
• Smart Factory (SmartSection and many others)
• XForge site (CBB forum, Wordpress, MediaWiki...)

Things Warranting Study

• Renaming of Directories - can use mod_rewrite, but still lots of work inside modules. This should be addressed in xoops core (like other CMSes).
• Thumbnails (from this post) - myAlbum's Image Manager Hack - Hack for Image Manager (2004-08-18, so may be dated) - Also this possibility.
• How to Clone a Module (FAQ)
• New Template Overwrite/overload system (2.0.14)
• New Theming Engine (2.0.14)
• Theming for Admin area
• Finishing Module Development tests, integrating with Waiting Contents Module, etc.
• UserPage - for Biographies and such