Comparison of the alternatives

People have asked about what makes Harmony and harmony_core different to other offerings, here are some things!

Core Forum module

Link to Documentation

The Forum module supplied by Drupal Core serves a basic purpose of providing a way to have discussions on your Drupal site. It works by providing a Topic Node type and allowing Comments on that Node, so the initial post is a Node and subsequent replies are Comments. This fundamental gluing together of data structures hamstrings the potential extensibility of the solution. You can probably accomplish whatever you need to but you'll work harder than you should, for example. To theme a Topic page you'll need to theme both the Topic Node and Comments on that Node type separately, that sucks!

So why's Harmony better? It's Entities! In this particular case it's architected so that the Thread entity is basically a Title (there's lots more but for the sake of simplicity), and Post is a text field with a reference back to the Thread it belongs to. This means that there's greater consistency where it makes sense, and is scalable because a suited structure has been created, instead of repurposing Nodes and Comments.

Bottom line, Core Forum is all it'll ever be, and future growth with it would be painful.

Advanced Forum

Link to project

This is based off of Core Forum, so suffers from the same architectural failings, though does give you more, if you're dedicated to the path of Core Forum I'd suggest you give Advanced Forum a look!

Acquia Commons

Link to project

Commons is a Distribution (collection of modules, theme and settings) which provides a solution for "building either internal or external communities. It provides a complete social business software solution for organization". Within this it has discussions provided (I'm referring to Posts) in the same way as ...Core Forum! With that approach already covered, there are other differences.

The approach with Commons is that you get the bundle which is Commons. It's a Distribution so that's what you'd expect right? Well because it's built tightly knitted together it can provide a lot, but that's also it's downfall in terms of working with it. Depending on your requirements you could spend time whittling back Commons to what it is that you want, it's components are coupled together.

With Harmony, the approach is you use harmony_core as a stable base for extending out of. There's the Harmony Forum and Harmony Community Distributions planned which will be the same, a series of modules combined to provide a strong set of features. But! harmony_core is designed to provide everything you need to have a Drupal Forum (key features, integrations can be found here: https://drupal.org/node/2233303).

If all that you want is a Forum that's all you need harmony_core will do that, if you'd like the ability to prevent SPAM in an automated way, throw in harmony_antispam. If you'd like to allow users to create their own groups with discussions within, add in harmony_og and harmony_access and use Organic Groups. The parts of Harmony are as loosely coupled as possible, making it your decision where to build out from and into. Harmony is aimed at being what you need it to be and nothing more than that unless you choose it to be. And plays well with others (like Organic Groups).

Third party integrations

Make me really sad. Here's a list of reasons why:

• You introduce software you may know less well.
• Another piece of software to keep an ear out for security issues.
• Requires knowledge of if you want to extend it for functionality or customise appearance-wise.
• Potential vendor lock in with propriety closed source software (if this is the case, $$$ too).
• It's not Drupal!

It's the last one that's key here, you already know Drupal and have things setup for Drupal, use Harmony! Ever had to figure out why vBulletin is not letting people login? Maybe it's because you're using Varnish like a good perf person for speedy pages and the software isn't setup to check the X_FORWARDED_FOR header when figuring out IP address, so everyone's IP is the same - making flood control kicking in and blocking logins from that IP. We got scars and such pain is the reason for creating Harmony. We don't wish these integrations on anyone!