Daniel, Short answer: Yes.
I have been previously and currently am involved with a few web app projects that were started or rewritten from scratch on Drupal. In fact, the reason that Drupal was chosen over any of the other CMS's available is specifically because of its superiority amongst its peers in the CMS space as a PHP development framework.
The most important thing in my experience is to make sure that you approach the project from a correct perspective. You'll get the best results if you think of the app being constructed *with* Drupal, doing it the Drupal way. This is a very different thing than building it *on top of* Drupal, where you try to reach down and leverage Drupal functionality when it suits you. This approach might cause you to rethink a lot of the application and data architecture in a rewrite. Drupal can do the job wonderfully, but know that it probably won't just be a "rewrite", but rather a "redesign", from the data model on up. Allowing Drupal to handle all of your user management, for example, sounds great, but thinking of how Drupal users are going to interact with your application's data will force you to rethink how Drupal will best do this. Ideally, it would become less and less your application's data and more and more Drupal's content, structured in the way that Drupal organizes its content (nodes, CCK, possibly OG's, ...), and accessed the way that Drupal accesses content (Views, perms, ...)
...if that makes sense ;)
Seth
Daniel Carrera wrote:
Hello,
Can you use Drupal core as a PHP development framework? Suppose you want to create a custom in-house web application which is not necessarily going to be a Drupal module. What would you use?
I am the maintainer of a custom PHP application. It's quite poorly written and I'm stuck maintaining it. I have been thinking that I'd like to rewrite it from scratch. I don't *need* any third party software to rewrite it, but it occurred to me that the final product might be better if I used a good PHP development framework. So I started googling for PHP application frameworks and I hit a Wikipedia page saying that some people use Drupal as a development framework. So I thought I'd ask about that here. Any thoughts?
I don't have a solid idea of what I'm looking for. I'm just looking to see what's available.
Cheers, Daniel.