Decoupled Frontend

Introduction

MindTouch as it ships consists of two conceptual components: (1) the .NET API and (2) the PHP front-end. Over time, we've moved most of the business logic away from the PHP layer, which has had the benefit of reducing database connections. The end goal is to completely remove all database connections from PHP, which will allow deployments to set-up servers which only handle processing PHP front-end requests. (However, keeping the two levels separate may not necessarily yield performance gains, as the network/Apache overhead price may be high). This is mainly considered a "cleanup" item, which will help the development team by funneling all business logic through one entry point (API) and be consistent with the conceptual architecture of MindTouch.

Since the Hayes release, we've removed almost all of the database connections from the front-end, but a couple ones remain.

As a note, although the application will remove database dependencies, MindTouch's upgrade scripts are written in PHP, and will still require database updates.

Status

Just being documented. 

Technical Specification

There are three locations where database look-ups are still used heavily.

1. includes/LinkCache.php - this keeps a cache of page titles with IDs and does a direct look-up against the pages table.
2. includes/Title.php - Detection of whether an article exists throughout the PHP is done by the assumption that articleID > 0 (based on a page title). This does a direct DB call. An effort was made to convert this over earlier, but when a page is restricted, an ID is not returned, and the skin assumes the page does not exist
3. includes/WatchedPages.php - Determines whether a page is watched or not through the db

There are other locations where DB calls are still made, and I've made an initial pass at the clean-up in the attached patch file.