The sphinx search system is partially separate from the rest of the CMS. It was selected after a detailed study of different search options and was optimal for searching catalogs of data vs. a crawler-based approach. The CMS modules built to integrate sphinx are not limited solely to front-end searches by users. The code that drives this is object oriented PHP.
One of the key attributes of Sphinx is that instead of indexing pages, it indexes database tables. When delivering a product search this became especially useful. The sphinx server would respond to any query with a series of productIDs and the relative weight/order of the products compared to the search. This would then be fed to the product display engine to show products. This had the added benefit of re-using already extant product display systems and unlike many other search products, the system did not require re-skinning for each new website created.