Convenience of inserting external data (products) as Drupal nodes I am building a multisite/multidomain site in Drupal 7. We have a section which will show details of thousand of products of the company and clients. We manage these products with an independent management tool. Is it recommended to insert these products in the database as nodes in order to get full capability of Views listings, search functions, etc.? I was going to use just PHP to manage listing, details page, etc., but I am no sure if keeping them outside of Drupal is a good idea. If it is better to include them as nodes, or any other entity... what contributed modules would be recommended and what would be the best approach? (Import them as csv files in a commerce module, insert them directly in nodes and related tables...).
IMHO, you have this choices :


Use the Feeds module to import data to nodes via CSV file, and you can use the powerful Views module to list all your product, or develop a simple module that can do that.
Use can develop a module that build entities based on your tables, with this approach, you can use your database without creating nodes/terms or other stuffs, but you need to create an admin interface to manage all your tables
If you plan to sell your products online, try to use Drupal Commerce, and import with Feeds module