Web Based Inventory and MRP Management System

Looking for an online solution ERP / MRP System to manage my manufacturing business. I need to track inventories of multiple clients (inventory they own and well as some inventory I own, establishing bills of materials and production orders, ? warehouse management, lot code tracking, as well as accounting functions. Software should have both reporting and invoicing functions as well as the ability to integrate with my customers SAP systems. Would like software to have security levels which allows access to different parts of the program to only authorized users. It is imperative that the software be web based and I own the code.