What is the relationship between the supplier and the customer?

Supplier is the middle man between the company that introduces the product and the customer.
supplier is responsible to provide the feed back to the company about increase or decrease in demand so company can monitor the production for certain goods also good supplier needs to focus on the customers feed back and comments about the product so quality measures can be implemented timely according to customer need.

Basically this question is related to the Middle Man job as a part of sales team activities.The relation between the supplier and customer always controll by the customer relationship management.and it is also correct that this type of relationship  between supplier to customer is the basic tooll of supply and chain management system and manager.. 

Integration as per the basic structure of the supply chain management system