Shipping provider model
Developers can implement shipping method processors of their choice using the “Shipping Provider Model”, a feature introduced in version 6.0. Once a developer implements their shipping carrier provider and configures it, the available shipping services from that carrier will be displayed on the shipping options page during the checkout process. The developer will need to contact the shipping carrier and ask for developer documentation and credentials. The merchant may need to sign up with the shipping carrier as well.
The Shipping Method Model works for shipping methods that publish an API using a web service, XML feed, etc.
We have already used this model in Sitefinity CMS to implement the three shipping carrier providers supported namely FedEx, UPS, and USPS, see For developers: Shipping carriers. The provider model lets developers implement the shipping method in the “Shipping methods” section of Sitefinity CMS backend.