Delivery and payment handling are one of the most important tasks in a web shop. Most often this involves connecting to external systems and pushing data to them. Therefore, it's vital that a shop system has a feature rich interface that is able to cope with all kinds of special requirements remote services demand.
In Aimeos, the service providers are adapters between the shop interfaces for delivery and payment handling and any remote gateway. They can have arbitrary configurations, individually defined for each service provider. The abstract base classes offer a rich set of methods that ease development and minimize the code that must be written.
Your service provider must be part of your project specific Aimeos extension you have to create and stored at ./<yourext>/lib/custom/src/MShop/Service/Provider/<Delivery|Payment>/<classname>.php to be available in your Aimeos installation.