1. A system, comprising: a resource for providing an IT-service; and a management engine computer having a management engine configured for: analyzing a service model of the IT-service, the service model comprising a node representing the resource; determining a resource type of the resource being indicated by the node; evaluating a service provider catalog to determine a resource manager being operable to instantiate the resource and an address of the resource manager; sending a request to the address of the resource manager for a description of a resource-manager-specific API of the resource manager; receiving the requested description from the resource manager; overriding at least one abstract method for instantiating the resource with a resource-manager specific method of the resource-manager-specific API, the resource-manager specific method being specified in the received description; and executing the resource-manager specific method for instantiating the resource represented by the node.