An increasing number of heterogeneous networks are connected with each other in the cloud. Both cloud controller platforms and cloud service providers have developed rapidly networking support. In most of the cloud networking service, users have to configure a variety of network-layer devices such as switches, subnets in heterogeneous networks. We propose a service-level network model which provides higher-level connectivity and policy abstractions, based on the Software defined networking (SDN) technology to closely integrate applications in the cloud with the heterogeneous networks through programmable interfaces and automatic operations. We describe the architecture of Hetersdn, an SDN controller platform that supports a service-level model for application networking in heterogeneous networks in clouds.