This paper presents a study about information sharing and domain ontological modeling within the framework of cloud computing services. We have investigated common practices on service oriented architectures design and knowledge engineering to support the composition of services in the cloud. Research results about information sharing and information modeling by using semantic annotations are discussed. Particularly we present how we use ontological models to represent management information and service lifecycle operations and thus control both system management operations and services running onto cloud infrastructure. We support the idea of look information sharing as a mechanism to facilitate the composition of services, thus ontology-based information modelling is used for this purpose. It enables information exchange by using interoperable data framework for different applications running on infrastructure and application layers. Ontologies support this information sharing approach by formalizing the necessary data needs to be shared or exchanged. An introductory application scenario is depicted. We discuss what implications this approach imposes on architectural design terms and also how virtual infrastructures and cloud-based systems can benefit from this ontological modelling approach.