The Reservoir model and architecture for open federated cloud computing aim to address the limitations of current cloud computing solutions, such as limited scalability, lack of interoperability, and insufficient support for business service management (BSM). The Reservoir project proposes a modular, extensible cloud architecture that supports business service management and the federation of clouds. The goal is to enable an open, service-based online economy where resources and services are transparently provisioned and managed across clouds on an on-demand basis at competitive costs with high-quality service. The Reservoir approach enables on-demand delivery of IT services at competitive costs without requiring a large capital investment in infrastructure. It is inspired by the desire to make the delivery of IT services similar to the delivery of common utilities. The Reservoir model separates the functional roles of service providers and infrastructure providers, with service providers offering service applications and infrastructure providers providing a seemingly infinite pool of computational, network, and storage resources. Infrastructure providers operate Reservoir sites that own and manage the physical infrastructure on which service applications execute. The federation of collaborating sites forms a Reservoir cloud. The Reservoir model supports different virtualization technologies transparently and enables the dynamic allocation and management of resources. The Reservoir architecture includes a service manager, virtual execution environment manager, and virtual execution environment host. The service manager is responsible for deploying and provisioning VEEs based on the service manifest and monitoring and enforcing SLA compliance. The virtual execution environment manager is responsible for the optimal placement of VEEs into VEE hosts and the federation of remote sites. The virtual execution environment host is responsible for the basic control and monitoring of VEEs and their resources. The Reservoir architecture is designed to provide a clean separation of concerns among the layers operating at different levels of abstraction. The layered design stresses the use of standard, open, and generic protocols and interfaces to support vertical and horizontal interoperability between layers. The Reservoir model and architecture are intended to serve as a potential foundation for delivering IT services as utilities over the Internet. The Reservoir project is in its early stages, and work on the implementation and evaluation of the concepts outlined in this paper continues. The Reservoir model explicitly addresses the limited scalability of a single-provider cloud, the lack of interoperability among cloud providers, and the lack of built-in BSM support in current cloud offerings. The Reservoir model and architecture are intended to serve as a potential foundation for delivering IT services as utilities over the Internet.The Reservoir model and architecture for open federated cloud computing aim to address the limitations of current cloud computing solutions, such as limited scalability, lack of interoperability, and insufficient support for business service management (BSM). The Reservoir project proposes a modular, extensible cloud architecture that supports business service management and the federation of clouds. The goal is to enable an open, service-based online economy where resources and services are transparently provisioned and managed across clouds on an on-demand basis at competitive costs with high-quality service. The Reservoir approach enables on-demand delivery of IT services at competitive costs without requiring a large capital investment in infrastructure. It is inspired by the desire to make the delivery of IT services similar to the delivery of common utilities. The Reservoir model separates the functional roles of service providers and infrastructure providers, with service providers offering service applications and infrastructure providers providing a seemingly infinite pool of computational, network, and storage resources. Infrastructure providers operate Reservoir sites that own and manage the physical infrastructure on which service applications execute. The federation of collaborating sites forms a Reservoir cloud. The Reservoir model supports different virtualization technologies transparently and enables the dynamic allocation and management of resources. The Reservoir architecture includes a service manager, virtual execution environment manager, and virtual execution environment host. The service manager is responsible for deploying and provisioning VEEs based on the service manifest and monitoring and enforcing SLA compliance. The virtual execution environment manager is responsible for the optimal placement of VEEs into VEE hosts and the federation of remote sites. The virtual execution environment host is responsible for the basic control and monitoring of VEEs and their resources. The Reservoir architecture is designed to provide a clean separation of concerns among the layers operating at different levels of abstraction. The layered design stresses the use of standard, open, and generic protocols and interfaces to support vertical and horizontal interoperability between layers. The Reservoir model and architecture are intended to serve as a potential foundation for delivering IT services as utilities over the Internet. The Reservoir project is in its early stages, and work on the implementation and evaluation of the concepts outlined in this paper continues. The Reservoir model explicitly addresses the limited scalability of a single-provider cloud, the lack of interoperability among cloud providers, and the lack of built-in BSM support in current cloud offerings. The Reservoir model and architecture are intended to serve as a potential foundation for delivering IT services as utilities over the Internet.