1. A service manager installed on one or more computing devices for operation in a distributed computing system, the distributed computing system for receiving workloads from one or more client applications and executing those workloads on one or more service instances running on one or more service hosts within the distributed computing system, wherein the distributed computing system dynamically assigns the service hosts and initiates the service instances on the service hosts according to the service needs and the availability of such service hosts and service instances, the service manager comprising: a) a workload input interface operable to receive workloads associated with an application from one or more clients for execution on the distributed computing system, wherein the one or more clients received address information of the service manager from a session director in response to an assignment request for the application from the one or more clients; b) a resource management interface operable to receive information from a resource manager identifying the available service hosts or service instances for computing the received workloads from the one or more clients, and wherein the resource manager and the service manager continue to operate if the session director fails; c) a workload output interface operable to send workloads to the one or more hosts or service instances; d) wherein at least one of the workload input interface, the resource management interface, and the workload output interface is a binary communications interface whereby the service manager is operable to communicate workloads with other elements of the distributed computing system that are directly or indirectly connected through that at least one interface using a binary communications protocol.