1. A computer-based system capable of communication with a plurality of different types of computing sources of functionality, each computing source of functionality being a service to a user, comprising: non-transitory computer readable medium that stores a semantic service description (SSD) that is associated with a service and, each SSD based upon one or more ontologies for filtering, composing and executing the service, and is discoverable as an available service according to one or more discovery protocols, wherein an SSD further comprises: a semantic description of the service, including a semantic description of input/output parameters of the service as semantic input/output parameters, based upon the one or more ontologies, a semantic filter parameter specifying relevance of the service, based upon the one or more ontologies, and a grounding including: a service invocation interface to the service; and an input/output parameter mapping between the semantic input/output parameters and syntactic input/output interface parameters of the service and/or an input/output parameter transformation function between the semantic input/output parameters and syntactic input/output interface parameters of the service; a computer processor capable of executing: dynamically discovering any available SSDs as available services through the one or more discovery protocols to discover the SSDs; supporting real-time composition by a user of a current executable task that is a combination of two or more of the available services by dynamically presenting to the user possible services by filtering the discovered available services according to a context of the user in a computing environment for a service selection from the available services and/or according to the current composed executable task, based upon the semantic filter parameters in the SSDs of the discovered available services; and executing a task by invoking the two or more available services that comprise the task, including enabling the user to interact with an invoked available service, based upon the grounding in the associated SSDs including the service invocation interface, and the input/output mapping and/or the transformation function between the semantic input/output parameters and the syntactic input/output parameters.