11. A non-transitory computer-accessible memory medium comprising program instructions for runtime execution of one or more tasks defined in a workflow process language, wherein the program instructions are executable by a processor to: at runtime: obtain a description of the one or more tasks from a process ontology (PO), the process ontology (PO) defining a hierarchical taxonomy of executable tasks, each task referring to at least one frame of a hierarchical frame taxonomy of the process ontology (PO); identify at least one task parameter as described in the frame description to which the task refers; resolve the value of the at least one task parameter, comprising determining the value of the at least one task parameter; select a most specific applicable version of the task from a plurality of versions of the task contained in the task taxonomy of the process ontology (PO) based on the resolved value of the at least one task parameter; execute the most specific applicable version of the task.
11. A non-transitory computer-accessible memory medium comprising program instructions for runtime execution of one or more tasks defined in a workflow process language, wherein the program instructions are executable by a processor to: at runtime: obtain a description of the one or more tasks from a process ontology (PO), the process ontology (PO) defining a hierarchical taxonomy of executable tasks, each task referring to at least one frame of a hierarchical frame taxonomy of the process ontology (PO); identify at least one task parameter as described in the frame description to which the task refers; resolve the value of the at least one task parameter, comprising determining the value of the at least one task parameter; select a most specific applicable version of the task from a plurality of versions of the task contained in the task taxonomy of the process ontology (PO) based on the resolved value of the at least one task parameter; execute the most specific applicable version of the task. 19. The non-transitory computer-accessible memory medium of claim 11 , wherein the description of each task comprises attributes defining the frame it refers to, one or more input parameters, one or more output parameters and a reference to an implementation of the task.