Patent ID: 8307379

Claim:
A method, comprising: indicating an association of parameter definitions with extensions in a runtime environment in a computer system, where each extension comprises a program capable of being selected to process at least one input object as part of an operation; receiving a call, in the runtime environment, for an extension point including at least one input object to determine one extension to use to process the at least one input object, wherein requirements are defined for the extension point, and wherein attributes of the at least one input object are associated with a hierarchy of the attributes; determining a set of candidate extensions capable of processing the at least one input object based on determining extensions whose parameter definitions are capable of satisfying the requirements defined for the extension point, and wherein a different priority is associated with each extension; and selecting from the set of candidate extensions one extension to use to process the at least one input object by: determining at least two extensions having parameter definitions that satisfy the attributes of the at least one input object at a lower level in the hierarchy than the parameter definitions of other extensions, wherein a determination cannot be made of which of the determined extensions satisfy attributes at a lowest level in the hierarchy; and selecting one of the determined at least two extensions that has a highest priority.