1. A computer storage media having computer-executable instructions for causing a computer to perform steps comprising: provide a declarative feature that is operable to allow a first plurality of partially ordered steps in an extensible process spanning multiple application components to be defined in a declarative format, the declarative feature allowing at least some of the partially ordered steps to have an associated step action, the first plurality of partially ordered steps including a step having an order specified relative to at least one other step of the first plurality of partially ordered steps; publish the existence of the first plurality of partially ordered steps to other application components; receive a second plurality of partially ordered steps from at least one of the other application components as a result of said publishing; and provide a sequencer that is operable to assemble the first plurality of partially ordered steps and the second plurality of partially ordered steps into a computational sequence having a total ordering, and to execute the computational sequence in the total ordering upon receiving an execution request.