Rational set of 'contexts' for webservice actions

Contexts are the current gui state (selection state, series of menu/mouse events leading up to menu selection). An example of context dependent webservice execution is the JPredClient :
The JPredClient code is currently run in two ways - dependent on the selection of a single sequence, or a set of sequences that also look like they are aligned. These correspond to a prediction based on single sequence + discovered homologs, or to a prediction run on a precalculated alignment.

This is currently implemented in an entirely ad-hoc manner. JPred is not the only secondary structure predictor, so we should be able to reuse the same 'context' with different prediction methods (or even all of them simultaneously!).

Geoff suggested one more way we might want to define a context - for local realignment, where one selects a region on a sequence or set of sequences and apply an alignment method to just that region - leaving the other regions untouched in the result. This is a rather specialized case of the 'analyze group' method.