'Minister, I have warned you before about the dangers of talking to people in the Department. I implore you to stay out of the minefield of local government. It is a political graveyard.' Bernard intervened. Just as nature abhors a vacuum, Bernard abominates a mixed metaphor. 'Actually, Sir Humphrey,' he explained confidentially, 'you can't have a graveyard in a minefield because all the corpses would...' and he made a vague explosion gesture. (The Complete Yes Minister, p. 384)I have a beef with the terms 'Choreography' and 'Orchestration'. I do not think I am alone in having problems distinguishing the two. This is partly due to the difficulty that arises when I think of the origins of these metaphors. Full marks to whoever used some imagination to come up with new terms but the terms needs to be consistent in their metaphorical context.
According to Thomas Earl (see references below) Choreography can enable collaboration between Orchestrations. Choreography is the process of collaboration between business processes of different organisations and Orchestration is the process of organising your services within a business. So why change from music to dance as a metaphor? The choreographer who organises the steps for the dancers does not look at the orchestration prepared for the musicians. This conjures up an image of Choreographers counting to 8 (for some reason choreographers always count to 8) and musicians carrying their instruments trying to step in time. The choreographer does not direct anything the musicians do. From my experience playing in a blues band, in general, musicians can not dance. The musician is the guy who sits in the orchestra pit, or on the stage, or in the corner of the room and plays with his instrument while everyone else dances.
I think a better term or 'Choreography' might be 'Creative Direction' or 'Production'. The term needs to be something that suggests authority over the orchestration process. It is a nice touch to borrow computing terms from the arts but the industry should look out for consistency.
Quote from "Yes Minister": http://moksheungming.tripod.com/yes.html
The reference to Thomas Earl is from figure 6.1 in his book "Services Service-Oriented Architecture: Concepts, Technology, and Design"
Some discussion by Mark Richards on Choreography and Orchestration is provided in http://www.infoq.com/presentations/Enterprise-Service-Bus
The observation that "musicians can't dance" came from Larry who was the drummer in the blues band "Sacred Blue Walrus" of which I was a member. It is generally considered that a drummer is a person who hangs around musicians, but Larry was talented musician and a perceptive social commentator.
There are other differences between orchestration and choreography in the world of web-services. WS-BPEL and WS-CDL come from different standards bodies. Choreography does not have a controlling process. Choreography is more a community interchange pattern. Choreography can be dynamically extended.