For starters (experts might have more complex reasons), what if your respective map and reduce logic becomes complex enough to demand separate classes? Why tie the clients to implement both by moving these in one Job interface. In the current design you can always implement both (map and reduce) interfaces if your logic is simple enough and go the other route, of separate classes if that is required. I think it is more flexible this way (you can always build up from and on top of granular design, rather than other way around.)
I hope I understood your concern correctly... Regards, Shahab On Tue, Aug 27, 2013 at 11:35 AM, Andrew Pennebaker <apenneba...@42six.com>wrote: > There seems to be an abundance of boilerplate patterns in MapReduce: > > * Write a class extending Map (1), implementing Mapper (2), with a map > method (3) > * Write a class extending Reduce (4), implementing Reducer (5), with a > reduce method (6) > > Could we achieve the same behavior with a single Job interface requiring > map() and reduce() methods? >
