The front of a building Façade.Firstly an introduction to Entity Aggregation would be a good idea before one jumps into service aggregation
This pattern works basically as an aggregator which collects many services and exposes it as a as a single service.
AKA : WRAPPER.
The sample attached exposes a Ticket service which return the fare for bus or train. This basically wrapps 2 different services called a BusService and a TrainService which return the fare for the bus and train journeys.
In the next few articles I would put up samples of the remaining SOA Benefit patterns.