1. A system including instructions recorded on a computer-readable medium and executable by at least one processor, the system comprising: an orchestration engine that is arranged and configured to cause the least one processor to execute multiple, concurrently running instances of a process model, wherein each of the instances of the process model includes one or more receiving objects; a messaging endpoint that is arranged and configured to be shared by the instances of the process model and that is arranged and configured to receive messages; a subscription handler that is arranged and configured to handle multiple subscriptions fog the multiple instances of the process model and arranged and configured to cause the least one processor to: define a first subscription for a first instance of the multiple instances of the process model, the first subscription including a correlation expression, an association with the messaging endpoint, and an association with a first receiving object of multiple receiving objects within the first instance, wherein the correlation expression allows a definition of one or more arbitrary correlation expressions to be used for matching operations on received messages, associate the first subscription with the first instance, and initialize the first subscription associated with the first instance; and a routing manager that is arranged and configured to cause the least one processor to route received messages that match the first subscription to the first receiving object.