1. A system comprising: an orchestration engine that is arranged and configured 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 for the instances and arranged and configured to: define a first subscription for a first instance of the multiple instances, the first subscription including a correlation expression, an association with the messaging endpoint, and an association with a first receiving object within the first instance, 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 route received messages that match the first subscription to the first receiving object.