1. A method for communicating with a plurality of services via an integration services network, the method comprising: receiving, via the integration services network, a business process definition describing a business process at a business process engine, the business process including a set of business-related activities invocable on behalf of a client for achieving a business goal, the business process configured to operate on data associated with a client device in communication with the integration services network; retrieving for use by the business process engine, a description of a first communication model and a second communication model from an information repository accessible to the business process engine, the information repository storing access information for a plurality of services, the access information including the first and second communication models, and the access information further comprising policy information specifying a first subset of the plurality of services that may be invoked by the client device; determining whether the first subset of the plurality of services comprises a first service and a second service, and that the first and second services are invoked according to the policy information specifying the first subset including the first and second services of the plurality of services that may be invoked by the client device; receiving, via the integration services network, from resources associated with the business process engine: communication protocol information indicating the first communication model and the second communication model, the communication protocol information being inaccessible to the client device via the integration services network, and aggregation information for the first communication model and the second communication model; invoking, via the integration services network, the first service to implement at least a portion of the business process, the first service capable of communicating with the business process engine using the first communication model; and invoking, via the integration services network, the second service to further implement the business process, the second service capable of communicating with the business process engine using the second communication model, the invoking of the second service comprising providing data received by the business process engine from the first service; aggregating, based on the aggregation information, two or more responses received from the first and second services into an aggregated response; and transmitting the aggregated response to the client device.