1. A method, comprising: identifying, by a processing device, a request to add a composition candidate to a service-oriented architecture (SOA) service model comprising a plurality of service candidates, each service candidate including one or more operation candidates to provide a set of logically associated capabilities; in response to the identified request, selecting, by the processing device, a set of service candidates from the plurality of service candidates; aggregating, by the processing device, the selected set of service candidates together to form the composition candidate; receiving, by the processing device, an input specifying an operational relationship between two or more service candidates of the composition candidate, the input identifying a first service candidate of the set of service candidates as a requestor service, and further identifying a second service candidate of the set of service candidates as a provider service; providing, in view of the received input, a visual representation of the operational relationship, the visual representation including visual designations of the requestor service and the provider service; and responsive to receiving a request to perform an action on the SOA service model, determining whether the action is allowable in view of the operational relationship.