The Aries Remote Service Admin (RSA) project allows to transparently use OSGi services for remote communication. OSGi services can be marked for export by adding a service property service.exported.interfaces=*. Various other properties can be used to customize how the service is to be exposed.
For more information, check out section "122 JPA Service Specification Version 1.0" in the "OSGi Service Platform Enterprise Specification, Release 4, Version 4.2" available for public download from the OSGi Alliance.