-extern int jbus_add_service_s(struct jbus *jbus, const char *method, void (*oncall)(struct jreq *, const char *));
-extern int jbus_add_service_j(struct jbus *jbus, const char *method, void (*oncall)(struct jreq *, struct json_object *));
+extern int jbus_add_service_s(struct jbus *jbus, const char *method, void (*oncall)(struct jreq *, const char *, void *), void *data);
+extern int jbus_add_service_j(struct jbus *jbus, const char *method, void (*oncall)(struct jreq *, struct json_object *, void *), void *data);