int vconn_recv_xid(struct vconn *, uint32_t xid, struct ofpbuf **);
int vconn_transact(struct vconn *, struct ofpbuf *, struct ofpbuf **);
int vconn_transact_noreply(struct vconn *, struct ofpbuf *, struct ofpbuf **);
int vconn_recv_xid(struct vconn *, uint32_t xid, struct ofpbuf **);
int vconn_transact(struct vconn *, struct ofpbuf *, struct ofpbuf **);
int vconn_transact_noreply(struct vconn *, struct ofpbuf *, struct ofpbuf **);