SDN Controller Programming Guide

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 Example: if one needs to flood out packets through a port, it can do a check using this
API to see if broadcast would be possible through this port. If this API indicates negative,
then it would mean the port is in blocked state.
 Provide hooks for interested components to get notified of topology changes
The API’s are described in the following listing. See Javadoc on page 9 for details.
Topology Service:
public interface TopologyService {
boolean pathExists(DataPathId source, DataPathId dest);
L2Path path(DataPathId source, DataPathId dest);
Set<BigPortNumber> ports(DataPathId switchDpid);
boolean isConnectionPoint(DataPathId switchDpid,
BigPortNumber portId);
List<TopologyCluster> clusters();
TopologyCluster cluster(DataPathId switchDpid);
boolean participateInBroadcast(DataPathId switchDpid,
BigPortNumber portId);
Map<DataPathId, Link> tree(long clusterId);
void addListener(TopologyListener listener);
void removeListener(TopologyListener listener);
}