SDN Controller Programming Guide

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In the following code examples, it is assumed that a reference to the controller service
implementation has been stored in the field cs:
private ControllerService cs = ... ;
Datapath Information
Information about datapaths that have connected to the controller is available; either all connected
datapaths, or a datapath with a given ID:
 getAllDataPathInfo() : Set<DataPathInfo>
 getDataPathInfo(DataPathId) : DataPathInfo
The DataPathInfo API provides information about a datapath:
 the datapath ID
 the negotiated protocol version
 the time at which the datapath connected to the controller
 the time at which the last message was received from the datapath
 the list of OpenFlow-enabled ports
 the reported number of buffers
 the reported number of tables
 the set of capabilities
 the remote (IP) address of the connection
 the remote (TCP) port of the connection
The following listing describes an example of how to use Datapath information:
Datapath Information Example:
DataPathId dpid = DataPathId.valueOf("00:00:00:00:00:00:00:01");
DataPathInfo dpi;
try {
dpi = cs.getDataPathInfo(dpid);
log.info("Datapath with ID {} is connected", dpid);
log.info("Negotiated protocol version is {}", dpi.negotiated());
for (Port p: dpi.ports()) {
...
}
} catch (NotFoundException e) {
log.warn("Datapath with ID {} is not connected", dpid);
}
Listeners
Application code may wish to be notified of events via a callback mechanism. A number of
methods allow the consumer to register as a listener for certain types of event:
 Message Listeners – notified when OpenFlow messages arrive from a datapath. At
registration, the listener specifies the message types of interest. Note that one exception to