How to fetch parameter of remote node using RemoteGetParamReq in processRequest of an Agent - unetstack

Question

I have written an Agent and added to node 1 to fetch PhysicalParameters (Propogation speed, nodes energy etc) of node 2 using RemoteGetParamReq which is working inside agents startup() method.How can I use RemoteGetParamReq inside agents processRequest() method as I want to get parameter values of remote node 2 when node 1 triggers a DatagramReq so that i can get latest parameter value.
class MyRemoteParam extends UnetAgent {
AgentID phy,rmt
RemoteGetParamReq req
Message rsp
#Override
protected void setup() {
super.setup()
register(Services.PHYSICAL);
register(Services.DATAGRAM);
}
void startup() {
phy = agentForService Services.PHYSICAL
rmt= agentForService Services.REMOTE
req = new RemoteGetParamReq();
req.setRecipient(rmt);
req.setRemoteAgentID(phy);
req.setTo(2);
req.get(PhysicalParam.propagationSpeed);
req.get(PhysicalParam.timestampedTxDelay);
req.get(MyEnergyParameters.init_energy);
rsp = phy.request(req, 2000);
System.out.println "Node 2 propogation speed:"+rsp.get(PhysicalParam.propagationSpeed)
System.out.println "Node 2 energy:"+rsp.get(MyEnergyParameters.init_energy)
}
#Override
Message processRequest(Message msg) {
if (msg instanceof DatagramReq) {
req = new RemoteGetParamReq();
req.setRecipient(rmt);
req.setRemoteAgentID(phy);
req.setTo(2);
req.get(PhysicalParam.propagationSpeed);
req.get(PhysicalParam.timestampedTxDelay);
req.get(MyEnergyParameters.init_energy);
rsp = phy.request(req, 2000);
System.out.println "Node 2 propogation speed:"+rsp.get(PhysicalParam.propagationSpeed)
System.out.println "Node 2 energy:"+rsp.get(MyEnergyParameters.init_energy)
return new Message(msg, Performative.AGREE)
}
return null
}//end of processrequest
}//end of MyRemoteParam class

Answer 1

The processRequest() method should complete in order to respond to the requester, and so it isn't a good idea to make your parameter request inside it and wait. You can, however, trigger a request for the parameters to happen asynchronously by adding a OneShotBehavior something like this:
#Override
Message processRequest(Message msg) {
if (msg instanceof DatagramReq) {
add(new OneShotBehavior() {
#Override
public void action() {
req = new RemoteGetParamReq();
req.setRecipient(rmt);
req.setRemoteAgentID(phy);
req.setTo(2);
req.get(PhysicalParam.propagationSpeed);
req.get(PhysicalParam.timestampedTxDelay);
req.get(MyEnergyParameters.init_energy);
rsp = phy.request(req, 2000);
System.out.println "Node 2 propogation speed:"+rsp.get(PhysicalParam.propagationSpeed)
System.out.println "Node 2 energy:"+rsp.get(MyEnergyParameters.init_energy)
} // action
} // one shot behavior
return new Message(msg, Performative.AGREE)
}
return null
} // process request
Side note: DatagramReq is perhaps not the right request to trigger this on, since it asks your agent to send a datagram. You may wish to define your own appropriately named request for this purpose for good programming style.