pt.lsts.imc.net

Class StaticIMCConnection

java.lang.Object

pt.lsts.imc.net.StaticIMCConnection

public class StaticIMCConnection
extends java.lang.Object

This class provides a simplified interface for sending and receiving IMC messages using a static (fixed ip/port) peer-to-peer connection through UDP. Example:

  // Listen for IMC messages on port 6070 and all messages sent will go to 127.0.0.1:6002
  StaticIMCConnection conn = new StaticIMCConnection("127.0.0.1", 6002, 6070);
  
  // activate listening for messages
  conn.setPolling(true); 
  
  // wait up to 1 second to receive a message of type "EstimatedState"
  IMCMessage m = conn.recv("EstimatedState", 1000); 
  
  if (m != null)
      m.dump(System.out);     // Print out the message if it was received
  
  // Print all incoming Temperature messages to screen
  while(true) {
      System.out.println(conn.poll("Temperature"));
  }
 

Constructor Summary

Constructors

Constructor and Description
StaticIMCConnection(java.lang.String remoteHost, int remotePort, int localPort) Create a connection to a remote IMC host

Method Summary

Modifier and Type	Method and Description
static void	main(java.lang.String[] args)
IMCMessage	poll(java.lang.String abbrev) Retrieve the last received message of a given type.
<T extends IMCMessage> T	recv(java.lang.Class<T> clazz, long timeoutMillis) Receive a message of given class.
IMCMessage	recv(java.lang.String abbrev, long timeoutMillis) Synchronously wait for a message of a specific type
boolean	send(IMCMessage m) Send an IMC message to the remote host
void	setPolling(boolean polling) Activates/deactivates polling mechanism for listening for incoming messages.
ImcSystemState	state() Retrieve the state of this connection
void	stop() Stop this connection and stops listening for messages.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

StaticIMCConnection

public StaticIMCConnection(java.lang.String remoteHost,
                           int remotePort,
                           int localPort)

Create a connection to a remote IMC host

Parameters:

remoteHost - The IP address of the remote host. Examples: "127.0.0.1", "192.168.0.109".

remotePort - The remote port to connect to.

localPort - The local port to bind to and listen for incoming messages

Method Detail

send

public boolean send(IMCMessage m)

Send an IMC message to the remote host

Parameters:

m - The message to be sent

Returns:

true if no error was found while sending. Since we are using UDP no guarantee is given in terms of successful message delivery, all we know is that the message was sent out.

stop

public void stop()

Stop this connection and stops listening for messages.

setPolling

public void setPolling(boolean polling)

Activates/deactivates polling mechanism for listening for incoming messages.
When active, previous message of any type can be returned instantaneously by using the method poll(String)

Parameters:

polling - Whether to use polling of messages.

recv

public IMCMessage recv(java.lang.String abbrev,
                       long timeoutMillis)

Synchronously wait for a message of a specific type

Parameters:

abbrev - The message type you want to receive. Examples: "Heartbeat", EstimatedState, etc.

timeoutMillis - Maximum amount of time to wait for a message to be received in milliseconds after which null will be returned ([] in Matlab).

Returns:

A message of given type or null if no new message of that type was received in timeoutMillis milliseconds

poll

public IMCMessage poll(java.lang.String abbrev)

Retrieve the last received message of a given type. This method also (re)activates polling if it is not currently active.

Parameters:

abbrev - The type of message to be retrieved. Examples: "Heartbeat", EstimatedState, etc.

Returns:

The last received message of given type or null if no message of that type was yet received in this connection.

See Also:

setPolling(boolean)

recv

public <T extends IMCMessage> T recv(java.lang.Class<T> clazz,
                                     long timeoutMillis)

Receive a message of given class. Similar to recv(String, long) but the message gets cast to selected class.

Parameters:

clazz - The class of the message to be received.

timeoutMillis - Amount of time to wait for a new message, in milliseconds.

Returns:

A message of given class or null if no new message of that type was received in timeoutMillis milliseconds

See Also:

recv(String, long)

state

public ImcSystemState state()

Retrieve the state of this connection

Returns:

the state

See Also:

ImcSystemState

main

public static void main(java.lang.String[] args)
                 throws java.lang.Exception

Throws:

java.lang.Exception