ch.aplu.tcp

Class TcpAgent

java.lang.Object

ch.aplu.tcp.TcpAgent

public class TcpAgent
extends java.lang.Object

Several agents may be running on the same host using the same port, because they behave like HTTP clients connected to the relay server. Partially event driven: connect blocks (with timeout)

Constructor Summary

Constructors

Constructor and Description
TcpAgent(java.lang.String relay, int port, java.lang.String relayID, java.lang.String sessionID, java.lang.String bridgeName) Create a TcpAgent instance for communications between agents using the given bridge.
TcpAgent(java.lang.String sessionID, java.lang.String bridgeName) Creates a TcpAgent instance for communications between agents.

Method Summary

Methods

Modifier and Type	Method and Description
void	addTcpAgentListener(TcpAgentListener listener) Registers a TcpAgentListener that reports data reception and connection state changes.
java.util.ArrayList<java.lang.String>	connectToRelay(java.lang.String agentName) Same as connectToRelay(agentName, timeout), but waits infinitely for connection.
java.util.ArrayList<java.lang.String>	connectToRelay(java.lang.String agentName, int timeout) Connects the agent to the tunneling relay, sessionID, requested nickname and timeout.
void	disconnect() Disconnects the agent from the tunneling relay.
java.lang.String	getAgentName() Returns the requested agent nickname when connecting to the relay.
long	getClockTime() Returns current time of internal clock synchronized with the relay's clock (in ms).
java.lang.String	getPersonalName() Returns the nickname attributed by the relay after successful connection.
int	getPort() Returns the IP port number used by the relay server.
java.lang.String	getRelay() Returns the IP address of the relay server.
TcpNode	getTcpNode() Returns the TcpNode reference responsible for the connection.
java.lang.String	getVersion() Returns current version information of TcpJLib.
boolean	isBridgeConnected() Returns true, if the bridge is connected to the relay.
boolean	isConnected() Returns true, if the connection to the relay is established.
void	send(java.lang.String destination, int... data) Send data to bridge including a destination agent indicator.
void	sendCommand(java.lang.String destination, int command, int... data) Send data to bridge including a destination agent indicator.
void	sendRelayRequest(java.lang.String request) Sends a request to the relay.
int	sendSynchRequest() Sends a clock synchronization request on a new TCP/IP channel (not influenced by the current traffic between the relay and the node).

Methods inherited from class java.lang.Object

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

Constructor Detail

TcpAgent

public TcpAgent(java.lang.String relay,
        int port,
        java.lang.String relayID,
        java.lang.String sessionID,
        java.lang.String bridgeName)

Create a TcpAgent instance for communications between agents using the given bridge. All communications between the agent and the bridge are tunneled through a relay. There is no direct communication link among agents nor between agents and the brigde.

Parameters:

bridgeName - the nickname of the bridge

TcpAgent

public TcpAgent(java.lang.String sessionID,
        java.lang.String bridgeName)

Creates a TcpAgent instance for communications between agents. All communications between the agent and the bridge are tunneled through a relay. The relay IP,the port and the relay ID are extracted from the TcpProperties file. If the file or an entry is not found, the following default values are used

RelayID: clab3.phbern.ch RelayPort: 80 RelayID: the ID of the server clab3.phbern.ch

Method Detail

connectToRelay

public java.util.ArrayList<java.lang.String> connectToRelay(java.lang.String agentName,
                                                   int timeout)

Connects the agent to the tunneling relay, sessionID, requested nickname and timeout. Blocking method until connection is established or timeout expires. Returns a list of all already connected agent nicknames, starting with the nickname the relay allocates to the connecting agent (may be appended by (n), if the same nickname already exists. If connectToRelay() returns with a timeout, the list is empty. An eventually already connected bridge is not contained in the list.

Parameters:

agentName - nickname of the current agent, may be appended by (n) if the same nickname already exists

timeout - in ms; if <= 0, wait infinitely for connection

Returns:

the list of all already connected agents starting with the nickname the relay attributes to the given agent

connectToRelay

public java.util.ArrayList<java.lang.String> connectToRelay(java.lang.String agentName)

Same as connectToRelay(agentName, timeout), but waits infinitely for connection.

Parameters:

agentName - nickname of the current agent, may be appended by (n) if the same nickname already exists

Returns:

the list of all already connected agents starting with the nickname the relay attributes to the given agent

disconnect

public void disconnect()

Disconnects the agent from the tunneling relay.

send

public void send(java.lang.String destination,
        int... data)

Send data to bridge including a destination agent indicator.

Parameters:

destination - the nickname of a agent to whom the bridge should send data, may be an emtpy string to indicate that the bridge decides where to send data (null set to empty string) For transmission (using the internal TcpNode) the integer array is converted into a string where each integer is separated by '&'. The string length is restricted to 500 characters for security reasons (relaying stopped, if exceeded).

data - an integer array or any number of integers

sendCommand

public void sendCommand(java.lang.String destination,
               int command,
               int... data)

Send data to bridge including a destination agent indicator. The first integer data element is considered to be a command tag.

Parameters:

destination - the nickname of a agent to whom the bridge should send data, may be an emtpy string to indicate that the bridge decides where to send data (null set to empty string) For transmission (using the internal TcpNode) the integer array is converted into a string where each integer is separated by '&'. The string length is restricted to 500 characters for security reasons (relaying stopped, if exceeded).

command - an integer that is interpreted as command tag

data - an integer array or any number of integers

sendRelayRequest

public void sendRelayRequest(java.lang.String request)

Sends a request to the relay. The relays answers with a status notification.

Parameters:

request - a string representing the request as defined as static in class TcpNode

addTcpAgentListener

public void addTcpAgentListener(TcpAgentListener listener)

Registers a TcpAgentListener that reports data reception and connection state changes.

Parameters:

listener - the listener to register

getAgentName

public java.lang.String getAgentName()

Returns the requested agent nickname when connecting to the relay.

Returns:

the nickname requested when connecting to the relay or empty if not yet connected

getPersonalName

public java.lang.String getPersonalName()

Returns the nickname attributed by the relay after successful connection. After connection the relay may append a (n) trailer to resolve name clashs.

Returns:

the nickname attributed by the relay or empty if not yet connected

isBridgeConnected

public boolean isBridgeConnected()

Returns true, if the bridge is connected to the relay. (Includes a Thread.sleep(1) to reduce CPU time in close loops.)

Returns:

true, if the bridget is connected to the relay; false if the bridge or the agent is not yet connected to the relay

isConnected

public boolean isConnected()

Returns true, if the connection to the relay is established.

Returns:

true, if connected to the relay; otherwise false

getRelay

public java.lang.String getRelay()

Returns the IP address of the relay server.

Returns:

the IP address of the relay as used when connecting (dotted notation or alias)

getPort

public int getPort()

Returns the IP port number used by the relay server.

Returns:

the port number

getVersion

public java.lang.String getVersion()

Returns current version information of TcpJLib.

Returns:

version information

getClockTime

public long getClockTime()

Returns current time of internal clock synchronized with the relay's clock (in ms).

Returns:

the current clock time in ms (zero arbitrarily) or 0, if not synchronized or not connected

sendSynchRequest

public int sendSynchRequest()

Sends a clock synchronization request on a new TCP/IP channel (not influenced by the current traffic between the relay and the node). The precision is typically better than 50 ms. Blocks until the reply is received or a timeout of 1 s is reached.

Returns:

the measured signal travel time from sending the request until receiving the reply (in ms). (The local clock is corrected by half this value, neglecting the difference of up- and download time and the time the relay needs to handle the request.) Returns -1 if the synch request failed because the node is not connected or the timeout is reached

getTcpNode

public TcpNode getTcpNode()

Returns the TcpNode reference responsible for the connection.

Returns:

the internal TcpNode reference