ch.aplu.tcp

Class TcpBridge

java.lang.Object

ch.aplu.tcp.TcpBridge

public class TcpBridge
extends java.lang.Object

A bridge acts as a TcpNode, thus seen from the network it is a HTTP client connected to the TcpRelay server. But seen from the application developer it is a server that communicates with TcpAgent clients. Several bridges may be running on the same host using the same port, from the host the look like HTTP clients connected to the relay server. Even the TcpRelay and TcpBridges and TcpAgents may run on the same host.

To synchronize events that should happen at the same time by all agents, synchronize first the clocks of all participant by calling sendSyncRequest(). Then transmit a send command containing the clock time when the event should happen (use TcpTools.toIntAry(), TcpTools.toLong() to split/merge clock times).

Constructor Summary

Constructors

Constructor and Description
TcpBridge(java.lang.String relay, int port, java.lang.String relayID, java.lang.String bridgeName) Creates a TcpBridge instance for communications between agents.
TcpBridge(java.lang.String sessionID, java.lang.String bridgeName) Creates a TcpBridge instance for communications between agents.

Method Summary

Methods

Modifier and Type	Method and Description
void	addTcpBridgeListener(TcpBridgeListener listener) Registers a TcpBridgeListener that pipes the data and reports connection state changes.
java.util.ArrayList<java.lang.String>	connectToRelay() Same as connectToRelay(timeout), but waits infinitely for connection.
java.util.ArrayList<java.lang.String>	connectToRelay(int timeout) Connects to the tunneling relay given sessionID and timeout.
void	disconnect() Disconnects the bridge from the relay.
java.lang.String	getBridgeName() Returns the requested bridge nickname.
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	isConnected() Checks if the bridge is connected to the relay.
void	send(java.lang.String source, java.lang.String destination, int... data) Sends data to destination including the given source indicator.
void	sendCommand(java.lang.String source, java.lang.String destination, int command, int... data) Sends data to destination including the given source indicator.
void	sendCommandToGroup(java.lang.String source, java.util.ArrayList<java.lang.String> destinations, int delay, int command, int... data) Same as sendCommand(), but sends the data to all members of the given list.
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).
void	sendToGroup(java.lang.String source, java.util.ArrayList<java.lang.String> destinations, int delay, int... data) Same as send(), but sends the data to all members of the given list.

Methods inherited from class java.lang.Object

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

Constructor Detail

TcpBridge

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

Creates a TcpBridge instance for communications between agents. All communications between the agent and the bridge are tunneled through a relay with given IP address, IP port and relay ID

TcpBridge

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

Creates a TcpBridge 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(int timeout)

Connects to the tunneling relay given sessionID and timeout. Blocking method until connection to the relay is established or timeout expires. Returns a list of all already connected node nicknames, starting with the nickname the relay allocates to the connecting bridge (may be appended by (n), if the same nickname already exists. If connect returns with a timeout, the list is empty.

Parameters:

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

Returns:

the list of all already connected agents

connectToRelay

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

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

Returns:

the list of all already connected agents

disconnect

public void disconnect()

Disconnects the bridge from the relay.

send

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

Sends data to destination including the given source indicator. 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).

Parameters:

source - the nickname of an agent that indicates the source of the data

destination - the nickname of a agent to whom the data will be sent

data - an integer array or any number of integers

sendCommand

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

Sends data to destination including the given source indicator. 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).

Parameters:

source - the nickname of an agent that indicates the source of the data

destination - the nickname of a agent to whom the data will be sent

command - an integer that is interpreted as command tag

data - an integer array or any number of integers

sendToGroup

public void sendToGroup(java.lang.String source,
               java.util.ArrayList<java.lang.String> destinations,
               int delay,
               int... data)

Same as send(), but sends the data to all members of the given list. Runs in its onw thread. When returned the data may not yet been arrived at all the destination. On a heavily loaded system with many opened Tcp/IP connections, data may get lost, when sent to many agents at the same time. Use delay to stagger.

Parameters:

source - the nickname of an agent that indicates the source of the data

destinations - the list of nicknames of the agents to whom the data will be sent

delay - the delay in ms between successive data sending to agents

data - an integer array or any number of integers

sendCommandToGroup

public void sendCommandToGroup(java.lang.String source,
                      java.util.ArrayList<java.lang.String> destinations,
                      int delay,
                      int command,
                      int... data)

Same as sendCommand(), but sends the data to all members of the given list. Runs in its onw thread. When returned the data may not yet been arrived at all the destination. On a heavily loaded system with many opened Tcp/IP connections, data may get lost, when sent to many agents at the same time. Use delay to stagger.

Parameters:

source - the nickname of an agent that indicates the source of the data

destinations - the nickname of a agent to whom the data will be sent

delay - the delay in ms between successive data sending to agents

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

addTcpBridgeListener

public void addTcpBridgeListener(TcpBridgeListener listener)

Registers a TcpBridgeListener that pipes the data and reports connection state changes.

Parameters:

listener - the listener to register

isConnected

public boolean isConnected()

Checks if the bridge is connected to the relay.

Returns:

true, if the connection is established; otherwise false

getRelay

public java.lang.String getRelay()

Returns the IP address of the relay server.

Returns:

the IP address of the relay

getPort

public int getPort()

Returns the IP port number used by the relay server.

Returns:

the port number

getBridgeName

public java.lang.String getBridgeName()

Returns the requested bridge nickname.

Returns:

the nickname requested when connecting to the relay

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

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