UDP Class

Properties Methods Events Config Settings Errors

The UDP class is used to facilitate UDP (datagram) communications. It can act both as a client and a server and communicate with any number of hosts simultaneously, as well as generate and receive broadcast packets.

Syntax

ipworks.Udp

Remarks

The interface of the class is similar to the interface of TCPClient, only much simpler. The class is activated/deactivated through the Active property. This property enables or disables sends or receives. The data can be sent in the same way as TCPClient, using the Send method and specifying the text to send. This is identical to assigning data to the DataToSend property. The destination is specified using the RemoteHost and RemotePort properties. Inbound data is received through the DataIn event.

If the UseConnection config setting is set to True, then a local association is created with the remote host. Otherwise, the class can receive datagrams (packets) from any host, and send datagrams to any host. Packets can be broadcast on the local net by setting the destination (RemoteHost) to 255.255.255.255.

The operation of the class is almost completely asynchronous. All calls, except the ones that deal with domain name resolution, operate through Windows messages (no blocking calls). The gain in performance is considerable when compared to using blocking calls.

Property List

The following is the full list of the properties of the class with short descriptions. Click on the links for further details.


AcceptData	This property enables or disables data reception (the DataIn event).
Active	Indicates whether the class is active.
DataToSend	A string of data to be sent to the remote host. Write-only property.
DontRoute	If this property is set to True, it forces the socket to send data directly to the interface (no routing).
LocalHost	The name of the local host or user-assigned IP interface through which connections are initiated or accepted.
LocalPort	The UDP port in the local host where UDP binds.
RemoteHost	The address of the remote host. Domain names are resolved to IP addresses.
RemotePort	The UDP port in the remote host.
TimeToLive	The maximum number of subnets that a datagram can traverse.

Method List

The following is the full list of the methods of the class with short descriptions. Click on the links for further details.


Activate	Enables sending and receiving of data.
Config	Sets or retrieves a configuration setting.
Deactivate	Disables sending and receive of data.
DoEvents	Processes events from the internal message queue.
PauseData	This method pauses data reception.
ProcessData	This method reenables data reception after a call to PauseData .
Reset	Reset the class.
ResolveRemoteHost	Resolves the hostname in RemoteHost to an IP address.
Send	Send data to the remote host.
SendBytes	Send data to the remote host.
SendText	Send data to the remote host.

Event List

The following is the full list of the events fired by the class with short descriptions. Click on the links for further details.


DataIn	Fired when data is received.
Error	Fired when information is available about errors during data delivery.
ReadyToSend	Fired when the class is ready to send data.

Config Settings

The following is a list of config settings for the class with short descriptions. Click on the links for further details.


CaptureIPPacketInfo	Used to capture the packet information.
DelayHostResolution	Whether the hostname is resolved when RemoteHost is set.
DestinationAddress	Used to get the destination address from the packet information.
DontFragment	Used to set the Don't Fragment flag of outgoing packets.
LocalHost	The name of the local host through which connections are initiated or accepted.
LocalPort	The port in the local host where the class binds.
MaxPacketSize	The maximum length of the packets that can be received.
QOSDSCPValue	Used to specify an arbitrary QOS/DSCP setting (optional).
QOSTrafficType	Used to specify QOS/DSCP settings (optional).
ShareLocalPort	If set to True, allows more than one instance of the class to be active on the same local port.
UseConnection	Determines whether to use a connected socket.
UseIPv6	Whether or not to use IPv6.
AbsoluteTimeout	Determines whether timeouts are inactivity timeouts or absolute timeouts.
FirewallData	Used to send extra data to the firewall.
InBufferSize	The size in bytes of the incoming queue of the socket.
OutBufferSize	The size in bytes of the outgoing queue of the socket.
BuildInfo	Information about the product's build.
GUIAvailable	Whether or not a message loop is available for processing events.
LicenseInfo	Information about the current license.
MaskSensitive	Whether sensitive data is masked in log messages.
UseDaemonThreads	Whether threads created by the class are daemon threads.
UseInternalSecurityAPI	Whether or not to use the system security libraries or an internal implementation.

AcceptData Property (UDP Class)

This property enables or disables data reception (the DataIn event).

Syntax


public boolean isAcceptData();


public void setAcceptData(boolean acceptData);

Default Value

True

Remarks

This property enables or disables data reception (the DataIn event). Setting this property to False, temporarily disables data reception (and the DataIn event). Setting this property to True, reenables data reception.

Note: It is recommended to use the PauseData or ProcessData method instead of setting this property.

This property is not available at design time.

Active Property (UDP Class)

Indicates whether the class is active.

Syntax


public boolean isActive();


public void setActive(boolean active);

Default Value

False

Remarks

This property indicates whether the class is currently active and can send or receive data.

If UseConnection is set to True, then a local association (connection) to the remote host and port is also created.

Note: Use the Activate or Deactivate method to control whether the class is active.

This property is not available at design time.

DataToSend Property (UDP Class)

This property is deprecated. Please use the SendBytes method or the SendText method instead.

A string of data to be sent to the remote host. Write-only property.

Syntax



public void setDataToSend(byte[] dataToSend);

Default Value

Remarks

Assigning a string to the DataToSend property makes the class send the string to the remote host. The Send method provides similar functionality.

Attempts to send the string assigned to DataToSend as a complete message. If system buffers are full, or the message cannot be delivered for any other reason, an error is fired, and no portion of the message is sent. This is different from TCP where portions of the messages can be sent. UDP sends either a complete message or nothing at all.

If you are sending data to the remote host faster than it can process it, or faster than the network's bandwidth allows, the outgoing queue might fill up. When this happens, DataToSend fails with exception 10035: "[10035] Operation would block" (WSAEWOULDBLOCK). You can check this error, and then try to send the data again.

Example (Send Data)

UDPControl.LocalPort = 8765 UDPControl.RemotePort = 8765 UDPControl.RemoteHost = "HostNameOrIPAddress" UDPControl.Active = True UDPControl.DataToSend = "Hello!"

This property is write-only and not available at design time.

DontRoute Property (UDP Class)

If this property is set to True, it forces the socket to send data directly to the interface (no routing).

Syntax


public boolean isDontRoute();


public void setDontRoute(boolean dontRoute);

Default Value

False

Remarks

If this property is set to True, it forces the socket to send data directly to the interface (no routing). Normally, IP sockets send packets of data through routers and gateways until they reach the final destination. If this property is set to True, then data will be delivered on the local subnet only.

This property is not available at design time.

LocalHost Property (UDP Class)

The name of the local host or user-assigned IP interface through which connections are initiated or accepted.

Syntax


public String getLocalHost();


public void setLocalHost(String localHost);

Default Value

Remarks

The LocalHost property contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.

In multi-homed hosts (machines with more than one IP interface) setting LocalHost to the value of an interface will make the class initiate connections (or accept in the case of server classs) only through that interface.

If the class is connected, the LocalHost property shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multi-homed hosts (machines with more than one IP interface).

NOTE: LocalHost is not persistent. You must always set it in code, and never in the property window.

LocalPort Property (UDP Class)

The UDP port in the local host where UDP binds.

Syntax


public int getLocalPort();


public void setLocalPort(int localPort);

Default Value

Remarks

The LocalPort property must be set before UDP is activated (Active is set to True). It instructs the class to bind to a specific port (or communication endpoint) in the local machine.

Setting it to 0 (default) enables the TCP/IP stack to choose a port at random. The chosen port will be shown by the LocalPort property after the connection is established.

LocalPort cannot be changed once the class is Active. Any attempt to set the LocalPort property when the class is Active will generate an error.

The LocalPort property is useful when trying to connect to services that require a trusted port in the client side.

RemoteHost Property (UDP Class)

The address of the remote host. Domain names are resolved to IP addresses.

Syntax


public String getRemoteHost();


public void setRemoteHost(String remoteHost);

Default Value

Remarks

The RemoteHost property specifies the IP address (IP number in dotted internet format) or Domain Name of the remote host.

If RemoteHost is set to 255.255.255.255, the class broadcasts data on the local subnet.

If the RemoteHost property is set to a Domain Name, a DNS request is initiated and upon successful termination of the request, the RemoteHost property is set to the corresponding address. If the search is not successful, an error is returned.

If UseConnection is set to True, the RemoteHost must be set before the class is activated (Active is set to True).

RemotePort Property (UDP Class)

The UDP port in the remote host.

Syntax


public int getRemotePort();


public void setRemotePort(int remotePort);

Default Value

Remarks

The RemotePort is the UDP port on the RemoteHost to send UDP datagrams to.

A valid port number (a value between 1 and 65535) is required.

If UseConnection is set to True, the RemotePort must be set before the class is activated (Active is set to True).

TimeToLive Property (UDP Class)

The maximum number of subnets that a datagram can traverse.

Syntax


public int getTimeToLive();


public void setTimeToLive(int timeToLive);

Default Value

Remarks

The default value for this property is 0, which tells the class to use the default TTL value of the underlying TCP/IP subsystem. Depending on the application, you can specify a value between 1 and 255.

Activate Method (Udp Class)

Enables sending and receiving of data.

Syntax

public void activate();

Remarks

This method enables sending and receiving of data. When called the class will create a communication endpoint (socket) which can be used for sending and receiving UDP messages. This method must be called before using the class to send and receive data.

If the UseConnection configuration setting is set to true, then a local association (connection) to the remote host is also created.

Config Method (Udp Class)

Sets or retrieves a configuration setting.

Syntax

public String config(String configurationString);

Remarks

Config is a generic method available in every class. It is used to set and retrieve configuration settings for the class.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

Deactivate Method (Udp Class)

Disables sending and receive of data.

Syntax

public void deactivate();

Remarks

This method disables sending and receiving of data. When called the class will destroy the existing socket and disable data communications.

DoEvents Method (Udp Class)

Processes events from the internal message queue.

Syntax

public void doEvents();

Remarks

When DoEvents is called, the class processes any available events. If no events are available, it waits for a preset period of time, and then returns.

PauseData Method (Udp Class)

This method pauses data reception.

Syntax

public void pauseData();

Remarks

This method pauses data reception when called. While data reception is paused, the DataIn event will not fire. Call ProcessData to reenable data reception.

ProcessData Method (Udp Class)

This method reenables data reception after a call to PauseData .

Syntax

public void processData();

Remarks

This method reenables data reception after a previous call to PauseData. When PauseData is called, the DataIn event will not fire. To reenable data reception and allow DataIn to fire, call this method.

Note: This method is used only after previously calling PauseData. It does not need to be called to process incoming data by default.

Reset Method (Udp Class)

Reset the class.

Syntax

public void reset();

Remarks

This method will reset the class's properties to their default values.

ResolveRemoteHost Method (Udp Class)

Resolves the hostname in RemoteHost to an IP address.

Syntax

public void resolveRemoteHost();

Remarks

This method resolves the hostname specified by RemoteHost to an IP address. The resolved value is available in the RemoteHost property after this method returns.

In most cases calling this method is not necessary, the class will resolve the hostname automatically when necessary. If DelayHostResolution is true this method may be called to manually resolve RemoteHost if desired.

Send Method (Udp Class)

Send data to the remote host.

Syntax

public void send(byte[] text);

Remarks

Calling this method is equivalent to setting the DataToSend property to Text.

Example (Send Data)

UDPControl.LocalPort = 8765 UDPControl.RemotePort = 8765 UDPControl.RemoteHost = "HostNameOrIPAddress" UDPControl.Active = True UDPControl.Send("Hello!")

SendBytes Method (Udp Class)

Send data to the remote host.

Syntax

public void sendBytes(byte[] data);

Remarks

Calling this method is equivalent to call SendBytes/SendText method.

Example (Send Data)

UDPControl.LocalPort = 8765 UDPControl.RemotePort = 8765 UDPControl.RemoteHost = "HostNameOrIPAddress" UDPControl.Active = True UDPControl.Send("Hello!")

SendText Method (Udp Class)

Send data to the remote host.

Syntax

public void sendText(String text);

Remarks

Calling this method is equivalent to call SendBytes/SendText method.

Example (Send Data)

UDPControl.LocalPort = 8765 UDPControl.RemotePort = 8765 UDPControl.RemoteHost = "HostNameOrIPAddress" UDPControl.Active = True UDPControl.Send("Hello!")

DataIn Event (Udp Class)

Fired when data is received.

Syntax

public class DefaultUdpEventListener implements UdpEventListener {
  ...
  public void dataIn(UdpDataInEvent e) {}
  ...
}

public class UdpDataInEvent {
  public byte[] datagram;
  public String sourceAddress;
  public int sourcePort;
}

Remarks

The DataIn event is fired every time a new datagram is received.

Datagram contains the packet as sent by the remote host.

SourceAddress contains the IP number (Internet address) of the remote host, and SourcePort contains the port from which the packet originated.

Note: Events are not re-entrant. Performing time-consuming operations within this event will prevent it from firing again in a timely manner and may affect overall performance.

Error Event (Udp Class)

Fired when information is available about errors during data delivery.

Syntax

public class DefaultUdpEventListener implements UdpEventListener {
  ...
  public void error(UdpErrorEvent e) {}
  ...
}

public class UdpErrorEvent {
  public int errorCode;
  public String description;
}

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the class throws an exception.

The ErrorCode parameter contains an error code, and the Description parameter contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

ReadyToSend Event (Udp Class)

Fired when the class is ready to send data.

Syntax

public class DefaultUdpEventListener implements UdpEventListener {
  ...
  public void readyToSend(UdpReadyToSendEvent e) {}
  ...
}

public class UdpReadyToSendEvent {
}

Remarks

The ReadyToSend event indicates that the underlying TCP/IP subsystem is ready to accept data after a failed DataToSend.

Config Settings (Udp Class)

The class accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

UDP Config Settings

CaptureIPPacketInfo: Used to capture the packet information.

If this is set to true, the component will capture the IP packet information.

The default value for this setting is False.

Note: This setting is only available in Windows.

DelayHostResolution: Whether the hostname is resolved when RemoteHost is set.

This setting specifies whether a hostname is resolved immediately when RemoteHost is set. If true the class will resolve the hostname and the IP address will be present in the RemoteHost property. If false, the hostname is not resolved until needed by the component when a method to connect or send data is called. If desired, ResolveRemoteHost may called to manually resolve the value in RemoteHost at any time.

The default value is false.

DestinationAddress: Used to get the destination address from the packet information.

If CaptureIPPacketInfo is set to true, then this will be populated with the packet's destination address when a packet is received. This information will be accessible in the DataIn event.

Note: This setting is only available in Windows.

DontFragment: Used to set the Don't Fragment flag of outgoing packets.

When set to True, packets sent by the class will have the Don't Fragment flag set. The default value is False.

LocalHost: The name of the local host through which connections are initiated or accepted.

The LocalHost setting contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.

If the class is connected, the LocalHost setting shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multi-homed hosts (machines with more than one IP interface).

LocalPort: The port in the local host where the class binds.

This must be set before a connection is attempted. It instructs the class to bind to a specific port (or communication endpoint) in the local machine.

Setting this to 0 (default) enables the system to choose a port at random. The chosen port will be shown by LocalPort after the connection is established.

LocalPort cannot be changed once a connection is made. Any attempt to set this when a connection is active will generate an error.

This; setting is useful when trying to connect to services that require a trusted port in the client side. An example is the remote shell (rsh) service in UNIX systems.

MaxPacketSize: The maximum length of the packets that can be received.

This setting specifies the maximum size of the datagrams that the class will accept without truncation.

QOSDSCPValue: Used to specify an arbitrary QOS/DSCP setting (optional).

UseConnection must be True to use this setting. This option allows you to specify an arbitrary DSCP value between 0 and 63. The default is 0. When set to the default value the component will not set a DSCP value.

Note: This setting uses the qWAVE API is only available on Windows 7, Windows Server 2008 R2, and later.

QOSTrafficType: Used to specify QOS/DSCP settings (optional).

UseConnection must be True to use this setting. You may specify either the text or integer values: BestEffort (0), Background (1), ExcellentEffort (2), AudioVideo (3), Voice (4), and Control (5).

Note: This setting uses the qWAVE API which is only available on Windows Vista and Windows Server 2008 or above.

Note: QOSTrafficType must be set before setting Active to true.

ShareLocalPort: If set to True, allows more than one instance of the class to be active on the same local port.

This option must be set before the class is activated through the Active property or it will have no effect.

The default value for this setting is False.

UseConnection: Determines whether to use a connected socket.

UseConnection specifies whether the class should use a connected socket or not. The connection is defined as an association in between the local address/port and the remote address/port. As such, this is not a connection in the traditional TCP sense. What it means is only that the class will send and receive data only to and from the specified destination.

The default value for this setting is False.

UseIPv6: Whether or not to use IPv6.

By default, the component expects an IPv4 address for local and remote host properties, and will create an IPv4 socket. To use IPv6 instead, set this to True.

Socket Config Settings

AbsoluteTimeout: Determines whether timeouts are inactivity timeouts or absolute timeouts.

If AbsoluteTimeout is set to True, any method which does not complete within Timeout seconds will be aborted. By default, AbsoluteTimeout is False, and the timeout is an inactivity timeout.

Note: This option is not valid for UDP ports.

FirewallData: Used to send extra data to the firewall.

When the firewall is a tunneling proxy, use this property to send custom (additional) headers to the firewall (e.g. headers for custom authentication schemes).

InBufferSize: The size in bytes of the incoming queue of the socket.

This is the size of an internal queue in the TCP/IP stack. You can increase or decrease its size depending on the amount of data that you will be receiving. Increasing the value of the InBufferSize setting can provide significant improvements in performance in some cases.

Some TCP/IP implementations do not support variable buffer sizes. If that is the case, when the class is activated the InBufferSize reverts to its defined size. The same happens if you attempt to make it too large or too small.

OutBufferSize: The size in bytes of the outgoing queue of the socket.

This is the size of an internal queue in the TCP/IP stack. You can increase or decrease its size depending on the amount of data that you will be sending. Increasing the value of the OutBufferSize setting can provide significant improvements in performance in some cases.

Some TCP/IP implementations do not support variable buffer sizes. If that is the case, when the class is activated the OutBufferSize reverts to its defined size. The same happens if you attempt to make it too large or too small.

Base Config Settings

BuildInfo: Information about the product's build.

When queried, this setting will return a string containing information about the product's build.

GUIAvailable: Whether or not a message loop is available for processing events.

In a GUI-based application, long-running blocking operations may cause the application to stop responding to input until the operation returns. The class will attempt to discover whether or not the application has a message loop and, if one is discovered, it will process events in that message loop during any such blocking operation.

In some non-GUI applications, an invalid message loop may be discovered that will result in errant behavior. In these cases, setting GUIAvailable to false will ensure that the class does not attempt to process external events.

LicenseInfo: Information about the current license.

When queried, this setting will return a string containing information about the license this instance of a class is using. It will return the following information:

Product: The product the license is for.
Product Key: The key the license was generated from.
License Source: Where the license was found (e.g., RuntimeLicense, License File).
License Type: The type of license installed (e.g., Royalty Free, Single Server).
Last Valid Build: The last valid build number for which the license will work.

MaskSensitive: Whether sensitive data is masked in log messages.

In certain circumstances it may be beneficial to mask sensitive data, like passwords, in log messages. Set this to true to mask sensitive data. The default is true.

This setting only works on these classes: AS3Receiver, AS3Sender, Atom, Client(3DS), FTP, FTPServer, IMAP, OFTPClient, SSHClient, SCP, Server(3DS), Sexec, SFTP, SFTPServer, SSHServer, TCPClient, TCPServer.

UseDaemonThreads: Whether threads created by the class are daemon threads.

If set to True (default), when the class creates a thread, the thread's Daemon property will be explicitly set to True. When set to False, the class will not set the Daemon property on the created thread. The default value is True.

UseInternalSecurityAPI: Whether or not to use the system security libraries or an internal implementation.

When set to false, the class will use the system security libraries by default to perform cryptographic functions where applicable.

Setting this configuration setting to true tells the class to use the internal implementation instead of using the system security libraries.

This setting is set to false by default on all platforms.

Trappable Errors (Udp Class)

UDP Errors


	104 UDP is already Active.
	106 You cannot change the LocalPort while the class is Active.
	107 You cannot change the LocalHost at this time. A connection is in progress.
	109 The class must be Active for this operation.
	112 Cannot change MaxPacketSize while the class is Active.
	113 Cannot change ShareLocalPort option while the class is Active.
	114 Cannot change RemoteHost when UseConnection is set and the class Active.
	115 Cannot change RemotePort when UseConnection is set and the class is Active.
	116 RemotePort can't be zero when UseConnection is set. Please specify a valid service port number.
	117 Cannot change UseConnection while the class is Active.
	118 Message can't be longer than MaxPacketSize.
	119 Message too short.
	434 Unable to convert string to selected CodePage

SSL Errors


	270 Cannot load specified security library.
	271 Cannot open certificate store.
	272 Cannot find specified certificate.
	273 Cannot acquire security credentials.
	274 Cannot find certificate chain.
	275 Cannot verify certificate chain.
	276 Error during handshake.
	280 Error verifying certificate.
	281 Could not find client certificate.
	282 Could not find server certificate.
	283 Error encrypting data.
	284 Error decrypting data.

TCP/IP Errors


	10004 [10004] Interrupted system call.
	10009 [10009] Bad file number.
	10013 [10013] Access denied.
	10014 [10014] Bad address.
	10022 [10022] Invalid argument.
	10024 [10024] Too many open files.
	10035 [10035] Operation would block.
	10036 [10036] Operation now in progress.
	10037 [10037] Operation already in progress.
	10038 [10038] Socket operation on non-socket.
	10039 [10039] Destination address required.
	10040 [10040] Message too long.
	10041 [10041] Protocol wrong type for socket.
	10042 [10042] Bad protocol option.
	10043 [10043] Protocol not supported.
	10044 [10044] Socket type not supported.
	10045 [10045] Operation not supported on socket.
	10046 [10046] Protocol family not supported.
	10047 [10047] Address family not supported by protocol family.
	10048 [10048] Address already in use.
	10049 [10049] Can't assign requested address.
	10050 [10050] Network is down.
	10051 [10051] Network is unreachable.
	10052 [10052] Net dropped connection or reset.
	10053 [10053] Software caused connection abort.
	10054 [10054] Connection reset by peer.
	10055 [10055] No buffer space available.
	10056 [10056] Socket is already connected.
	10057 [10057] Socket is not connected.
	10058 [10058] Can't send after socket shutdown.
	10059 [10059] Too many references, can't splice.
	10060 [10060] Connection timed out.
	10061 [10061] Connection refused.
	10062 [10062] Too many levels of symbolic links.
	10063 [10063] File name too long.
	10064 [10064] Host is down.
	10065 [10065] No route to host.
	10066 [10066] Directory not empty
	10067 [10067] Too many processes.
	10068 [10068] Too many users.
	10069 [10069] Disc Quota Exceeded.
	10070 [10070] Stale NFS file handle.
	10071 [10071] Too many levels of remote in path.
	10091 [10091] Network subsystem is unavailable.
	10092 [10092] WINSOCK DLL Version out of range.
	10093 [10093] Winsock not loaded yet.
	11001 [11001] Host not found.
	11002 [11002] Non-authoritative 'Host not found' (try again or check DNS setup).
	11003 [11003] Non-recoverable errors: FORMERR, REFUSED, NOTIMP.
	11004 [11004] Valid name, no data record (check DNS setup).