UDPSocket

The UDPSocket class allows you to send and receive UDP packets. UDP (User Datagram Protocol) is an easy-to-implement protocol for sending data. It is faster and simpler than TCP (only 8 bytes of header as opposed to at least 20 bytes in TCP), but it does not offer the same level of reliability. It is useful for applications where data must arrive at their destination quickly. However, it does not allow verification of delivery, nor does it allow error-checking or recovery of data that was not delivered correctly.

The UDPSocket class is available from the 4D class store. You can create a UDP connection using the 4D.UDPSocket.new() function, which returns a UDPSocket object.

Thanks to the standard 4D object refcounting, a UDPSocket is automatically released when it is no longer referenced, i.e. when no more references to them exist in memory. Esto ocurre típicamente, por ejemplo, al final de una ejecución de un método para variables locales. Consequently, the associated resources are properly cleaned up without requiring explicit closure. However, if you want to "force" the closure of a socket at any moment, nullify its references by setting them to Null.

4DTCPUDPLog.txt file

For debugging and monitoring, you can use the 4DTCPUDPLog.txt log file that records events related to UDP sockets. Los eventos incluyen transmisión de datos, errores e información del ciclo de vida de la conexión.

Historia

Lanzamiento	Modificaciones
20 R10	Clase añadida

Ejemplo

Objeto UDPSocket

Un objeto UDPSocket no es modificable y no es streamable.

UDPSocket objects provide the following properties and functions:

errors : Collection a collection of error objects associated with the socket
port : Number the port number to listen to
.send( data : Blob ; hostName : Text ; remotePort : Integer ) sends data to the remote hostName server on the specified remotePort

4D.UDPSocket.new()

4D.UDPSocket.new() : 4D.UDPSocket
4D.UDPSocket.new( options : Object ) : 4D.UDPSocket
4D.UDPSocket.new( port : Integer ) : 4D.UDPSocket
4D.UDPSocket.new( port : Integer ; options : Object ) : 4D.UDPSocket

Parámetros	Tipo		Descripción
port	Integer	->	Local port used for UDP socket (0 or omitted = find any unused port to use)
options	Object	->	Configuration options for the socket
Resultado	UDPSocket	<-	Nuevo objeto UDPSocket

Descripción

The 4D.UDPSocket.new() function creates a new UDP socket using the defined options (if any) on the specified port (if any) or on a random unused port, and returns a 4D.UDPSocket object.

Parámetro options

In the options parameter, you can pass an object that contains the following properties:

Propiedad	Tipo	Descripción	Por defecto
onData	Formula	Retrollamada activada cuando se reciben datos	Indefinido
onError	Formula	Retrollamada en caso de error	Indefinido
onTerminate	Formula	Retrollamada activada cuando se libera el puerto	Indefinido

Función callback (retrollamada)

Todas las funciones de retrollamada reciben dos parámetros:

Parámetros	Tipo	Descripción
$socket	UDPSocket object	La instancia UDPSocket actual.
$event	UDPEvent object	Contiene información sobre el evento.

Secuencia de retrollamadas:

1. onData se activa cada vez que se reciben datos.
2. onError se activa si se produce un error.
3. onTerminate is always triggered just before the port is released (socket is closed or an error occured).

Objeto UDPEvent

A UDPEvent object is returned when a callback function is called.

.errors

errors : Collection

Descripción

The .errors property contains a collection of error objects associated with the socket. Cada objeto de error incluye el código de error, una descripción y la firma del componente que causó el error.

Propiedad		Tipo	Descripción
errors		Collection	Pila de error 4D en caso de error
	[].errCode	Number	Código de error 4D
	[].message	Text	Descripción del error 4D
	[].componentSignature	Text	Firma del componente interno que ha devuelto el error

.port

port : Number

Descripción

The .port property contains the port number to listen to. Esta propiedad es de solo lectura.

.send()

.send( data : Blob ; hostName : Text ; remotePort : Integer )

Parámetros	Tipo		Descripción
data	Blob	->	Datos a enviar
hostName	Text	->	Nombre o dirección IP del servidor
remotePort	Integer	->	Puerto remoto al que conectarse (0=cualquiera)

Descripción

The send() function sends data to the remote hostName server on the specified remotePort.

hostName is the name or IP address of the server where the data will be sent.

remotePort is the number of the port to be connected to. Si pasa 0, se utilizará cualquier puerto disponible.

Ver también

UDPEvent