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. Isso geralmente ocorre, por exemplo, no final da execução de um método para variáveis locais. 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. Events include data transmission, errors, and connection lifecycle information.

História

Release	Mudanças
20 R10	Classe adicionada

Exemplo

UDPSocket Object

A UDPSocket object is immutable, non 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( options : Object ) : 4D.UDPSocket
4D.UDPSocket.new( port : Integer ; options : Object ) : 4D.UDPSocket

Parâmetro	Tipo		Descrição
port	Integer	->	Local port used for UDP socket (0 or omitted = find any unused port to use)
options	Object	->	Configuration options for the socket
Resultados	UDPSocket	<-	New UDPSocket object

Descrição

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

options parameter

No parâmetro options, passe um objeto que possa conter as seguintes propriedades:

Propriedade	Tipo	Descrição	Por padrão
onData	Formula	Callback acionado quando os dados forem recebidos	Indefinido
onError	Formula	Callback acionado no caso de um erro	Indefinido
onTerminate	Formula	Callback triggered when the port is released	Indefinido

Funções Callback

Todas as funções de chamada de retorno recebem dois parâmetros de objectos:

Parâmetro	Tipo	Descrição
$socket	UDPSocket object	The current UDPSocket instance.
$event	UDPEvent object	Contém informações sobre o evento.

Sequência de chamadas de retorno:

1. onData é acionado cada vez que os dados são recebidos.
2. onError é acionado se ocorrer um erro.
3. onTerminate is always triggered just before the port is released (socket is closed or an error occured).

UDPEvent object

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

.errors

errors : Collection

Descrição

The .errors property contains a collection of error objects associated with the socket. Cada objeto de erro inclui o código de erro, uma descrição e a assinatura do componente que causou o erro.

Propriedade		Tipo	Descrição
errors		Collection	pilha de erros 4D em caso de erro
	[].errCode	Number	Código de erro 4D
	[].message	Text	Descrição do erro 4D
	[].componentSignature	Text	Assinatura da componente interna que devolveu o erro

.port

port : Number

Descrição

The .port property contains the port number to listen to. Essa propriedade é somente leitura.

.send()

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

Parâmetro	Tipo		Descrição
data	Blob	->	Dados a serem enviados
hostName	Text	->	Name or IP address of server
remotePort	Integer	->	Remote port to connect to (0=any)

Descrição

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. If you pass 0, any available port will be used.

Veja também

UDPEvent