Actions

The ballerina/udp package exposes the following clients:

Client	Purpose
Client	Sends and receives UDP datagrams without a fixed remote host connection.
Connect Client	Sends and receives UDP data to/from a fixed remote host and port.

For event-driven integration, see the Trigger Reference.

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Client

Sends and receives UDP datagrams without a fixed remote host connection.

Configuration

Field	Type	Default	Description
timeout	decimal	300	Socket read timeout in seconds.
localHost	string	()	Local network interface to bind the socket to.

Initializing the client

import ballerina/udp;

udp:Client udpClient = check new ();

Operations

Datagram operations

sendDatagram

Sends a datagram to a specified remote host and port.

Parameters:

Name	Type	Required	Description
datagram	Datagram	Yes	The datagram containing remoteHost, remotePort, and data fields.

Returns: Error?

Sample code:

check udpClient->sendDatagram({
    remoteHost: "localhost",
    remotePort: 8080,
    data: "Hello from UDP client".toBytes()
});

receiveDatagram

Receives a datagram from any remote host. Blocks until data arrives or the timeout is reached.

Returns: readonly & Datagram|Error

Sample code:

udp:Datagram datagram = check udpClient->receiveDatagram();

Sample response:

{"remoteHost": "localhost", "remotePort": 8080, "data": [72, 101, 108, 108, 111]}

close

Closes the UDP client socket and frees the associated resources.

Returns: Error?

Sample code:

check udpClient->close();

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Connect client

Sends and receives UDP data to/from a fixed remote host and port.

Configuration

Field	Type	Default	Description
timeout	decimal	300	Socket read timeout in seconds.
localHost	string	()	Local network interface to bind the socket to.

Initializing the client

import ballerina/udp;

udp:ConnectClient udpConnectClient = check new ("localhost", 8080);

Operations

Byte operations

writeBytes

Sends bytes to the connected remote host. If the data exceeds the maximum datagram size, it is sent across multiple datagrams.

Parameters:

Name	Type	Required	Description
data	byte[]	Yes	The byte array to send.

Returns: Error?

Sample code:

check udpConnectClient->writeBytes("Hello from connected client".toBytes());

readBytes

Reads bytes from the connected remote host. Blocks until data arrives or the timeout is reached.

Returns: readonly & byte[]|Error

Sample code:

byte[] received = check udpConnectClient->readBytes();

Sample response:

[72, 101, 108, 108, 111]

close

Closes the connected UDP client socket and frees the associated resources.

Returns: Error?

Sample code:

check udpConnectClient->close();