SlungClient
The main client class for connecting to Slung and sending events.
Constructor
new SlungClient(url?: string)
url
string
default:"ws://127.0.0.1:2077"
WebSocket URL of the Slung server
Example
import { SlungClient } from "@slunghq/client";
const client = new SlungClient("ws://127.0.0.1:2077");
connect()
async connect(): Promise<void>
Returns
Promise that resolves when the connection is established.
Throws
Throws an error if the connection fails.
Example
try {
await client.connect();
console.log("Connected to Slung");
} catch (err) {
console.error("Connection failed:", err);
}
sendEvent()
sendEvent(event: SlungEvent): void
Numeric value associated with the event
Unix timestamp in microseconds. Use Date.now() * 1000 or the nowUnixMicros() helper.
Series name identifying the metric or measurement
Array of tags in key=value format
Throws
Throws an error if the WebSocket is not connected. Call connect() first.
Example
import { nowUnixMicros } from "@slunghq/client";
client.sendEvent({
value: 23.5,
timestamp: nowUnixMicros(),
series: "temp",
tags: ["sensor=1", "location=datacenter", "rack=A1"]
});
startSimulatedStream()
startSimulatedStream(options?: SimulatedStreamOptions): () => void
Configuration options for the simulated stream
Milliseconds between events
Random variance magnitude applied each interval
Series name for generated events
options.tags
string[]
default:"[\"sensor=1\", \"env=dev\"]"
Tags array for generated events
Returns
A function that stops the simulated stream when called.
Example
const stop = client.startSimulatedStream({
intervalMs: 10,
initialValue: 90,
jitter: 1.2,
series: "cpu_usage",
tags: ["host=server1", "env=prod"]
});
// Stop after 10 seconds
setTimeout(() => {
stop();
console.log("Stopped simulated stream");
}, 10000);
close()
close(code?: number, reason?: string): void
WebSocket close code (e.g., 1000 for normal closure)
Human-readable reason for closing
Example
// Normal closure
client.close(1000, "shutdown");
// Simple close
client.close();
Utility Functions
nowUnixMicros()
function nowUnixMicros(): number
Returns
Current time as microseconds since Unix epoch.
Example
import { nowUnixMicros } from "@slunghq/client";
const timestamp = nowUnixMicros();
console.log(timestamp); // e.g., 1709481234567890
encodeEventBinary()
function encodeEventBinary(event: WireEvent): Buffer
Returns
Buffer containing the encoded event data.
Example
import { encodeEventBinary } from "@slunghq/client";
const buffer = encodeEventBinary({
timestamp: Date.now() * 1000,
value: 42.0,
series: "requests",
tags: ["method=GET", "status=200"]
});
decodeEventBinary()
function decodeEventBinary(buf: Buffer): WireEvent | null
Buffer containing encoded event data
Returns
Decoded WireEvent object, or null if the buffer is invalid.
createEventBinaryEncoder()
function createEventBinaryEncoder(
series: string,
tags: string[]
): (timestamp: number, value: number) => Buffer
Series name to encode in all events
Tags array to encode in all events
Returns
Encoder function that takes (timestamp, value) and returns an encoded Buffer.
Example
import { createEventBinaryEncoder } from "@slunghq/client";
const encode = createEventBinaryEncoder("temp", ["sensor=1", "env=prod"]);
// Reuse the encoder for multiple events
const buf1 = encode(Date.now() * 1000, 23.5);
const buf2 = encode(Date.now() * 1000, 24.1);