Connecting to a Specific Server

The NATS client libraries can take a full URL, nats://demo.nats.io:4222, to specify a specific server host and port to connect to.

Libraries are removing the requirement for an explicit protocol and may allow demo.nats.io:4222 or just demo.nats.io. In the later example the default port 4222 will be used. Check with your specific client library's documentation to see what URL formats are supported.

For example, to connect to the demo server with a URL you can use:

Go
Java
JavaScript
Python
Ruby
TypeScript
C
Go
// If connecting to the default port, the URL can be simplified
// to just the hostname/IP.
// That is, the connect below is equivalent to:
// nats.Connect("nats://demo.nats.io:4222")
nc, err := nats.Connect("demo.nats.io")
if err != nil {
log.Fatal(err)
}
defer nc.Close()
// Do something with the connection nc = Nats.connect("nats://demo.nats.io:4222");
Java
Connection nc = Nats.connect("nats://demo.nats.io:4222");
// Do something with the connection
nc.close();
JavaScript
let nc = NATS.connect("nats://demo.nats.io:4222");
nc.on('connect', (c) => {
// Do something with the connection
doSomething();
// When done close it
nc.close();
});
nc.on('error', (err) => {
failed(err);
});
Python
nc = NATS()
await nc.connect(servers=["nats://demo.nats.io:4222"])
# Do something with the connection
await nc.close()
Ruby
require 'nats/client'
NATS.start(servers: ["nats://demo.nats.io:4222"]) do |nc|
# Do something with the connection
# Close the connection
nc.close
end
TypeScript
// will throw an exception if connection fails
let nc = await connect("nats://demo.nats.io:4222");
// Do something with the connection
// Close the connection
nc.close();
C
natsConnection *conn = NULL;
natsStatus s;
// If connecting to the default port, the URL can be simplified
// to just the hostname/IP.
// That is, the connect below is equivalent to:
// natsConnection_ConnectTo(&conn, "nats://demo.nats.io:4222");
s = natsConnection_ConnectTo(&conn, "demo.nats.io");
if (s != NATS_OK)
// handle error
// Destroy connection, no-op if conn is NULL.
natsConnection_Destroy(conn);
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