# glats
[![Package Version](https://img.shields.io/hexpm/v/glats)](https://hex.pm/packages/glats)
[![Hex Docs](https://img.shields.io/badge/hex-docs-ffaff3)](https://hexdocs.pm/glats/)
A NATS client for Gleam. This wraps Elixir's client, [Gnat](https://hex.pm/packages/gnat).
## Publish
```gleam
import gleam/result
import glats
import glats/settings
pub fn main() {
use conn <- result.then(
settings.new("localhost", 4222)
|> glats.connect,
)
// Publish a single message to "some.subject".
assert Ok(Nil) = glats.publish(conn, "some.subject", "hello world!")
Ok(Nil)
}
```
## Subscribe
```gleam
import gleam/io
import gleam/result
import gleam/erlang/process
import glats
import glats/settings
import glats/message
pub fn main() {
use conn <- result.then(
settings.new("localhost", 4222)
|> glats.connect,
)
let subject = process.new_subject()
// Subscribe to "some.subject".
// Messages will be delivered to the erlang subject passed in.
assert Ok(sid) = glats.subscribe(conn, subject, "some.subject")
// Publish a single message to "some.subject".
assert Ok(Nil) = glats.publish(conn, "some.subject", "hello world!")
// Receive from erlang subject.
assert Ok(glats.ReceivedMessage(
conn: _conn, // Reference to the conn used
sid: _sid, // Subscription ID for the subscription
message: message.Message(
subject: _subject, // "some.subject"
headers: _headers, // empty map
reply_to: _reply_to, // None
body: _body, // "hello world!"
)
)) = process.receive(subject, 1000)
// Unsubscribe from the subscription.
assert Ok(Nil) = glats.unsubscribe(conn, sid)
Ok(Nil)
}
```
## Request handler
```gleam
import gleam/option.{None}
import gleam/result
import gleam/erlang/process
import glats
import glats/settings
import glats/handler.{Reply, Request, Response}
pub fn main() {
use conn <- result.then(
settings.new("localhost", 4222)
|> glats.connect,
)
// Start a request handler actor that will call `ping_pong_handler` for
// every request received from NATS subject "do.ping".
assert Ok(_actor) =
handler.handle_request(conn, [], "do.ping", None, ping_pong_handler)
process.sleep_forever()
Ok(Nil)
}
pub fn ping_pong_handler(req: Request, state) {
// Got message: Hello
io.println("Got message: " <> req.body)
// Reply with a message with the same headers and append to body.
Reply(
Response(
headers: req.headers,
reply_to: None,
body: req.body <> " from glats!",
),
state,
)
}
```
Then in shell with `natscli`.
```sh
$ nats req do.ping 'Hello'
12:16:47 Sending request on "do.ping"
12:16:47 Received with rtt 427.64µs
Hello from glats!
```
## Installation
```sh
gleam add glats
```
and its documentation can be found at <https://hexdocs.pm/glats>.