377 lines
14 KiB
Markdown
377 lines
14 KiB
Markdown
# Subscribe via API
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You can create and subscribe to a topic in the [web UI](web.md), via the [phone app](phone.md), via the [ntfy CLI](cli.md),
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or in your own app or script by subscribing the API. This page describes how to subscribe via API. You may also want to
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check out the page that describes how to [publish messages](../publish.md).
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You can consume the subscription API as either a **[simple HTTP stream (JSON, SSE or raw)](#http-stream)**, or
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**[via WebSockets](#websockets)**. Both are incredibly simple to use.
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## HTTP stream
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The HTTP stream-based API relies on a simple GET request with a streaming HTTP response, i.e **you open a GET request and
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the connection stays open forever**, sending messages back as they come in. There are three different API endpoints, which
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only differ in the response format:
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* [JSON stream](#subscribe-as-json-stream): `<topic>/json` returns a JSON stream, with one JSON message object per line
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* [SSE stream](#subscribe-as-sse-stream): `<topic>/sse` returns messages as [Server-Sent Events (SSE)](https://en.wikipedia.org/wiki/Server-sent_events), which
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can be used with [EventSource](https://developer.mozilla.org/en-US/docs/Web/API/EventSource)
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* [Raw stream](#subscribe-as-raw-stream): `<topic>/raw` returns messages as raw text, with one line per message
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### Subscribe as JSON stream
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Here are a few examples of how to consume the JSON endpoint (`<topic>/json`). For almost all languages, **this is the
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recommended way to subscribe to a topic**. The notable exception is JavaScript, for which the
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[SSE/EventSource stream](#subscribe-as-sse-stream) is much easier to work with.
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=== "Command line (curl)"
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```
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$ curl -s ntfy.sh/disk-alerts/json
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{"id":"SLiKI64DOt","time":1635528757,"event":"open","topic":"mytopic"}
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{"id":"hwQ2YpKdmg","time":1635528741,"event":"message","topic":"mytopic","message":"Disk full"}
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{"id":"DGUDShMCsc","time":1635528787,"event":"keepalive","topic":"mytopic"}
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...
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```
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=== "ntfy CLI"
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```
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$ ntfy subcribe disk-alerts
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{"id":"hwQ2YpKdmg","time":1635528741,"event":"message","topic":"mytopic","message":"Disk full"}
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...
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```
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=== "HTTP"
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``` http
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GET /disk-alerts/json HTTP/1.1
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Host: ntfy.sh
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HTTP/1.1 200 OK
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Content-Type: application/x-ndjson; charset=utf-8
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Transfer-Encoding: chunked
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{"id":"SLiKI64DOt","time":1635528757,"event":"open","topic":"mytopic"}
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{"id":"hwQ2YpKdmg","time":1635528741,"event":"message","topic":"mytopic","message":"Disk full"}
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{"id":"DGUDShMCsc","time":1635528787,"event":"keepalive","topic":"mytopic"}
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...
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```
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=== "Go"
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``` go
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resp, err := http.Get("https://ntfy.sh/disk-alerts/json")
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if err != nil {
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log.Fatal(err)
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}
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defer resp.Body.Close()
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scanner := bufio.NewScanner(resp.Body)
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for scanner.Scan() {
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println(scanner.Text())
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}
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```
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=== "Python"
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``` python
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resp = requests.get("https://ntfy.sh/disk-alerts/json", stream=True)
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for line in resp.iter_lines():
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if line:
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print(line)
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```
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=== "PHP"
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``` php-inline
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$fp = fopen('https://ntfy.sh/disk-alerts/json', 'r');
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if (!$fp) die('cannot open stream');
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while (!feof($fp)) {
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echo fgets($fp, 2048);
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flush();
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}
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fclose($fp);
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```
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### Subscribe as SSE stream
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Using [EventSource](https://developer.mozilla.org/en-US/docs/Web/API/EventSource) in JavaScript, you can consume
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notifications via a [Server-Sent Events (SSE)](https://en.wikipedia.org/wiki/Server-sent_events) stream. It's incredibly
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easy to use. Here's what it looks like. You may also want to check out the [live example](/example.html).
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=== "Command line (curl)"
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```
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$ curl -s ntfy.sh/mytopic/sse
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event: open
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data: {"id":"weSj9RtNkj","time":1635528898,"event":"open","topic":"mytopic"}
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data: {"id":"p0M5y6gcCY","time":1635528909,"event":"message","topic":"mytopic","message":"Hi!"}
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event: keepalive
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data: {"id":"VNxNIg5fpt","time":1635528928,"event":"keepalive","topic":"test"}
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...
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```
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=== "HTTP"
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``` http
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GET /mytopic/sse HTTP/1.1
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Host: ntfy.sh
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HTTP/1.1 200 OK
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Content-Type: text/event-stream; charset=utf-8
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Transfer-Encoding: chunked
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event: open
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data: {"id":"weSj9RtNkj","time":1635528898,"event":"open","topic":"mytopic"}
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data: {"id":"p0M5y6gcCY","time":1635528909,"event":"message","topic":"mytopic","message":"Hi!"}
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event: keepalive
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data: {"id":"VNxNIg5fpt","time":1635528928,"event":"keepalive","topic":"test"}
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...
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```
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=== "JavaScript"
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``` javascript
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const eventSource = new EventSource('https://ntfy.sh/mytopic/sse');
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eventSource.onmessage = (e) => {
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console.log(e.data);
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};
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```
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### Subscribe as raw stream
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The `/raw` endpoint will output one line per message, and **will only include the message body**. It's useful for extremely
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simple scripts, and doesn't include all the data. Additional fields such as [priority](../publish.md#message-priority),
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[tags](../publish.md#tags--emojis--) or [message title](../publish.md#message-title) are not included in this output
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format. Keepalive messages are sent as empty lines.
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=== "Command line (curl)"
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```
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$ curl -s ntfy.sh/disk-alerts/raw
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Disk full
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...
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```
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=== "HTTP"
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``` http
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GET /disk-alerts/raw HTTP/1.1
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Host: ntfy.sh
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HTTP/1.1 200 OK
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Content-Type: text/plain; charset=utf-8
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Transfer-Encoding: chunked
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Disk full
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...
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```
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=== "Go"
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``` go
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resp, err := http.Get("https://ntfy.sh/disk-alerts/raw")
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if err != nil {
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log.Fatal(err)
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}
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defer resp.Body.Close()
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scanner := bufio.NewScanner(resp.Body)
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for scanner.Scan() {
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println(scanner.Text())
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}
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```
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=== "Python"
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``` python
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resp = requests.get("https://ntfy.sh/disk-alerts/raw", stream=True)
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for line in resp.iter_lines():
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if line:
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print(line)
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```
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=== "PHP"
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``` php-inline
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$fp = fopen('https://ntfy.sh/disk-alerts/raw', 'r');
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if (!$fp) die('cannot open stream');
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while (!feof($fp)) {
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echo fgets($fp, 2048);
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flush();
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}
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fclose($fp);
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```
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## WebSockets
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You may also subscribe to topics via [WebSockets](https://en.wikipedia.org/wiki/WebSocket), which is also widely
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supported in many languages. Most notably, WebSockets are natively supported in JavaScript. On the command line,
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I recommend [websocat](https://github.com/vi/websocat), a fantastic tool similar to `socat` or `curl`, but specifically
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for WebSockets.
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The WebSockets endpoint is available at `<topic>/ws` and returns messages as JSON objects similar to the
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[JSON stream endpoint](#subscribe-as-json-stream).
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=== "Command line (websocat)"
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```
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$ websocat wss://ntfy.sh/mytopic/ws
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{"id":"qRHUCCvjj8","time":1642307388,"event":"open","topic":"mytopic"}
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{"id":"eOWoUBJ14x","time":1642307754,"event":"message","topic":"mytopic","message":"hi there"}
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```
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=== "HTTP"
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``` http
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GET /disk-alerts/ws HTTP/1.1
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Host: ntfy.sh
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Upgrade: websocket
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Connection: Upgrade
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HTTP/1.1 101 Switching Protocols
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Upgrade: websocket
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Connection: Upgrade
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...
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```
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=== "Go"
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``` go
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import "github.com/gorilla/websocket"
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ws, _, _ := websocket.DefaultDialer.Dial("wss://ntfy.sh/mytopic/ws", nil)
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messageType, data, err := ws.ReadMessage()
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...
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```
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=== "JavaScript"
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``` javascript
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const socket = new WebSocket('wss://ntfy.sh/mytopic/ws');
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socket.addEventListener('message', function (event) {
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console.log(event.data);
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});
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```
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## Advanced features
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### Poll for messages
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You can also just poll for messages if you don't like the long-standing connection using the `poll=1`
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query parameter. The connection will end after all available messages have been read. This parameter can be
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combined with `since=` (defaults to `since=all`).
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```
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curl -s "ntfy.sh/mytopic/json?poll=1"
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```
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### Fetch cached messages
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Messages may be cached for a couple of hours (see [message caching](../config.md#message-cache)) to account for network
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interruptions of subscribers. If the server has configured message caching, you can read back what you missed by using
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the `since=` query parameter. It takes either a duration (e.g. `10m` or `30s`), a Unix timestamp (e.g. `1635528757`)
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or `all` (all cached messages).
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```
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curl -s "ntfy.sh/mytopic/json?since=10m"
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```
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### Fetch scheduled messages
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Messages that are [scheduled to be delivered](../publish.md#scheduled-delivery) at a later date are not typically
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returned when subscribing via the API, which makes sense, because after all, the messages have technically not been
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delivered yet. To also return scheduled messages from the API, you can use the `scheduled=1` (alias: `sched=1`)
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parameter (makes most sense with the `poll=1` parameter):
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```
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curl -s "ntfy.sh/mytopic/json?poll=1&sched=1"
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```
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### Filter messages
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You can filter which messages are returned based on the well-known message fields `message`, `title`, `priority` and
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`tags`. Here's an example that only returns messages of high or urgent priority that contains the both tags
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"zfs-error" and "error". Note that the `priority` filter is a logical OR and the `tags` filter is a logical AND.
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```
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$ curl "ntfy.sh/alerts/json?priority=high&tags=zfs-error"
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{"id":"0TIkJpBcxR","time":1640122627,"event":"open","topic":"alerts"}
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{"id":"X3Uzz9O1sM","time":1640122674,"event":"message","topic":"alerts","priority":4,
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"tags":["error", "zfs-error"], "message":"ZFS pool corruption detected"}
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```
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Available filters (all case-insensitive):
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| Filter variable | Alias | Example | Description |
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| `message` | `X-Message`, `m` | `ntfy.sh/mytopic?message=lalala` | Only return messages that match this exact message string |
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| `title` | `X-Title`, `t` | `ntfy.sh/mytopic?title=some+title` | Only return messages that match this exact title string |
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| `priority` | `X-Priority`, `prio`, `p` | `ntfy.sh/mytopic?p=high,urgent` | Only return messages that match *any priority listed* (comma-separated) |
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| `tags` | `X-Tags`, `tag`, `ta` | `ntfy.sh/mytopic?tags=error,alert` | Only return messages that match *all listed tags* (comma-separated) |
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### Subscribe to multiple topics
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It's possible to subscribe to multiple topics in one HTTP call by providing a comma-separated list of topics
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in the URL. This allows you to reduce the number of connections you have to maintain:
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```
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$ curl -s ntfy.sh/mytopic1,mytopic2/json
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{"id":"0OkXIryH3H","time":1637182619,"event":"open","topic":"mytopic1,mytopic2,mytopic3"}
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{"id":"dzJJm7BCWs","time":1637182634,"event":"message","topic":"mytopic1","message":"for topic 1"}
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{"id":"Cm02DsxUHb","time":1637182643,"event":"message","topic":"mytopic2","message":"for topic 2"}
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```
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## JSON message format
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Both the [`/json` endpoint](#subscribe-as-json-stream) and the [`/sse` endpoint](#subscribe-as-sse-stream) return a JSON
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format of the message. It's very straight forward:
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| Field | Required | Type | Example | Description |
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| `id` | ✔️ | *string* | `hwQ2YpKdmg` | Randomly chosen message identifier |
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| `time` | ✔️ | *int* | `1635528741` | Message date time, as Unix time stamp |
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| `event` | ✔️ | `open`, `keepalive` or `message` | `message` | Message type, typically you'd be only interested in `message` |
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| `topic` | ✔️ | *string* | `topic1,topic2` | Comma-separated list of topics the message is associated with; only one for all `message` events, but may be a list in `open` events |
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| `message` | - | *string* | `Some message` | Message body; always present in `message` events |
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| `title` | - | *string* | `Some title` | Message [title](../publish.md#message-title); if not set defaults to `ntfy.sh/<topic>` |
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| `tags` | - | *string array* | `["tag1","tag2"]` | List of [tags](../publish.md#tags-emojis) that may or not map to emojis |
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| `priority` | - | *1, 2, 3, 4, or 5* | `4` | Message [priority](../publish.md#message-priority) with 1=min, 3=default and 5=max |
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Here's an example for each message type:
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=== "Notification message"
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``` json
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{
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"id": "wze9zgqK41",
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"time": 1638542110,
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"event": "message",
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"topic": "phil_alerts",
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"priority": 5,
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"tags": [
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"warning",
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"skull"
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],
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"title": "Unauthorized access detected",
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"message": "Remote access to phils-laptop detected. Act right away."
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}
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```
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=== "Notification message (minimal)"
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``` json
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{
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"id": "wze9zgqK41",
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"time": 1638542110,
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"event": "message",
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"topic": "phil_alerts",
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"message": "Remote access to phils-laptop detected. Act right away."
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}
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```
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=== "Open message"
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``` json
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{
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"id": "2pgIAaGrQ8",
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"time": 1638542215,
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"event": "open",
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"topic": "phil_alerts"
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}
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```
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=== "Keepalive message"
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``` json
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{
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"id": "371sevb0pD",
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"time": 1638542275,
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"event": "keepalive",
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"topic": "phil_alerts"
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}
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```
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## List of all parameters
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The following is a list of all parameters that can be passed when subscribing to a message. Parameter names are **case-insensitive**,
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and can be passed as **HTTP headers** or **query parameters in the URL**. They are listed in the table in their canonical form.
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| Parameter | Aliases (case-insensitive) | Description |
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| `poll` | `X-Poll`, `po` | Return cached messages and close connection |
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| `scheduled` | `X-Scheduled`, `sched` | Include scheduled/delayed messages in message list |
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| `message` | `X-Message`, `m` | Filter: Only return messages that match this exact message string |
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| `title` | `X-Title`, `t` | Filter: Only return messages that match this exact title string |
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| `priority` | `X-Priority`, `prio`, `p` | Filter: Only return messages that match *any priority listed* (comma-separated) |
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| `tags` | `X-Tags`, `tag`, `ta` | Filter: Only return messages that match *all listed tags* (comma-separated) |
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