# spoke_packet
[](https://hex.pm/packages/spoke_packet)
[](https://hexdocs.pm/spoke_packet/)
`spoke_packet` contains Gleam data structures to represent MQTT packets
and encode/decode them to/from their binary representation.
The data structures strive to make representing invalid states impossible,
which is why they sometimes might feel a bit far from their binary representations.
```sh
gleam add spoke_packet@1
```
```gleam
import gleam/bytes_tree
import spoke/packet
import spoke/packet/client/incoming
import spoke/packet/client/outgoing
pub fn main() {
// Represent MQTT packets in code
let subscribe_packet =
outgoing.Subscribe(
packet_id: 42,
topic: packet.SubscribeRequest("my/topic", packet.QoS1),
other_topics: [],
)
// And encode them into binary. Prints
// <<130, 13, 0, 42, 0, 8, 109, 121, 47, 116, 111, 112, 105, 99, 1>>
let bytes = outgoing.encode_packet(subscribe_packet)
echo bytes_tree.to_bit_array(bytes)
// Decode binary data, which may contain multiple packets or be incomplete:
let assert Ok(#(packets, rest)) =
incoming.decode_packets(<<32, 2, 0, 1, 64, 2, 0, 42, 208>>)
// As there was two full packets in the data, prints
// [ConnAck(Error(UnacceptableProtocolVersion)), PubAck(42)]
echo packets
// As the third packet was incomplete, prints <<208>>
echo rest
}
```
