elstat/docs/streaming.md

Streaming API

Elstat's Streaming API enables clients to receive realtime updates from the server.

Clients can subscribe just to certain channels in the case they don't want to have a lot of overhead, or they can just not use the Streaming API at all. It is optional.

Common payload format

Payloads can not exceed 256 bytes in size. Payloads are JSON encoded.

{
    "op": ANY_INTEGER
}

Extra fields are on each OP's description, instead of being in some d field (like Discord's Gateway API).

Error codes

Error code	Name
4200	INVALID_PAYLOAD
4420	TOO_MUCH

OP Codes

OP Int	OP Name	Sent/Received by client
-1	UNSUBSCRIBE	Sent
0	SUBSCRIBE	Sent
1	SUBSCRIBED	Received
2	UNSUBSCRIBED	Received
3	DATA	Received

OP Payloads

• SUBSCRIBE
  • field: channels (list[str]), array of channels you want to subscribe to.
  • reply: SUBSCRIBED payload.
• UNSUBSCRIBE
  • field: channels (list[str]), array of channels you want to unsubscribe from.
  • reply: UNSUBSCRIBED payload.
• SUBSCRIBED
  • field: channels (list[str]), array of channels you succesfully subscribed to.
• UNSUBSCRIBED
  • field: channels (list[str]), array of channels you succesfully unsubscribed from.
• DATA
  • field: c (str), the channel the data is coming from.
  • data: d (list[any]), the data coming in from the channel.
    • The first element of d is an integer, encoding an UNIX timestamp with millisecond precision.
    • The second element of d is described on Channel types

Channel names

Channels are what clients subscribe to receive data about that channel. Channels are specified as <type>:<name>

e.g status:elixire and graph:elixire

Channel types

• status channel
  • Returns a boolean, representing the status of the service
• latency channel
  • Returns an integer, representing the latency of the service, in milliseconds.

Connection logic

• Connect a websocket to /api/streaming.
• Send a SUBSCRIBE payload, receive SUBSCRIBED back
• Listen to DATA payloads and update local state as needed.