Cryo

Cryo is a small binary protocol for sending arbitrary messages, large data and real-time information over WebSocket. It uses fixed frame types for acknowledgements, heartbeats, UTF-8 text, binary payloads and streamed transactions.

This is an implementation of the Cryo protocol specified at Cryo-Protocol

Cryo-Client-Browser / Overview

The Cryo Browser client takes care of the following:

• Authentication at the server
• Correct framing and structuring of received and sent data

The client provides a public API for creating and destroying an instance. It provides access incoming communication via events

Setup

To set up a Cryo Client, simply import the cryo function from the cryo-client-browser package.

The cryo-function takes two arguments:

• host
  • a required host string
• bearer
  • a required authentication token string
• timeout
  • an optional timeout value, indicating how long the client should wait until a connection request to the server is aborted

CryoClientWebsocketSession / Overview

Public methods

| Name | Parameter | Description | Returns | |------------------------|------------------------------------------------|--------------------------------------------|---------------------| | SendUTF8 | message: string | Streams a Readable to the server | | | SendBinary | message: CryoBuffer | Streams a Readable to the server | | | Stream | source: ReadableStream, name?: string | Streams a Readable to the server | | | WaitForStream | streamName?: string , timeout?: number | Waits for a named stream | Promise | | SetIncomingFlowControl | behaviour: TX_PULL | TX_PUSH | Sets the remote flow control | |
| StreamFetchRange | stream: CryoStream, start: number, end: number | Fetches chunk start-end of a given stream | | | Close | | Closes the underlying Websocket connection | | | Destroy | code?: number, message?: string | Tears down the session | |

Data Events

These events are emitted when the server-side session receives data from a client-side session

| Name | Parameter | Description | |----------------|------------|----------------------------------------------------------------| | message-utf8 | string | Emitted, when the session receives a utf8 text message | | message-binary | CryoBuffer | Emitted, when the session receives an arbitrary binary message |

Meta events

This category of events is emitted when the session state changes

| Name | Parameter | Description | |--------------|--------------------------------|-------------------------------------------------| | connected | | Emitted, when the session successfully connects | | disconnected | | Emitted, when the session has been disconnected | | reconnected | | Emitted, when the session has reconnected | | closed | [code: number, reason: string] | Emitted, when the session is closed |

Cryo-Client / Example

import {cryo} from "cryo-client-browser";

const HOST = "localhost:8080";
const TOKEN = "SOME_AUTH_TOKEN";

const client = await cryo(HOST, TOKEN, 10000);
client.on("connected", () => {
    console.info(`Successfully connected to ${HOST}`);
});