Crate cometd_client

source ·
Expand description

This crate aims to make a client for CometD protocol.

This project is in progress and might change a lot from version to version.

Table of contents

Connect endpoints

Client has ability to customize endpoints base paths:

  1. CometdClientBuilder::handshake_base_path;
  2. CometdClientBuilder::subscribe_base_path;
  3. CometdClientBuilder::connect_base_path;
  4. CometdClientBuilder::disconnect_base_path;

For example to change handshake base path and get http://[::1]:1025/notifications/node/0/handshake you can do this:

use cometd_client::CometdClientBuilder;

let client = CometdClientBuilder::new(&"http://[::1]:1025/notifications/".parse()?)

Same for others endpoints.


There is 2 options to authenticate on server, through authorization header and cookie.

Authentication through authorization header

To use access token with authorization header, you must set it through CometdClientBuilder::access_token. This library provide 2 default structs: types::access_token::Bearer and [types::access_token::Basic].

use cometd_client::{CometdClientBuilder, types::access_token::{Bearer, Basic}};

// let access_token = Bearer::new("access-token");
let access_token = Basic::create("username", Some("optional password"))?;

let client = CometdClientBuilder::new(&"http://[::1]:1025/notifications/".parse()?)

But you can make you own access token for authorization header:

use core::fmt::{Formatter, Debug};
use cometd_client::types::AccessToken;

struct OAuth(String);

impl Debug for OAuth {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        write!(f, "OAuth(***)")

impl OAuth {
    pub fn new(access_token: &str) -> Self {
        Self(format!("OAuth {access_token}"))

impl AccessToken for OAuth {
    fn get_authorization_token(&self) -> &str {

If you use session cookies for authentication (or other reasons) you can set it (or them) through CometdClientBuilder::cookie or CometdClientBuilder::cookies.

use cometd_client::CometdClientBuilder;

let client = CometdClientBuilder::new(&"http://[::1]:1025/notifications/".parse()?)
    .cookie("cookie0-name", "cookie0-value")
        ("cookie1-name", "cookie1-value"),
        ("cookie2-name", "cookie2-value")

How to interact with client?

Client use MPMC channel to send messages and errors. CometdClientBuilder::build spawn task which do handshake and start wait for messages. If handshake request was unsuccessful with types::Reconnect::Handshake or types::Reconnect::Retry advice from server, then client tries redo it by CometdClientBuilder::number_of_retries times. In other cases task send error to event channel and stops.

After successful handshake task start listen messages coming from server. If during that requests occurs error with types::Reconnect::Handshake advice, then client will tries redo handshake (look above). If error will be with types::Reconnect::Retry advice, then it will try redo it by CometdClientBuilder::number_of_retries times.

To send subscribe command you must use CometdClient::subscribe. If error occurs it will be redone by same scheme as for connect (look above).

To get event channel receiver use CometdClient::rx.

use cometd_client::{types::CometdClientEvent, CometdClientBuilder};

let client = CometdClientBuilder::new(&"http://[::0]:1025/notifications/".parse()?)

let mut rx = client.rx();

tokio::spawn(async move {
    while let Some(event) = rx.recv().await {
        match event {
            CometdClientEvent::Message(messages) => println!("got messages: `{messages:?}`."),
            CometdClientEvent::Error(error) => eprintln!("got error: `{error:?}`."),   


  • Contains various structs, enums and traits.