send message from the server

[smblee]

Hello! This is a great addition to ably.

I am porting over my old custom chat flow to this lib, and one item remaining is sending a system/admin message to a chat room. Before I could just use the ably rest client to send chats. How can i do this with the ably-chat-js library?

Noticed theres a separate chat API, wonder if i can hit that somehow with a custom server's clientId

┆Issue is synchronized with this Jira Task by Unito

[smblee]

Also have a use case to bulk publish the chats (~500 message at once across multiple channels).

[AndyTWF]

Hi @smblee!

Thanks for your question! Yes you can absolutely send system initiated chat messages. You can do this in two ways:

1. You can use the Chat SDK on your server (setting the clientId to be the special ID you have for your server when you initialise the client).

2. You can call the REST API directly using the base Ably SDK (ably-js), by calling the request method, as the chat SDK does. If you look at the ChatApi class in this repo, it should be fairly straightforward to replicate. We still need to write up the full documentation for the HTTP API, so we'll get right on that!

We don't currently have a batch publish API for Chat, but it's certainly something we'll explore. It is possible however for you to achieve the desired behaviour using the underlying PubSub APIs. You just need to publish a PubSub message in the underlying message format we use for Chat, which is (cut down for brevity):

{
  name: "chat.message",
  data: {
    text: "Your message here"
  }
}

The underlying channel ID is <chat-room-id>::$chat::$chatMessages.

[smblee]

pubsub api approach works, but it only publishes but doesnt persist. if I refresh the chat, the messages are gone

[smblee]

had to write this to for bulk publishing that persists

export const publishSystemChat = async (messages: { chatId: string; texts: string[] }[]) => {
  const apiKey = env.ABLY_ROOT_API_KEY;
  const base64ApiKey = Buffer.from(apiKey).toString("base64");

  try {

    const results = await Promise.all(
      messages.flatMap(message =>

        message.texts.map(async text => {
          const response = await fetch(
            `https://realtime.ably.io/chat/v2/rooms/${message.chatId}/messages?envelope=json&rnd=${Date.now()}`,
            {
              method: "POST",
              headers: {
                "Content-Type": "application/json",
                Authorization: `Basic ${base64ApiKey}`,
                "X-Ably-ClientId": Buffer.from("system").toString("base64")
              },
              body: JSON.stringify({ text })
            }
          );

          if (!response.ok) {
            const errorText = await response.text();
            throw new Error(`Ably API error: ${response.status} ${errorText}`);
          }

          return response;
        })
      )
    );

    return results;
  } catch (error) {
    logger.error("Failed to publish system chat messages", error as Error, { messages });
    throw error;
  }
};

[AndyTWF]

Thanks for the update! I've created a backlog item to look into fully supporting batch publish in Chat, as it's a use-case we're likely to see a lot of.

If you've got access to ably-js on your systems backend, you can also create an instance of the REST client and use the request method there, which will handle auth, clientID/headers and fallback/retries for you.

Let me know if there's anything else I can do to help!