Multi-room chat

drmistral

Hello,
I was trying to generalize the chat example to obtain a multi-rooms chat. I'd like to connect clients to rooms. Each room and its clients behaves exactly as the actual chat example.

I spent some time modifying the actual example (addressing rooms from "chat_room" parameter, replacing actual singleton room with a hashmap of rooms) but i can't see a way to associate a client (detected a metadata level) with a room (defined a data adapter level).

Any suggestion?

Gianluca Finocchiaro

Hi drmistral,

could you please specify you would manage different rooms? Are they somehow statically defined in terms of number and identifier, for example in the code? How do client address the target room?

Please let us know.

Regards
Gianluca

drmistral

Ciao Gianluca,

I'm new in LS. I'm trying to obtain a typical facebook-like experience in an app where people can send a post in a community and other people may comment the post. So posts act as the rooms, and they are dynamically user-generated.

My idea was to "attach" a LS-powered chat to the initial post as soon as someone starts commenting on it.
The initial post is already managed by the app and it could be be used to address its chat-room.

Thanks for any help.

Gianluca Finocchiaro

Hi drmistral,

to address you scenario you need to use two different kinds of subscription modes:

COMMAND mode, to manage the list of dynamically user-generated posts
DISTINCT MODE, to manage the comments attached to each post.

Each client will first subscribe to an item in COMMAND mode, let's name it "POSTS", which will be used by the the Adapter to ADD new posts to the current list.

An user interested in viewing comments attached to an existing post, should subscribe in DISTINCT mode to an item whose name is related to the post itself: for example, you might want to use a specific post identifier, so such item may be in the form of "POST_1", "POST_2", etc..
Upon DataProvider.subscribe invocation, the DataAdapter should keep track (for example in a Map) of the item handle associated to the item name

A comment will be generated by the user through the LighststreamerClient.sendMessagemethod, and then intercepted by the MetadataAdapter.notifyUserMessage method, where you'll parse the message in order to extract the post identifier and the attached comment, which will be routed to the corresponding item, by looking up the corresponding item handle from the map populated as described above.

A new post will be generated by the user by using the same client side API. Once again, upon MetadataAdapter.notifyUserMessage, you'll need to extract the post identifier and let the Adapter add it to POSTS item, in order to update the current list of posts.

Please have a look at our Basic Messenger Demo for an example of the COMMAND mode usage.

Let me know whether my explanation has been clear.

Thanks and Regards
Gianluca

drmistral

Hi Gianluca,

Ok I've just get the chat working in multi-room mode! :cool:

My main problem was to relate a user client, through the "chat_room" in JS client, to a map
HashMap<String, Object> room declared in ChatDataAdapter.java: how to send the chat_room value from JS client up to DataAdapter?
Finally I've embedded it as 3rd field of message: <"CHAT", text, chat_room>, of course I've removed all controls in the demo to force singleton room and changed another couple of things and finally it worked: a client simply starts a chat with an identifier and get in a new or existing room.

The part about COMMAND is not necessary for now because it is already managed but however useful to know.

Thank you very much for your promptly help!

Gianluca Finocchiaro

Hi drmistral,

What is the purpose of the HashMap in the ChatDataAdapter?
Is "<"CHAT", text, chat_room>" the message string sent through the sendMessage method?
Is "CHAT" the item to which your client is subscribing to?
Could you please provide more info about item and fields model?

Thanks
Gianluca

drmistral

Hi Gianluca, here is some details about my test to move from single room to multi-room chat. Starting point was the actual "Basic Chat Demo", client and server components downloaded from your demo page, changed parts are red.

JS CLIENT

First, in the client JS side I manage the name of the room through a global variable chat_room which can be set, in my case, with a reference to the post (room) id .

[JS.1] In the Subscription management:

//  create the Subscription; field names will be extracted from the grid
var chatSubscription = new Subscription("DISTINCT", [COLOR=#ff0000][B]chat_room[/B][/COLOR], chatGrid.extractFieldList());

[JS.2] In the submit form:

var mex = "CHAT|" + text [B][COLOR=#ff0000]+ "|" + chat_room[/COLOR] [/B];

ChatMetaDataAdapter

The expected message contains a 3rd more part: the name of the room, so we address it.

private void handleChatMessage(String[] pieces, String message, String session) throws NotificationException {
        //extract session infos

        if (pieces.length != [COLOR=#ff0000][B]3[/B][/COLOR]) {
            logger.warn("Wrong message received: " + message);
            throw new NotificationException("Wrong message received");
        }

        Map<String,String> sessionInfo = sessions.get(session);
        if (sessionInfo == null) {
             logger.warn("Message received from non-existent session: " + message);
             throw new NotificationException("Wrong message received");
        }
        //read from infos the IP and the user agent of the user
        String ua = sessionInfo.get("USER_AGENT");
        String ip =  sessionInfo.get("REMOTE_IP");

        //Check the message, it must be of the form "CHAT|message"
        if (pieces[0].equals("CHAT")) {
            //and send it to the feed
            if (!this.chatFeed.sendMessage(ip,ua,pieces[1][B][COLOR=#ff0000], [/COLOR][COLOR=#ff0000]pieces[2][/COLOR][/B])) {
                 logger.warn("Wrong message received: " + message);
                 throw new NotificationException("Wrong message received");
            }
        } else {
             logger.warn("Wrong message received: " + message);
             throw new NotificationException("Wrong message received");
        }
    }

ChatDataAdapter.java

[COLOR=#931A68]private [/COLOR][COLOR=#931A68]volatile[/COLOR] Object subscribed;

was replaced with the map

[COLOR=#931A68]private  [/COLOR][COLOR=#931A68]volatile[/COLOR]HashMap<String, Object> rooms = [COLOR=#931A68]null[/COLOR];

that is initialized in the init method with

rooms =  [COLOR=#931A68]new[/COLOR]HashMap<String, Object>();

The purpose of this map is to associate a chat name key to a Item handler, instead of the singleton handler (Object subscribed).

In the subscribe method the item name is associated with the passed Handler:

    public void subscribe(String item, Object handle, boolean arg2) throws SubscriptionException, FailureException {


//        if (!item.equals(ITEM_NAME)) {
//            // only one item for a unique chat room is managed
//            throw new SubscriptionException("No such item");
//        }
//        assert(subscribed == null);
//        subscribed = handle;
        
        [B][COLOR=#ff0000]rooms.put(item, handle);[/COLOR][/B]
...

In the sendMessage method we get the right Item from the map.

    public boolean sendMessage(String IP, String nick, String message, String room) {
        final Object currSubscribed = [B][COLOR=#ff0000]rooms.get(room)[/COLOR][/B];
        if (currSubscribed == null) {
            return false;
        }
    ...

Finally in the adapter_log_conf.xml i commented out the following block

        <!-- Optional, managed by the inherited LiteralBasedProvider. See LiteralBasedProvider javadoc. 
        <param name="item_family_1">chat_room</param>
        <param name="modes_for_item_family_1">DISTINCT</param>
        -->

That's it. It's just a quick&dirty test, and it's also possible that I've misunderstood the usage philosophy of classes.
Does it make sense?

Thanks

Gianluca Finocchiaro

Hi drmistral,

thank you very much for your great effort in showing me complete details of your work. You did a very good job, in compliance of the usage philosophy.

My only concern is related to the use of an HashMap, you should use instead a ConcurrentHashMap as concurrent threads my access such object.

Let me know if you need any further clarification.

Thanks and Regards,
Gianluca

drmistral

Hi Gianluca, thanks a lot for your check, it was very important for me to know if I was using this stuff in the right way.
Yes, of course ConcurrentHashMap has to be used. That was just a quick test, now I'm going to integrate LS in my project, let's see...

Thanks for your time.

Cheers
Ferdinando

webcamer30

Hi! I'm having the same issue here, I want to create some kind of chat experience, the one that is used to webcam shows online, it think it works amazing, but when I tried to do the same thing, it didn't work :Smile_Ac: . I thought it was because of what you said, that you embedded it as 3rd field of message: <"CHAT", text, chat_room>. But still, it didn't work.

Do you know why could be this happening? or what else should I try to make it work? I'm really interested to get multi-room chat with the webcam service online. Thank you for your help!

Giuseppe Corti

Hi webcamer30,

In the above discussion the third parameter, chat_room, is used to assign the destination of each message so that the Adapters can dispatch it to all the participants of the specific chat room.
Please let me recap the main changes involved compared to our classic demo chat.
- The client, each time sends a message, should specify the room for which it is intended:

        var chat_room_b = "Blue_Chat_Room";
        var chat_room_r = "Red_Chat_Room";
 
        var mex_1 = "CHAT|" + text + "|" + chat_room_b;
        client.sendMessage(mex_1);

        var mex_2 = "CHAT|" + text + "|" + chat_room_r;
        client.sendMessage(mex_2);

and should also subscribe to specific chat room item (or items if can be present simultaneously in more than one room ):

        var chatSubscription = new Subscription("DISTINCT",chat_room_b,chatGrid.extractFieldList());

        ...

        var chatSubscription = new Subscription("DISTINCT",chat_room_r,chatGrid.extractFieldList());

- The adapters should should extract the room name from the received message and dispatch the text as a push update for the specific Item.
Which is exactly what is shown in the ChatMetaDataAdapter and ChatDataAdapter pieces of code just few posts above.

That said, if you are still in troubles please share some extra details about your issue.

Regards,
Giuseppe