I am trying to learn websockets with Go. I have been looking at examples with gorilla websocket.
I have checked out these 2 examples that show how to use gorilla websocket:
https://github.com/gorilla/websocket/tree/master/examples
https://www.youtube.com/watch?v=ysAZ_oqPOo0
All of these examples show how to connect to a websocket server, send and receive texts. But what I don't understand is how you can send to only one client. Because in a real world application you will have users, and we don't want all users to receive the same message and same data. Is there a way for me to get the unique id of a connection which I can save in a database like redis and link it to a user id in the same database, and then use that websocket id to send back to a specific client if that user id received a message or a notification? Is this how one would go about and achieve something like this? If that is the case, how would I that?
Is there a way for me to get the unique id of a connection which I can
save in a database like redis and link it to a user id in the same
database, and then use that websocket id to send back to a specific
client if that user id received a message or a notification?
Sure! You can generate Id by yourself while user registering. Just add userId field in connection structure
In chat example you have hub, which contains connections pool. That pool is using to broadcast messages to all users:
case m := <-h.broadcast:
for c := range h.connections {
select {
case c.send <- m:
default:
close(c.send)
delete(h.connections, c)
}
}
}
So there you go. You should make method to send private message, depend on userId
Related
Hi everyone as a beginner in WebSockets i want to put a condition that will query when a client will be online or offline for such a time on my server node.js using socket.io
socket.on('disconnect', function() {
db.query("MY_SQL_REQUEST");
});
As a example when the user is disconnected for 10secondes it does the request. I think the solution is to use a loop if, but i dont know how to process after ...
If you need more informations about my code dont hesitate to ask
Thanks :)
when user online then you can store socket id in specific user.
when user disconnect then automatically call socket disconnect event and you will get disconnected socket id. once you receive socket id
you can update query for user offline using disconnected socket id.
socket.on('disconnect',function(){
console.log("socket disconnect called: ",socket.id);
db.query("MY_SQL_REQUEST"); // where socketId = socket.id
})
How is it possible to send message in slack directly to the user, by user.id as application.
this application has scope: bot,channels:write,emoji:read,users:read,users:read.email
I find how to send message only as DM or by webhooks, but there is no scope for that. Any one has idea?
If I understand your question correctly, you want to send direct messages to users in the app channel instead of the standard slackbot channel.
In order to do that you need to
Your app needs the bot scope and a bot user
Open a direct message channel from your app with the user with conversations.open. You get back a direct message ID.
Send a message with chat.postMessage to the the direct message channel ID
Make sure to use your bot access token (not the user access token) from your Slack app.
The bot scope gives you all permissions needed to open and send DMs to users from your bot channel. No other scopes are required.
You can also use the new conversations methods, which work for all kind of channel types to do the same.
See also this question on the same topic.
There is an alternative way to solve this, which can be more suitable if your app uses a bot to operate with Slack API.
You need to call chat.postMessage API method and specify channel argument equal to the user ID (e.g. U0G9QF9C6) you want to message and as_user argument is true.
Important detail - ensure you are using bot access token (learn here how to obtain it).
Example:
curl -X POST "https://slack.com/api/chat.postMessage" -H "accept: application/json" -d token=BOT_ACCESS_TOKEN -d channel=U0G9QF3C6 -d text=Hello -d as_user=true
In this way, your message will be always sent on behalf (name and icon) of your bot and will be display like a direct message in the app channel (YourAppChannel in the Slack sidebar).
Compared to the approach of #ErikKalkoken you have no need to create a channel in advance and as a result, keep track of its ID (it may be good or bad depending on your needs).
For those who is still searching for detailed answer:
First of all you need to make call to this endpoint.
You need to make call with bot token and provide into users param value of user you want to send message.
Also you need set prevent_creation and return_im to true.
Example:
Authorization: Bearer {your_bot_token}
{
"users": "U12345679",
"prevent_creation": true,
"return_im": true
}
After that you will have your channel id to which you want to send message.
Example response:
{
"ok": true,
"no_op": true,
"already_open": true,
"channel": {
"id": "D123456789", <-- this is your id
...
"unread_count": 0,
"unread_count_display": 0,
"is_open": true,
"priority": 0
}
}
and then with same bot token and user id send message with help of this one
Blockquote I keep getting {"ok":false,"error":"not_in_channel"} do i need to manually add the bot to a channel?? –
Abhijeet Bajracharya
Feb 4 '20 at 8:04
you need to get scope that allow to send messages like this
There is no need to use the conversation.info, you can post message (DM), by using the users.list endpoint and fetch the user id, which then you can use in chat.postMessage
I cloned a chat application project that uses spring boot websocket on github.
Here is code:
#MessageMapping("/chat.private.{username}")
public void filterPrivateMessage(#Payload ChatMessage message, #DestinationVariable("username") String username, Principal principal) {
message.setUsername(principal.getName());
simpMessagingTemplate.convertAndSend("/user/" + username + "/exchange/amq.direct/chat.message", message);
}
Example: username variable is: foo#gmail.com, it mean the link to for client subscribe should be: /user/foo#gmail.com/exchange/amq.direct/chat.message
But in client code:
chatSocket = Stomp.over(new SockJS(url)); //use sockjs and stompjs
chatSocket.subscribe("/user/exchange/amq.direct/chat.message"
I do not understand how to the application can send to correct client, when the client listen the different url (without foo#gmail.com).
Can someone explain to me?
Thanks.
The key is the /user/ prefix in the subscribe url, which will be transformed by Spring to deliver the message to the specific user. It is described in the User Destinations section in the docs:
An application can send messages targeting a specific user, and Spring’s STOMP support recognizes destinations prefixed with /user/ for this purpose. For example, a client might subscribe to the destination /user/queue/position-updates. This destination will be handled by the UserDestinationMessageHandler and transformed into a destination unique to the user session, e.g. /queue/position-updates-user123. This provides the convenience of subscribing to a generically named destination while at the same time ensuring no collisions with other users subscribing to the same destination so that each user can receive unique stock position updates.
I am trying to create a chat app using spring websocket and stomp.
I am using Spring 4.1.1,Stomp.js, ActiveMQ 5.9
In this user can send message to each of his/her friends, who are also logged in, by logging into the app.
For sending message to particular user I take following steps:
1) User logs in
2) User subscribes to "/user/queue/messaging" destination.
This will be used to send private messages of users to each other.
3) when user wants to send a message he sends it to destination :
/user/{user_id}/queue/messaging where user_id is recipients user id.
I am trying to send this from client using STOMP.js send method.
4) Expected behaviour : now if recipient is logged in and his session id, for example, is DFT0GH then the message in step e should be delivered to Queue destination with name messaging-userDFT0GH. Instead of this it is delivered to the same user's queue destination who sent it.
Please find my example scenario :
1) User John logs in .
He subscribes to /user/queue/messaging
His user id is john
His session id is ABCD01
Queue is created with name on activemq broker as
messaging- userABCD01
2) User Alice logs in .
She subscribes to /user/queue/messaging
His user id is alice
Her session id is XYZ01
Queue is created with name on activemq broker as messaging- userXYZ01
3) user John sends a message through STOMP.js send method to Alice
using destination as "/user/alice/queue/messaging"
4) now instead of delivering the message to queue
messaging- UserXYZ01 it gets delivered to John's queue destination i.e
messaging- userABCD01. Why is it so?
When i debugged this , I found following line in method
private DestinationInfo parseUserDestination(Message message) of DefaultUserDestinationResolver class :
if (SimpMessageType.MESSAGE.equals(messageType)) {
........
sessionIds = (sessionId != null ?
Collections.singleton(sessionId) : this.userSessionRegistry.getSessionIds(user));
}
In this sessionId is logged in user's (Principal) session id which is not null as user is logged in and so his sessionIds is returned and message is delivered to his queue even if intended recipient user is different.
When i check usersessionregistry's sessionIds collection I find an entry [alice]:XYZ01.
Shouldn't above line return session id if the user instead of logged in user's session to identify destination queue.?
Sorry I am trying this for the first time. So Please let me know if I miss anything here and of there is
1) any way to satisfy my use case
2) or my use case itself is invalid.
Thanks in advance.
Just so this question stays out of the unanswered list - this is indeed a bug and you raised it as SPR-12444.
This will be fixed in Spring Framework 4.1.3.
As a side note, I'd like to point out that if you're deploying your application with multiple instances, session registries are not shared between instances by default - so this will cause issues when sending a message from a alice (with a session to server #1) to bob (session to server #2).
I wrote a small project that uses Spring MVC 4 with Websockets and RabbitMQ as the broker.
I am trying to send back to a single user (convertAndSendToUser) but I can't seem to have it working. Here is what the application does:
authenticate to Spring Security over HTTP. The authentication is over AJAX and the backend assigns a UUID as the username to every new connection. There might be multiple clients with the same username so I would like to be able to target individual browsers although they may be logged in with the same username
after authenticating over AJAX the webapp connects to the APIs using STOMP over Websockets.
These are the headers that get send back in the CONNECT FRAME
body: ""
command: "CONNECTED"
headers: Object
heart-beat: "0,0"
server: "RabbitMQ/3.3.1"
session: "session-OGzAN6T8Y0X9ft3Jq04fiQ"
user-name: "88dc9424-72e3-4814-be8c-e31dbf89b521"
version: "1.1"
As you can see there is no frame-suffix or session-id field.
When I use convertAndSendToUser from the backend, the response is send to a unique queue like: /exchange/jobs-userh6g_48h9. The queue name is /exchange/jobs but Spring automatically attaches the suffix -userh6g_48h9. The username is "user" and the sessionId is "h6g_48h9" This is fine and I want this behavior but the problem is that the client (webapp) doesn't get this session id in the CONNECT frame and there is no way for it to actually subscribe to that unique queue.
How to solve this? I want the queue-suffix/session id sent back to me on connect so that the client can get this suffix and subscribe to his unique queues. Currently no messages come back from the server because of this lack of information.
Correct me if I'm wrong, but due to the UserDestinationMessageHandler, clients should be able to subscribe to /user/exchange/jobs and that message handler will correct the queue name for you.
As a side note, you should also consider adding a configuration class extending AbstractSecurityWebSocketMessageBrokerConfigurer similar to the following:
#Configuration
public class WebSocketSecurityConfig extends AbstractSecurityWebSocketMessageBrokerConfigurer {
#Override
protected void configureInbound(MessageSecurityMetadataSourceRegistry messages) {
messages
.antMatchers(SimpMessageType.MESSAGE, "/topic/**", "/queue/**").denyAll() // Prevent users sending messages directly to topics and queues
.antMatchers(SimpMessageType.SUBSCRIBE, "/queue/**/*-user*", "/topic/**/*-user*").denyAll() // Prevent users from subscriptions to private queues
.antMatchers("/user/queue/errors").permitAll()
.anyMessage().hasRole("ANY_OPTIONAL_ROLE_ETC")
;
}
}
This will prevent "enterprising" users from subscribing to things that they shouldn't.