Using imap I can see that on the server there are new messages that are not in my local cache. However how to know if those new messages are actually just received and never seen by the user, instead of messages moved from another folder into Inbox?
Related
I am using ActionCable to provide Browser Notification which is easy to implement. The problem is coming when a user has open the multiple tabs in the browser and I need to send the data to only one tab i.e to only one WebSocket in user room. How can this be done?
Isolating a single pub/sub client isn't directly possible with the pub/sub approach, because the whole idea is that publishers have no knowledge of subscribers.
However, there are two common ways to solve this:
to use a different named channel per connection, saving the named channel in the database and forwarding all messages to that specific named channel (i.e. saving the channel user-ID-TIMESTAMP in the database and using it as the target connection).
another, somewhat more reliable approach (though more complex) is to send the message to all clients but create a race condition that allows only a single client to receive the actual message. This would look something like this:
server sends "you have a message" to all clients.
client polls "undelivered" messages from the server.
server locks the message pool or uses a database transaction in order to retrieve undelivered messages and mark the messages as delivered. The server sends the undelivered messages to the client (optionally setting an ACK timeout).
a single client connection receives the undelivered messages the rest get an empty array of messages (since they were all delivered to the other client) or receive a "delivered" flag so the data is updated but no notification is raised.
(optional) the client sends and ACK.
(optional) the server marks the message delivery as complete. If no ACK was received before "timeout", server unmarks delivery and resends the "you have a message" message.
Good luck!
Every time a new connection is made we will create a new room. So for example when the user is making a new connection we can give the room name as users:user_id:some_unique_random_string which may be equal to users:user_id:123j123b1h2b1j23bh12b3 and when the same user makes another connection by opening another tab we will also do the same and create a separate room.
Now one thing the ActionCable provides is that we can find all the room name followed by any prefix.
Lets the user has made three connections and their rooms are users:128:123n1jh123ko9876, users:128:asdas23412cs1234, users:128:asni9202h5i3jens then we can obtain these room name using ActionCable also.
user_id = 128
pubsub = ActionCable.server.pubsub
channel_with_prefix = pubsub.send(:channel_with_prefix, RoomChannel.channel_name)
channels = pubsub.send(:redis_connection).pubsub('channels', "#{channel_with_prefix}:users:#{user_id}:*")
Now the channels is an array consisting of the rooms name.
So puts channels
["chatapp_production:users:128:123n1jh123ko9876", "chatapp_production:users:128:asdas23412cs1234", "users:128:asni9202h5i3jens"]
This is how we can find all the rooms related to a single user without using any external database and API calls.
I have set up a chat server with Ejabberd, It is working fine. Messages are getting sent from one user to another user. Problem is that when the receiving user is offline, Sender messages should get stored and get delivered to receiver when he comes back to online. But offline messages are not getting delivered. I have not changed anything in configuration file because it looks already configured for the offline storage and offline message delivery. Do I need to make any other changes apart from the below lines?
ejabberd.cfg:
{access, max_user_offline_messages, [{5000, admin}, {100, all}]}.
{mod_offline, [{access_max_user_messages, max_user_offline_messages}]}
Please update your ejabberd from 2.1.10 to 16.10, as you using the older version certain func. may not work as expected.
I am facing an issue with the presence status, following the documentation and XMPPframework example code. I have written a chat application.
Problem : When the user 1 & 2 are online I get the status successfully and they can chat with each other. However when the user 2 goes physically offline via (Wifi OFF / 3G Off) User 1 is not getting the offline status from XMPP and hence what ever messages are sent from that instant of time are lost when the user 2 comes online.
It seems since the user 2 is not notified or stored as offline in XMPP and hence its not storing the offline messages to push back to user 2 when it comes online.
I have tried to resolve this by explicitly writing a [goOffline] call to XMPP, however the call is shown in 'SEND log' for 'user 2' but not received in 'RECV log' in user 1 from XMPP, due to which the message are lost in between.
Also tried with other sources replies.
Set status for presence available and send XMPP
priority changed with values non-negative
XMPPArchiving work but this is not what I wanted.
Server side Mod_zero push enables but get only first message push notification sometimes.
Setting limit on ejabberd.cfg file for users and offline message limit.
request for offline message pull.
Can anyone help me with this?
This is very typical situation where client losses network but server can't detect that it is offline.
To detect status of each client, server need to send PING packets to every client and wait for response.
If client responds then fine otherwise server will mark that client as offline and every other online client will be informed automatically.
Here is PING Module implementation for ejabberd XMPP Server (hope you are using ejabberd server):
mod_ping:
send_pings: true
ping_interval: 10
timeout_action: kill
ping_ack_timeout: 10
This has to be written in ejabberd.yml configuration file.
At client side also we need to enable ping module to respond to server pings as:
private var xmppPing: XMPPPing?
xmppPing = XMPPPing()
xmppPing!.activate(xmppStream!)
This code has to be written while we setupStream() for iOS.
For detailed info, please go through mod_ping documentations.
Sounds like your problem is at server level. The server thinks that the user is online so it sends the message but nobody gets it. This does not really have a simple solution.
1.
The best solution would be delivery receipts. Where basically when the message is sent to your client, your client returns a confirmation of delivery receipt. If the server does not get that receipt it would resend the message every n time. Depending on your XMPP server you might find a already made solution, of not you would have to roll out your own.
2.
A possible hack would be to have your server always store and deliver last 10 messages and then at client side you discard repeated... This also depends on your server implementation. XMPP MUC and PubSub have resources along these lines.
For a long term scalable solution, you'll need to deal with this both at server and client level.
I'm developing a messaging system in Delphi. I'm using idTcpServer in my Server Application and idTcpClient in my client application. the client application pings the server every 10 seconds to see if the connection is active and tell the server to set the status of the user to Online. and also the user may send messages to his contacts. all these requests are followed by a response from server which i get by socket.readln command right after i send the request. for example for pinging the server:
TcpClient.socket.writeln('i am online');
if TcpClient.socket.readln = 'ok' then
begin
{commands}
end;
I also check for new messages using Long Polling. I send 'check for new messages ' + timestamp from tcpClient and then on the server, I check the database for new messages newer than the timestamp i recieved in a While loop so when there is a new message the loop breaks and notification is sent to the client.
But this system doesn't work for me. Sometimes I get the responses intended to be for checking for new messages when the client application is pinging the server.
I have developed the same system in php without a problem. but here there must be a problem.
I think it is not asynchronous. what should I do?
Regarding the check for new messages request, the server should not be looping waiting for new messages to arrive. Either there are new messages available at the time of the request or there are not. Get the request, do the query, report the result, and move on. The client can send a new check for new messages request periodically. Alternatively, have the client tell the server one time that it wants new messages, and then the server can actively push new messages to the client in real-time as they arrive on the server, instead of polling for them (similar to IMAP's IDLE command).
I would suggest you redesign your communication protocol to run asynchronously. Most modern IM services are asynchronous. When the client sends a request, do not expect a reply right away. Just let the client move on to other things. Have it run a separate timer/thread that reads all inbound data. When a reply does arrive, the client can act on it. If needed, include an identifier in the request that gets echoed in the reply so the client can keep track of the requests it sends. This also allows the server to use asynchronous processing on its end, so if a request takes a long time to run, the server can push it off to another thread/process and continue processing other requests in the meantime. Send the final reply when it is ready.
I am developing a test application and running the whole thing on my work pc. I am using my corporate mail server to send mails. It works fine normally. I was wondering how to handle any conditions like if the mail server is not reachable from my pc.
As far as i have read about it, the rails application just sends the mail and that's it. There is no way to know if the mail reached the recipient, if the recipient mail id was correct etc.
Any thoughts on how to handle this scenario?
Thanks and Regards,
Anjali
I believe you're mixing together two problems here, those are quite unrelated really.
First problem - making sure that the email was accepted by the corporate mail server (that is mail relay in this case). To solve this you can either build a local queue of messages (store them in the database, queue server, whatever) - and send them with a separate worker process, that will pull each message from a queue, try to deliver it and delete it only if it was accepted by the mail relay.
Or, if you don't need low-level manual control of the process, you can set up a simple local mail server on your machine and instead if sending emails directly to your corporate mail relay, just give them to your local mail server. It will then make sure that the emails were delivered to the corporate properly.
But in both cases you won't get any info about where the message was delivered to the final recipient - like whether the email address was valid, user's mailbox was not full, etc.
Second problem - track mail delivery errors. To properly and completely solve this problem you need to catch all mail bounced back to you from the remote servers and analyze it, as many errors are unknown at the moment when the email is send - but they come back later in the form of mail bounces. If you catch and track these bounces you'll be able to catch errors likefull mailboxes, invalid emails, just temporarily delivery failures, etc.
It's the way it is done in mail lists management software - for example, phpList operates in exactly the same way.
I thought about this problem. My thought was to store the message into a separate model called "mailqueue" and then run a ruby script that will pull and delete a message from that mailqueue only if the corporate mail server is available (which I already have the code to do that, I believe). Of course, if there is a better way, I would welcome it as well.