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Hasses is a small notification server using Server Sent Events (SSE). It has asynchronous design to handle more clients in same thread. It uses linux epoll() function.
Most SSE example uses server side codes holds a connection to each client. It is usually means a process/thread for each client connection, which is not optimal when the number of clients are rising. This daemon act as a minimal web server which suitable to handle SSE connections only, and can handle all incoming connections in one thread. The main web server environment (which serve the web pages) can send the notifications to the clients through a FIFO file. The clients can connect to the hasses server with a special token(s), which are usable to address messages to a subset of clients or even one client.
The daemon has a rich logging and client tracking possibility, it can receive commands on the control FIFO file, while the output is written to the log file.
Available an Alpine linux container with the configured hasses daemon: Docker hub:
Downloadable (pullable) image name:
hyperprog/hassesdaemon
The image expose the 8080 port to SSE connections and the 8085 for control channel communication messages. The sse requests matches to the /sse locations by default.
If you would like get informations about the hasses internal state, get statistics or client information you can send commands to the hasses communication channel to modify the internal state, or get information to the log output.
These commands are:
"status" - Print status/statistics to the log
"clientlist" - List clients to the log
"loglevel_quiet" - Set loglevel to minimal
"loglevel_normal" - Set loglevel to normal
"loglevel_debug" - Set loglevel to maximum
"reinit_enable" - Enable re-initialize opened connections
"reinit_disable" - Enable re-initialize opened connections
"<token>=<message>" - Send message to the subscribers of <token>
"<token>=<message>;<token2>=<message2>" - Send more messages
"<token>-<rId>=<message>" - Send message to the subscribers of <token> except <rId>
"*=<message>;" - Send message to all clients
To send the "status" command to the /var/run/myprog/hassesfifo file:
echo "status" | /var/run/myprog/hassesfifo
To send the "status" command to the 8085 tcp port communication channel (on 192.168.1.10 ip)
echo "status" | netcat 192.168.1.10 8085
The "status" command will generate similar message to the log:
------- status of hasses -------
Version: 1.22
Compiled: May 7 2020
Pid: 3217
Uid: 0 (not set)
Running time: 00:00:26
Mode: unencrypted (http)
Loglevel: 2
Reinit allowed: no
CORS-base url: *
Count of connected clients: 0
Current registred SSE clients: 0
Maximum number of connections: 0
Total client handshaked: 0
Total reinit connection: 0
Total message processed: 0
Total message sent: 0
------------- end --------------
The "clientlist" command will generate output like this:
------- requested client list -------
List of clients:
#1 - <6> info: 192.168.1.151:50190 S:SSE Err: 0 Messages: 3 Reinit: 0 SSL:No
Connection time: 00:03:00 Handshaked time: 00:03:00 UniqId:
Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:76.0) Gecko/20100101 Firefox/76.0
Subscribes: room624
#2 - <7> info: 192.168.1.151:50200 S:SSE Err: 0 Messages: 0 Reinit: 0 SSL:No
Connection time: 00:00:09 Handshaked time: 00:00:09 UniqId:
Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.129 Safari/537.36
Subscribes: room686
---------------- end ----------------