myps.broker v1.0.6

myps.broker

myps stands for MyPubSub, a small service that implementing publish/subscribe model over Unix Domain Socket

Usage

$ myps.broker --help
Options:
  --help          Show help                                            [boolean]
  --version       Show version number                                  [boolean]
  --sockfile, -s  path to socket file. Default: ${process.cwd()}/myipc.sock'
  --debug, -d     debug output true/false

Protocol

Overview

It uses JSON messages encapsulated into BDSM frame to communicate between broker and clients.

|B|D|S|M|<LB>|<LE>|<DATA>|<C>|

where DATA is JSON message, <L> is two byte field in BE that contains length of <DATA>, <C> is checksum of <DATA> (sum of all bytes modulo 256). BDSM is a string header of message.

JSON message

DATA field is a JSON message that uses method and payload fields as required. For requests from client also request_id field may be used.

Messages sent from server. method field.

greeting sends server when client connected. As a payload it transmits connection id. {"method": "greeting", "payload": 1317678194084}.

message client receives when a message on subscribed topic occured. {"method": "message", "payload": {"topic": "given topic", "message": "given message", "connection_id": 42}}.

success signals that request was successful {"response_id": 42, "method": "success", "payload": "something"}.

error signals that something went wrong with request {"response_id": 42, "method": "error", "payload": "error description"}.

Messages sent from client to server. method field.

subscribe server receives when client wants to subscribe to topic given in payload. {"request_id": 42, "method": "subscribe", "payload": "given topic"}.

unsubscribe when client want to unsubscribe {"request_id": 42, "method": "unsubscribe", "payload": "given topic"}.

publish client sends when want to publish message to topic. {"request_id": 42, "method": "publish", "payload": {"topic": "given topic", "message": "given string message or object"}.

Installing

sudo npm i -g myps.broker@latests

I would advice to run myps.broker as a systemd daemon using followind service file:

vim /etc/systemd/system/myps.service

Edit content of this file:

[Unit]
Description=PubSub service running on nodejs

[Service]
User=yourusername
ExecStart=/usr/bin/env myps-broker
Restart=on-failure
RestartSec=10
RuntimeDirectory=myps
RuntimeDirectoryMode=0775
# and now working dir.
# make sure it is located at `/run/${RuntimeDirectory}`
# which is in this example myps
WorkingDirectory=/run/myps

[Install]
WantedBy=multi-user.target

Enable and start service:

sudo systemctl daemon-reload
sudo systemctl enable myps.service
sudo systemctl start myps.service

Check status:

systemctl status myps.service
● myps.service - PubSub service running on nodejs
   Loaded: loaded (/etc/systemd/system/myps.service; enabled; vendor preset: disabled)
   Active: active (running) since Wed 2018-09-12 13:51:54 MSK; 2min 49s ago
 Main PID: 31066 (node)
    Tasks: 11 (limit: 4915)
   Memory: 12.0M
   CGroup: /system.slice/myps.service
           └─31066 node /usr/bin/myps-broker

Sep 12 13:51:54 the-undefeated systemd[1]: Started PubSub service running on nodejs.

Check if runtime directory was created:

ls -hlatr /run
.......
drwxr-xr-x  7 root       root      160 Sep 12 13:21 udev
drwxr-xr-x 27 root       root      640 Sep 12 13:51 .
drwxrwxr-x  2 undefeated lp         60 Sep 12 13:51 myps
drwxr-xr-x 18 root       root      440 Sep 12 13:52 systemd

As you can see in example, there is myps directory, so look inside it:

ls -hlatr /run/myps
total 0
drwxr-xr-x 27 root       root 640 Sep 12 13:51 ..
srwxr-xr-x  1 undefeated lp     0 Sep 12 13:51 myipc.sock
drwxrwxr-x  2 undefeated lp    60 Sep 12 13:51 .

That's it. Now we can use it for own purposes.