Glome Notification Broker (GNB)

GNB is a simple message broker written in Node.js. It sits between Glome's Redis server and the web clients connecting via websockets (or HTTP).

GNB establishes two connections to the Redis server for duplex communication.

One of the connections is the downlink that carries messages from Glome towards the clients.

The other connection is the uplink that transfers messages from the clients towards Glome.

Installation

  $ npm install

This command will download the dependcies into the node_modules directory.

Start

  $ node index.js

This command will start the broker with default configuration, ie. listening on port 8082.

Configuration

The following envrironment variables can be used to configure the broker:

• GNB_PORT

  The port where GNB is listening for incoming requests (default: 8082).

• REDIS_URL

  URL of Glome's Redis server to connect to.

Redis channels

• glome:{uid}

  For downlink where {uid} identifies the 3rd party Glome service. The {uid} is allocated when requesting Glome API access.

• glome:app

  For uplink purposes (when the client sends messages to Glome).

Client events

The following events can be emitted by the clients:

• gnb:connect

  A service wants its user to get connected to GNB.

• gnb:disconnect

  A service wants its user to be disconnected from GNB.

GNB events

These are the events that are emitted by GNB so that the clients can listen to them:

• gnb:connected

  The client has succesfully connected to GNB.

• gnb:broadcast

  Glome sends a broadcast to all users of a service.

• gnb:message

  Glome sends a direct message to a specific user of a service.

• gnb:notification

  Glome sends a direct message to a specific client. It is meant only for machine to machine communication.

Firewall and web server setup

• Make sure the node app port is only available from localhost

    # iptables -A INPUT -i lo -p tcp --dport 8082 -j ACCEPT
    # iptables -A INPUT -p tcp --dport 8082 -j DROP

• Proxy SSL requests with Apache 2.4

    <VirtualHost some.site.name:443>

      ServerName some.site.name

      SSLEngine on
      SSLCertificateFile /etc/ssl/certs/some.site.name.crt
      SSLCertificateKeyFile /etc/ssl/private/some.site.name.pem

      <Proxy *>
        Require host localhost
      </Proxy>

      Define gnb localhost:8082/

      RewriteEngine On
      RewriteCond %{REQUEST_URI}  ^/socket.io                 [NC]
      RewriteCond %{QUERY_STRING} transport=websocket         [NC]
      RewriteRule /(.*)           ws://${gnb}/$1              [P,L]

      ProxyPreserveHost On
      ProxyPass / http://${gnb}
      ProxyPassReverse / http://${gnb}

      DocumentRoot {the_location_of_gnb}

      LogLevel info
      # cronolog is great!
      ErrorLog "||/usr/bin/cronolog -S /var/log/apache2/current_some.site.name_https_error /var/log/apache2/%Y/%m/%d/some.site.name_https_error.log"
      CustomLog "||/usr/bin/cronolog -S /var/log/apache2/current_some.site.name_https_transfer /var/log/apache2/%Y/%m/%d/some.site.name_https_access.log" common
    </VirtualHost>

• Proxy request with Nginx 1.4+

  TODO

Licensing

Author: ferenc at glome dot me

License: MIT

Copyright (c) 2014 Glome Inc