navigator-push-server

Server for pushing traffic disruption notifications to navigator clients (https://github.com/jannesuo/navigator-proto).

The server consists of two parts: HTTP server and message sender. They can be run in the same process or as two separate applications that share the database. In the latter case, it is possible to run multiple HTTP servers. However, there should be only one message sender instance.

Installing and running

Install Node.js and MongoDB. Downloading and unzipping pre-compiled binaries could be the easiest way to get up-to-date versions.

You may need to modify your PATH so that you can use the commands without specifying the full path to the binary.

Install coffeescript globally (a node module): npm install -g coffee-script

Install local node modules for this project. Run in this directory: npm install

Start Mongo server before starting this server: mongod

You can start HTTP server and message sender either separately or together in a single process.

Start separately: coffee http-server.coffee, coffee message-sender.coffee
Start together: coffee start-both.coffee

If you want to compile CoffeeScript to JavaScript, use the command coffee -c *.coffee. Then, start the program or programs using commands of the form node <file>.js instead of the coffee commands above.

Environment variables

MONGODB_URI (optional): MongoDB URI. Not needed with MongoLab Heroku plugin.
HTTP_PORT (HTTP server only, optional): HTTP server port. Not needed with Heroku.
UPDATE_INTERVAL (message sender only, optional): The interval in milliseconds for fetching updates from HSL servers.
GCM_PUSH_API_KEY (message sender only, required): Google Cloud Messaging API key.
TEST_PUSH (HTTP server only, optional): if set to anything except false, no, off, or 0, enable sending test messages. See below.

Sending test messages

The HTTP server has a test message sending functionality, which can be enabled by setting the environment variable TEST_PUSH to anything except false, no, off, or 0. To send a test message, send a HTTP POST request to the path /send-test-message with the following fields in the body as either form data or JSON:

msg: message
category (optional): category of the lines in text form
lines (optional): lines (in JSON as array; in form data in the form lines[]=11&lines[]=22&...)

Note that duplicate message detection works as with normal messages: Messages identical to any previously sent message are not sent to clients that have already received the message.

Heroku deployment

The server can be deployed to Heroku as described below. However, note that if there is only one 1X or 2X web dyno, Heroku puts it into sleep mode after 1 hour of no HTTP requests. As a consequence, it is not possible to use start-both.coffee in production with Heroku, because there can be only one message sender instance, and if it goes to sleep, messages are not sent. For testing and development, there is a separate branch, shared-heroku-dyno, with Procfile that runs start-both.coffee in a single shared dyno that can go to sleep.

Deployment instructions:

heroku login
Create Heroku application: heroku apps:create --region eu
Add MongoLab plugin: heroku addons:add mongolab (see MongoLab documentation for more information)
Set Google Cloud Messaging API key: heroku config:set GCM_PUSH_API_KEY=...
git push heroku master
heroku ps:scale web=1 worker=1 (there can be many web dynos, but there should be only one worker dyno)

Terms of use