Alchemy Router

Alchemy Router is the gateway from HTTP to Alchemy Resources for the Alchemy Micro-services Framework. It can be used directly as an application or as a library to build and customise using express middleware and routes.

Router Application

To install the alchemy router run:

npm install -g alchemy-router

Then execute:

alchemy-router

You can configure the router with the environment variables:

1. AMQP_URI default 'amqp://localhost': the location of the (RabbitMQ) AMQP server
2. PORT default 8080: the port to open the HTTP server on
3. TIMEOUT default 5000: the router will return a 408 timeout response after waiting for the service.
4. PATHS default '{}': the JSON string that matches service queues directly with paths, e.g. PATHS='{"/hello" : 'service.hello'}' will direct all calls that start with path /hello to the queue service.hello.

Docker

This repository also comes with an example Docker container, which is published to the docker hub.

Build the Docker container with:

docker build -t alchemy-router:$VERSION .

Push the docker container with:

docker push alchemy-router:$VERSION

Router Library

To install the router as a library:

npm install alchemy-router

To start a router:

AlchemyRouter = require 'alchemy-router'
router = new AlchemyRouter()
router.start()

Middleware

Middleware can be used to extend the routers with custom functionality. Middleware are objects with a callback that is an express middleware callback function, an optional start and stop functions that can control the life cycle of the middleware.

logging_middleware = {
  callback: (req, res, next) ->
    console.log req.path
    next()

  # promise to start middleware
  start: -> true

  # promise to stop middleware
  stop: -> true
}

AlchemyRouter = require 'alchemy-router'
router = new AlchemyRouter()
router.start({
  middleware: [logging_middleware]
})

Additional Routes

Additional hard-coded routes can be added to the router, these can be useful for health-checks, logging, versioning ... Note: these routes will override any service routes.

hello_route = (app) ->
  app.get '/hello', (req, res) =>
    res.send {say: "hello"}
    res.end()

AlchemyRouter = require 'alchemy-router'
router = new AlchemyRouter()
router.start({
  additional_routes: [hello_route]
})

Notes

The Router will not override any provided x-interaction-id headers, and will generate the header with a UUID if not present. This is to preserve traceability when calling between different platforms. If you require Interaction IDs to be unique within your platform, you may wish to extend the Router with a piece of middleware that generates your own Interaction IDs.

Documentation

This Alchemy-Router documentation is generated with docco from its annotated source code.

The Alchemy-Router package exports Router:

module.exports = require("./router")

Examples

• Sending a message to a Resource