The main goal with the implementation of easer is to have a general purpose, cloud ready server that connects client applications with backend services using configuration only, but no infrastructure coding is required.
The clients want to access to the backend services through standard synchronous REST APIs, and/or asynchronous websocket channels. easer makes this possible, and it needs only some configuration parameter and a standard description of the REST API.
easer is a generic web server built on top of express, that has pre-built middlewares and components to deliver the following features:
- Acts as static web content server.
- Provides REST API that is described by Swagger/OpenApi descriptors.
- Serves examples defined in the swagger files in mocking mode.
- Acts as edge server. Accomplishes messaging gateway functionality that maps the REST API calls to synchronous NATS calls towards service implementations, that can be implemented in different programming languages.
- Connects the frontend applications to backing services and pipelines via asynchronous topic-like messaging channels using websocket and NATS.
- Implements internal features required for graceful shutdown, logging, monitoring, etc.
These are the typical usage scenarios:
- Static web server.
- Mock server.
- Edge server / NATS Gateway: Exposes Micro Services through the REST API via NATS topics.
- WS/NATS Gateway: WebSocket Server and Gateway to NATS topics using Pattern Driven Micro Service calls and asynchronous data pipelines.
Visit the easer project website or download the PDF version to read the detailed documentation.
In order to run the server, you need to have the Node.js and npm installed on your machine.
The easer is made to act as a standalone application server, so it's preferred installation is:
npm install -g easerFor development purposes clone the easer server into a folder:
clone [email protected]:/easer.gitInstall the required dependencies:
cd easer
npm installIn global mode you can start the server with the easer command. To get help, execute the following:
easer --help
Options:
--version Show version number [boolean]
-c, --config The name of the configuration file
[default: "config.yml"]
-b, --basePath The base-path URL prefix to each REST endpoints
[string] [default: "/"]
-d, --dumpConfig Print the effective configuration object to the console
[boolean] [default: false]
-l, --logLevel The log level [string] [default: "info"]
-t, --logFormat The log (`plainText` or `json`)
[string] [default: "plainText"]
-p, --port The port the server will listen[string] [default: 3007]
-r, --restApiPath The path to the REST API descriptors
[string] [default: "/home/tombenke/topics/easer"]
-s, --useCompression Use middleware to compress response bodies for all
request [boolean] [default: false]
-u, --useMessaging Use messaging middleware to forward REST API calls
[boolean] [default: false]
--topicPrefix The topic prefix for messaging based forwarding of REST
API calls [string] [default: "easer"]
--parseRaw Enable the raw body parser for the web server.
[boolean] [default: true]
--parseJson Enable the JSON body parser for the web server.
[boolean] [default: false]
--parseXml Enable the XML body parser for the web server.
[boolean] [default: false]
--parseUrlencoded Enable the URL Encoded body parser for the web server.
[boolean] [default: false]
-n, --natsUri NATS server URI used by the nats adapter.
[string] [default: ["nats://localhost:4222"]]
-w, --useWebsocket Use WebSocket server and message forwarding gateway
[boolean] [default: false]
-i, --inbound Comma separated list of inbound NATS topics to forward
through websocket [string] [default: ""]
-o, --outbound Comma separated list of outbound NATS topics to forward
towards from websocket [string] [default: ""]
-m, --enableMocking Enable the server to use examples data defined in
swagger files as mock responses.
[boolean] [default: false]
--help Show help [boolean]During development, execute the following command in the project folder:
Start the server:
$ npm start ./dist/app.js
2019-05-11T15:21:56.389Z [[email protected]] info: Start up webServer
2019-05-11T15:21:56.414Z [[email protected]] info: Express server listening on port 3007
2019-05-11T15:21:56.415Z [[email protected]] info: App runs the jobs...Open the http://localhost:3007/ URL with browser and check the server log. You should see something like this:
2019-05-11T15:23:03.550Z [[email protected]] info: HTTP GET /
2019-05-11T15:23:03.557Z [[email protected]] info: HTTP GET /docs/bootstrap/css/bootstrap.min.css
2019-05-11T15:23:03.558Z [[email protected]] info: HTTP GET /docs/stylesheets/jumbotron-narrow.css
2019-05-11T15:23:05.186Z [[email protected]] info: HTTP GET /docs/assets/ico/favicon.ico
See configuration page.