ServiceTemplateNode/Overview

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Service Template Overview[edit]

This service template allows you to quickly dive into coding your own RESTful API service.

Stack[edit]

The template makes use the following components:

Everything begins and ends with service-runner. It is the supervisor in charge of starting the service and controlling its execution. It spawns worker processes, each of which accepts and handles connections. If some workers use too much heap memory, they are restarted. Additionally, it provides your service with configurable logging and metrics facilities.

When it comes to request handling, express.js and Bluebird take the centre stage. express.js is in charge of receiving the requests, routing and dispatching them to the correct handlers and send responses back to the clients. Bluebird comes into play when there are actions which warrant asynchronous processing (such as reading files, dispatching requests to external resources, etc.). You can find example route handlers constructing the response both synchronously and asynchronously in this template's routes directory.

Finally, testing is an important aspect of service programming, not only for their creators, but also testers (think CI) and consumers. The template uses mocha for carrying out the testing, and istanbul for reporting code coverage with tests. There are quite a few tests available for you to check out.

The WMF is in the process of switching its production servers to Debian Jessie. As people developing services might use different platforms, the template provides also a Dockerfile, with which one can execute their service inside a container running the production OS.

Repository Outline[edit]

Below is a simplified repository outline listing the important files/directories for service development.

  • package.json - the file containing the service's name and dependencies
  • config.dev.yaml and config.prod.yaml - contain development and production configuration settings for the service
  • server.js - the service's starter script
  • app.js - contains the application declaration and loading logic
  • routes - contains the definitions of the loaded routes; this is where most of your coding is to take place
  • lib/util.js - contains some utility functions and classes
  • static - this is where served static files go (HTML, CSS, client-side JS, etc.)
  • test - contains the test files for the example routes in the template; you should add your own here
  • docker script - a utility script building the service's docker image and starting the container, now part of service-runner