Geocoder

http://ec2-18-223-164-119.us-east-2.compute.amazonaws.com/

Abstract

A nodeJs application that handles all the CRUD operation and also geocoding and reverse-geocoding for the Geocoder application

Installation

Kindly do an npm install at the root directory of both the applications to install the required packages. Following are the libraries that are used

• enzyme v3.10.0
• node-geocoder v3.23.0

npm install

Serving Locally

Once the packages have been installed you may the serve applications locally. You may run npm start on the root directory of the applications to serve them locally. The application runs here:

• geocoder-node : http://localhost:8081

The backend and the frontend applications must be served simultaneously to persist data

Scripts

npm run start - Serves the app locally on http://localhost:8081

npm run test - Runs the test scrips on the specific application

Deployment

• The application has been deployed on AWS to an EC2 instance.
• port 8081 has been opened to accept inbound request
• A node process runs the application on port 8081.
• The proxied request from apache is served by the node application.

Architecture

The front-end and back-end application for geocoder are closely integrated. Any operation related to markers is handled in the back-end which is immediately fetched from the front-end to have the latest version of the data available at all times. Following is an integrated architecture of the applications

Description

The application follows a head-less micro-service based approach. A list of API is defined in the application that handles the various CRUD operations from the front-end.

geocode - Makes an API request to the google maps to retrieve the coordinates based on the search term

reverseGeocode - Makes an API request to the google maps to retrieve the address information based on the coordinates

saveMarker - Saves the marker data to a local array

editMarker - Edits the marker value of a specific element in the array

deleteMarker - Removes a marker from the array.

getMarkers - Fetches the marker array.

Design

The micro-service based architecture suits well for an application of this stature since it is an approach that easy to spin-up and easy to manage. node-geocoder was used to manage the integration with google maps as it offers easy customizability.

Integrational configurations

node-geocoder makes it easy to switch the third-party API's. The options object provides the necessary properties related to the third-party API's

var options = {
  provider: "google",
  httpAdapter: "https",
  apiKey: "AIzaSyCnz169tp7MAkt0ef4AF4Xc_mBNFpU-aas",
  formatter: null
};

provider

The elaborated list of third party integrations available with node-geocoder can be found here

httpadapter

• https: This adapter uses the Https nodejs library (default)
• http: This adapter uses the Http nodejs library
• request: This adapter uses the request nodejs library

You can specify request timeout using parameter options.timeout

Formatter

• gpx : format result using GPX format
• string : format result to an String array (you need to specify options.formatterPattern key)
  • %P country
  • %p country code
  • %n street number
  • %S street name
  • %z zip code
  • %T State
  • %t state code
  • %c City

Error Handling

Various steps have been taken to handle errors under the boundaries of the application as well as to handle the errors with third party API's as well. A 500 response with the necessary response is returned when either of the above occurrences happens

app.get("/geocode", (req, res) => {
  var resp = res;
  geocoder.geocode(req.query.address, function(err, res) {
    if (err) {
      resp.status(500).json({ Error: "The data cannot be fetched from the provider. Check your credentials and try again" });
    } else {
      resp.send(res);
    }
  });
});