courier-service

This repository contains the full-stack website for the online courier service.

This web app consists of three screens:

The first screen displays the QR code used to authenticate the delivery
The second screen is an in-browser camera for the courier to optionally take a proof of delivery image that gets uploaded to our server.
The third screen is a confirmation screen indicating to the courier that they can close the tab

Refer to the mock screens below for a general idea of what these screens will look like.

1. Use Case

The typical use case from the courier's perspective can be seen below:

URL contains delivery ID as query strings
Client script will access corresponding delivery hash for authentication from database
Client script renders QR code on loading of first screen
QR code scanning is detected and triggers database update
Successful scan results in camera screen
After (optionally) taking a picture of delivery, courier is free to close tab

2. Tech Stack

This repository is built on two core technologies

Flutter on Web
Firebase

3. Usage

In order to run the application, you will first have to check that chrome (web) is listed as one of the flutter devices by running

flutter devices

If you have Chrome installed, this device should appear in this list.

After ensuring the device is available, you can run the following command to execute the application locally:

flutter run -d chrome

This will open a terminal session that supports hot restarting for development purposes (hot reload not currently supported by Flutter Web).

To edit and view the local database emulator, first ensure that firebase-tools is installed on your machine, otherwise install via npm. You can then navigate to the backend directory in the root folder and execute the command to start the firebase emulators.

npm install -g firebase-tools
cd backend 
firebase emulators:start

To use the local emulator, make sure to import the appropriate JSON tree structure to inbox-sdp-default-rtdb, otherwise the data will not be visible to the app.

If you are running the latest version of firebase-tools you will need to have Java 11 installed for this step to work as Firebase CLI has dropped support for older versions of Java

4. QR Code Details

In the current implementation, the QR code is generated from a string in the format deliveryID+hashCode where deliveryID uniquely identifies a delivery in the Firestore Cloud database and hashCode refers to an MD5 hash stored as a field under that delivery's record.

5. REST-API

External systems can interact with the Firebase Realtime DB data by sending the appropriate HTTPS request.

The URL to use will vary depending on whether the app is running using the live server or the local Realtime DB emulator.

The endpoint for the live server is the following:

https://inbox-sdp-default-rtdb.europe-west1.firebasedatabase.app/<dir>/<subdir>/<jsonfile>

By contrast, the endpoint for the emulated server is:

http://HOST//<dir>/<subdir>/<jsonfile>/?ns=inbox-sdp

An example GET request to read user1 in the database is shown below

curl "https://inbox-sdp-default-rtdb.europe-west1.firebasedatabase.app/users/user1.json"