Three-tier architecture application

Project members :

• BOBEUF Jules LinkedIn
• SANTORO Thomas LinkedIn

I/ Implementation of the application using Flask

So, the application was made with Flask, a micro framework for web development in Python.

We will build a web application based on a three-tier architecture.

The two-tier architecture characterises client/server systems in which the client requests a resource and the server provides it directly. This means that the server does not call on another application to provide the service. In the 3-tier architecture, there is an intermediate tier, i.e. there is usually a shared architecture between :

1. The client (the resource requester)
2. The application server (also called middleware, i.e. the server responsible for providing the resource but calling on another server)
3. The secondary server (usually a database server … providing a service to the first server)

In the three-tier architecture, by contrast, server-level applications are delocalised, i.e. each server is specialised in one task (web server and database server, for example). Thus, the three-tier architecture allows :

• greater flexibility
• greater security (security can be defined for each service)
• better performance (tasks are shared)

Hence, we have adopted the following architecture for our project:

├── README.md
├── __pycache__
│   ├── app.cpython-310.pyc
│   ├── basedonnee.cpython-310.pyc
│   └── visualisationDonnees.cpython-310.pyc
├── app.py
├── basedonnee.py
├── bd.sqlite
├── logs.txt
├── static
│   ├── images
│   │   └── visualisation
│   │       ├── humidite.png
│   │       ├── pression.png
│   │       └── temperatures.png
│   └── styles
│       └── style.css
├── templates
│   ├── base.html
│   ├── contact.html
│   ├── form.html
│   ├── index.html
│   └── infosVille.html
├── tests
│   ├── __pycache__
│   │   └── conftest.cpython-310-pytest-7.2.0.pyc
│   ├── conftest.py
│   └── functional
│       ├── __init__.py
│       ├── __pycache__
│       │   ├── __init__.cpython-310.pyc
│       │   └── testsPages.cpython-310-pytest-7.2.0.pyc
│       └── testsPages.py

II/ Database

For our 3^rd layer, the database layer, we used SQLite.

Below is the diagram generated by PyCharm of the database we modelled:

III/ API requests

To get the data, we used the following API: wttr

In Python, to make API requests, the use of the requests module is necessary.

IV/ Data visualization

To perform a visualization of the data, we used the python module matplotlib.pyplot.

V/ Form

For the site form, we used the flask_wtf module from python.

VI/ Unit tests [experimentation]

I decided to try this part of the project which was optional.

I therefore proceeded as follows:

• Enclose our entire application in the create_app(test_config) function
• Create a .env file for a better organisation of the project. In this file the variable SECRET_KEY has been placed.

def create_app(test_config=None):
    app = Flask(__name__, instance_relative_config=True)

    if test_config is None:
        app.config.from_mapping(
            SECRET_KEY=os.environ.get('SECRET_KEY'),
        )
    else:
        app.config.from_mapping(test_config)