DEV Community: Jaël Kalvin

Demystifying Object-Oriented Programming: Classes, Objects, Inheritance, and Abstraction Explained for Tech Newbies

Jaël Kalvin — Mon, 10 Jul 2023 10:22:13 +0000

Introduction

In the world of programming, one fundamental paradigm that has gained immense popularity is Object-Oriented Programming (OOP). Understanding OOP concepts is essential for any aspiring developer. In this article, we will demystify four core concepts of OOP: classes, objects, inheritance, and abstraction. We will break them down into simple terms to help tech newbies grasp these fundamental concepts easily.

Classes

In OOP, a class can be thought of as a blueprint or a template for creating objects. It defines the properties (attributes) and behaviors (methods) that the objects of that class will possess. Imagine a class as a cookie cutter, and the objects as the cookies. The cookie cutter defines the shape and characteristics of the cookies, while each cookie is an instance of that shape with its unique traits.

Objects

Objects are the instances of a class. They represent the actual entities that exist based on the class definition. Going back to our cookie analogy, an object is a specific cookie created using a cookie cutter. Each object has its own set of attributes and can perform actions defined in the class. For example, a class called "Car" could have objects like "BMW," "Toyota," or "Audi," each with its specific properties and abilities.

Inheritance

Inheritance is a powerful feature in OOP that allows one class to inherit properties and behaviors from another class. The class that is being inherited from is called the parent class or superclass, while the class that inherits is called the child class or subclass. This concept is similar to how traits or characteristics pass down from parents to children in real life. Inheritance promotes code reuse and helps to organize classes in a hierarchical manner, creating a more maintainable codebase.

Abstraction

Abstraction is the process of simplifying complex systems by breaking them down into smaller, more manageable components. In OOP, abstraction involves creating abstract classes or interfaces that define a set of methods without providing their implementation details. These abstract classes act as a blueprint for other classes to implement their own versions of those methods. Abstraction allows developers to focus on high-level design and functionality without worrying about the intricate implementation details.

Conclusion

Understanding the core concepts of object-oriented programming, such as classes, objects, inheritance, and abstraction, is crucial for any tech newbie stepping into the world of programming. Classes provide a blueprint for creating objects, which are instances of those classes. Inheritance enables the reuse of code and promotes code organization. Abstraction allows for the simplification of complex systems by providing high-level design without exposing implementation details.

By grasping these fundamental concepts, you will be better equipped to analyze and design software systems using object-oriented principles. Keep practicing, and soon you'll be able to harness the power of object-oriented programming to build robust and scalable applications.

Remember, learning to code is a journey, and mastering these concepts will lay a solid foundation for your future as a developer. Happy coding!

SCA Final Evaluation

Jaël Kalvin — Sun, 21 May 2023 22:19:26 +0000

Mastering the Foundations of Microsoft Azure: Essential Insights for Success part 1

Jaël Kalvin — Sat, 13 May 2023 14:19:40 +0000

Microsoft Azure, often referred to as Azure is a cloud computing platform operated by Microsoft that provides access, management, and development of applications and services via globally-distributed data centres. I guess you know this already. It is the definition given by our well known "WikiPedia". But if you know what Microsoft Azure is all about, why should you read this article? Hugh, read! But to make things easier, let me give you an outline of the article.
First things first: let me present myself. I am Kalvin and I will guide you through the whole reading. Yeah, you can count on me.

1. AZURE FUNDAMENTALS

Five fundamental concepts in Azure are regions, availability zones, region pairs, resources and resource groups. Let me define each of these concepts for you.

A. Regions

An Azure region is a set of data centres, deployed within a latency-defined perimeter and connected through Azure’s own dedicated regional low-latency network. Two points to keep in this definition are:

❑Each region is in a specific geographic location.

❑Each geographic location has a cluster of data centres.

<-- Dig deeper -->
Let's talk about Azure geography. An Azure geography is a segmented market containing one or more regions, that preserves data residency and compliance boundaries. This enables customers with specific data-residency and compliance needs to keep their data and applications in specific locations.
Tip: Use Azurespeed to identify the closest datacenter to you based on average latency per millisecond

Note: There exist special government regions like the US Gov Virginia and much more.

B. Availability zones

Azure Availability Zones are unique physical locations within an Azure region made up of one or more data centres equipped with independent power, cooling and networking.

Note that a zone can have more than one data centres but there must be a minimum of 3 zones in a single region also
while one zone can contain more than one data centre, no two zones share same data centre. This said, you may wonder why grouping data centres into availability zones if regions exist already? Three points:
❑ High availability.
❑ High redundancy(replication of your workload and protection against downtime due to data centre failure and resiliency within a region).
❑ High networking and connectivity.

C. Region Pairs

An Azure Region Pair is a relationship between 2 Azure Regions within the same geographic region for disaster recovery purposes. But why was this concept created? I have a question for you: What happens when there is a regional disaster or catastrophic event like hurricane, electricity black, civil unrest out likely to affect all Availability zones in a region? The magic answer Microsoft Azure has to this question is offering to users the ability to replicate their workload in two regions. If one goes down, you are able to access workload in the other region. This is called Region pairing.

Note:
❑ Although replicating in another region, it is still within same geography except for Brazil South- South Central US.
❑ If both regions are affected, Azure will prioritise one before the other.

D. Resources

In Azure, a resource is an entity managed by Azure. Virtual machines, virtual networks, and storage accounts are all examples of Azure resources. Simply put, resources represents the services offered by Azure.

E. Resource group

A resource group is a logical container hosting your resources deployed in Azure. Just take it like this: you are using different Azure resources. Hmmmm, it may be a virtual machine with additional disk storage...... You want to deploy this. What you should do is to create a kind of container to host these resources. You can also add these resources to an existing resource group. Is it clear enough? I hope so :)

Note:
❑ A resource can only be in one resource group at a time and resource groups cannot be nested.
❑ Resource group gives order to your portal. You can assign resources into resource groups based on type, lifecycle, departments etc.

Knowing these five concepts will definitely make the rest of this article more digest to read. Hey, do you know what? Let's practice a little bit. But before let me present the the tool we will be using.

RESOURCE MANAGER

Azure Resource Manager is the deployment and management service for Azure. It provides a management layer that enables you to create, update, and delete resources in your Azure account. You use management features, like access control, locks, and tags, to secure and organise your resources after deployment.

<-- Recap -->
❑ Users can create resources via Azure portal, PowerShell, CLI and ARM templates.
❑ All these interfaces connects to the resource manager.
❑ Resource manager is the management layer for all resources and resource groups.

But who can manage your different resources? Good question. Do you know what is an Azure subscription? It is simply a subscription that provides an authenticated and authorised access to azure resources. Voila Voila!!!! But this doesn't give an answer to the question right? The answer is Management group. But what is it all about?

Management groups are containers that help you manage access, policy, and compliance across multiple subscriptions. Create these containers to build an effective and efficient hierarchy that can be used with Azure Policy and Azure Role Based Access Controls. So yeah, the main aim of this is to ensure security and control access.

Key points:

❑ Management groups provide hierarchy for governance and structure to enable one manage access, policies and compliance for many subscriptions.
❑ A management group can support up to 6 levels of depth.
❑ The root management group cannot be deleted or moved unlike other management groups.

2. AZURE COMPUTE SERVICES

Azure compute is an on-demand computing service that provides disks, processors, memory, networking and OS. These include Azure Virtual Machines (VMs), Azure Container Service, Azure App Services, Azure Batch and Azure ServiceFabric. Let's talk about some Azure compute services.

a. Virtual Machines(VMs)

A VM is a virtual emulation of your physical computer. It is an ideal choice when in need of total control over the OS and ability to run custom software capable of meeting your needs.
But how do you create a VM in Azure?

Prerequisites:

Create a Microsoft Azure free account. Why should the account be free? Because if you forget a resource you will be definitely billed for it. So hmmm, just pick a free account for a start.

Step 1: Search VM in the search bar

Step 2: Open VM creation form

Step 3: Review and create

<-- Dig deeper -->
To manage VMs further, you can also use

❑ Virtual Machine scale set which allows you scale group of identical machines created from same image to meet your work demands in a number of mins. To create a virtual machine scale set, follow the steps mentioned for the VM creation. Search for "scale set" in the search bar.

❑ Virtual Machine availability sets designed to promote resiliency and high availability. It groups VMs into update domain and fault domain. Update domain groups VM to be updated at the same time. AN update group is given 30 minutes to recover before the next update domain starts. Fault domain groups VM sharing same power and network switch. Protects against power and network failure.

Note:
Availability set is free, you only pay for instances created.

b. Containers

Containers are packages of software that contain all of the necessary elements to run in any environment. In this way, containers virtualise the operating system and run anywhere, from a private data centre to the public cloud or even on a developer's personal laptop. Keep these points in your mind about containers:

❑ While VM’s are a good way of cutting cost with physical infrastructure, it is limited to one OS per virtual machine. Containers allow you run multiple instances without need of a full guest OS.
❑ Contains application codes, libraries and dependencies so they can run anywhere.
❑ Good for legacy applications,
❑Created from container images, which are templates that contain the system, applications and environment for the container.

Have we talked of update domain and fault domain already? No? Oh, hmmm. Let's take a break and come back. In the part two of this article, we are going to discuss these different domains but not only. We will discover storage services, azure analytics and azure database.

If you found this article helpful please like, share and follow

Build your first static web app #tuto1

Jaël Kalvin — Sat, 15 Apr 2023 14:56:15 +0000

Today, we are going to learn how to deploy your first static web app on Microsoft Azure. What is a static web app/website? A static website consists of a series of HTML files, each one representing a physical page of a website. These sites are often used to build portfolios or what french people call site vitrine. Trêve de bavardage, let's go.

Prerequisites

❑ A Microsoft Azure account ( A free one :) for tests)
❑ A Github repository containing your source files. You are free to use a framework or not. Just make sure you have an index.html file in the source folder. Why? Why? Why not?? ;)

Now let's go......

Step 1: Search for the term "static web" in the search bar of the azure portal.

Step 2: Create the web app

Step 3: Fill the form and choose the free hosting plan.

Step 4: Choose GitHub as deployment model and sign-in.

Step 5: Choose the repository, the branch and the build presets. Now note this if you have a simple folder structure, just choose HTML but if it is any type of custom folder structure, choose structure. Actually, choose any structure that suits your project.
Now, don't forget to select as file location the folder with your index.html file. The root folder is generally presented by /, but depending on your folder it can be /src etc.

Now, let's Azure review your resource. Boom pa Boom pa............

Step 6: Click the create button.

Step 7: Now that your resource is created, inspect it.

Step 8: Click on the URL.

It is done :). You have just created your first static web app. Let's have a look a it okay?

But, this is not our app. Why are we seeing this. The reason is simple. If you go to your GitHub repo you will discover the created GitHub action is still running. It will look like something like this:

So hmmm, a bit of patience. All will be fine. If you are sure the repo selected is the one containing your index.html, just give it a bit of time. So yeah, let's wait.
Tic toc, Tic toc, Tic toc....... Do it a couple of times and Boom. This is your newly deployed site.

Well done, you have just created and deployed your first Microsoft Azure static web app. Now that this is done, don't forget to delete your resource. Yes, I will always remind you to delete your created resource. Well done.

Have you encountered any problem following any of these steps? If yes, leave your problem in the comments section. If not, like share and don't forget to follow to be notified of each amazing article I publish. :)

Cloud Computing : A fun Introduction.

Jaël Kalvin — Sat, 08 Apr 2023 23:25:01 +0000

The Cloud, you have probably heard about this term again and again. You may wonder, what is it all about? Googling the expression Cloud Computing probably lead you to discover IAAS,PAAS and SAAS acronyms; What are they?
In this article we are going to discover what is cloud computing. To help you through this journey, we are going to use examples, common terms you probably know and at the end of this reading, you will definitely understand the main cloud concepts. Are you ready? Let's go.

Let's start with an example.
Kalvin is a mobile application developer and she just launched her first mobile application. It is a social media app. One week after launching, the app has 1000 users but 10 days after the number of users amazingly increases. She now has 100 000 users to manage. This is huge right? But the worst is still to come. Actually at the start of the project she did not foresee such an amazing growth. The resources she allocated to the project were quite small. Which resources? Storage, Network, Hardware, etc. Now, with this abrupt growth she must increase her infrastructure. But think about it, increasing her infrastructure means having new buildings, augmenting the storage structures, hiring more employees...... It simply means investing more time and money in the project for unpredictable human behaviours. Having this example in mind, let's define cloud computing.

1. WHAT IS CLOUD COMPUTING?

Cloud computing is the on-demand delivery of compute power, database storage, applications and other IT resources through a cloud service platform via the internet with pay as you go pricing.
Let us break down this definition into key points.

On-demand: In the cloud, the resources or services are delivered based on the demand made by the clients. It may seem obvious, but stick and continue reading.
Cloud service platform or Service provider: This denotes the fact that to access a cloud service, you must pass through a platform or the provider of that service.
Pay as you go: This is one of my favourite point, you pay resources used as per their usage.

Now that you know what is cloud computing, you can easily figure out why cloud computing is used over traditional data centres.

2. BENEFITS OF CLOUD COMPUTING

Low cost: Cloud computing reduces cost by trading capital expenses(CaPex) for operational expenses(OpEx). But what are these? CaPex represents all the upfront cost endorsed when building a data centre (i.e costs for the building, servers and supporting the equipments). OpEx on the other hand represents the day to day expenses of a business. Take it like this, after the initial build of a data centre, ongoing connectivity, utility and maintenance costs are considered OpEx.
Benefit from massive economies of scale: Cloud services are used by multiple users at different scales. The services providers can hence offer these services at affordable prices. Also remember the Pay as you go concept. This helps each enterprise to pay just the resources they use at a certain point in time.
High availability: Availability in cloud computing is the extent to which an app is fulfilling its intended business purpose. Applications that are highly available are built in a manner where a single failure won't lessen the application's ability to be fully operational. The different services offered by cloud providers often increases availability.
High scalability: Scalability refers to the ability to increase or decrease IT resources as needed to meet changing demand. In cloud we have two types of scalabilities.

a. Horizontal Scaling: This is adding additional instance(s) of the resource(s) you have. To better understand, imagine you have a Virtual Machine running in the cloud. Scaling Horizontally implies adding the number of identical Virtual Machines in the cloud. See it like duplicating your resources.

b. Vertical Scaling: Vertical scaling refers to adding more or faster CPUs, memory, or I/O resources to an existing server, or replacing one server with a more powerful server. Here we simply increase the size of the resources we need.

Increase speed and agility: This makes a major difference between a traditional data centre and cloud. It takes a matter of minutes, seconds or hours to provision resources when needed once requested. Yes cloud computing helps us go global in minutes.
High security: Cloud helps ensure that all your resources deployed are safe from natural disaster, cyber threats and also meet regulatory and compliance requirements.
Stop guessing capacity: No need to be guessing capacity as the resources can adjust their sizes based on the demand/usage.

3. CLOUD COMPUTING CONCEPTS

- Elasticity: This is the ability to acquire resources as you need them and release resources when you no longer need them. This joins the on-demand point explained above. In the cloud, you generally want to do this automatically.

- Reliability: This is a solution's ability to provide functionality for its users when it is needed.

- Agility: The cloud lowers the cost of truing new ideas , reduces the time required to maintain infrastructure, reduces risk for the organisation around security and compliance and provides to emerging technologies.

4. TYPES OF CLOUD COMPUTING SERVICES

There are 3 main types of cloud computing services.

a. IAAS(Infrastructure As A Service): IAAS is a form of cloud computing that delivers fundamental compute, network, and storage resources to consumers on-demand, over the internet, and on a pay-as-you-go basis. This is the most flexible type of cloud service as it provides users with control and flexibility over the application. While the the cloud provider manages the infrastructure, it places a responsibility on the users to manage the platform, the application and the data.

Use Case:Lifting and shift migration
Example:Machine

b. PAAS(Platform As A Service): Platform as a service supplies an on-demand platform for developing, testing and managing software applications. The purpose of PAAS is to make it easy for developers to quickly create an application without having to worry about the underlying infrastructure.
It is the middle ground between renting a space in a datacenter (IAAS) and paying for a complete and deployed service (SAAS). In PAAs, the cloud provider maintains the physical infrastructure as well as the platform, while user manages application and data.

Example:Azure web application

c. SAAS(Software As A Service): Software as a service (SaaS) is a software distribution model in which a cloud provider hosts applications and makes them available to end users over the internet. In this model, an independent software vendor (ISV) may contract a third-party cloud provider to host the application.
Here, the cloud provider hosts and manages the infrastructure, platform and application. In this case, the user is completely renting or using a fully developed application. This is the least flexible, easiest to run and requires the least amount of technical knowledge.

Example: Outlook, Skype, One drive, etc.

To summarise this section always remember IAAS offers maximum control and SAAS minimum maintenance with PAAS in the middle.

5. CLOUD DEPLOYMENT MODELS

Let's now talk of 3 cloud deployment models.

- Public Cloud
Owned and controlled by cloud services providers.Here customers pay for services consumed and resources in the cloud are shared with other consumers.

Advantages

No capital expenditure to set up
Scalability
On demand self-service

Disadvantages

Less control
Less security

- Private Cloud
Computing, storage and network resources are provided for a single entity or organisation without sharing e.g IBM.

Advantages

Full control and management over the cloud system.
Regulatory governance.
Good for legacy application.

Disadvantages

Higher cost
Full responsibility
Less flexibility

- Hybrid Cloud
Uses both public and private cloud.

Advantages

Scalability
Lower CaPex expenditure
Better security management

Disadvantages

Complexity to manage
Difficult to implement

CONCLUSION

This article help us discover what is cloud computing. What are its main concepts, deployment models and services. What's next? Like, share and follow for more articles.

A comprehensive guide to S3 and EC2 AWS Cloud Services

Jaël Kalvin — Sat, 08 Apr 2023 11:54:08 +0000

Amazon Simple Storage Service (S3) and Amazon Elastic Compute Cloud (EC2) are two major storage services offered by AWS. But What are these services all about? What are they used for? and How can you use them? This article will respond to each of these questions.

A. SERVICES PRESENTATION

SE3:

An Amazon S3 bucket is a public cloud storage resource available in Amazon Web Services (AWS).Simple Storage Service(S3) is an object storage offering service. S3 is lightweight and provides the capability to store data. Having used Firebase for long I can say SE3 matches the firebase storage service.

EC2:

An Amazon EC2 instance is a virtual server in Amazon's Elastic Compute Cloud (EC2) for running applications on the Amazon Web Services (AWS) infrastructure. EC2 is a web service that provides secure, resizable computing capacity in the cloud. Do you know what are virtual machines and how they are used? Actually EC2 gives you the possibility to create a virtual machine.

B. COMPARING SE3 AND EC2

But when do we use each of these service? Hmmm, I found an amazing recap on this image.

C. CREATING AN SE3 INSTANCE

To follow the following steps, you have to create an AWS account.

i. Go to the AWS official website.

ii. Sign in to the console.

iii. Enter your credentials and login.

iv. Search for SE3 in the search bar and navigate to the console.

v. The next step is quite simple. Create a bucket.

Note: While naming your bucket, please choose a unique name. If not, the bucket will not be created and you will be prompted an error. So yeah, choose a unique name, as unique as you are....

Make no change on the configurations and create your bucket. Yeah, it is done. You have just created your first bucket.

But now, come on. As a cloud practitioner you will not only have to create buckets. You will have to upload data. Do you want to try it now? Let's give a try.......

**UPLOADING A FILE IN A BUCKET(Optional)**

a. Click on upload and select the file/folder you want to upload.

Congrats, it is done. You have just uploaded your file/folder. But question: Can you access this file from anywhere? To have the question, try and click on the link in the description box of your newly added resource. Can you access your resource? Ooooopppppsss! Mine is not working. Have a look at my error.

Do you know why we have this error ? The reason is simple; if you go back to your SE3 console you. will notice that all the public access are blocked by default. This is actually a security measure. You don't want anyone to access your data right? But if you want to make it public, you definitely have to change this default configuration.

To do it(Optional):

i. Click on the edit button.

ii. Uncheck the block public access and confirm.

Back to permissions, you will discover that the access parameter changed from all to Objects can be public.
Let's continue......

iii. Edit the Object Ownership. Here enable ACLs and confirm.

iv. Go back to the permissions.

Here you will notice that the Access control list(ACL) is editable. Click on the edit button and check the list and read.

Even once this step done, you can't still access your uploaded resource from the internet. Why? Because you have changed the bucket configurations and not the object's ones. To fix this, you have to follow the same steps for the objects. Are you ready? Don't worry, we are almost done.

v. Click on the object, go to permissions and edit Access control list.

Congratulations, you are done. Click on the link and let the magic happen. Can you access your resource now? What a question. Yes of course........

D. LAUNCHING AN EC2 INSTANCE

Stop asking yourself while this title is launching an EC2 instance instead of creating one. The reason is simple. On the AWS console, to create an instance, you just need to click on the launch button. But let's go gradually okay?

i. Search EC2 in the search bar.

ii. Launch an instance and let's go.

iii. Add a name and select the OS image you want.

I'll choose Windows OS. Why? Because I am using a MacOS and I want to show to you what to do in this case.

Once done launch the instance.

For MacOS(Optional)

a. Go to AppStore and download Microsoft Remote Desktop

iv. Go back to the EC2 Management Console and click on connect to your instance. Is it done? Okay.

v. Now connect using RDP client and download the remote desktop file.

vi. Create a key pair associated with the instance you are creating.

Why? Why not???? Actually, it is also a security measure. Only you should have the access key to your machine right? Once the key created, you will have to download it in your local storage.

vii. Open the .rdp file you have downloaded.

Now, you will have to enter a username and a password. The default username is Administrator. To have your password, decrypt the key you have downloaded when creating your key pair.

Once decrypted, you can access and copy your password and boom!!!!!!

You have a brand new machine created.

Congratulations. You have just created an EC2 instance.

Hey: Note please, you must always as a newbie terminate your instances and delete your resources..... Always do that, if not you may receive an unexpected bill.

It was a pleasure sharing this article with you. Do you have questions? Comment them out and I'll definitely help you through.