Smart Contract is a contract but instead of written in human language, it is written in a programing language. Like a contract, a Smart Contract defines conditions and financial obligations among participants. Unlike a contract, with a Smart Contract, financial obligations can be executed automatically if conditions are met, without underwriters, lawyers or law enforcement entities.
A contract can protect financial rights of participants only if there is a government enforce and operate. Financial obligations in contracts is money. Money is managed and operated by banks. A Smart Contract is a program and only execute on Blockchain. Blockchain is a network of computers, obey to a protocol that provide services similar to a bank such as : holding balances, transferring value, recording ownership, enforcing rules automatically, and keeping an immutable transaction history.
What Conditions can be added to a Smart Contract ?
Not every statement in contract can be converted to Smart Contract. Smart Contract is a program so it works well with precise numbers and clearly defined if-else conditions such as: money amount, date time, vote counting, temperature.
For example that a company is using Smart Contract to pay employees salary. The Smart Contract can easily implement the agreement that, at every 1st of each month, a fixed amount of money is automatically transferred from the company’s wallet to each employee’s wallets, provided that sufficient funds have been deposited in advance.
Once deployed, the smart contract does not rely on the company’s willingness to pay or on any manual action from accountants or banks. If the date condition is met, the payment is executed exactly as written. If the funds are not available, the payment simply does not occur, making the failure transparent and verifiable to all parties.
In this way, the smart contract replaces trust in the employer or intermediaries with trust in predefined rules and automated execution, ensuring predictable and timely salary payments without human discretion.
However, the smart contract cannot determine whether the employee actually worked, worked well, or should be fired. Those human decisions must be made outside the system. The smart contract only enforces what was clearly defined in advance: who gets paid, how much, and when.
What Conditions can NOT be added to a Smart Contract ?
Smart Contract can not work with Emotions, Quality Judgements, Real Life Events.
For example that a company hires a developer under this agreement:
“The developer will build a high-quality mobile app that meets business needs. Payment will be made if the work is satisfactory.”
This is where Smart Contract can not replace contract. A smart contract, as a program, can not decide:
Whether the app is “high-quality”
Whether it “meets business needs”
Whether the work is “satisfactory”
These require:
Human judgment
Discussion
Interpretation
Sometimes negotiation or compromise
Smart contracts are excellent at enforcing clear rules, but they cannot replace contracts that rely on human judgment, quality assessment, or trust.
If $99 per year is dust to you then this post is not for you 🙂
If it is not, then please take a look !
A fact is that it will cost $99 per year to be able to publish mobile applications to AppStore. For any indie developers that is at the first step of publishing their app, this cost might cause some hesitation.
In case that your application is simple, which is not depends system level APIs such as GPS, File System, Bluetooth, Background Activities or Push Notification, it is possible to make use of PWA feature that is supported by Safari browser which always available on iOS and MacOS.
PWA stands for Progressive Web App. It is a web app, but can be installed into smart phones like a mobile app. Simply put, instead of accessing via a web browser like Safari or Chrome, users can find an icon on their phone, tap it and open the app. This experience makes it feel like it is a mobile app, but under beneath, it opens a browser session and render HTML, JS, CSS code. Although the feel when using PWA app is not as smooth and optimized as when on mobile app, it is acceptable for simple tools, content-first applications, or admin dashboards.
I will take one of my favorite PWA application, Meme Express, as an example. Meme Express is a meme editor that I am using on my Macbook and iPhone whenever I want to make a meme. This meme editor is built with Flutter framework. It has a native app on PlayStore for Android, and a PWA version for the rest of OS including: iOS, MacOS, Window and Linux, essentially, any device can run a browser.
How is PWA version of Meme Express made ?
Framework
Align with mobile first design, Flutter is in used. For simple tools, Flutter is a perfect cross-platform solution, when we can write code once then port to iOS, Android, WebApp, Window and Linux application.
Deploy
For Android version, it is published via Playstore normally, at here: https://play.google.com/store/apps/details?id=com.ease_studio.meme. Unlike other cross-platform framework that utilize in-app web view to mimic mobile app, Flutter ports application to a native Android app.
For iOS version, Flutter can port app to native iOS code as well. But because 99$/year is not an option here, PWA version comes as a rescue.
To publish a PWA version, a hosting server is required. A hosting server requires monthly cost. Luckily, Github Page allow us to deploy a web app from a repository for free and it can be accessed via URL username.github.io/app-name , for example with Meme Express, it is https://ease-studio.github.io/meme-pwa/ . Github Page also allows to map a domain name to it. For example here, https://meme-express.io.vn/ actually points to https://ease-studio.github.io/meme-pwa/ .
Here is a poster in Vietnam that every buildings have to place to warn citizen about online scammer. Scammers now are tech + government powered criminals, well funded and well-organized !
Above poster lists popular tricks that have been used by scammer for decade and caused extreme financial damage to citizen. Below is a summary on what happened and existing solutions at the end of this post
Impersonate bankers
Scammers pretend to be bank employees, using forged caller IDs or fake emails to convince victims that their accounts have problems or suspicious activity. They pressure people to provide OTPs, passwords, or transfer money to “secure accounts,” exploiting the victim’s fear of losing funds.
Love trap on social networks
Criminals create fake profiles on Facebook, Zalo, or dating apps, using attractive photos and sweet messages to build emotional bonds. After gaining trust, they fabricate emergencies, travel problems, or gifts stuck at customs and ask the victim to send money to “help.”
Impersonate telecommunication officer
Fraudsters pose as telecom staff claiming your SIM will be locked, your number is involved in illegal activity, or you must update customer information. They then guide victims to provide ID details or install malicious apps that allow remote control of the phone.
Fake Sim 4G upgrade
Scammers contact victims saying their SIM card needs to be upgraded to 4G/5G and ask for OTP verification. When the victim shares the OTP, the scammer hijacks the phone number, enabling them to reset banking passwords and steal funds.
Recruit Partner
These scams offer “partnership” opportunities with fake companies or online stores. Victims are promised high profits or commissions, but after investing money, they cannot withdraw earnings, or the scammers disappear entirely.
Impersonate Social Insurance
Scammers claim to be from the social insurance authority, saying the victim has unpaid contributions, benefits problems, or involvement in illegal records. They create panic and manipulate victims into sharing personal data or making payments.
Impersonate charity
Fraudsters pose as charity organizations, exploiting compassion by collecting “donations” for fake causes such as medical emergencies, disaster relief, or orphan support. The collected money goes directly to the scammers’ accounts.
Gambling
Many scams involve illegal online betting sites. Victims are lured with promises of guaranteed wins or insider tips. After depositing money, the site manipulates the results or locks the account, making withdrawal impossible.
Impersonate Financial Organization
Scammers pretend to be from loan companies or investment firms, offering high returns or easy loan approval. They require “processing fees,” “insurance,” or initial deposits—after receiving the money, they vanish.
Forced loan
Victims is transferred an amount of money from strangers. Then strangers call them and tell that it is borrowed from black credit firms, and threaten that if they do not pay, they can come with force.
Fake Crypto Trading Platform
Fraudulent crypto apps or websites show manipulated profit charts to convince victims they are earning money. When victims deposit larger amounts, withdrawals are blocked, and the platform disappears.
Recruit house cleaner
Scammers post fake job ads for housekeeping, offering high salaries. Applicants are then asked to pay “training fees,” “uniform fees,” or deposits for tools. Once paid, the job offer is withdrawn and the scammer disappears.
Buy / sell on digital platforms
In online marketplaces, scammers sell products they never deliver, or buy goods and send fake payment receipts. Some also lure victims into sending deposits to “hold” an item, then immediately block them.
Missions via strange apps
Victims are assigned “simple online tasks” such as liking posts or rating products, with small initial payouts. Later, the tasks require larger deposits to continue earning, and once enough money is collected, the scammers cut off contact.
Clone Facebook account
Fraudsters impersonate the victim by cloning their facebook account, asking friends and family to send emergency money or mobile card codes. Others use the hacked account to run ads or steal linked personal information.
Impersonate government officers
Scammers masquerade as police, prosecutors, or tax officials, claiming the victim is involved in money laundering, tax evasion, or criminal cases. They use intimidation to force victims into transferring money to “verify” or “clear” their records.
Fake jackpot / gift
Victims receive messages claiming they’ve won a prize, iPhone, or overseas gift package. To claim it, they must pay customs fees or taxes. After sending the money, the supposed prize never arrives.
Terrorism via phone calls
Some scammers make threatening calls pretending to be criminals or debt collectors. They use fear—claiming harm, kidnapping, or legal consequences—to force victims to transfer money quickly without thinking.
Impersonate law firms
Scammers pose as lawyers claiming there is a lawsuit, unpaid debt, or urgent legal issue. They pressure victims to pay consulting fees or settlement amounts immediately to avoid prosecution.
Terribly, this keeps going on, at least at the moment of this post, regardless many effort from Vietnam, Korea, Singapore, etc polices. Because it is backed by some other governments, it is really hard to eliminate them all.
Well-organized criminal networks
Scam centers in Cambodia are hard to destroy because they are often backed by well-organized criminal networks that operate across multiple countries. These groups have resources, connections, and the ability to relocate quickly when law enforcement pressure increases. Their cross-border structure makes it difficult for any single government to completely shut them down.
Corruption & weak enforcement
Another reason is the presence of corruption and weak enforcement in certain regions. Some scam compounds operate in areas where local authorities have limited oversight or where bribery and influence allow criminals to continue operating with minimal interference. Even when raids happen, the networks frequently rebuild in nearby locations or migrate to neighboring countries.
Many scam centers also hide behind the facade of legal businesses, such as casinos, entertainment centers, or investment companies. These fronts make investigations more complicated because law-enforcement agencies need strong evidence before taking action. Criminals exploit this ambiguity to stay operational for long periods.
Human trafficking victims
Additionally, these scam operations rely on a steady supply of human trafficking victims brought in from various countries. Victims are forced to work under threats, making the operations difficult to expose. Because the workers are often imprisoned and isolated, reliable information rarely reaches the outside world, slowing down international rescue efforts.
High profitability and Low traceability
Finally, global factors contribute to their persistence. The rapid rise of online scams, cryptocurrency, and digital anonymity provides scam centers with high profitability and low traceability. As long as these operations generate massive revenue with relatively low risk, shutting them down completely requires coordinated international action—something that remains complex and slow.
Solutions
So looks like that citizens have to protect themself before government get things done.
And below is some protection tactics that can be observed in Vietnam
Chongluadao.vn is a Vietnamese cybersecurity initiative that maintains a large database of verified scam websites, phishing pages, and fake online services. It allows users to check whether a link is safe and relies heavily on community submissions to keep its blacklist updated. It focuses on suspicious urls and websites. User can search for past reports to know whether a page is scam.
TrangTrang.com is another platform supporting community reporting of suspicious phone numbers. It focuses on gathering public complaints about calls. Users can search past reports before pick up a call, helping them avoid risks.
Firewalls on smartphone
Smartphone Firewalls can act as a digital shield that monitors network traffic to detect and block malicious connections. Unlike antivirus software that only reacts after threats appear, firewalls proactively prevent dangerous apps or websites from communicating with scam servers. They help stop phishing pages, data exfiltration, and suspicious background activities. This makes them especially useful in preventing scams delivered through fake apps or hidden links.
SafePhone is a specialized mobile firewall designed to filter both internet traffic and incoming call threats. It can block incoming calls from known scam numbers. It also can prevent users to access scam websites when tapping urls on messengers. By putting blacklists right on user’s smartphone, it helps users defend against risks more seamlessly without frequently looking up on other websites.
Browser Extensions
Browser extensions can add an additional security layer directly inside the user’s web browser. They can warn about dangerous websites before loading, block trackers, stop pop-ups, and identify phishing attempts. Extensions with anti-scam features check every website against a global blacklist and use heuristics to detect fake login pages or fraudulent shopping sites. This type of protection is crucial because most scams start with a single click on a malicious link.
SafePhone includes a feature called SafeBrowser. SafeBrowser is a secure browsing mode inside the SafePhone ecosystem. It routes traffic through SafePhone’s protection filters, blocking malicious domains and preventing users from accidentally accessing scam websites. This controlled environment is especially useful for elderly users, children, or anyone who prefers a safe but still simple browsing experience.
Have you ever wonder why powerful tools like Google Search, Gmail, Facebook, X, Tiktok, etc are all free to use ?
When you see they sell nothing, then you are what to be sold !
Advertisement is the main profit source that keep most of online tools free nowadays. Advertisement is not bad when it brings information to us in proactive way so we don’t have to spend time investigating market options. But due to this indirect method of advertising, we can’t know who actually behind it. And in fact, this has become an ideal channel for scammers to lure users via social networks. A lot of students, elders were victims because they has least knowledge and experience online. And when many companies systems were infiltrated, hacked, stolen data, personal data of users is leaked globally. These problems, when combine together, harms our privacy !
This post reveals some methods around online advertising industry found on Facebook and the same also can be applied in every social networks as well.
How anyone can make you read something while using Facebook ?
Given that we are all using some banking or non-banking applications, and on the news we hear about companies behind those application are hacked, and data is leaked on some dark web. Dark webs are websites operated outside the laws and are the ideal places for criminal activities which selling hacked data is the most popular. Today anyone can buy leaked data using Bitcoin or Ethereum to hide their identity completely. When someone has our name, phone numbers, emails or even addresses, they can search for and start stalking us on social networks such as Facebook, Instagram, X, etc, then after that they pay to run a targeted ads campaign with information they know about us, and let Facebook algorithm handle presenting that ads to our mobile phone.
How can advertisers control who will see their ads:
1. Custom Audiences
Facebook allows anyone to use phone numbers, emails, or names to directly target a specific user:
Advertisers upload a list of customer data (CSV) to Facebook Ads Manager.
Facebook matches the data (phone/email/name) with existing user accounts.
Once matched, only those users in the list will see the ads.
This is the most direct method of delivering ads to a known individual.
2. Lookalike Audiences
Based on a seed audience (e.g., 100 users with names and emails), Facebook finds other users with similar behavior.
This is indirect targeting, used to expand reach to similar users even advertisers don’t know names or emails.
3. Geotargeting / Geofencing
Facebook allow anyone to use the user’s location (address or GPS) to limit where an ad appears. This usually being used by physical stores. If you ever notice when you pass by some stores, you more likely see their ads on news feed.
4. Interest, Demographic, and Behavioral Targeting
When no personal data is available, Facebook allows anyone to filter audiences by:
Age, gender, region, job title
Online behavior (e.g., searching for a laptop, following specific pages)
Past engagement with posts, videos, or websites
This is an indirect ways but still get ads appear to us.
Lesson
By utilize above methods, anyone, real advertisers, or even scammers, can show some messages to our face when we are scrolling on Facebook, Youtube, Instagram, etc. Social Network applications, one hand, create free tools to soothe the desire of connection in people, and one hand, sell privacy to anyone willing to pay.
Although most of ads is not harmful, make sure to share just enough on social networks, to avoid worst situations that scammers can use ads too !
It is certainly that there is a lot of programming languages on the market. Each language creates itself job positions and even programming “religion” where engineers prefer using a certain language over others, and thanks to that, the software development market can thrive because the diversity in language increase the scarcity in workforce.
So why some language offer higher salary than others ?
Well, language is tool, each tool is more appropriate for a certain purpose. Salary is the compensation from the budget assigned for a purpose. So actually there is no standard market price assigned to each language. It still is the supply-demand game. The difference is the demand is influenced by big boys in the industry. Big boys create programing languages, frameworks that overcome limitations of the ones exists before. The limitation can be speed, memory efficiency, friendly syntax, built-in solution for repeatable tasks. As the result, it can save money in renting physical resource (computers) and save working hours (constructing and error fixing) and that savings also contribute to the compensation, or the salary.
Can an engineer learn multiple language ?
Absolutely Yes.
Learning a language is always hard and time-consuming. There is a lot to remember: syntax. And syntax can be translated from one to another by the same principle as human language. So far, for each language, what we need to remember are:
How to declare variable
How to write conditional check (if-else)
How to do the loop (for-while)
How to separate code in reusable blocks (class, method, function, interface)
How to handle concurrency (process, thread, event loop)
What libraries are offered out-of-the-box per each language.
The tactic is, for the first language, learn it carefully and practice a lot. For new languages, compare it to the one we knew, and find the translation between syntax sets, then practice a lot.
Another tip is to search for open-source projects, and read their code. This is also a quickest way to learn from top engineers.
Is it worthy to know more than one language?
Yes, I think.
If we only need a stable job, one language is enough. But remember that technology changes everyday, and any project has the starting date and the end date. So, ensure your adaptability.
If we are interested in technology, learning new languages can provide us a deeper understanding about computer as well as to see more than 1 way to solve same issues. It keeps us open-minded, curios and provide a broad range of knowledge, which is a truly stability, so far as what I learn from many professionals.
And, the whole programing activities is a career, not a single language itself.
How will you explain software development process to your non-developer friends or colleagues ?
I’d like to compare it to building a house. Which steps do we need to go through when building a house :
Know your budget & need
Design or buy design
Transform the design to construction plan
Estimate cost and adjust the design by cost
Hire and manage workers
Prepare construction site
Choose materials
Build the foundation & Framing
Install walls, doors, windows, roofs, grounds
Hook up to water line & electricity line then install other devices
Decorate
Check Endurance & verify with design requirements
Maintain, fix or replace broken parts.
Each above step has a corresponding phase in software development with corresponding roles :
Building steps
Software Team Role (a person can take many roles)
Know your budget & need
Project Owner, – Has Money, Business Domain Knowledge & Idea Business Analyst – Deep Understanding on Business Domain and User needs – To clarify which features should be developed
Design or buy design
Designer – Drawing: Photoshop,Illustrator, – Art concepts, – UX understanding
Transform the design to construction plan
Architect Developer – Broad knowledge on technologyto choose appropriate solutions – Experience on Scalability, Latency, Security, Performance issues
Estimate cost
Architect Developer/Project Manager – Knowledge on solution’s pricing and average salary for developers & other roles
Hire and manage workers
Project Manager – Hiring – Assigning works and report the progress to Product Owner – Internal & External communication – Develop working environment, policies
Prepare construction site
System Engineer – Setup machines, connect machines to machines and configure/tune them – Linux or other operating systems knowledge to install requested components – Monitoring system & handle system issues – Benchmark test(latency, maximum load)
Architect Developer – Deep experience on Programing to define a healthy source code structure, coding conventions and solutions, building life-cycle and other communication support tools like task manager, group chat, source code management, etc…
Build wall, doors, windows, roofs, ground, wall
Back-end Developer – Experience on chosen languages & frameworks tocreate components, connect components to solve businessideas
Hook up to water line & electricity line then install other devices
Back-end Developer – Integrating to third-party services
Decorate
Front-end developer – Create interfaces (website, mobile applications,… ) to let users to interactas designed
Depends on each project’s complexity and budget, some roles are included in another role. It is the same to the differences between building a small house and a skyscraper. For example, for a system that to serve millions to billions users, the role of Architect Developer is extremely important and Architect problems are far more difficult and complex than coding problems. This kind of system contains a number of machines, maybe located cross over the world and that requires real need of System Engineer. And on the contrary, a common system that only have to server hundreds to thousands users is easy to achieve by simply applying existing solutions without any significant tuning. This project level usually only need Senior developers with strong programming skill. For a small team (3-4 members), communication can be more transparent than a large team, so the role of Project Manager can be merged into other. But for a large team, communication become more problems and to maximize member abilities and avoid duplicating work as well as conflicting work, it needs a Project Manager.
Different from building a house, the design of a software can be changed more frequently, even in the middle of progress and because it is easier to change than reconstructing a building, it is ok and in fact, it happens every time. Business Analyst is the role that has closest contact with users, has clearest vision in the business and is the one who writes the requirements. For small team, Product Owner is usually the Business Analyst too. Depends on those requirements, the design may be changed and some may lead to changes in infrastructure too. And of course, every changes COSTs.
The endurance of a building depends on materials & construction methods. Similarly, the code written by developers determines the endurance of a software which is called Stability. The measurement of Stability is corresponding to the number of bugs and errors. Bug is the symptom of mistakes, human makes mistakes, and coding method is to reduce the changes of make mistakes. A building built with some mistakes can kill people. A software with bug can’t kill people but it does damage to the business, much or less. Tester or QA/QC is the role to ensure this criteria.
Above is some thoughts that I hope can help to give clearer insight for people who always wonder what us – developers do daily.
Target audience : People with intent to be a software developer
Let’s skip the part of reasons and motivations that make you decide to be a developer, it’s maybe your interesting, or it’s just about money, or the life just pushes you to, etc , this post is to give you some guideline to go on this road.
Developers is likely heroes in games you play. What skill that hero should have, how to level up, which criteria to put points to after level up, which bosses to defeat and the most important thing is whether you understand the story behind the game you are playing, to enjoy it !
Let’s start with the story of developer
SoftwareDeveloper world map
Developers, software developers is to create applications to solve real life problems to serve human need. Finding the need is a difficult task too and it deserves to discuss in another post.
There are many kind of applications. Names of application kinds depends on where it run and how it run. It is up to you to choose to follow one or many.
Desktop application : Applications that run on computer / laptop with UI for user to interact with
Web application : Applications that put in a server and you access by using web browsers. There is 2 parts of a Web application called Client side & Server side. Technology used in each side is different too.
Mobile application : Applications that run on mobile phones, now include Android & iOS
iOT application : Applications that run on multiple devices connected to each others in some network model
Imagine this is hero class selecting phase of the game you gonna play. Let thanks god because you don’t have to name your character :)). But each kind of application requires you to use appropriate tool sets.
There is another kind of define developer class when model client-server application model is dominant nowaday, it is :
Front-end developer : Is ones who take care of Graphical User Interface (GUI) for user to interact with. It includes Desktop Application, Mobile Application and the client side of Web Application
Back-end developer : Is ones who take care of something like system architecture, database, etc, things that are not visible to normal users.
To create any application, you are required to know
A programing language for your kind of application
A Integration Development Environment (IDE)
A framework or libraries for your kind of application
A database for your kind of application
A package management tool for your kind of application
Know how to deploy/release your kind of application
Know how to test your applications
Languages
Programing language is your weapon. It will determine which kind of application you can make. Below is the most popular languages at the moment of this post
Java : well-known as a cross platform language, Java can be used to create desktop application, server-side of web applications, Android applications
C# : for Desktop applications on Window
Javascript, HTML, CSS : This combo is essential for client-side of web application
Python : good for build tools but also good to build Web application
NodeJS : built upon Javascript, well-known for server-side of web application
Kotlin : well-known for Android development and as a replacement for Java in mobile world
Object-C, Swift : well-known for iOS development
PHP : well-known for decades in web application development
A lot of languages right ! Everyone wonders which is better than others. The answer is none. Each language has its own benefits and use cases that we will discuss later. And nowaday, it is very normal that a developer can use more than 1 language.
IDE
IDE is the software built for developers, to make their life easier when dealing with common problems while writing code:
Remember syntaxes
Remember boilerplate codes
Command lines
Compile code, debug & run
Setup environment
Search usages of a function or varible
Search a piece of code / text among a bunch of files in a project
Organize project
Format your code for readability
….
The most of IDE provide features like code suggestion or auto complete to that help you type faster and more correct and more readable, to avoid most of typo mistakes. They also have excellent text searching feature that really helpful for troubleshooting problems with your code. Some advance IDEs even can suggest you what need to do and what to do next in what you are doing. And debugging support, this one will save you a lot of time – sometime you have no idea what you are writing, trust me :)), debugging is the only way to figure out. Below is the most advances IDEs currently :
IntelliJ : the best at my point of view, but it is not free. But you may find some crack somewhere :))
NetBean : Free, very equal to IntelliJ
Visual Studio : Free, most popular IDE, usually used in academic courses
Android Studio : Dedicated for Android developing
XCode : Dedicated for iOS developing
…
Learning to use a IDE may take time too but it is worthy. It helps you more efficient and look professional too.
Framework / Libraries
Language is weapon but know how to use weapon deadly is matter too. Imagine it is likely that why you need to learn kung-fu while you have arms & legs already. Framework is built by top level developers and it is embedded with programing experience in decades. It provides ready to use structural solutions in for very common programing problems , kinda of best practices. A little different from framework, Library is a set of tools that help you solve programing problems but not strict in a predefine structure like a framework, you are the one who are responsible for that structure. Below is some most popular nowaday framework/ libraries. The popularity here depends on the demand on job market : (the order is no meaning)
JavaFX : built from Java, for Desktop application
.NET : built from C# ,well-known good to build Desktop application, but it also can build Mobile Application, Web Application and iOT application too.
Spring : built from Java, for server-side of Web application
ExpressJS : built from NodeJS, for server-side of Web application
ReactJS, AngularJS, VueJS : built from Javascript, for client-side of Web application
Android Studio itself contains a framework to develop Android application
XCode itself contains a framework to develop iOS application
Laravel : built from PHP, for Web application
Django : built from Python, for Web application
Database
Database to store data. Depend on your purpose , it can be the most advanced storing technology or just simple files.
Below is some popular database technologies to learn about database for Web application:
SQL : Typical relational database. – Relational database means it requires data to be stored in a structural way, with clear relationships between them. SQL offers a strong transactional query (that we will learn later) that ensure consistency of data. – SQL is a good candidate for applications that dignify the data consistency over other features ( like banking system, accounting system for example ).
MongoDB : Typical Non-relational database (NoSQL), easy to scale but requires extra setup effort. – MongoDB can be a great choice if you need scalability and caching for real-time analytics; however, it is not built for transactional data. – MongoDB is frequently used for mobile apps, content management, real-time analytics, and applications involving the Internet of Things. If you have a situation where you have no clear schema definition, MongoDB can be a good choice.
PostgreSQL : like SQL but more advanced with additional features.
Couchbase : NoSQL type, with Sync Gateway allowing to synchronize data between server and client side seamlessly. If you need an application with realtime data update, Couchbase can be a good choice
Cassandra : NoSQL type, support scaling out-of-the-box. If you need a database that is easy to setup and maintain regardless of how much your database grows, Cassandra can be a good option. If you work in an industry where you need rapid growth of your database, Cassandra offers easier rapid growth than MongoDB.
…
Databases for Web application are usually hosted in dedicated server for best performance to serve from hundreds to millions requests per minute
Different from Web application databases, Client side applications like Desktop application or Mobile application require more lightweight solutions to store data locally. Data that client side applications store usually are application settings, user preferences, static data, cache data from remote database (if it has a server side), etc
SQLite : SQL type
Realm : NoSQL type and faster than SQLite in common operations
Couchbase Lite : a counter part with Couchbase database in server side, with builtin sync features
…
Thanks to community , each language today has it own libraries to interact with databases. Unlike language, you should know more than 1 type of databases, at least 1 in SQL type and 1 in NoSQL type to feel different ways to solve a problem.
Package management tool
Building an application means solving a lot of problems. Thanks to community, the world of open source, most of problems are solved and packaged out there. When you build an application, you always need a few or a lot of them.
To manage the structure of the project and to bring more autonomous to application building process, each language usually has its own package manager tool(s) to :
Install/Update/Uninstall packages
Create a building cycle of the application for continuous development and integration
Manage project structure in consistent way but easy to expand too
Below is some Package management tools for each language :
For Java application : Maven
For Android application : Gradle
For Javascript application : NPM
For HTML & CSS : Bower
For PHP application : Composer
For Python application : pip
For C# : NuGet
Deploy/Release process
This is the critical phase of building an application. It is bring what you build to the real world, where people can access it, and use it. It depends on kind of application that we use term deploy or release. If you are building the server-side application, we use term deploy, because you are going to send your application to a server, to execute. And if you are building the client-side application , like Desktop app or Mobile app, we use term release.
Android & iOS applications have its own release processes that you can find in official documents of them. IDEs usually support application release process . Then you have to learn the process to uploading your applications to Play Store (for Android) and Apple store (for iOS)
Desktop application is easiest, the version you build while developing can be used as release version already. Your next work is to introduce it to your customer
Deployment process is more complicated. Because the server is mostly run on Linux OS nowaday, it is very recommended to learn how to operate a Linux OS, at least know how to connect to a remoteLinux server via SSH & execute command lines when a tutorial asks you to do. More detail about Linux will be in another dedicated post. It depends on the language or the technology you choose that has a different deploy process. We will mention in another posts case by case.
Test your application
Last but not least, testing your application before delivering to the real world is an important phase that make sure you don’t disappointed people or lost customers.
The most basic technique of testing is manual test. Yes, you try your application in every cases and every ways can have to make sure it does not crash.
The more advanced technique is automation test, where you write code to simulate every use cases with your applications. This way is more professional, and more efficient, but also more skill to be required.
In automation test, there is a few sub kinds too. I name here only kinds I mostly use :
Unit test : is to test the correctness of functions or a set of functions.
Integration test : is to test the correctness in functioning of a group of components of your applications. In integration test, you have to simulate every actions in UI to interact with the application
To learn about automation test, below is some libraries for doing test in languages :
JUnit : Unit test library to test Java program
Chai & Mocha : Unit test library to test Javascript program
PHPUnit : Unit test to test PHP program
unittest : Unit test library to test Python program
Selenium : great tool to do integration test for Web application. It is a browser basically but controlled by developers
AutoIt, Appnium : great too to do integration test for Desktop application
Espresso : included in Android Studio, to do integration test for Android application
XCUITests : included in XCode, to fo integration test for iOS application
Wrap it up
You may concern that why iOT application is rarely mentioned in above lists. It is because iOT application includes many applications in many devices. Depends on what kind of device, you may choose yourself any tool above to develop. For example, You may have a phone to control electric circuit in your house, so you have to develop an Android application and a Java application on the device controlling the circuit, a Rasperri Pi for example.
To wrap it up, I note down below some popular skill sets currently for you upcoming hero to choose:
Web application in Java : Linux, Java, Servlet, Maven, JUnit, Selenium, ReactJS, HTML, CSS, PostgreSQL
Web application in Javascript : Linux, NodeJS, ExpressJS, NPM, Mocha, Chai, HTML, CSS, ReactJS, Selenium, MongoDB / Couchbase
Web application in PHP : Linux, PHP, Laravel, HTML, CSS, Javascript, PHPUnit, Selenium, SQL / PostgreSQL
Android application : Kotlin, Gradle, Expresso, Realm / Couchbase Lite
iOS application : Swift, XCUITest, Realm / Couchbase Lite
…
To proficient in any skillset is time consuming, it can take you years but don’t worry, most of companies don’t require you to master all of this before applying for a job unless you are applying for Senior position. Most of times, people master their skill via their job. So keep learning and learn in the right track
TheTechLead 