Amigoscode

Founder

Bright Network

Software Engineering Consultant

Starling Bank

Backend Engineer & DevOps Engineer

- Tech stack:
Core Java, PostgreSQL, Golang, Bash, AWS, Docker, Kubernetes, Terraform, Cloudformation, Nginx, Teamcity, Github Actions, CI/CD, JS, React

- Projects: 
Onboarding V3, PayNearBy, SettleUp, Service Announcements (Notifications), Secrets Management, Vault PoC (Serverless), Terraform Migration from Cloudformation , Kubernetes Migration from EC2

Software Engineer

Citi

Software Engineer Intern

Colt Technology Services

Database Entry

🚀 Follow me for software engineering, devops, and system design content!

Meet Nelson, a software engineer and the founder of Amigsocode.

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📧 Have any questions or feedback? Reach out to us at 👉🏿 hello@amigoscode.com.

💡 Coding Tip - Use Declarative Programming

- Why Senior's Code is Better: Streams allow for declarative, functional-style programming. 

- This improves readability and avoids mutable variables (names in the junior example).

- Real-World Impact: Stream pipelines are optimized for performance and can easily handle parallel processing, making them ideal for large datasets.

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Nelson Djalo

🚀 Founder of Amigoscode | Helping millions of people break into Software Engineering and DevOps 🤝| 500K Community

Coding Tip - Efficient String Concatenation

𝗪𝗵𝘆 𝗦𝗲𝗻𝗶𝗼𝗿'𝘀 𝗖𝗼𝗱𝗲 𝗶𝘀 𝗕𝗲𝘁𝘁𝗲𝗿: Strings in Java are immutable. Every time += is used, a new string object is created, and the old one is discarded. 

This creates unnecessary memory overhead and slows down performance.

Real-World Impact: In scenarios where strings are concatenated in loops (e.g., building a report, constructing logs), StringBuilder significantly improves performance by minimizing memory allocation and garbage collection.

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💡 Coding Tip - Handle Nulls With Optionals

Why Senior's Code is Better: Using Optional reduces the risk of NullPointerException and encourages developers to think explicitly about nullability. Optional introduces a declarative, more readable way of handling nulls. 📚

Real-World Impact: Null checks are a common source of bugs, especially in complex codebases. 🔍

By adopting Optional, developers follow a functional programming paradigm that makes code cleaner and safer. 🛡️

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graphical user interface, text, application

𝟭𝟮 𝗠𝗶𝗰𝗿𝗼𝘀𝗲𝗿𝘃𝗶𝗰𝗲𝘀 𝗕𝗲𝘀𝘁 𝗣𝗿𝗮𝗰𝘁𝗶𝗰𝗲𝘀

▷ Docker
  - Manages containers through Docker Daemon.
  - Uses a registry to store container images.
  - Clients can interact with the service or host to deploy containers.

▷ Container Orchestration
  - Manages multiple containers and nodes.
  - Example: Kubernetes is the orchestrator for deploying and managing containerized applications.

▷ Caching
  - Improves application performance by using distributed caches.
  - Reduces database load by temporarily storing frequently accessed data.

▷ Single DB
  - Multiple services (Service A, Service B, Service C) connect to a single, shared database.
  - Simplifies data consistency but can create a bottleneck.

▷ Distributed Tracing
  - Tracks requests across multiple services in a microservices architecture.
  - Useful for troubleshooting and monitoring service interactions.

▷ Monitoring and Tracing
  - Provides visibility across frontend and backend components.
  - Ensures performance monitoring and issue detection across services.

▷ Logging
  - Centralizes logs from different microservices (Microservice 1, Microservice 2).
  - Allows for easier tracking and troubleshooting of issues.

▷ Event Bus
  - Facilitates communication between microservices through an event-driven architecture.
  - Ensures asynchronous processing of events across services.

▷ Service Discovery
  - Helps services find each other automatically.
  - Uses a service registry and load balancer to connect service providers and consumers.

▷ Load Balancing
  - Distributes incoming requests evenly across multiple servers.
  - Improves application scalability and fault tolerance.

▷ API Gateway
  - Acts as a single entry point for clients to access multiple services.
  - Handles routing, authentication, and rate limiting.

▷Cloud Provider
  - Hosts infrastructure in the cloud for scalability.
  - Allows for flexible resource provisioning and management.

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12 Microservices Best Practices

JWT (JSON Web Token) For Dummies

Think of JWT like a movie ticket for your app. It proves who you are and what you're allowed to do. 

Here's how it works:

- 1. Login: You log in to an app.
- 2. JWT Creation: The server creates a token with your info (like user ID) and signs it with a secret.
- 3. Token Use: The token is sent to your app, and every time you make a request, it’s sent back to prove it’s you.
- 4. Server Verifies: The server checks the token's signature to confirm it hasn’t been tampered with.

Why use it? 

JWT is self-contained, secure, and doesn’t require the server to store session data. Just make sure to avoid sensitive info in the token and always use HTTPS!

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𝗝𝗮𝘃𝗮 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗲𝗿 𝗥𝗼𝗮𝗱𝗺𝗮𝗽 𝗙𝗼𝗿 𝗕𝗲𝗴𝗶𝗻𝗻𝗲𝗿𝘀

1. Linux and Git  
2. Core Java  
   - IDE: IntelliJ, Eclipse, VSCode  
   - Object-Oriented Programming: Classes, Objects, Polymorphism, Inheritance, Interfaces  
   - Variables, Strings, Loops, File I/O  

3. Collections  
   - Arrays, Lists, Maps, Stacks, Queues  
   - Optionals, Streams  

4. Advanced Topics  
   - Dependency Injection, Design Patterns  
   - JVM Internals, Generics  
   - Multithreading  

5. Exception Handling  
   - Checked and Unchecked Exceptions  

6. Streams and Functional Programming  

7. Testing  
   - Unit Testing, Integration Testing, Mocking  
   - Debugging, Contract Testing  

8. Databases  
   - Relational Database Design, Queries, Indexes, Joins  
   - JDBC, NoSQL, Schema Migration Tools (Flyway, Liquibase)  

9. Clean Code  
   - SOLID Principles, Immutability, N-Tier Architecture  

10. Logging and Multithreading  

11. Build Tools  
   - Maven, Gradle, Bazel  

12. HTTP  
   - REST APIs, GraphQL, API Design  

13. Frameworks  
   - Spring Boot, Play, Quarkus  

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𝗔𝗣𝗜 𝗣𝗿𝗼𝘁𝗼𝗰𝗼𝗹𝘀 𝗳𝗼𝗿 𝗠𝗼𝗱𝗲𝗿𝗻 𝗔𝗽𝗽𝗹𝗶𝗰𝗮𝘁𝗶𝗼𝗻𝘀

REST 🌍: Popular architectural style for stateless, HTTP-based API communication.

Webhooks 🔔: Real-time HTTP callbacks for event-driven notifications.

GraphQL 🕸️: Flexible query language allowing clients to request only the data they need.

SOAP 📜: XML-based protocol for structured data exchange.

WebSockets 🔗: Enables full-duplex communication for real-time data transfer.

EDA (Event-Driven Architecture) 🔄: Supports asynchronous data flows, ideal for modern microservices.

EDI 📑: Standardized data exchange for automated B2B transactions.

SSE (Server-Sent Events) 🔄: Efficient server-push notifications over HTTP.

AMQP 📨: Protocol for reliable, message-oriented middleware communication.

MQTT 📶: Lightweight protocol for IoT, optimized for low-bandwidth networks.

gRPC 🚀: High-performance RPC framework using Protocol Buffers.

Choosing the right API protocol enhances communication efficiency, scalability, and system resilience!

Image creds Ivan Novikov 

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Reducing Nesting with Early RETURN

✅ Why Senior's Code is Better: Early returns reduce nesting, making the code easier to read and understand. It simplifies the control flow by handling special cases upfront.

✅ Real-World Impact: Cleaner code improves maintainability and reduces the chances of bugs introduced by deeply nested conditions.

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𝗛𝗼𝘄 𝗧𝗼 𝗦𝘁𝗿𝘂𝗰𝘁𝘂𝗿𝗲 𝗦𝗽𝗿𝗶𝗻𝗴 𝗕𝗼𝗼𝘁 𝗔𝗽𝗽𝘀

controller: Handles incoming HTTP requests and maps them to service methods.
service: Contains business logic for each feature.

repository: Interacts with the database using JPA or similar.

model: Defines data structures and database entities.

dto: Holds Data Transfer Objects for requests and responses.

config: Houses configurations, such as security settings.

This structure separates concerns and organizes your project in a scalable way, fitting the Spring Boot architecture style.

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Java's enhanced switch expressions allow for more compact and readable code. 

By using the new arrow syntax (->), this reduces boilerplate (break statements) and organizes the code more clearly. 

This approach is less error-prone and easier to read, especially as more cases are added.

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Tester and my code  🙈

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Polymorphism for Reusable Code

The senior developer abstracts calculateArea by using polymorphism, creating a more flexible design. 

Now, Shape could be an interface with calculateArea defined for different shapes, eliminating the need to add a new method each time a new shape is introduced.

This design follows the 𝗢𝗽𝗲𝗻/𝗖𝗹𝗼𝘀𝗲𝗱 𝗣𝗿𝗶𝗻𝗰𝗶𝗽𝗹𝗲, allowing the code to extend without modification.

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graphical user interface, text, application, email

Alhaldullilah its Friday. Jumma Mubarak Amigos.

Its been a very productive week for the Amigoscode team building 2.0 platform.

Stay tuned as are weeks away of launching the new platform.

Are you ready?

Pre order here: https://bit.ly/3UhMDxg

#coding #interviewtips #startup #tech

Master Spring Boot: A Complete Guide to Essential Annotations

1. @SpringBootApplication
2. @EnableAutoConfiguration
3. @SpringBootConfiguration
4. @ComponentScan
5. @RestController, @Controller
6. @RequestMapping, @GetMapping, @PostMapping, @PutMapping, @DeleteMapping, @PatchMapping
7. @ResponseBody
8. @PathVariable, @RequestParam
9. @CrossOrigin
10. @Component, @Service, @Repository
11. @Autowired
12. @Qualifier
13. @Primary
14. @Bean
15. @Value
16. @ConfigurationProperties
17. @PropertySource
18. @Profile
19. @Conditional
20. @Scheduled
21. @SpringBootTest, @DataJpaTest, @WebMvcTest, @JsonTest, @WebFluxTest

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Life of Java Developers. Which version are you using?


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🔐 Understanding Linux File Permissions 🔐

Linux file permissions control access to files and directories, ensuring security and proper functionality. 

Here’s a quick guide:

1. File Types:
   - `d` - directory
   - `-` - file
   - `l` - link

2. Permissions:
   - r (read): View file contents or directory listings.
   - w (write): Modify file contents or directory contents (add/delete files).
   - x (execute): Run the file or access directory contents.

3. Entities:
   - User: The file owner.
   - Group: Users in the file's group.
   - Other: Everyone else.

Permissions are displayed as `rwx` (read, write, execute) for each entity. Example: `drwxr--r--` means a directory where:
- User has read, write, and execute access.
- Group has read access.
- Others have read access.

Master these basics to enhance your command line proficiency! 🚀

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𝟭𝟴 𝗦𝗸𝗶𝗹𝗹𝘀 𝗙𝗼𝗿 𝗦𝗼𝗳𝘁𝘄𝗮𝗿𝗲 𝗘𝗻𝗴𝗶𝗻𝗲𝗲𝗿𝘀

1 - Programming Languages: Mastery in Python, Java, C++, crucial for coding.  
2 - Algorithms & Data Structures: Core problem-solving tools for coding.  
3 - SDLC (Software Development Life Cycle): Knowledge from planning to software maintenance.  
4 - Version Control: Expertise in Git for code collaboration.  
5 - Debugging & Testing: Identifying, fixing bugs, and testing code.  
6 - Databases: Operate databases like MySQL, MongoDB efficiently.  
7 - Operating Systems: Insights into memory, processes, and file systems.  
8 - Networking Basics: Understanding TCP/IP, DNS, and HTTP for web apps.  
9 - Cloud Computing: Use AWS, Azure for app deployment and management.  
10 - CI/CD (Continuous Integration/Continuous Deployment): Automate tests and deployment with pipelines.  
11 - Security Practices: Secure apps against common vulnerabilities.  
12 - Software Architecture: Designing robust software structures.  
13 - Problem-Solving: Tackle complex software issues effectively.  
14 - Communication: Clear verbal and written interaction with teams.  
15 - Project Management: Plan and monitor software projects.  
16 - Machine Learning: Know-how in ML algorithms for AI projects.  
17 - AI (Artificial Intelligence): Use tools like ChatGPT to speed up development.  
18 - Continuous Learning: Stay updated with technological advancements.  

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𝗥𝗮𝗯𝗯𝗶𝘁𝗠𝗤 𝗘𝘅𝗰𝗵𝗮𝗻𝗴𝗲 𝗧𝘆𝗽𝗲𝘀 𝗬𝗢𝗨 𝗠𝗨𝗦𝗧 𝗞𝗡𝗢𝗪

Direct Exchange 📨

Routes messages to queues based on an exact routing key match.
Topic Exchange 🧩

Routes messages to queues based on pattern matching in routing keys, perfect for complex routing logic.

Fanout Exchange 📡

Broadcasts messages to all bound queues, ignoring routing keys.

Headers Exchange 🗂️

Routes messages based on message headers instead of routing keys, allowing for flexible matching.

Default Exchange ⚙️

Routes messages directly to a queue if the routing key matches the queue name.

Dead Letter Exchange (DLX) ☠️

Captures undeliverable messages, helping with error handling and retries.

Optimize your RabbitMQ setup with the right exchange type for reliable and efficient message handling

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18 Most-Used Linux Commands Every Developer Should Know

1. `ls` 📂 - Lists files and directories.
2. `mv` 🔄 - Moves or renames files.
3. `ssh` 🔐 - Connects to remote machines.
4. `cd` 📂 - Changes directories.
5. `cat` 📄 - Displays file content.
6. `sudo` 🔒 - Executes commands with admin privileges.
7. `pwd` 📌 - Prints the current directory.
8. `grep` 🔍 - Searches patterns in files.
9. `top` 📊 - Shows system resource usage.
10. `mkdir` 📁 - Creates directories.
11. `find` 🔎 - Searches files and directories.
12. `wget` ⬇️ - Downloads files from the web.
13. `rm` 🗑️ - Removes files and directories.
14. `chmod` 🔐 - Changes file permissions.
15. `tar` 📦 - Archives files.
16. `cp` 📄 - Copies files and directories.
17. `chown` 🔑 - Changes file ownership.
18. `gzip` 📦 - Compresses files.

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𝟭𝟮 𝗚𝗶𝘁 𝗖𝗼𝗺𝗺𝗮𝗻𝗱𝘀 𝗬𝗼𝘂 𝗠𝘂𝘀𝘁 𝗞𝗻𝗼𝘄

1. git pull: Downloads the latest commits from a remote repository and merges them with your local branch.

2. git commit: Records the changes in the staging area as a new snapshot in the local repository, with a descriptive message.

3. git init: Creates a new local repository in the current directory.

4. git diff: Shows differences between two commits, branches, files, or between the working directory and the staging area.

5. git add: Adds changes in your working directory to the staging area.

6. git branch: Lists, creates, renames, or deletes branches in your local repository.

7. git clone: Copies an existing remote repository to your local machine.

8. git log: Shows the commit history of the current branch, including messages, authors, and dates.

9. git status: Displays the state of your working directory and staging area.

10. git checkout: Switches to a different branch or commit.

11. git merge: Combines changes from one branch into another, creating a new commit if no conflicts exist.

12. git push: Uploads local changes to a remote repository, like GitHub or GitLab.

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