Course (Part 614)

Course: Backend Developer

N&M delivery GmbH is recruiting backend developers for its tech arm, HEXbyte, to build robust backend systems using Go and RESTful APIs. The position is aimed at early-career engineers, with at least one year of experience preferred but freshers are encouraged to apply. The role is hands-on and emphasizes practical engineering over superficial or "vibe" coding. Applicants should be comfortable using Postman (or similar) for API testing and using Git for version control. Nice-to-have skills include familiarity with Gin or Echo, basic Docker knowledge, ORM experience (GORM, sqlx), and JWT-based authentication. The posting specifies two vacancies, a negotiable salary, and an age cap of 30, with the workplace offering both office and remote options. The job is based in Dhaka and was published on 17 April 2025, with an application deadline of 26 April 2025. HEXbyte, powered by N&M delivery GmbH, focuses on software solutions that streamline logistics and supply-chain operations for B2B and mobility startups. Candidates with backgrounds in supply chain, logistics startups, or shared mobility will find their domain experience relevant. The company values problem-solving, decision-making, and algorithmic thinking as part of the skill set for successful applicants. This role suits engineers who want to own backend features, implement secure APIs, and participate in a startup environment that turns operational challenges into software products. Prospective applicants should prepare curated code samples, API design examples, and evidence of collaborative development using Git. Interested candidates must ensure they meet the age and educational criteria and submit applications ahead of the deadline.

Lesson

Topic: N&M delivery GmbH — Backend Developer (Go) Position & Core Backend Concepts

Learning Outcomes

• Identify core job requirements for a Go backend developer in a logistics startup.
• Explain RESTful API design and testing approaches using Postman.
• Recognize supporting technologies: Gin/Echo, Docker, ORMs, JWT, Git.
• Translate technical job specs into a practical development plan for backend features.

Answer

The learning outcomes above highlight hiring criteria, essential skills in Go and REST, and complementary tooling. Learners should be able to map job requirements to concrete skills and produce a short implementation plan for an API-based feature.

Conceptual Explanation

N&M delivery GmbH recruits backend engineers to build production-grade services primarily with Go, focusing on RESTful architectural patterns. Go is chosen for its concurrency model, performance, and simple deployment. RESTful APIs establish resource-oriented endpoints, stateless interactions, and common HTTP methods (GET, POST, PUT, DELETE). Postman or equivalent tools provide request/response validation during development and enable automated test collections. Version control with Git is mandatory for collaborative development and code reviews. Frameworks like Gin and Echo accelerate routing, middleware, and request handling while ORMs such as GORM or sqlx simplify database queries and migrations. Docker enables consistent development and deployment environments. JWT (JSON Web Tokens) supports stateless authentication across microservices. In a logistics/B2B context, reliable APIs, idempotent operations, and clear error handling are essential. For startups, engineers must balance rapid iteration with maintainable, testable code and clear API contracts.

Answer

Key conceptual points: Go for performance and concurrency; REST for resource-based APIs; Postman for API testing; Git for source control; Gin/Echo and ORMs speed development; Docker for environment parity; JWT for auth. Emphasis should be on testable, maintainable backend services suitable for logistics and B2B domains.

Bilingual (EN → বাংলা)

Key Terms and Translations

English	বাংলা (Bangla)
Backend Developer	ব্যাকএন্ড ডেভেলপার
RESTful API	রেস্টফুল এপিআই
Postman	পোস্টম্যান (এপিআই পরীক্ষার টুল)
Docker	ডকার (কনটেইনার প্রযুক্তি)
JWT (Authentication)	JWT (প্রমাণীকরণ টোকেন)
Vacancy	শূন্যপদ

Answer

Use these translations when preparing bilingual job materials or explaining technical terms in Bengali during interviews or team onboarding.

Important Notes

• Vacancies: 2
• Application Deadline: 26 Apr 2025 (published 17 Apr 2025)
• Location: Dhaka (Work from home or work at office)
• Age: at most 30 years; Experience: at least 1 year (freshers encouraged)
• Education: BEngg or BSc preferred
• Salary: Negotiable
• Company: HEXbyte powered by N&M delivery GmbH — logistics software focus

Answer

Applicants should confirm eligibility for the age and education criteria, prepare a CV with relevant domain experience (supply chain, logistics, shared mobility), and provide code or API samples demonstrating Go and REST skills.

Job Summary Table

Position Overview

Field	Detail
Company	N&M delivery GmbH (HEXbyte)
Role	Backend Developer (Go)
Vacancies	2
Location	Dhaka
Deadline	26 Apr 2025
Experience	At least 1 year (freshers encouraged)
Age Limit	At most 30 years
Workplace	Remote / Office

Answer

This table condenses the main administrative and logistical details of the vacancy for quick reference by candidates and instructors.

Exercises

True / False

1. Advanced knowledge of Go is a mandatory requirement.
2. JWT is required for every project in the role.
3. Docker familiarity is listed as a nice-to-have skill.
4. Freshers are not allowed to apply.

Answer

1. True — the posting specifies advanced-level familiarity with Go as a must-have.
2. False — JWT is a nice-to-have, not strictly required for every project.
3. True — Docker is included under nice-to-have skills.
4. False — freshers are encouraged to apply.

Fill in the Blanks

1. The role emphasizes building backend systems using the programming language _______.
2. API testing with _______ or similar tools is a must-have skill.
3. One common Go web framework mentioned is _______ or Echo.
4. Stateless authentication using _______ is a nice-to-have capability.

Answer

1. Go
2. Postman
3. Gin
4. JWT

Multiple Choice Questions (MCQ)

1. Which of the following is a primary focus of this backend role?
   • a) Frontend UI design
   • b) Building backend systems and APIs
   • c) Marketing and sales
   • d) Hardware engineering
2. Which tool is recommended for version control?
   • a) SVN
   • b) Git
   • c) FTP
   • d) Dropbox
3. Which domain experience is explicitly relevant for applicants?
   • a) Fashion retail
   • b) Supply Chain and Logistics startups
   • c) Agriculture only
   • d) Construction management

Answer

1. b) Building backend systems and APIs
2. b) Git
3. b) Supply Chain and Logistics startups

Matching

Match the left column (tools/terms) with the right column (purpose).

Term	Purpose
a) Postman	1) Containerization
b) Docker	2) API testing
c) GORM	3) ORM for database queries
d) JWT	4) Stateless authentication token

Answer

Correct matches: a→2 (Postman = API testing), b→1 (Docker = containerization), c→3 (GORM = ORM), d→4 (JWT = stateless authentication).

Descriptive

Question: Draft a short implementation plan (4 steps) for delivering a "Create Order" REST endpoint in Go for a logistics microservice.

Answer

1. Define API contract: POST /orders with request/response schema (JSON), validation rules, and error codes.
2. Implement handler in Go using Gin/Echo: parse JSON, validate payload, and apply business rules (idempotency checks, address validation).
3. Persist the order with an ORM (GORM/sqlx) within a transaction; publish an "order.created" event if applicable; add unit and integration tests (using Postman collections for API tests).
4. Containerize the service (Docker), add Git-based CI steps for linting, tests, and build; deploy to staging and verify with end-to-end tests, including JWT-protected routes if required.

Creative

Task: Sketch a lightweight microservice architecture (names and responsibilities) for a delivery startup using Go. Provide components and a one-line purpose for each.

Answer

1. API Gateway — Single entry point, rate limiting, basic auth routing to internal services.
2. Order Service (Go) — Accepts and validates orders, persists to DB, emits events.
3. Driver Service (Go) — Manages driver availability, assignments, and tracking.
4. Notification Service — Sends SMS/email updates to customers and drivers.
5. Auth Service — Issues and verifies JWTs, manages user sessions and roles.
6. Event Bus / Message Queue — Decouples services for reliable asynchronous processing.
7. Monitoring & Logging — Aggregates metrics and logs for observability and alerts.

Activities, Vocabulary, Homework, Practice Task

Activities

• Code review session: examine a small Go REST handler and suggest improvements.
• Pair programming: implement a simple CRUD endpoint with tests.

Answer

Focus on idiomatic Go patterns, error handling, context propagation, and test coverage during activities.

Vocabulary

• Idempotency
• Middleware
• Connection pooling
• Schema migration

Answer

Explain each: Idempotency — repeatable requests yield same result; Middleware — request/response interceptors; Connection pooling — reused DB connections; Schema migration — code-managed DB changes.

Homework

1. Build a minimal Go service with one POST endpoint, include a Postman collection, and link to a Git repo.
2. Write a README documenting API contract and setup steps (including Dockerfile).

Answer

Deliverables: Git repo URL, Dockerfile, Postman collection file, README with endpoints and example requests/responses.

Practice Task

Implement JWT-protected GET /profile endpoint that reads user ID from token and returns user metadata.

Answer

Expected: middleware to validate JWT, extract claims, handler to fetch profile from DB or mock, and tests verifying access with valid/invalid tokens.

Company Information

N&M delivery GmbH / HEXbyte
HEXbyte is a dynamic software startup powered by N&M DELIVERY GMBH, focused on transforming ideas into powerful digital solutions that enhance operational efficiency and streamline logistics.

Answer

HEXbyte operates as the tech-driven arm of N&M delivery GmbH and seeks engineers to build B2B software products for logistics and shared mobility sectors.