BPSC (Ministry of Agriculture) Assistant Programmer Exam: 15.02.2022প্রশ্ন ও সমাধান

An API (Application Programming Interface) is a defined set of rules and protocols that lets one software application request services or data from another, without either side needing to know the other's internal implementation - only the agreed request/response format.

Example: a weather app calling a weather API

sequenceDiagram
  participant App as Client App
  participant API as Weather API Server
  participant DB as Weather Database
  App->>API: GET /weather?city=Dhaka
  API->>DB: Query latest weather data for Dhaka
  DB-->>API: Temperature, humidity, forecast
  API-->>App: JSON response - temp 31, humidity 78%

The app never touches the weather database directly - the API is the only door in, enforcing authentication (API key), rate limits, and a stable data format.

Types of API

Type	Description
REST	Uses HTTP verbs (GET/POST/PUT/DELETE) and JSON; most common on the web
SOAP	XML-based, strict contract (WSDL), used in legacy enterprise systems
GraphQL	Client specifies exactly which fields it needs in one query
Public/Open	Freely available to any developer (e.g., Google Maps API)
Private/Internal	Used only within an organization's own systems

Real examples: payment APIs (bKash, Nagad), the Google Maps API for location, and social-media login via an OAuth API.

Exam takeaway: An API is a contract for communication, not the software itself - it hides implementation details and lets independently built systems (client app, server, database) interoperate through a stable, well-documented interface.

A Data Administrator (DA) manages data as a strategic organizational asset - policies, standards, and data models - independent of any specific DBMS. A Database Administrator (DBA) manages the physical database itself - installation, performance tuning, security, and recovery - for a specific DBMS product.

graph TD
  M[IT / Business Management] --> DA[Data Administrator - policy and data modeling]
  DA --> DBA[Database Administrator - implementation and operations]
  DBA --> DB[(Physical Database)]

Difference

Aspect	Data Administrator	Database Administrator
Level of work	Strategic / managerial	Technical / operational
Focus	Data as an enterprise resource - naming standards, data dictionary, data quality	The physical database - schema implementation, tuning, backup, security
DBMS dependency	DBMS-independent	DBMS-specific
Typical tasks	Data governance, conceptual/logical data modeling, defining data ownership	Installing/upgrading DBMS software, access control, performance monitoring, disaster recovery
Output	Data policies, ER models, data standards documents	A running, secure, well-tuned production database

Exam takeaway: Think of the DA as defining what the organization's data should look like and mean, and the DBA as making sure the actual database software that stores it runs securely, efficiently, and recoverably.