References

Assorted reference information

• References
  • Symantic Versioning
  • Express
    • Definitions
    • Express Middleware
  • HTTP Methods
  • Model - View - Controller (MVC) Pattern
  • Array Methods
  • API Terms
    • Definition
    • Endpoint
    • HTTP API Methods
    • Request
    • Response
    • Status Codes
    • Authentication
    • Parameters
    • Headers
    • Authorisation
    • Rate Limiting
    • API Key
    • JSON
    • Webhook
    • oAuth

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Symantic Versioning

Uses 3 numbers, seperated by a period. e.g. 1.2.4

Breaking changes . New features . Bug fixes

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Express

Definitions

• Express JS is used to handle HTTP logic
• Express middleware is a function which runs between the request and response.
• Express-Validators validates routes according to business rules
• EJS is a templating engine for injecting data into View files

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Express Middleware

• Express.json(): (Built-in) Parses incoming requests with JSON payloads
• Express.urlencoded(): (Built-in) Parses incoming requests with URL-encoded payloads
• Express.static(): (Built-in) Serves static files
• Morgan: HTTP request logger
• Cors: Enables cross-origin resource sharing
• Helmet: Secdures express apps by setting HTTP headers

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HTTP Methods

Method	Code	Purpose
GET	200	Fetch data
POST	201	Create data
PUT	200	Update record
PATCH	204	Update partial record
DELETE	204	Deleted record
ERROR	400	Bad request
ERROR	500	Signifies server error

Examples

Code	Implementation
200	Get record or record
200	Full record updated
201	Record added
202	Request received for processing, but not completed
204	Partial record update completed (No content returned)
204	Record deleted (No content returned)
206	Partial content
300	Redirect
400	Rejected API call - missing required header
401	Unauthorised request
403	Forbidden
404	Record not found
408	Request timeout
409	Rejected API call - Operation in progress
422	Rejected API call - Invalid header/data sent
500	Internal server error
503	Service / Server unavailable (e.g maintenance)

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Model - View - Controller (MVC) Pattern

Can be server, client, or both.

Model

Data that is required to populate a page or control (partial)

View

The page, or partial page, which will display the information. (Often EJS)

Controller

Needed to render model data to a view, or partial. Which handles any API calls for CRUD or to external sites, and for managing any dynamic functionality on the web page.

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Array Methods

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API Terms

Definition

• Enables communications between software systems
• Defines structured rules for integration

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Endpoint

• Represents specific API functionality path
• Unique URL for accessing resources

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HTTP API Methods

• Enable standardised CRUD operation handling
• Define action performed on resources

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Request

• Client sends structured data payload
• Includes headers, parameters, and body

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Response

• Server returns processed result data
• Contains status code, and payload

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Status Codes

• Indicate outcome of API request
• Help identify errors and success

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Authentication

• Verifies identity of requesting entity
• Uses token keys or credentials

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Parameters

• Transfers additional data within requests
• Support filtering, sorting, and pagination

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Headers

• Carry metadata about HTTP requests
• Specify content type and authorisation

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Authorisation

• Determines user access permission levels
• Enforces role-based access control (RBAC)

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Rate Limiting

• Restricts the number of allowed requests
• Prevents abuse and server overload

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API Key

• Unique identifier for client access
• Used for simple authentication mechanisms

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JSON

• Lightweight structured data exchange format
• Commonly used in REST APIs

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Webhook

• Sends automated event triggered callbacks to a URL
• Enables real-time system updates

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oAuth

• Secure delegated access authorisation framework
• Issues tokens for controlled access

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