URLShortner Microservice

Overview

The URLShortner microservice provides URL shortening functionality for the Publisher platform. It creates short, unique identifiers for long URLs and provides redirection services, enabling easier sharing and tracking of URLs in marketing campaigns and user communications.

Business Purpose

This service enables the Publisher platform to: - Create shortened URLs for marketing campaigns and email communications - Provide clean, trackable links for analytics and reporting - Reduce URL length for better user experience in SMS and social media - Enable centralized URL management and redirection control

Architecture

Service Type

Deployment: AWS Lambda serverless function
Runtime: Node.js
Database: AWS DynamoDB
Trigger: HTTP API Gateway

Key Components

URLShortner.js: Main Lambda handler for URL operations
URLShortenerModel.js: DynamoDB data model using Dynogels ORM
Configuration: Environment-specific settings

Data Flow

graph TD
    A[HTTP Request] --> B{Request Method}
    B -->|POST| C[Create Short URL]
    B -->|GET| D[Retrieve & Redirect]

    C --> E[Generate URL Key]
    E --> F[Save to DynamoDB]
    F --> G[Return Short URL Key]

    D --> H[Lookup URL Key]
    H --> I[DynamoDB Query]
    I --> J{URL Found?}
    J -->|Yes| K[302 Redirect]
    J -->|No| L[404 Not Found]

Dependencies

External Services

AWS DynamoDB: URL storage and retrieval
AWS API Gateway: HTTP request routing
AWS Lambda: Serverless compute platform

NPM Dependencies

dynogels: DynamoDB ORM for Node.js
idgen: Unique identifier generation
joi: Data validation schema

Configuration

Environment-Specific Configs

config.js: Development configuration
config.int.js: Integration environment
config.prod.js: Production environment

Key Configuration Parameters

ENV: Environment identifier (DEV/INT/PROD)
Region: AWS region (us-east-1)

API Endpoints

POST /

Creates a new shortened URL.

Request Body:

{
  "url": "https://example.com/very/long/url/path"
}

Response (200 OK):

{
  "urlkey": "generated_16_char_key"
}

Error Response (500):

{
  "error": "Error details"
}

GET /{urlkey}

Redirects to the original URL associated with the short key.

Parameters: - urlkey: The 16-character unique identifier

Response (302 Found): - Headers: location: original_url - Body: Empty (redirect)

Error Response (404 Not Found):

URL with url key {urlkey} does not exist

Data Model

DynamoDB Table: URLShortner

Schema: - Hash Key: urlkey (String) - 16-character unique identifier - Attributes: - url (String) - Original long URL

Table Configuration: - Table Name: URLShortner - Primary Key: urlkey (String) - Region: us-east-1

URL Key Generation

Key Properties

Length: 16 characters
Character Set: Alphanumeric (generated by idgen library)
Uniqueness: Statistically unique across all generated keys
Format: Random string (e.g., "a1b2c3d4e5f6g7h8")

Generation Process

Generate 16-character random string using idgen
Store mapping in DynamoDB
Return key to client
No collision detection (relies on statistical uniqueness)

Error Handling

Common Error Scenarios

Invalid HTTP Method: Returns 400 Bad Request
URL Not Found: Returns 404 Not Found for GET requests
DynamoDB Errors: Returns 500 Internal Server Error
Invalid JSON: Parsing errors for POST requests

Error Responses

400: Invalid HTTP method
404: Short URL not found
500: Database or internal server errors

Performance Characteristics

Scalability

Serverless: Automatically scales with AWS Lambda
DynamoDB: Scales based on configured read/write capacity
Stateless: No server-side session management

Latency

Cold Start: Initial Lambda invocation may have higher latency
Warm Requests: Sub-second response times
DynamoDB: Single-digit millisecond read/write operations

Security Considerations

Access Control

No authentication required (public service)
Rate limiting handled by API Gateway
Input validation through Joi schemas

Data Protection

URLs stored in plaintext (no sensitive data encryption)
No personal data collection
Short keys are not predictable

Development

Local Setup

Install dependencies: npm install
Configure AWS credentials
Set up local DynamoDB or use AWS DynamoDB
Run tests using Test.js

Testing

Test.js: Basic functionality testing
Tests both POST (create) and GET (redirect) operations
Manual testing with sample URLs

Deployment

Package as AWS Lambda deployment package
Configure API Gateway endpoints
Set up DynamoDB table with appropriate permissions

Monitoring and Logging

AWS CloudWatch

Lambda execution logs
Error tracking and alerting
Performance metrics (duration, memory usage)

DynamoDB Metrics

Read/write capacity utilization
Throttling events
Error rates

Custom Logging

URL creation events
Redirect access patterns
Error conditions and debugging

This service may integrate with: - Email Marketing Services: Shortened URLs in email campaigns - Analytics Services: Click tracking and reporting - Campaign Management: Marketing campaign URL generation - Social Media Tools: Shortened URLs for social sharing

Troubleshooting

Common Issues

DynamoDB Connection Errors: Check AWS credentials and region configuration
Lambda Timeout: Monitor execution duration and memory allocation
High Error Rates: Check DynamoDB capacity and throttling
Invalid URLs: Validate input URL format and accessibility

Monitoring Points

Lambda invocation count and error rate
DynamoDB read/write operations
API Gateway request/response metrics
URL creation vs. access ratio

Limitations

Current Constraints

No URL expiration mechanism
No analytics or click tracking
No custom short URL aliases
No bulk URL operations
No URL validation beyond basic format

Potential Enhancements

Click analytics and reporting
URL expiration and cleanup
Custom short URL aliases
Bulk URL creation API
URL validation and safety checks
Rate limiting per client
Admin interface for URL management