Weather Forecast API with In-Memory Caching

This repository demonstrates a simple implementation of an ASP.NET Core Web API that fetches weather data from an external API and caches it using in-memory caching for improved performance.

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Features

• Weather Data Fetching: Retrieves current weather data for a given city code using an external weather API.
• In-Memory Caching: Stores weather data temporarily in memory to reduce redundant API calls and improve performance.
• Automatic Expiration: Cache entries expire after 2 minutes, ensuring data freshness.

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How It Works

1. Caching Mechanism:
   When a request is made with a cityCode, the controller checks if the weather data for that city is already in the cache.

   • If cached data is found, it returns the cached response.
   • If cached data is not found, it fetches fresh data from the weather API, caches it, and then returns the response.

2. External API Integration:
   The application uses the WeatherAPI to fetch current weather information.

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API Endpoint

GET /WeatherForecast

Fetches the weather data for a specified city code.

Query Parameters

• cityCode (required): The city zip code (US) to fetch the weather data for.
  Example: GET /WeatherForecast?cityCode=10012

Response

• If data is found in the cache: Returns the cached weather data.
• If data is not in the cache: Fetches and returns fresh weather data.

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Technologies Used

• ASP.NET Core: Framework for building web APIs.
• IMemoryCache: In-memory caching for optimized data retrieval.
• HttpClient: To make HTTP requests to the external weather API.

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Setup and Running the Project

Prerequisites

• .NET 6 or later installed.
• An API key from WeatherAPI (replace f7d132db2ce54be49ee81138241811 in the code with your API key).

Steps

1. Clone the repository:

2. Replace the placeholder API key in WeatherForecastController with your API key:

   var response = await _httpClient.GetStringAsync($"https://api.weatherapi.com/v1/current.json?q={cityCode}&key=YOUR_API_KEY");

3. Run the project:

   dotnet run

4. Test the endpoint using a tool like Postman or cURL:

   curl "http://localhost:5000/WeatherForecast?cityCode=10012"

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Example Usage

1. First Request:
   Sends a request for weather data for a city code (e.g., London).

   • Result: Fetches fresh data from the external API and caches it.

2. Subsequent Request:
   Sends another request for the same city code within 2 minutes.

   • Result: Returns the cached data.

3. After Cache Expiration:
   Sends a request for the same city code after 2 minutes.

   • Result: Fetches fresh data from the external API again.

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Notes

• The caching duration is currently set to 2 minutes. You can adjust this in the TimeSpan.FromMinutes(2) line in the WeatherForecastController.
• This implementation uses in-memory caching, which is not shared across multiple instances of the application. For distributed scenarios, consider using a distributed cache like Redis.

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Future Improvements

• Distributed Caching: Replace in-memory cache with Redis or another distributed cache for scalability in multi-server environments.
• Enhanced Error Handling: Add proper error handling for external API failures or invalid inputs.
• Logging: Add structured logging for better debugging and monitoring.

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Feel free to contribute by creating issues or submitting pull requests! 🎉