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# Azure API Management

## Overview

Azure API Management is a hybrid and multicloud platform designed to manage APIs across various environments, including Azure, other clouds, and on-premises. Key features include API gateway deployment, security and compliance measures, developer portals, and tools for transforming legacy services into modern APIs. It supports authentication, authorization, usage limits, and monitoring. Azure API Management accelerates business growth by enabling API-first approaches, improving API discoverability, and ensuring comprehensive security and compliance. Flexible pricing options are available to suit different needs.

## Key Features

- **API Gateway Deployment**: Deploy API gateways to manage API traffic.
- **Security and Compliance**: Implement robust security and compliance measures.
- **Developer Portals**: Offer developer portals for API documentation and usage.
- **Legacy Service Transformation**: Tools to convert legacy services into modern APIs.
- **Authentication and Authorization**: Support for various authentication and authorization methods.
- **Usage Limits**: Define and enforce usage limits for APIs.
- **Monitoring and Analytics**: Monitor API usage and performance with built-in analytics.

## Use Cases

- **API Gateway**: Centralized management of API traffic and policies.
- **Security**: Protect APIs with advanced security features.
- **Developer Collaboration**: Enhance collaboration with developer portals.
- **Legacy Modernization**: Transform legacy services into modern APIs.
- **Policy Enforcement**: Implement and enforce API policies.
- **Analytics**: Gain insights into API usage and performance.

## Getting Started

### Prerequisites

- An active Azure subscription.

### Steps to Get Started

1. **Create an API Management Instance**
    - Navigate to the Azure portal.
    - Select "Create a resource" and search for "API Management".
    - Click "Create" and fill in the necessary details (like name, resource group, and pricing tier).
    - Click "Review + create" and then "Create".

2. **Add an API**
    - In the API Management service instance, navigate to the "APIs" section.
    - Click "+ Add API" and select from various options such as OpenAPI, GraphQL, or WebSocket.
    - Provide the necessary details like API name, description, and URL.
    - Click "Create".

3. **Configure Policies**
    - Select the created API and navigate to the "Design" tab.
    - Click on the "Inbound processing" section and add policies like rate limiting, IP filtering, etc.
    - Save the changes.

4. **Deploy API Gateway**
    - Navigate to the "Gateways" section.
    - Click "+ Add" to create a new gateway.
    - Provide a name for the gateway and select the APIs you want to deploy.
    - Click "Create".

5. **Enable Developer Portal**
    - Navigate to the "Developer portal" section.
    - Click "Publish" to make the portal accessible to developers.
    - Customize the portal with branding and documentation.

6. **Monitor and Analyze**
    - Navigate to the "Analytics" section.
    - Monitor API usage, performance, and errors.
    - Set up alerts and notifications as needed.

### Sample API Policy Configuration

Below is an example of a rate-limiting policy configuration:

```xml
<inbound>
    <rate-limit calls="10" renewal-period="60" />
</inbound>
```

### Sample C# Code for Calling an API

```csharp
using System;
using System.Net.Http;
using System.Threading.Tasks;

namespace APICallExample
{
    class Program
    {
        private static readonly HttpClient client = new HttpClient();

        static async Task Main(string[] args)
        {
            client.DefaultRequestHeaders.Add("Ocp-Apim-Subscription-Key", "your_subscription_key");

            HttpResponseMessage response = await client.GetAsync("https://yourapi.azure-api.net/endpoint");
            response.EnsureSuccessStatusCode();

            string responseBody = await response.Content.ReadAsStringAsync();
            Console.WriteLine(responseBody);
        }
    }
}
```

### Mermaid Diagram: API Management Workflow

:::mermaid
graph TD;
    A["Create API Management Instance"] --> B["Add API"];
    B --> C["Configure Policies"];
    C --> D["Deploy API Gateway"];
    D --> E["Enable Developer Portal"];
    E --> F["Monitor and Analyze"];
:::

## Conclusion

Azure API Management provides a comprehensive platform for managing APIs across various environments. By following the steps outlined above, you can quickly get started with creating, securing, and monitoring your APIs. The platform's robust features and flexibility make it an excellent choice for businesses looking to implement an API-first approach.