Aqueduct Middleware
Aqueduct Middleware[edit]
Aqueduct Middleware is a key component in the Aqueduct framework for Dart. It provides a modular and flexible way to modify and enhance the request-response lifecycle of an Aqueduct application. Middleware functions as a pipeline, where each piece of middleware has the ability to process requests and responses, as well as modify or halt their flow.
Key Features[edit]
Key features of Aqueduct Middleware include:
- **Pipeline Execution**: Middleware executes in a specified order, allowing for sequential processing of requests and responses.
- **Request Processing**: Middleware can intercept and process incoming requests, allowing for request modifications or enhancements.
- **Response Processing**: Middleware can modify the outgoing response before sending it back to the client.
- **Error Handling**: Middleware can handle and catch errors thrown during request processing, providing custom error responses when needed.
Modular and Reusable Middleware[edit]
Aqueduct Middleware is designed to be modular and reusable. Developers can create their own custom middleware by implementing the Middleware class and overriding the necessary methods. This allows for fine-grained control over the request-response lifecycle.
Additionally, Aqueduct provides a set of built-in middleware components to handle common tasks, such as:
- **Logging Middleware**: Logs detailed information about requests and responses, aiding in debugging and monitoring.
- **Security Middleware**: Adds security-related enhancements, such as enforcing authentication and authorization rules.
- **CORS Middleware**: Enables Cross-Origin Resource Sharing (CORS) for handling requests from different origins.
- **Compression Middleware**: Compresses response data to optimize network performance.
Example Usage[edit]
Below is an example of how Aqueduct Middleware can be used in an Aqueduct application:
```dart import 'package:aqueduct/aqueduct.dart';
class CustomMiddleware extends Middleware {
@override
Future<void> handle(Request request) async {
// Pre-processing logic
// ...
await next.handle(request);
// Post-processing logic // ... }
}
class MyController extends ResourceController {
@Operation.get()
Future<Response> getResource() async {
return Response.ok('Hello, world!');
}
}
void main() async {
final app = Application<MyController>() ..pipeline.addMiddleware(CustomMiddleware()) ..initialize();
await app.start(numberOfInstances: 2);
} ```
In the example above, a custom middleware `CustomMiddleware` is created by extending the `Middleware` class. It defines custom pre-processing and post-processing logic. The middleware is then added to the application's pipeline using the `addMiddleware` method.
The `MyController` class represents a RESTful resource controller that handles HTTP GET requests. When the controller's `getResource` method is invoked, it returns a simple "Hello, world!" response.
By running the application and navigating to the corresponding URL, the request flows through the custom middleware before reaching the resource controller. The middleware can process the request, modify it if needed, and perform any necessary post-processing actions.
Conclusion[edit]
Aqueduct Middleware is a powerful tool that allows developers to modify and enhance the request-response lifecycle in Aqueduct applications. With its modular and reusable nature, developers can create custom middleware or utilize built-in middleware components to handle various tasks such as logging, security, CORS, and response compression.
By properly utilizing middleware, Aqueduct applications can be customized and extended to meet specific requirements, enabling developers to create robust and scalable server-side applications using Dart.