OpenFeign/feign
Feign
Feign is a declarative Java HTTP client framework that maps method signatures to REST API requests. It functions as an HTTP interface mapper, allowing the creation of type-safe clients by defining service interfaces with annotations to eliminate manual request logic.
The framework features a pluggable HTTP transport layer, which decouples request definition from execution by routing network traffic through interchangeable underlying HTTP engines.
It provides a comprehensive request management pipeline including interceptors for modifying headers, policy-driven retry logic for failure recovery, and strategy-based encoders and decoders to transform request objects and response bodies. The toolset also includes capabilities for asynchronous request execution, traffic logging, and client metrics collection.
Features
- HTTP Clients - Provides a declarative framework for creating type-safe HTTP clients to execute network requests and manage connectivity.
- REST Clients - Functions as a declarative REST client that maps Java interfaces directly to HTTP requests.
- REST API Integration Frameworks - Maps Java method signatures to RESTful endpoints to simplify sending requests and decoding responses.
- Pluggable Transport Layers - Decouples request definition from execution by providing a modular interface to swap the underlying network transport implementation.
- HTTP Interface Mappers - Converts interface method calls into HTTP requests and decodes responses back into Java objects.
- Declarative API Clients - Implements a declarative style for defining network endpoints and mapping method signatures to REST API requests via annotations.
- Dynamic Proxies - Generates client implementations at runtime using Java dynamic proxies to map interface calls to HTTP requests.
- HTTP Request Interceptors - Provides request lifecycle hooks to modify outgoing requests for authentication tokens or tracing headers.
- Transport Engine Integrations - Decouples request definition from execution by allowing requests to be routed through interchangeable HTTP transport engines.
- Request Interceptors - Implements a chain of pluggable handlers to modify outgoing requests and incoming responses for cross-cutting concerns.
- Request Mappings - Translates method signatures and annotations into HTTP request templates including URI paths and headers.
- Type-Safe API Clients - Enables the creation of type-safe API clients through declarative interfaces, eliminating manual request logic.
- Request Retries - Triggers automatic request retries on network failures or specific exceptions based on a configurable retry policy.
- Microservices Communications - Facilitates communication between distributed Java microservices with built-in support for retries and request interceptors.
- HTTP Request Customization - Provides mechanisms to intercept and customize HTTP request headers and metadata globally or per target.
- HTTP Response Processors - Provides utilities to parse and transform raw HTTP responses into type-safe objects, strings, or streams.
- Request Header Configuration - Offers mechanisms to set static or dynamic HTTP headers using annotations or interceptors.
- Asynchronous Request Execution - Allows API calls to return future-based instances for non-blocking execution of HTTP requests.
- API Error Handling Patterns - Handles non-success HTTP responses by wrapping failures into exceptions or triggering recovery actions.
- Data Encoders and Decoders - Converts request objects to payloads and response bodies to type-safe objects using swappable encoder and decoder implementations.
- Retry Policies - Governs request repetition on failure through configurable mechanisms that determine retries based on exception types.
- Response Body Decoders - Provides a pluggable system to transform text-based HTTP responses into typed Java objects.
- Form Data Support - Supports encoding request bodies as url-encoded or multipart form data to handle files and custom objects.
- Request Body Handling - Implements a process to serialize Java objects into HTTP request payloads using pluggable encoders.
- Request Parameter Parsers - Resolves URI templates and query strings using annotated method parameters and expression patterns.
- HTTP Clients - Declarative HTTP client binder for RESTful services.
