Retrofit

A type-safe HTTP client for Android and Java. https://square.github.io/retrofit/

Circuit Breaking

Circuit breaking http client calls is based upon the CircuitBreaker instance provided to a CircuitBreakerCallAdaptor.

Java

// Create a CircuitBreaker
private final CircuitBreaker circuitBreaker = CircuitBreaker.ofDefaults("testName");

// Create a retrofit instance with CircuitBreaker call adapter
Retrofit retrofit = new Retrofit.Builder()
                .addCallAdapterFactory(CircuitBreakerCallAdapter.of(circuitBreaker))
                .baseUrl("http://localhost:8080/")
                .build();

// Get an instance of your service with circuit breaking built in.
RetrofitService service = retrofit.create(RetrofitService.class);

Timeouts

To trigger circuit breaking by timeout, the time thresholds should be set on a OkHttpClient instance passed into the Retrofit.Builder.

Java

// Create a CircuitBreaker
private final CircuitBreaker circuitBreaker = CircuitBreaker.ofDefaults("testName");

final long TIMEOUT = 300; // ms
OkHttpClient client = new OkHttpClient.Builder()
        .connectTimeout(TIMEOUT, TimeUnit.MILLISECONDS)
        .readTimeout(TIMEOUT, TimeUnit.MILLISECONDS)
        .writeTimeout(TIMEOUT, TimeUnit.MILLISECONDS)
        .build();

Retrofit retrofit = new Retrofit.Builder()
        .addCallAdapterFactory(CircuitBreakerCallAdapter.of(circuitBreaker))
        .baseUrl("http://localhost:8080/")
        .client(client)
        .build();

Error responses

Java

Retrofit retrofit = new Retrofit.Builder()
        .addCallAdapterFactory(CircuitBreakerCallAdapter.of(circuitBreaker, (r) -> r.code() < 500));
        .baseUrl("http://localhost:8080/")
        .build();

Rate Limiting

Rate limiting of http client calls is based upon the configuration passed to the RateLimiterCallAdaptor.

Java

RateLimiter rateLimiter = RateLimiter.ofDefaults("testName");

Retrofit retrofit = new Retrofit.Builder()
        .addCallAdapterFactory(RateLimiterCallAdapter.of(rateLimiter))
        .baseUrl("http://localhost:8080/")
        .build();

If the number of calls are exceeded within the period defined by the RateLimiter, a HTTP 429 response (too many requests) will be returned.