# Calls

The HTTP client’s job is to accept your request and produce its response. This is simple in theory but it gets tricky in practice.

## [Requests](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-request/)

Each HTTP request contains a URL, a method (like `GET` or `POST`), and a list of headers. Requests may also contain a body: a data stream of a specific content type.

## [Responses](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-response/)

          A result(Collector<T, A, R> collector, Iterable<T> inputs) {
        A accum = collector.supplier().get();
        for (T input : inputs) {
          collector.accumulator().accept(accum, input);
        }
        return accum;
      }
    },
    /** Get one accumulator for each element and merge the accumulators left-to-right. */
    MERGE_LEFT_ASSOCIATIVE {
      @Override

OkHttp Zstandard (zstd) Integration
===================================

This module enables [Zstandard (zstd)][1] response compression in addition to Gzip, as long as
the `Accept-Encoding` header is not otherwise set. Web servers must be configured to return zstd
responses.

Note that zstd is not used for sending requests.

```java
OkHttpClient client = new OkHttpClient.Builder()
  .addInterceptor(ZstdInterceptor.INSTANCE)
  .build();
```

import okhttp3.Gzip
import okio.BufferedSource
import okio.Source
import okio.source
import org.brotli.dec.BrotliInputStream

/**
 * Transparent Brotli response support.
 *
 * Adds Accept-Encoding: br to request and checks (and strips) for Content-Encoding: br in
 * responses.  n.b. this replaces the transparent gzip compression in BridgeInterceptor.
 */
object BrotliInterceptor : CompressionInterceptor(Brotli, Gzip)

     * GET
     * 2
     * Accept-Language: fr-CA
     * Accept-Charset: UTF-8
     * HTTP/1.1 200 OK
     * 3
     * Content-Type: image/png
     * Content-Length: 100
     * Cache-Control: max-age=600
     * ```
     *
     * A typical HTTPS file looks like this:
     *
     * ```
     * https://google.com/foo
     * GET
     * 2
     * Accept-Language: fr-CA
     * Accept-Charset: UTF-8

 * introduced in Unicode 3.1. One implication of this is that it rejects <a
 * href="http://www.unicode.org/versions/corrigendum1.html">"non-shortest form"</a> byte sequences,
 * even though the JDK decoder may accept them.
 *
 * @author Martin Buchholz
 * @author Clément Roux
 * @since 16.0
 */
@GwtCompatible
public final class Utf8 {
  /**

    AtomicInteger deliveries = new AtomicInteger();
    EventBus bus = new EventBus();
    bus.register(
        new Object() {
          @Subscribe
          public void accept(String str) {
            holder.set(str);
            deliveries.incrementAndGet();
          }
        });

    String EVENT = "Hello!";
    bus.post(EVENT);

User-Agent: OkHttp Example
Host: publicobject.com
Connection: Keep-Alive
Accept-Encoding: gzip

INFO: Received response for https://publicobject.com/helloworld.txt in 80.9ms
Server: nginx/1.4.6 (Ubuntu)
Content-Type: text/plain
Content-Length: 1759
Connection: keep-alive
```

    @Test
    public void testHeaderMethod() {
        CurlRequest request = new CurlRequest(Method.GET, "https://example.com");

        CurlRequest result = request.header("Content-Type", "application/json").header("Accept", "application/json");

        assertSame(request, result); // Fluent API
    }

    @Test
    public void testThreadPoolMethod() {

        // The network request has everything: User-Agent, Host, Accept-Encoding.
        val networkRequest = chain.request()
        assertThat(networkRequest.header("User-Agent")).isNotNull()
        assertThat(networkRequest.header("Host")).isEqualTo(
          server.hostName + ":" + server.port,
        )
        assertThat(networkRequest.header("Accept-Encoding")).isNotNull()