# 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/5.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/5.x/okhttp/okhttp3/-response/)

object WebSocketProtocol {
  /** Magic value which must be appended to the key in a response header. */
  internal const val ACCEPT_MAGIC = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"

  /*
  Each frame starts with two bytes of data.

   0 1 2 3 4 5 6 7    0 1 2 3 4 5 6 7
  +-+-+-+-+-------+  +-+-------------+
  |F|R|R|R| OP    |  |M| LENGTH      |
  |I|S|S|S| CODE  |  |A|             |

    }
    Object result;
    try {
      result = supplier.get();
    } catch (Throwable t) {
      if (predicate.apply(t)) {
        // We are careful to set up INSTANCE_OF to match each Predicate to its target Class.
        @SuppressWarnings("unchecked")
        T caught = (T) t;
        return caught;
      }
      throw new AssertionError(

  abstract int distinctElements();

  // Object methods

  /**
   * {@inheritDoc}
   *
   * <p>This implementation returns {@code true} if {@code object} is a multiset of the same size
   * and if, for each element, the two multisets have the same count.
   */
  @Override
  public final boolean equals(@Nullable Object object) {
    return Multisets.equalsImpl(this, object);
  }

  /**
   * {@inheritDoc}

   * "plain {@code T}." This API provides that.
   */
  @SuppressWarnings({"nullness", "TypeParameterUnusedInFormals", "ReturnMissingNullable"})
  // The warnings are legitimate. Each time we use this method, we document why.
  @ParametricNullness
  static <T extends @Nullable Object> T uncheckedNull() {
    return null;
  }

  private NullnessCasts() {}

    }
    Object result;
    try {
      result = supplier.get();
    } catch (Throwable t) {
      if (predicate.apply(t)) {
        // We are careful to set up INSTANCE_OF to match each Predicate to its target Class.
        @SuppressWarnings("unchecked")
        T caught = (T) t;
        return caught;
      }
      throw new AssertionError(

  }

  static ListFrobber nop() {
    return new ListFrobber() {
      @Override
      public void perform(List<Integer> list) {}
    };
  }

  /** A list that mutates itself after every call to each of its {@link List} methods. */
  interface ConcurrentlyMutatedList<E> extends List<E> {
    /**
     * The elements of a {@link ConcurrentlyMutatedList} are added and removed over time. This

   * java.util.Collection} specified in the {@link Map} interface.
   */
  @Override
  Set<V> values();

  /**
   * Returns the inverse view of this bimap, which maps each of this bimap's values to its
   * associated key. The two bimaps are backed by the same data; any changes to one will appear in
   * the other.
   *

        HashSet<RemoteRepository> set = new HashSet<>(repositories);
        if (repositories.size() != set.size()) {
            throw new IllegalArgumentException(
                    "Repository list contains duplicate entries. Each repository must be unique based on its ID and URL. "
                            + "Found " + repositories.size() + " repositories but only " + set.size()
                            + " unique entries.");
        }

///

## Abkürzung zur Erinnerung an die Namen { #shortcut-to-remember-the-names }

Lassen Sie uns das vorherige Beispiel noch einmal anschauen:

{* ../../docs_src/response_status_code/tutorial001_py310.py hl[6] *}

`201` ist der Statuscode für „Created“ („Erzeugt“).

Aber Sie müssen sich nicht merken, was jeder dieser Codes bedeutet.