* take advantage of the {@linkplain Futures utilities built atop the class}. The way that you will
 * create {@code ListenableFuture} instances depends on how you currently create {@code Future}
 * instances:
 *
 * <ul>
 *   <li>If you receive them from an {@code java.util.concurrent.ExecutorService}, convert that

        Assume.assumeTrue(getContext().getConfig().getResolveOrder().contains(ResolverType.RESOLVER_DNS));
        long start = System.currentTimeMillis() / 1000 * 1000;
        // this is not too great as it depends on timing/clockskew
        // first we need to obtain a ticket, therefor need valid credentials
        // then we need to wait until the ticket is expired
        int wait = 10 * 1000;

      TestByteSource okSource = new TestByteSource(bytes);
      assertThrows(IOException.class, () -> okSource.copyTo(new TestByteSink(option)));
      // ensure stream was closed IF it was opened (depends on implementation whether or not it's
      // opened at all if sink.newOutputStream() throws).
      assertTrue(
          "stream not closed when copying to sink with option: " + option,

複数のメッセージを送信（および受信）できます。

<img src="/img/tutorial/websockets/image04.png">

そして、これらの通信はすべて同じWebSocket接続を使用します。

## 依存関係

WebSocketエンドポイントでは、`fastapi` から以下をインポートして使用できます。

* `Depends`
* `Security`
* `Cookie`
* `Header`
* `Path`
* `Query`

これらは、他のFastAPI エンドポイント/*path operation* の場合と同じように機能します。

```Python hl_lines="58-65  68-83"
{!../../docs_src/websockets/tutorial002.py!}

        )
      },
      construct = {
        Validity(
          notBefore = it[0] as Long,
          notAfter = it[1] as Long,
        )
      },
    )

  /** The type of the parameters depends on the algorithm that precedes it. */
  private val algorithmParameters: DerAdapter<Any?> =
    Adapters.usingTypeHint { typeHint ->
      when (typeHint) {

 * elements, including {@code null}, are permitted.
 *
 * <p>{@code contains(x)}, {@code add(x)} and {@code remove(x)}, are all (expected and amortized)
 * constant time operations. Expected in the hashtable sense (depends on the hash function doing a
 * good job of distributing the elements to the buckets to a distribution not far from uniform), and
 * amortized since some operations can trigger a hash table resize.
 *

      TestCharSource okSource = new TestCharSource(STRING);
      assertThrows(IOException.class, () -> okSource.copyTo(new TestCharSink(option)));
      // ensure reader was closed IF it was opened (depends on implementation whether or not it's
      // opened at all if sink.newWriter() throws).
      assertTrue(
          "stream not closed when copying to sink with option: " + option,

    .connectionSpecs(Collections.singletonList(spec))
    .build();
```

### Debugging TLS Handshake Failures

The TLS handshake requires clients and servers to share a common TLS version and cipher suite. This
depends on the JVM or Android version, OkHttp version, and web server configuration. If there is no
common cipher suite and TLS version, your call will fail like this:

```

      TestCharSource okSource = new TestCharSource(STRING);
      assertThrows(IOException.class, () -> okSource.copyTo(new TestCharSink(option)));
      // ensure reader was closed IF it was opened (depends on implementation whether or not it's
      // opened at all if sink.newWriter() throws).
      assertTrue(
          "stream not closed when copying to sink with option: " + option,

 * supported. The elements can be any objects.
 *
 * <p>{@code contains(x)}, {@code add(x)} and {@code remove(x)}, are all (expected and amortized)
 * constant time operations. Expected in the hashtable sense (depends on the hash function doing a
 * good job of distributing the elements to the buckets to a distribution not far from uniform), and
 * amortized since some operations can trigger a hash table resize.
 *