{* ../../docs_src/server_sent_events/tutorial005_py310.py hl[14] *}

## 技术细节 { #technical-details }

FastAPI 开箱即用地实现了一些 SSE 的最佳实践。

- 当 15 秒内没有任何消息时，发送一个**保活 `ping` 注释**，以防某些代理关闭连接，正如 [HTML 规范：Server-Sent Events](https://html.spec.whatwg.org/multipage/server-sent-events.html#authoring-notes) 中建议的那样。
- 设置 `Cache-Control: no-cache` 响应头，**防止缓存**流。

        this.flags2 = fl;
    }

    /**
     * Adds flags to the flags2 field using bitwise OR
     * @param fl flags to add
     */
    public final void addFlags2(final int fl) {
        this.flags2 |= fl;
    }

    /**
     * Removes flags from the flags2 field using bitwise AND NOT
     * @param fl flags to remove
     */
    public final void remFlags2(final int fl) {

        request.flags2 |= flags2;
        request.useUnicode = useUnicode;
        request.response = response; /* needed by sign */
        if (request.digest == null) {
            request.digest = digest; /* for sign called in encode */
        }

        try {
            if (response == null) {
                doSend0(request);
                return;
            }

	}
	if n != len(p) {
		err = io.ErrShortWrite
		b.closeWithErr(err)
	}
	return n, err
}

func (b *streamingBitrotWriter) Close() error {
	// Close the underlying writer.
	// This will also flush the ring buffer if used.
	err := b.iow.Close()

	// Wait for all data to be written before returning else it causes race conditions.
	// Race condition is because of io.PipeWriter implementation. i.e consider the following

   *       the same.
   *   <li>The special characters ".", "-", "*", and "_" remain the same.
   *   <li>The space character " " is converted into a plus sign "+".
   *   <li>All other characters are converted into one or more bytes using UTF-8 encoding and each
   *       byte is then represented by the 3-character string "%XY", where "XY" is the two-digit,
   *       uppercase, hexadecimal representation of the byte value.

Das kann nützlich sein, wenn Sie beispielsweise in einem Land leben, in dem bestimmte URLs eingeschränkt sind.

### Die automatische Dokumentation deaktivieren { #disable-the-automatic-docs }

Der erste Schritt besteht darin, die automatische Dokumentation zu deaktivieren, da sie standardmäßig das Standard-CDN verwendet.

{* ../../docs_src/server_sent_events/tutorial005_py310.py hl[14] *}

## 技術詳細 { #technical-details }

FastAPI は SSE のいくつかのベストプラクティスを標準で実装しています。

- メッセージがない場合は 15 秒ごとに「キープアライブ」用の `ping` コメントを送信し、一部のプロキシが接続を閉じるのを防ぎます（[HTML 仕様: Server-Sent Events](https://html.spec.whatwg.org/multipage/server-sent-events.html#authoring-notes) の推奨に従います）。
- ストリームの**キャッシュを防止**するため、`Cache-Control: no-cache` ヘッダーを設定します。

  public static @Nullable Long tryParse(String string) {
    return tryParse(string, 10);
  }

  /**
   * Parses the specified string as a signed long value using the specified radix. The ASCII
   * character {@code '-'} (<code>'&#92;u002D'</code>) is recognized as the minus sign.
   *
   * <p>Unlike {@link Long#parseLong(String, int)}, this method returns {@code null} instead of

### Existing properties in existing classes

}

// UnaryTerm represents a single negated term or a primary term
type UnaryTerm struct {
	Negated *NegatedTerm `parser:"  @@"`
	Primary *PrimaryTerm `parser:"| @@"`
}

// NegatedTerm has a leading minus sign.
type NegatedTerm struct {
	Term *PrimaryTerm `parser:"\"-\" @@"`
}

// PrimaryTerm represents a Value, Path expression, a Sub-expression
// or a function call.
type PrimaryTerm struct {