# Server-Sent Events (SSE) { #server-sent-events-sse }

**Server-Sent Events** (SSE) を使うと、クライアントへデータをストリーミングできます。

これは[JSON Lines のストリーミング](stream-json-lines.md)に似ていますが、`text/event-stream` フォーマットを使用します。これはブラウザがネイティブに [`EventSource` API](https://developer.mozilla.org/en-US/docs/Web/API/EventSource) でサポートしています。

/// info | 情報

FastAPI 0.135.0 で追加されました。

///

## Server-Sent Events とは { #what-are-server-sent-events }

*   Grappler:
    *   Disable default Grappler optimization timeout to make the optimization
        pipeline deterministic. This may lead to increased model loading time,
        because time spent in graph optimizations is now unbounded (was 20
        minutes).
*   Deterministic Op Functionality (enabled by setting `TF_DETERMINISTIC_OPS` to
    `"true"` or `"1"`):
    *   Add a deterministic GPU implementation of

     */
    int NTLMSSP_NEGOTIATE_ALWAYS_SIGN = 0x00008000;

    /**
     * Sent by the server in the Type 2 message to indicate that the
     * target authentication realm is a domain.
     */
    int NTLMSSP_TARGET_TYPE_DOMAIN = 0x00010000;

    /**
     * Sent by the server in the Type 2 message to indicate that the
     * target authentication realm is a server.
     */

{* ../../docs_src/stream_json_lines/tutorial001_py310.py ln[33:36] hl[34] *}

## Server-Sent Events (SSE) { #server-sent-events-sse }

    return v


class ServerSentEvent(BaseModel):
    """Represents a single Server-Sent Event.

    When `yield`ed from a *path operation function* that uses
    `response_class=EventSourceResponse`, each `ServerSentEvent` is encoded
    into the [SSE wire format](https://html.spec.whatwg.org/multipage/server-sent-events.html#parsing-an-event-stream)
    (`text/event-stream`).

OkHttp Server-Sent Events
=========================

Experimental support for server-sent events.
API is not considered stable and may change at any time.

### Download

```kotlin
testImplementation("com.squareup.okhttp3:okhttp-sse:5.3.0")

    client.webSocket!!.finishReader()
    taskFaker.runTasks()
    assertThat(client.closed).isTrue()
    client.listener.assertFailure(
      ProtocolException::class.java,
      "Server-sent frames must not be masked.",
    )
    server.listener.assertClosing(1000, "Hello")
    server.listener.assertExhausted() // Client should not have sent second close.
  }

  @Test

    Note over client,operation: Response is already sent, can't change it anymore
    opt Tasks
        operation -->> tasks: Send background tasks
    end
    opt Raise other exception
        tasks -->> tasks: Handle exceptions in the background task code
    end
```

/// info

async def create_file(file: Annotated[bytes | None, File()] = None):
    if not file:
        return {"message": "No file sent"}
    else:
        return {"file_size": len(file)}


@app.post("/uploadfile/")
async def create_upload_file(file: UploadFile | None = None):
    if not file:
        return {"message": "No upload file sent"}
    else:

     *
     * @param primary true if primary
     */
    public void setPrimary(boolean primary) {
        this.isPrimary = primary;
    }

    /**
     * Get number of bytes sent
     *
     * @return bytes sent
     */
    public long getBytesSent() {
        return bytesSent.get();
    }

    /**
     * Get number of bytes received
     *
     * @return bytes received
     */