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

You can stream data to the client using **Server-Sent Events** (SSE).

This is similar to [Stream JSON Lines](stream-json-lines.md), but uses the `text/event-stream` format, which is supported natively by browsers with the [`EventSource` API](https://developer.mozilla.org/en-US/docs/Web/API/EventSource).

/// info

Added in FastAPI 0.135.0.

///

    val client =
      OkHttpClient
        .Builder()
        .sslSocketFactory(sslContext.socketFactory, trustManager)
        .build()

    // An example test URL that returns client certificate details.
    val request =
      Request
        .Builder()
        .url("https://prod.idrix.eu/secure/")
        .build()

    client.newCall(request).execute().use { response ->

  val clientTestRule = OkHttpClientTestRule()

  private var client = clientTestRule.newClientBuilder().build()

  @StartStop
  private val server = MockWebServer()

  val request by lazy { Request(server.url("/")) }

  @Test
  fun suspendCall() {
    runTest {
      server.enqueue(MockResponse(body = "abc"))

      val call = client.newCall(request)

      call.executeAsync().use {

    return result


@app.get("/", dependencies=[Depends(parent_dep)])
async def get_main():
    return {"msg": "Hello World"}


client = TestClient(app)


def test_dependency_set_status_code():
    response = client.get("/")
    assert response.status_code == 201, response.text

        return "test"


@needs_py310
def test_stringified_annotations():
    app = FastAPI()

    client = TestClient(app)

    @app.get("/test/")
    def call(test: Annotated[str, Depends(Dep())]):
        return {"test": test}

    response = client.get("/test")

import javax.net.ssl.TrustManagerFactory
import javax.net.ssl.X509TrustManager
import okhttp3.HttpUrl.Companion.toHttpUrl
import okhttp3.OkHttpClient
import okhttp3.Request
import org.junit.jupiter.api.Test
import org.mockserver.client.MockServerClient
import org.mockserver.configuration.Configuration
import org.mockserver.logging.MockServerLogger
import org.mockserver.model.HttpRequest.request
import org.mockserver.model.HttpResponse.response

    }

    /**
     * Creates a new witness client with a custom RPC client (for testing).
     *
     * @param witnessServer the witness server address
     * @param context the CIFS context
     * @param rpcClient the RPC client to use
     */
    protected WitnessClient(InetAddress witnessServer, CIFSContext context, WitnessRpcClient rpcClient) {

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

Sie können Daten mithilfe von **Server-Sent Events** (SSE) an den Client streamen.

Das ist ähnlich wie [JSON Lines streamen](stream-json-lines.md), verwendet aber das Format `text/event-stream`, das von Browsern nativ mit der [die `EventSource`-API](https://developer.mozilla.org/en-US/docs/Web/API/EventSource) unterstützt wird.

/// info | Info

Hinzugefügt in FastAPI 0.135.0.

///

     * Constructs a ValidateNegotiateInfo request
     *
     * @param capabilities
     *            the client capabilities flags
     * @param clientGuid
     *            the client GUID
     * @param securityMode
     *            the security mode flags
     * @param dialects
     *            the SMB dialects supported by the client
     */

async def create_message(input_message: str) -> Message:
    return Message(
        input=input_message,
        output=MessageOutput(body=f"Processed: {input_message}"),
    )


client = TestClient(app)


def test_create_message():
    response = client.post("/messages", params={"input_message": "Hello"})
    assert response.status_code == 200, response.text
    assert response.json() == {
        "input": "Hello",