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--- title: Using Server-sent events with Application Gateway description: This article provides guidance for using Server-sent events with your Azure Application Gateway. services: application-gateway author: jaesoni ms.service: azure-application-gateway ms.topic: concept-article ms.date: 09/15/2025 ms.author: jaysoni # Customer intent: "As a cloud architect, I want to configure Server-sent events on Azure Application Gateway, so that I can enable real-time streaming of event data between backend servers and clients efficiently." --- # Using Server-sent events with Application Gateway Azure Application Gateway offers support for Server-sent events (SSE). This document provides guidelines to ensure the seamless operation of this feature when used with Azure Application Gateway. ## Configuring Application Gateway ### Response Buffer The [Response Buffers on Application Gateway resource](proxy-buffers.md) should be disabled. This configuration enables your application gateway resource to send responses to clients as streams from the backend server are received. ### Backend Setting - Request timeout Ensure that the [Request time-out (seconds) in Backend Settings](configuration-http-settings.md?tabs=backendhttpsettings#request-timeout) is configured to exceed the idle time between events. Otherwise, your application gateway resource terminates the connection prematurely. ## Configuring backend server The backend server should send the following Response headers to ensure proper stream handling by the clients and any intermediaries. Note, these headers aren't a requirement for Application Gateway as a proxy. ### Content-Type: text/event-stream This header notifies the client that the response will be a stream of events, enabling them to correctly handle the Server-sent events (SSE) protocol. ### Connection: keep-alive This header maintains the TCP connection, allowing the backend server to send events to the client continuously. ### Transfer-Encoding: chunked This header allows the server to send responses in chunks without requiring a Content-Length header. It's necessary for streaming responses through SSE when the total size can't be determined in advance. ### Cache-Control: no-cache It's advisable to use this header to prevent intermediaries like CDNs from caching the SSE response. > [!Note] > - The response time recorded in [Access logs](monitor-application-gateway-reference.md#resource-logs) represents the total duration for which the connection was established. Multiple event streams may pass through during this connection period. ## Next steps Learn about [Request and Response Proxy Buffers](proxy-buffers.md) in Application Gateway.