# sse 4.2.0 Provides client and server functionality for setting up bi-directional communication through Server Sent Events (SSE) and corresponding POST requests. ## Installing ``` export PUB_HOSTED_URL=https://pub.mirror.p-hatan.com flutter pub add sse ``` Published: 2026-04-08T23:21:06.407449Z Expected archive SHA-256: a9a804dbde8bfd369da3b4aa241d44d63a6486a97388c54ec166073d88c52302 Available in cache; verification: upstream_checksum ## Direct dependencies - async: ^2.0.8 - collection: ^1.0.0 - logging: ^1.0.0 - pool: ^1.5.0 - shelf: ^1.1.0 - stream_channel: ^2.0.0 - web: >=0.5.0 <2.0.0 ## Package README (untrusted upstream documentation) [![Build Status](https://github.com/dart-lang/tools/actions/workflows/sse.yaml/badge.svg)](https://github.com/dart-lang/tools/actions/workflows/sse.yaml) [![pub package](https://img.shields.io/pub/v/sse.svg)](https://pub.dev/packages/sse) [![package publisher](https://img.shields.io/pub/publisher/sse.svg)](https://pub.dev/packages/sse/publisher) This package provides support for bi-directional communication through Server Sent Events and corresponding POST requests. This package is not intended to be a general purpose SSE package, but instead is a bidirectional protocol for use when Websockets are unavailable. That is, both the client and the server expose a `sink` and `stream` on which to send and receive messages respectively. Both the server and client have implicit assumptions on each other and therefore a client from this package must be paired with a server from this package. ## Changelog ## 4.2.0 - Update the minimum Dart SDK version to `3.11.0`. - Handle out of order disconnects and reconnects. - Allow SSE connections to be reused if not in a keep alive period. - Allow a debounce period after connections to ignore disconnects which may be from prior connections. - Add logging when messages are received out of order. ## 4.1.8 - Simplify the format of client ID strings. ## 4.1.7 - Move to `dart-lang/tools` monorepo. ## 4.1.6 - Require package `web: '>=0.5.0 <2.0.0'`. ## 4.1.5 - Drop unneeded dependency on `package:js`. - Update the minimum Dart SDK version to `3.3.0`. - Support the latest `package:web`. ## 4.1.4 - Fix incorrect cast causing failure with `dart2wasm`. ## 4.1.3 - Update the minimum Dart SDK version to `3.2.0`. ## 4.1.2 - Send `fetch` requests instead of `XHR` requests. - Add an optional `debugKey` parameter to `SseClient` to include in logging. - Add a dependency on `package:js`. - Update the minimum Dart SDK version to `2.16.0`. ## 4.1.1 - Apply `keepAlive` logic to `SocketException`s. - Switch from using `package:pedantic` to `package:lints` - Rev the minimum required SDK to 2.15. - Populate the pubspec `repository` field. ## 4.1.0 - Limit the number of concurrent requests to prevent Chrome from automatically dropping them on the floor. ## 4.0.0 - Support null safety. ## 3.8.3 - Require the latest shelf and remove dead code. ## 3.8.2 - Complete `onConnected` with an error if the `SseClient` receives an error before the connection is successfully opened. ## 3.8.1 - Fix an issue where closing the `SseConnection` stream would result in an error. ## 3.8.0 - Add `onConnected` to replace `onOpen`. - Fix an issue where failed requests would not add a `done` event to the connection `sink`. ## 3.7.0 - Deprecate the client's `onOpen` getter. Messages will now be buffered until a connection is established. ## 3.6.1 - Drop dependency on `package:uuid`. ## 3.6.0 - Improve performance by buffering out of order messages in the server instead of the client. \*\* Note \*\* This is not modelled as a breaking change as the server can handle messages from older clients. However, clients should be using the latest server if they require order guarantees. ## 3.5.0 - Add new `shutdown` methods on `SseHandler` and `SseConnection` to allow closing connections immediately, ignoring any keep-alive periods. ## 3.4.0 - Remove `onClose` from `SseConnection` and ensure the corresponding `sink.close` correctly fires. ## 3.3.0 - Add an `onClose` event to the `SseConnection`. This allows consumers to listen to this event in lue of `sseConnection.sink.done` as that is not guaranteed to fire. ## 3.2.2 - Fix an issue where `keepAlive` may cause state errors when attempting to send messages on a closed stream. ## 3.2.1 - Fix an issue where `keepAlive` would only allow a single reconnection. ## 3.2.0 - Re-expose `isInKeepAlivePeriod` flag on `SseConnection`. This flag will be `true` when a connection has been dropped and is in the keep-alive period waiting for a client to reconnect. ## 3.1.2 - Fix an issue where the `SseClient` would not send a `done` event when there was an error with the SSE connection. ## 3.1.1 - Make `isInKeepAlive` on `SseConnection` private. **Note that this is a breaking change but in actuality no one should be depending on this API.** ## 3.1.0 - Add optional `keepAlive` parameter to the `SseHandler`. If `keepAlive` is supplied, the connection will remain active for this period after a disconnect and can be reconnected transparently. If there is no reconnect within that period, the connection will be closed normally. ## 3.0.0 - Add retry logic. **Possible Breaking Change Error messages may now be delayed up to 5 seconds in the client.** ## 2.1.2 - Remove `package:http` dependency. ## 2.1.1 - Use proper headers delimiter. ## 2.1.0 - Support Firefox. ## 2.0.3 - Fix an issue where messages could come out of order. ## 2.0.2 - Support the latest `package:stream_channel`. - Require Dart SDK `>=2.1.0 <3.0.0`. ## 2.0.1 - Update to `package:uuid` version 2.0. ## 2.0.0 - No longer expose `close` and `onClose` on an `SseConnection`. This is simply handled by the underlying `stream` / `sink`. - Fix a bug where resources of the `SseConnection` were not properly closed. ## 1.0.0 - Internal cleanup. ## 0.0.1 - Initial commit.