simple_sse 1.0.1

An SSE event transformer and client for Dart applications.

SSE Client

An SSE event transformer and client for Dart applications.

Use an event transformer to convert raw String responses into SSE-spec events or use the provided lightweight client to open an SSE event stream without the hassle.

The transformer and client are provided as simple classes to support easier mocking and testing of your application logic.

Features

This package is split into two exports to reduce redundant dependencies. Specifically, if you want your own client implementation, there's no use in forcing you to use this one or depend on the http package.

The two exports are core and client:

├── src
│   ├── core
│   │   ├── sse_event.dart
│   │   └── sse_event_transformer.dart
│   └── client
│       └── sse_client.dart
├── sse_core.dart
└── sse_client.dart

Core

The core export includes an SseEvent model and an SseEventTransformer that can be used to transform a Stream<String> into a Stream<SseEvent>.

SseEvent

class SseEvent {
    /// The event ID.
  final String? id;

  /// The event type.
  final String? event;

  /// The event data.
  final String data;

  /// The retry time in milliseconds (optional).
  final int? retry;

  /// Creates a new [SseEvent].
  /// [id] The event ID.
  /// [event] The event type.
  /// [data] The event data.
  /// [retry] The retry time in milliseconds (optional).
  SseEvent({this.id, this.event, required this.data, this.retry});
}

SseEventTransformer

flowchart LR
  A(String) --> B(SseEventTransformer) --> C(SseEvent)

Client

The client export includes everything in core plus a lightweight SseClient that can be used to connect to an SSE stream and receive Stream<SseEvent> while supporting different HTTP methods, headers, and body parameters.

Stream<SseEvent> connect(
    Uri uri, {
    String method = 'GET',
    Map<String, String>? headers,
    Object? body,
  }) ...

Note: If the [body] is supplied but is not a Map or a List, it will be converted to a String.

Getting started

Add this package to your app's dependencies.

dart/flutter pub add simple_sse

Usage

SseEventTransformer

You can use the core SseEventTransformer to convert a stream of String responses into SseEvent models in a custom client implementation:

import 'package:simple_sse/sse_core.dart';

final stream = response
    .stream
    .transform(const LineSplitter())
    .transform(const SseEventTransformer());

Note: Be sure to use the LineSplitter before the SseEventTransformer.

SseClient

If you don't want to implement your own client logic, use the SseClient directly:

import 'package:simple_sse/sse_client.dart';

final client = SseClient();
final events = client.connect(Uri.parse('https://sse.dev/test'));