SseReconnect class final

The reconnection rules of an event stream: whether, after how long and how many times it connects again when its connection ends or breaks.

An event stream is meant to last, but connections drop: a proxy times out, the phone changes networks, the server restarts. A browser's EventSource reconnects by itself, and so does connectServerSentEvents, following these rules. It waits delay, or the delay the server sent in a retry: field, and sends the last event id in Last-Event-ID so the server can resume.

Feign clients build one from their configuration (the event-stream.reconnect, event-stream.reconnect-delay and event-stream.max-attempts keys), so applications set properties rather than create it. You write one when you call connectServerSentEvents yourself.

// Retry quickly, but give up after five connections in a row that
// bring no event.
const SseReconnect(delay: Duration(seconds: 1), maxAttempts: 5);

// A one-shot stream: it ends with its first connection.
SseReconnect.never;

Spring (Java): no built-in reconnection; the usual way is Flux.retryWhen(Retry.fixedDelay(...)) on a WebClient stream.

Constructors

SseReconnect({bool enabled = true, Duration delay = const Duration(seconds: 3), int? maxAttempts, bool retryIf(Object error) = _isTransportError})

Rules that reconnect when enabled (the default), after delay (3 seconds by default). maxAttempts limits the connections in a row that bring no event (null, the default: no limit). retryIf picks the errors worth another try; by default only an HttpTransportException, that is a network failure or a timeout.

const

Properties

delay → Duration

The wait before connecting again. Once the server has sent a retry: field, its value is used instead.

final

enabled → bool

Whether to reconnect at all. When false the other fields do not matter.

final

hashCode → int

The hash code for this object.

no setter, inherited

maxAttempts → int?

How many connections in a row may end without bringing an event before the stream gives up and ends (with the last error, if there was one). The first connection counts, and any event with data starts the count again. null for no limit.

final

retryIf → bool Function(Object error)

Decides whether a failure is worth another try. An error it rejects ends the stream with that error, such as a 4xx that connect turned into an exception. A connection that simply ends is always retried.

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited

Constants

never → const SseReconnect

Rules that never reconnect: the stream ends when its first connection ends, and fails with its error.