Better reconnection logic for Blazor Server · Issue #32113 · dotnet/aspnetcore (original) (raw)

Summary

Currently there is an issue with Blazor Server-side where it is not reconnecting circuits automatically and losing connection especially on mobile browsers.

See #23340 #26985

Motivation and goals

Automatically reload page on Reconnection attempt to the circuit was rejected by the server. This may indicate that the associated state is no longer available on the server.
Automatically reload page on mobile browsers that lost connection (probably due to browser tab being suspended), see Blazor Server Side. JS doesn't start after a long downtime on mobile browsers. #23340 Investigate behavior of Blazor Server on mobile when switching apps #26985

In scope

Automatically refresh the page when circuit was rejected
Add onReconnectionFailed event
onReconnectionFailed could be used to automatically refresh the page instead of asking user to do that manually like in a screenshot shown below
Change DefaultReconnectionHandler.attemptPeriodicReconnection to try to reconnect first and then delay, instead of delaying first and then trying to reconnect. (Possibly could fix Blazor Server Side. JS doesn't start after a long downtime on mobile browsers. #23340 Investigate behavior of Blazor Server on mobile when switching apps #26985)

Out of scope

Risks / unknowns

Difficult to test on mobile browsers

Examples

`DefaultReconnectionHandler.ts`

async attemptPeriodicReconnection(options: ReconnectionOptions) { for (let i = 0; i < options.maxRetries; i++) { this.reconnectDisplay.update(i + 1);

  const delayDuration = i == 0 && options.retryIntervalMilliseconds > ReconnectionProcess.MaximumFirstRetryInterval
                        ? ReconnectionProcess.MaximumFirstRetryInterval
                        : options.retryIntervalMilliseconds;
  this.logger.log(LogLevel.Debug, `Reconnecting in ${delayDuration}`);
  await this.delay(delayDuration);
  //code..
  //try { reconnect() }
  
 //instead of delaying 3000ms first and trying to reconnect later
 //we could try to reconnect first and delay afterwards
 //this could possibly fix reconnection on suspended mobile browsers

Example `onReconnectionFailed` event default implementation

Blazor.defaultReconnectionHandler.onReconnectionFailed = function (d) {
    document.location.reload(); 
}

I can take care of the implementation of this task.

#23340
#26985
#40721
#30344
#41791