Long-Running Jobs

Status: ✅ Implemented — @Action(background, sse), @Trigger

Intent

Give asynchronous processes a dignified UX without freezing the interface.

Problem

A process that takes seconds or minutes and blocks the entire screen is the Spinner Prison: the user cannot do anything and does not know if the system is still alive. Long operations must be launched, tracked, and reacted to without a hard block.

Solution

Non-blocking launch

Set background = true on the action. The server starts the job and returns immediately; the UI remains interactive.

@Action(background = true, sse = true)
public void generateReport() {
    // runs asynchronously; progress is streamed back
    reportService.generate();
}

Live progress via SSE

With sse = true, the server can push progress events back to the client. Use a ProgressBar or a @Status field to reflect the current state.

Polling with @Trigger

When push is not available, use @Trigger to poll for state:

@Trigger(type = TriggerType.OnLoad, times = 20, timeoutMillis = 3000)
public JobStatus checkStatus() {
    return jobService.getStatus(jobId);
}

Reacting to outcome

@Trigger(type = TriggerType.OnSuccess)
public View onJobSuccess() { ... }

@Trigger(type = TriggerType.OnError)
public View onJobError() { ... }

Structure

Generate report

  [Start report]

  ─────────────────────────────────
  ████████████████░░░░  67%
  Processing 1,234 of 1,841 records…

  [Cancel]

After completion:

  ✓ Report ready — 1,841 records processed in 4.2 s
  [Download]  [View online]

Principles served

• Recoverability — the user can cancel; errors surface as actionable feedback
• Preserve context — the rest of the UI stays usable while the job runs
• Consistency — progress and outcome feedback follow the same pattern everywhere