TimerDemo (Blazor WebAssembly, .NET 8)

A Blazor WebAssembly demo showcasing a lightweight hierarchical task timing & progress reporting utility. It simulates “making breakfast” by orchestrating parallel and nested tasks (coffee, toast, eggs, bacon, juice) while demonstrating:

• Nested task timing (parent / child relationships)
• Weighted progress aggregation (percent of total work)
• Start / complete / cancel / error / expiration events
• Max duration vs expiration semantics
• Cooperative cancellation via CancellationTokenSource
• Parallel slice processing (toast & bacon) using Parallel.ForEachAsync
• UI status reporting via a TaskReport component

Contents

Page	Route	Purpose
Breakfast.razor	/	Full orchestration demo with cancellation + nested timers
BasicTimer.razor	/timer	Minimal example with three weighted tasks

Core Concepts

TaskTimer

Represents a unit of work (primary or sub-task). Features:

• Start(), Complete(), Cancel(), Stop(), Restart()
• Optional: PercentOfWorkForParentTask
• MaxDurationInSeconds → triggers "Error" (burnt)
• ExpirationInSeconds → triggers "Expired" (cold/stale)
• ParentTask + automatic aggregation of progress
• Event hooks (e.g., OnCancelEvent)
• Elapsed time tracking (Stopwatch + timers)

TaskReport (UI Facade)

(Not shown here, but inferred)

• Registers TaskTimer instances
• Emits status lines (Started / Completed / Error / Expired / Cancelled / Info / Alert)
• Provides SimulateDelay(...) helper (wrapping Task.Delay + cancellation)

Breakfast Workflow

Primary task: “Breakfast” Subtasks executed concurrently:

• MakeCoffee (with max + expiration timers)
• ToastBread (per-slice parallelization + optional butter/jam subtasks)
• MakeEggs (pan warm + fry eggs, includes max + expiration)
• FryBacon (per-slice timers with burn/cold thresholds)
• PourJuice (simple timed task)

Cancellation triggers cleanup messages (e.g., turning off pan / coffee pot).

Basic Timer Page

Simplifies usage to three sequential weighted tasks (20% / 50% / 30%) to illustrate progress composition.

Example Usage Pattern

## Cancellation

Each sub-task can attach OnCancelEvent to perform contextual cleanup messaging.

Parallelism Notes (WebAssembly)

Parallel.ForEachAsync is used for toast & bacon slices. In WebAssembly:

• Without multithreading enabled, this may run effectively sequentially.
• To enable threading, ensure:
  • Property true in the project file
  • Hosted in a secure cross-origin-isolated context (COOP/COEP headers) If threading is not enabled, logic still functions—just without true parallel speedup.

Build

Prerequisites:

• .NET 8 SDK
• Modern browser (Chromium, Firefox, Edge)

Extending

Goal	Approach
Add new task type	RegisterSubTask + Start/Complete
Add retry logic	Wrap SimulateDelay / work block with Polly or manual loop
Persist history	Inject a state service; cache TaskEventArgs sequence
UI customization	Modify TaskReport rendering (e.g., color-code statuses)
Real workloads	Replace SimulateDelay with I/O or compute operations

Error vs Expiration

• MaxDurationInSeconds → Task ran too long (treated as failure condition / “burnt”)
• ExpirationInSeconds → Task completed (or not) but exceeded freshness window (“cold”)

Summary

TimerDemo illustrates structured, cancellable, hierarchical task timing inside a Blazor WebAssembly UI, providing an educational pattern for progress reporting, task composition, and lifecycle signaling.

Happy timing!