WJb 1.0.0-beta1

📘 WJb — Lightweight Priority Job Runner for .NET

🚀 What is WJb?

WJb is a lightweight, priority‑aware, workflow‑capable background job runner for .NET. It focuses on simplicity, predictability, testability, and full control — without forcing EF Core, hosted queues, or external services.

⭐ Features

• ✔ In‑memory priority queue (ASAP / High / Normal / Low) with backpressure, fairness & in‑flight limits
• ✔ Parallel job processing (MaxParallelJobs)
• ✔ DI-friendly Actions (IAction / IActionFactory)
• ✔ Workflow chaining (success → next, failure → fail)
• ✔ Cron‑based scheduling (JobScheduler)
• ✔ JSON-based job payloads
• ✔ Built‑in Telemetry — Metrics + Activity tracing

📦 Install

dotnet add package WJb

🛠️ Register in Program.cs

services.AddWJbActions(map =>
{
    map["Email"] = new ActionItem(
        type: typeof(EmailAction).AssemblyQualifiedName!,
        more: new JsonObject());
});

services.AddWJbBase(opts =>
{
    opts["MaxParallelJobs"] = 4;
});

📨 Enqueue a Job

await processor.EnqueueJobAsync(
    await processor.CompactAsync("Email", new { to = "user@example.com" }),
    Priority.High);

🔁 Workflow Chaining

WJb supports deterministic branching using next_* and fail_* keys.

{
  "Start": {
    "type": "WorkflowAction",
    "more": {
      "next": "SendEmail",
      "next_to": "user@example.com",
      "fail": "LogError",
      "fail_message": "Startup failed"
    }
  },
  "SendEmail": {
    "type": "EmailAction",
    "more": {
      "from": "noreply@example.com",
      "subject": "Welcome!"
    }
  },
  "LogError": {
    "type": "LogAction",
    "more": { "level": "Error" }
  }
}

Rules

• Only next_* / fail_* keys are forwarded
• Prefix removed → merged into next action
• Child‑wins merge (job overrides action defaults)
• Priority may be overridden using:
  • next_priority
  • fail_priority

Telemetry & Metrics (since 0.23+)

WJb now includes first‑class Telemetry:

✔ Metrics via System.Diagnostics.Metrics

Built‑in instruments:

Counters

• jobs_queued
• jobs_compacted
• jobs_expanded
• jobs_started
• jobs_completed
• jobs_failed

Histograms

• job_duration_ms (per job execution)

Every measurement includes rich tags (e.g., action_type, priority, reason, outcome).

Example Setup

var meter = new Meter("WJb.JobProcessor", "1.0.0");
services.Configure<WJbTelemetryOptions>(opts =>
{
    opts.OnJobCompleted = evt => Console.WriteLine($"Job completed: {evt.ActionName}");
});

🧭 Activity Tracing (OpenTelemetry‑friendly)

WJb emits:

• WJb.Job — per-job execution activity
• WJb.JobEnqueued — enqueue events

Tags include:

• actionName
• priority
• attempt
• durationMs

Works with:

• OpenTelemetry Collector
• Azure Application Insights
• Jaeger / Zipkin
• Grafana Tempo

⏳ Priority Queue

The in‑memory queue includes:

Backpressure

Blocking writers when per‑priority queues are full.

Per‑priority concurrency limits

MaxInFlightASAP, MaxInFlightHigh, MaxInFlightNormal, MaxInFlightLow

Fairness

Weighted round‑robin:

• WeightASAP
• WeightHigh
• WeightNormal
• WeightLow

Ensures:

• High responsiveness for ASAP/High
• Guaranteed progress for Normal/Low

🏷 License

MIT License (see LICENSE file)

🙌 Support

If WJb helps you — ⭐ the repo or support via PayPal.