Document embedded .NET workflow engine options and Azure cost gates

[Copilot]

Research the trade-offs for embedding durable, code-first workflows in ASP.NET Core while reusing Azure SQL, Service Bus, Storage, and App Service infrastructure. Cover durable waits, external events, fork/join, recovery, browsing, persistence, and workflow versioning.

• Engine evaluation

  • Compare Elsa, Durable Task/Functions, Temporal, Workflow Core, Dapr, Orleans, Stateless, Hangfire, Quartz, Rebus, MassTransit, Wolverine, Logic Apps, and Azure primitives.
  • Include code-first workflow examples and compatibility/versioning guidance.
  • Identify Elsa as the strongest embedded SQL-backed candidate and Durable Functions MSSQL as the strongest SQL-oriented Functions option.

• Durable Task Scheduler constraints

  • Document Consumption limitations: no HA/multi-zone support, 500 actions/sec ceiling, and 30-day retention.
  • Document Dedicated HA requirements: three CUs minimum.
  • Capture the indicative planning cost of approximately €1,500/month for three CUs at €500/CU, excluding compute and dependent Azure services.
  • Link official billing and pricing references.

• Cost and architecture comparison

  • Compare scheduler, compute, persistence, messaging, licensing, HA, and operational ownership across alternatives.
  • Identify lower-cost paths using Durable Functions with Azure Storage or MSSQL providers.
  • Distinguish true in-process hosting, co-resident Function Apps, and external execution platforms.

• Reliability patterns

  • Specify optimistic concurrency, idempotent fork/join completion, correlation-keyed external events, inbox/outbox processing, durable timers, projections, and version-safe rolling deployments.

Representative durable approval pattern:

await Task.WhenAll(notifications);

var approval = context.WaitForExternalEventAsync<bool>("Approval");
var timeout = context.CreateTimer(
    context.CurrentUtcDateTime.AddDays(7));

var completed = await Task.WhenAny(approval, timeout);