Workers

Target Architecture — Final-State Design

This page describes the final-state background workers of the Marketplace Platform. Workers are MassTransit consumers hosted from ConnectSoft.Template.Worker-derived projects, triggered by commands and events on Azure Service Bus, and deployed as independently scaled units.

The Marketplace runs five background workers that handle the asynchronous, long-running, and event-driven work behind publishing, installation, indexing, and quality assurance. Each worker is an idempotent consumer that deduplicates on eventId, asserts tenantId, and emits canonical events on completion.

Worker catalog

Worker	Trigger	Purpose	Input	Output	Retry	Idempotency
MarketplacePublishingWorker	PublishAsset / ReleaseAssetVersion command	Drives the publishing saga: stages the package, invokes quality scan, applies the policy gate, signs, and releases.	Publish command + staged package ref	AssetPublished, AssetVersionReleased; updated AssetVersion	Exponential backoff, 5 attempts; saga compensation on terminal failure	Keyed on (assetId, version); re-running a released version is a no-op
AssetQualityScanWorker	ScanAssetQuality command (from publishing saga)	Runs static, structural, security, and policy quality checks on a submitted asset package.	Staged package blob ref	AssetQualityScanned (verdict + findings)	3 attempts; transient scanner errors retried, content failures terminal	Keyed on package content hash; identical content reuses prior verdict
AssetIndexingWorker	AssetPublished / AssetVersionReleased / AssetReviewed events	Builds and updates the search index documents and catalog read models for discovery and ranking.	Catalog/version/review events	Updated search index; AssetIndexed	At-least-once with 5 attempts; idempotent upsert	Keyed on (assetId, version, indexDocVersion); upserts are naturally idempotent
CompatibilityEvaluationWorker	EvaluateCompatibility command / AssetVersionReleased event	Computes compatibility verdicts asynchronously (full-matrix and on-demand), caching results.	Asset version + target descriptor	CompatibilityEvaluated; cached AssetCompatibility verdict	3 attempts; cache-miss recompute on failure	Keyed on (assetId, version, targetHash); cached verdict short-circuits re-evaluation
InstallationWorker	InstallAsset command / CompatibilityEvaluated + LicenseGranted + DependenciesResolved events	Drives the installation saga: resolve dependencies, verify compatibility and license, apply the asset, and record provenance with rollback.	Install command + resolved graph	AssetInstalled or AssetInstallationFailed; updated AssetInstallation	Exponential backoff, 5 attempts; compensating rollback on terminal failure	Keyed on installationId; partially applied installs resume or roll back deterministically

Event-flow diagram

flowchart TB
    PublishCmd["PublishAsset / ReleaseAssetVersion"] --> MPW["MarketplacePublishingWorker"]
    MPW -->|"ScanAssetQuality"| AQW["AssetQualityScanWorker"]
    AQW -->|"AssetQualityScanned"| MPW
    MPW -->|"AssetPublished / AssetVersionReleased"| Bus["Azure Service Bus"]

    Bus -->|"AssetPublished / AssetVersionReleased"| AIW["AssetIndexingWorker"]
    Bus -->|"AssetVersionReleased"| CEW["CompatibilityEvaluationWorker"]
    Bus -->|"AssetReviewed"| AIW

    InstallCmd["InstallAsset"] --> IW["InstallationWorker"]
    IW -->|"EvaluateCompatibility"| CEW
    CEW -->|"CompatibilityEvaluated"| IW
    IW -->|"resolve dependencies"| DRS["DependencyResolutionService"]
    DRS -->|"DependenciesResolved"| IW
    IW -->|"check entitlement"| LS["LicenseService"]
    LS -->|"LicenseGranted"| IW
    IW -->|"AssetInstalled"| Bus
    AIW -->|"AssetIndexed"| Bus

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Worker semantics

• Hosting — each worker is a separate deployable derived from ConnectSoft.Template.Worker, scaled by queue depth (KEDA on Azure Service Bus). See Deployment.
• Saga coordination — MarketplacePublishingWorker and InstallationWorker host MassTransit state-machine sagas that persist saga state and emit compensating actions on failure.
• Idempotency — all workers deduplicate on eventId and a handler-specific idempotency key (see Event Envelope); reprocessing never produces duplicate releases or installs.
• Poison handling — unprocessable messages move to a dead-letter subqueue with the full envelope preserved for replay and investigation by the Observability tooling.
• Tenant guard — every handler asserts the message tenantId against the operation scope before touching any store.
• Tracing — traceId and correlationId propagate into OpenTelemetry spans and Serilog context so a publish or install can be followed end to end.

Continue to Events, Workflows, and Observability.