Tasks Service - Event Catalog

Overview

The Tasks service uses RabbitMQ via MassTransit 8.2.5 for asynchronous messaging. It operates two bus instances and uses BusProxy for outbound publishing with fallback strategies.

Bus Architecture

Bus	Purpose	Consumers
Main Bus	Core task events, generation requests	TaskInstanceGenerationConsumer, BusinessUnitChangeConsumer
Scheduling Bus	Schedule lifecycle events from external Scheduling service	ScheduleCreatedConsumer, ScheduleRemovedConsumer, TaskUpdatedConsumer, MassSchedulesRemovedConsumer

Delivery & Fallback

Environment	Primary Handler	Fallback Handler
Production/Sandbox	WebServiceHandler (HTTP)	S3Handler (AWS S3)
Local/Integration	WebServiceHandler (HTTP)	SqlServerHandler (SQL Server)

Publishing timeout: 45 seconds

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Consumed Events (Inbound)

From Customers Service

IBusinessUnitChangeV1

• Source: DSE.TELS.Customers.Events NuGet package
• Queue: TELS.Tasks.MQServices.BusinessUnitChange
• Consumer: BusinessUnitChangeConsumer
• Retry: 5 intervals (5s, 30s, 1m, 3m, 5m)
• Action: When a business unit is activated, schedules recurring task instance generation via Quartz
• Schema: IBusinessUnitChangeV1 { BusinessUnitId: int BusinessUnitType: BusinessUnitType (enum) BusinessUnitStatus: BusinessUnitStatus (enum) }

From Scheduling Service

IScheduleCreatedEvent

• Source: TELS.Scheduling.Events v1.4.3 NuGet package
• Queue: Configured via SchedulingMqOptions.Queue
• Consumer: ScheduleCreatedConsumer
• Action: Triggers task instance generation for the affected facility/schedule

IScheduleRemovedEvent

• Source: TELS.Scheduling.Events v1.4.3
• Queue: Configured via SchedulingMqOptions.Queue
• Consumer: ScheduleRemovedConsumer
• Action: Handles cleanup when a schedule is removed externally

ITaskUpdatedEvent

• Source: TELS.Scheduling.Events v1.4.3
• Queue: Configured via SchedulingMqOptions.Queue
• Consumer: TaskUpdatedConsumer
• Action: Handles task definition changes from the Scheduling service

IMassSchedulesRemovedEvent

• Source: TELS.Scheduling.Events v1.4.3
• Queue: Configured via SchedulingMqOptions.Queue
• Consumer: MassSchedulesRemovedConsumer
• Action: Handles bulk schedule removal

Internal (Self-Consumed)

ITaskInstanceGenerationRequested

• Source: TELS.Tasks.Contracts
• Queue: Main Bus (TaskInstanceGenerationConsumer queue)
• Consumer: TaskInstanceGenerationConsumer
• Trigger: Quartz scheduled job or requeue from locked facility
• Action: Generates task instances for a facility. Uses lock-based concurrency control; requeues if facility is locked.
• Schema: ITaskInstanceGenerationRequested { FacilityId: int }

IScheduleRecurringTaskInstanceGenerationRequest

• Source: TELS.Tasks.Contracts
• Queue: Main Bus
• Consumer: TaskInstanceGenerationConsumer
• Trigger: API endpoint /commands/scheduleRecurringTaskInstanceGeneration
• Pattern: MassTransit Request/Response
• Responses: ScheduleRecurringTaskInstanceGenerationSucceeded or ScheduleRecurringTaskInstanceGenerationFailed
• Schema: IScheduleRecurringTaskInstanceGenerationRequest { FacilityId: int }

IUnscheduleRecurringTaskInstanceGenerationRequest

• Source: TELS.Tasks.Contracts
• Queue: Main Bus
• Consumer: TaskInstanceGenerationConsumer
• Trigger: API endpoint /commands/unscheduleRecurringTaskInstanceGeneration
• Pattern: MassTransit Request/Response
• Responses: UnscheduleRecurringTaskInstanceGenerationSucceeded or UnscheduleRecurringTaskInstanceGenerationFailed
• Schema: IUnscheduleRecurringTaskInstanceGenerationRequest { FacilityId: int }

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Published Events (Outbound)

Domain Events (via BusProxy)

TaskInstanceCompletedEvent

• Trigger: API - completing a task instance (/Instances/{id}/commands/complete)
• Delivery: BusProxy with S3/SQL fallback
• Consumers: External systems
• Schema: ITaskInstanceCompletedEvent { TaskInstanceId: int // additional completion details }

TaskInstanceDocumentCreated

• Trigger: API - attaching a file to an instance (/Instances/{id}/files)
• Delivery: BusProxy with S3/SQL fallback
• Consumers: External systems
• Schema: ITaskInstanceDocumentCreated { TaskInstanceId: int FileGuid: Guid // additional document metadata }

ScheduleCreatedEvent

• Trigger: API - creating or updating a schedule (/Schedules)
• Delivery: BusProxy with S3/SQL fallback
• Consumers: Scheduling Service, external systems
• Source: TELS.Scheduling.Events

ScheduleRemovedEvent

• Trigger: API - deleting a schedule (/Schedules/{id})
• Delivery: BusProxy with S3/SQL fallback
• Consumers: Scheduling Service, external systems
• Source: TELS.Scheduling.Events

OutboundEmailEnvelope

• Trigger: Service layer (email notifications)
• Delivery: BusProxy with S3/SQL fallback (scheduled)
• Consumers: Unity Notifications Service
• Source: Unity.Notifications.Messaging v1.10
• Schema: OutboundEmailEnvelope { Message: OutboundEmailMessage { To: string Subject: string Body: string Attachments: OutboundEmailAttachment[] } }

Request/Response Messages (via MassTransit)

ScheduleRecurringTaskInstanceGenerationSucceeded

• Trigger: Successful scheduling of recurring generation
• Pattern: Response to IScheduleRecurringTaskInstanceGenerationRequest

ScheduleRecurringTaskInstanceGenerationFailed

• Trigger: Failed scheduling of recurring generation
• Pattern: Response to IScheduleRecurringTaskInstanceGenerationRequest

UnscheduleRecurringTaskInstanceGenerationSucceeded

• Trigger: Successful unscheduling of recurring generation
• Pattern: Response to IUnscheduleRecurringTaskInstanceGenerationRequest

UnscheduleRecurringTaskInstanceGenerationFailed

• Trigger: Failed unscheduling of recurring generation
• Pattern: Response to IUnscheduleRecurringTaskInstanceGenerationRequest

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Quartz Scheduling

Backend: PostgreSQL persistent store Scheduler ID: AUTO (clustered) Serializer: Newtonsoft JSON Max Batch Size: 10 triggers per batch Misfire Threshold: 1.5 hours

Scheduled Jobs

Job	Message	Description
GenerateTaskInstancesSchedule	ITaskInstanceGenerationRequested	Recurring per-facility task instance generation

Schedule Identity:

Schedule ID: FacilityScheduleId(facilityId)  // unique per facility
Group: ScheduleGroupName                      // shared group

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Retry Policies

Context	Retries	Backoff	Exception
BusinessUnitChange consumer	5	5s, 30s, 1m, 3m, 5m	All
SQL connection (MQServices)	5	Exponential: 10ms → 100s	SqlException
Task instance generator	5	Exponential: 10ms → 100s	All
HTTP clients (Polly)	Configured	Exponential	Transient HTTP

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Message Flow Diagrams

1. Business Unit Activation → Task Generation

Customers Service
  → publishes IBusinessUnitChangeV1
  → RabbitMQ (Main Bus)
  → BusinessUnitChangeConsumer
  → TaskInstanceGenerationHandler
  → Schedules Quartz job for recurring generation
  → Quartz fires ITaskInstanceGenerationRequested
  → TaskInstanceGenerationConsumer
  → Generates task instances in SQL Server

2. Schedule Lifecycle

API: POST /Schedules (create)
  → Persists to SQL Server
  → Publishes ScheduleCreatedEvent via BusProxy
  → Scheduling Service receives event

Scheduling Service
  → Publishes IScheduleCreatedEvent
  → RabbitMQ (Scheduling Bus)
  → ScheduleCreatedConsumer
  → Triggers instance generation

3. Task Completion

API: POST /Instances/{id}/commands/complete
  → Updates instance status in SQL Server
  → Publishes TaskInstanceCompletedEvent via BusProxy
  → External systems receive event

4. Recurring Instance Generation (Request/Response)

API: POST /commands/scheduleRecurringTaskInstanceGeneration
  → MassTransit RequestClient
  → IScheduleRecurringTaskInstanceGenerationRequest
  → TaskInstanceGenerationConsumer
  → Configures Quartz schedule
  → Responds: Succeeded or Failed
  → API returns result to caller

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Contract Packages

Package	Version	Events Provided
TELS.Tasks.Contracts	(local)	ITaskInstanceCompletedEvent, ITaskInstanceDocumentCreated, ITaskInstanceGenerationRequested, schedule/unschedule request/response types
TELS.Scheduling.Events	1.4.3	IScheduleCreatedEvent, IScheduleRemovedEvent, ITaskUpdatedEvent, IMassSchedulesRemovedEvent, ScheduleCreatedEvent, ScheduleRemovedEvent
DSE.TELS.Customers.Events	1.0.287926	IBusinessUnitChangeV1
Unity.Notifications.Messaging	1.10.846068	OutboundEmailEnvelope, OutboundEmailMessage, OutboundEmailAttachment
DSE.TELS.Assets.Contracts	2.724197.0	Asset data contracts (referenced, not MQ)
DSE.TELS.Customers.Contracts	1.78.0	Customer data contracts (referenced, not MQ)