scadalink-design/Component-NotificationService.md

Component: Notification Service

Purpose

The Notification Service provides email notification capabilities to scripts running at site clusters. It manages notification lists, handles email delivery, and integrates with the Store-and-Forward Engine for reliable delivery when the email server is unavailable.

Location

Central cluster (definition management). Site clusters (email delivery).

Responsibilities

Definitions (Central)

• Store notification lists in the configuration database: list name, recipients (name + email address).
• Store email server configuration (SMTP settings).
• Deploy notification lists and SMTP configuration uniformly to all sites. Deployment requires explicit action by a user with the Deployment role.
• Managed by users with the Design role.

Delivery (Site)

• Resolve notification list names to recipient lists.
• Compose and send emails via SMTP.
• On delivery failure, submit the notification to the Store-and-Forward Engine for buffered retry.

Notification List Definition

Each notification list includes:

• Name: Unique identifier (e.g., "Maintenance-Team", "Shift-Supervisors").
• Recipients: One or more entries, each with:
  • Recipient name.
  • Email address.

Email Server Configuration

• SMTP server address, port, authentication credentials, TLS settings.
• Retry settings: Max retry count, fixed time between retries (used by Store-and-Forward Engine).
• Defined centrally, deployed to all sites.

Script API

Notify.To("listName").Send("subject", "message")

• Available to instance scripts (via Script Execution Actors), alarm on-trigger scripts (via Alarm Execution Actors), and shared scripts (executing inline).
• Resolves the list name to recipients, composes the email, and attempts delivery.
• On failure, the notification is handed to the Store-and-Forward Engine.

Dependencies

• Configuration Database (MS SQL): Stores notification list definitions and SMTP config.
• Store-and-Forward Engine: Handles buffering for failed email deliveries.
• Security & Auth: Design role manages notification lists.
• Configuration Database (via IAuditService): Notification list changes are audit logged.

Interactions

• Site Runtime (Script/Alarm Execution Actors): Scripts invoke Notify.To().Send() through this component.
• Store-and-Forward Engine: Failed notifications are buffered here.
• Deployment Manager: Receives updated notification lists and SMTP config as part of system-wide artifact deployment (triggered explicitly by Deployment role).