Activity Diagram: Weather Station System

The Activity Diagram of the Weather Station system illustrates the sequence of operations starting from the collection of environmental data to the generation of alerts and reports. This helps students visualize how various components and actions interact during the execution of the system.

High-Level Description

The system begins with the initialization of the weather station and the activation of all connected sensors. The sensors continuously collect weather-related parameters such as temperature, humidity, wind speed, and rainfall. The data is periodically fetched and passed to a centralized module responsible for logging and analyzing. Based on the recorded values, the system checks whether any thresholds have been crossed. If so, alerts are triggered. Finally, users can access this information or request weather reports.

Key Steps in the Activity Flow

Start

• The system is powered on or scheduled to start automatically.
• All components are initialized including sensors, loggers, and network services.

Initialize Sensors

• Each sensor (Temperature, Humidity, Wind Speed, Rainfall) is initialized and verified for proper functionality.

Read Sensor Data

• All sensors collect real-time weather data.
• This step can occur on a schedule (e.g., every minute) or triggered by specific events.

Store Data in Logger

• The collected sensor values are passed to a DataLogger module.
• Each reading is timestamped and stored persistently for future reference and analysis.

Analyze Data

• The logged data is analyzed to determine if it falls within acceptable weather conditions.
• This is handled by the AlertSystem or a separate rule evaluation module.

Is Threshold Breached? (Decision Node)

• The system checks whether any weather parameter has crossed a predefined threshold (e.g., temperature > 45°C, wind speed > 70 km/h).
• If No, the system continues to monitor.
• If Yes, it proceeds to generate an alert.

Trigger Alert

• An alert is generated and possibly escalated via email, SMS, or system notifications.
• This includes information about the condition, sensor involved, and timestamp.

User Requests Report (Optional User-Initiated Action)

• A user logs into the system and requests a report for a specific time period or parameter.
• The system compiles data and presents it in a readable format (table, graph, etc.).

Display Report

• The requested weather report is generated and displayed to the user via a dashboard or report module.

End

• The cycle repeats or is terminated based on user interaction or scheduled system shutdown.

Diagram Components (Textual View for Students)

You can guide your students to draw the activity diagram using standard UML elements as follows:

• Initial Node: Start
• Action Nodes: Initialize Sensors → Read Sensor Data → Store Data in Logger → Analyze Data
• Decision Node: Is Threshold Breached?
• Action Branch 1: (No) → Return to Read Sensor Data
• Action Branch 2: (Yes) → Trigger Alert
• Swimlane (User): Request Report → Display Report
• Final Node: End