Energy Trade Simulator is a modular Java project designed to simulate a simplified energy trading ecosystem using microservices, REST communication, and event-driven logging.
The project is built with Spring Boot, Undertow, and Log4j2, aiming to demonstrate real-world service orchestration, observability, and maintainability in a distributed architecture.
- Simulate a realistic trading lifecycle across loosely coupled services.
- Enable real-time observability via a centralized log collector.
- Serve as a blueprint for multithreaded, resilient, and modular system design.
- Showcase code readability, testability, and configuration best practices.
- Java 11
- Spring Boot 2.7
- Undertow (replaces default Tomcat)
- Log4j2 (with custom HTTP appender)
- H2 (in-memory DB)
- Maven
- Windows batch scripting (for orchestration)
order-service: Handles client trade requests and order emission.pricing-service: Simulates price retrieval or external price integration.audit-service: Persists events related to transactions and system actions.notification-service: Sends external communications (e.g., email, webhook).external-cotation-gw: Acts as a stubbed external pricing API.log-collector-service: Captures and centralizes logs from all services.integration-sim: CLI-based simulation client to trigger application scenarios.
- Custom
HttpLogCollectorAppenderfor centralized structured JSON logging - Environment-controlled boot process with readiness detection
- Health-check loop ensures log collector starts before other services
- Structured logs enriched with service metadata (
serviceName) for filtering
The tag v1.4.0-pricing delivers a Strategic Architecture Decision for Market Pricing, documenting how and when market prices are captured and used within the platform.
This milestone does not include new logic or feature changes but instead defines the system’s approach to price acquisition — favoring stored values at order creation time — following best practices from real-world trading engines.
✅ Documented Strategy
- Orders will store the current market price at creation time (
marketPrice) - The matching engine will not query external pricing services during execution
- This decision improves performance, determinism, and fault tolerance
- External pricing is still queried via
pricing-service, backed by a mock gateway - The service architecture is now ready for future evolution (e.g. pricing streams, slippage analysis, multi-asset pricing)
→ Full changelog: v1.4.0-pricing Release Page
v1.4.0-pricing.
The tag v1.3.0-cancel introduces Order Cancellation, allowing clients to cancel pending orders safely and traceably.
This version enhances system integrity by ensuring canceled orders cannot be matched or executed, while maintaining a full audit trail of user actions.
✅ Implementation
- New endpoint
POST /orders/{id}/cancelto cancel a pending order - Orders must be in
PENDINGorPARTIALstate to be eligible - Status updated to
CANCELLEDand persisted with timestamp (cancelledAt) - AuditEvent
ORDER_CANCELLEDis dispatched to the audit service - Optional Notification triggered to inform administrators of the cancellation
- Unit and integration test coverage for edge cases (e.g. canceling already executed or expired orders)
- Simulation test in
integration-simvalidates full cancellation flow
→ Full changelog: v1.3.0-cancel Release Page
v1.3.0-cancel.
The tag v1.2.0-expiry introduced Order Expiration & Cleanup, expanding the robustness and integrity of the matching system.
This version ensures that expired orders are never executed, and introduces a scheduled cleanup task to maintain data consistency over time.
✅ Implementation
- Validation of expiration timestamp for incoming orders
- Filtering out expired counterpart orders during matching
- Status
EXPIREDautomatically assigned when appropriate - Scheduled cleanup task (
@Scheduled) to mark asEXPIREDallPENDINGorders past their expiration timestamp - Configurable cleanup interval via
application.properties - Test coverage for expired incoming orders and expired candidates
- Full audit and logging of expired order handling
→ Full changelog: v1.2.0-expiry Release Page
v1.2.0-expiry.
The tag v1.1.0-matching introduced the Order Matching Engine, the first intelligent execution component of the platform.
This version builds on v1.0.0-base by adding logic for matching BUY and SELL orders based on price and timestamp, tracking volume execution, and handling state transitions.
✅ Implementation
- Automatic matching between BUY and SELL orders based on price and timestamp
- Partial and full execution logic with volume tracking
- Status transitions:
PENDING,PARTIAL,EXECUTED - Audit events and notifications dispatched on match
- Rejection of invalid orders (e.g. negative volume)
- Pretty-printed JSON logs for simulation and verification
- Extended simulation coverage with edge cases
→ Full changelog: v1.1.0-matching Release Page
The tag v1.0.0-base marked the first stable and functional snapshot of this project.
This version delivers a foundational, end-to-end working system with structured logging, microservice orchestration, and order creation capabilities through a command-line simulator.
✅ Implementation
- Services compile and run independently
- Structured logs are correctly emitted and collected centrally
- Logs are traceable to originating service via metadata
- Batch scripts orchestrate service startup with dependency awareness
- Orders can be created and logged using
integration-sim
These features will be released incrementally and tagged for easy comparison.
| Feature | Status | Tag (planned) |
|---|---|---|
| Order Matching Engine (buy/sell execution) | ✅ Delivered | v1.1.0-matching |
| Order Expiration & Cleanup | ✅ Delivered | v1.2.0-expiry |
| Order Cancellation | ✅ Delivered | v1.3.0-cancel |
| Pricing Feed & Dynamic Simulation | ✅ Delivered | v1.4.0-pricing |
| Full Audit Trail & Reporting | Planned | v1.5.0-audit |
| Observability: Dashboards or CLI tools | Planned | v1.6.0-visuals |
| Stress Tests & Load Simulation | Planned | v1.7.0-stress |
Each milestone will be versioned, tagged, and documented.
energy-trade-sim/
├── order-service/
├── pricing-service/
├── audit-service/
├── notification-service/
├── external-cotation-gw/
├── log-collector-service/
├── integration-sim/
└── common-logging/
This project includes a Windows batch script (start-all.bat) that automates the startup of all core services in separate terminal windows.
- Java 11+ installed and configured in your system PATH
- Maven installed and accessible via command line (
mvn -v) - A terminal that supports UTF-8 and emojis (Windows Terminal or CMD with chcp 65001)
- Ports 8080–8085 available for service binding
- Open a terminal as Administrator (if needed for port permissions).
- Navigate to the root of the project where
start-all.batis located. - Execute:
start-all.batThis will:
- Open a new terminal window for each service:
- Order Service
- Pricing Service
- Audit Service
- Notification Service
- External Cotation Gateway
- Integration Simulator
- Display colored log output with emojis if UTF-8 is correctly configured.
- Look for the message
🚀 [Service Name] is up and running! 🌐in each terminal. - The integration simulator will fetch prices, post several test orders (including edge cases), and log results.
- Confirm that:
- Logs from all services appear in the log collector
- Audit events are stored and printed
- Order matching is happening based on volume and price
- Buy/Sell pairs that match fully or partially
- Orders with extreme or invalid values (e.g. negative volume)
- Pretty-printed logs for easy inspection
If you face any encoding issues, ensure your terminal code page is set to UTF-8 using:
chcp 65001This project is licensed under the MIT License. See LICENSE file for details.