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Legacy Todo Application (Pre-Containerization)

This is the legacy version of the Todo application, demonstrating an older 'legacy' Java web application practices and common antipatterns.

Features

  • Create, read, update, and delete todo items
  • Filter todos by status (All, Active, Completed)
  • Sort by creation date (Newest First, Oldest First)
  • Track creation and completion timestamps for todos
  • Responsive web interface
  • Technical overview page

Running the Application

Prerequisites

  • Java 8 or higher
  • Maven 3.x

Building and Running

../run-legacy.sh run

The application will be available at: http://localhost:8080/legacy-todo

Debugging

../run-legacy.sh debug

Then in VS Code:

  1. Set breakpoints in your code
  2. Select "Debug Legacy Todo" configuration
  3. Press F5

Technical Details

Architecture

Client Layer (Browser)
    │
    ▼
Presentation Layer (JSP)
    │    - index.jsp: Main UI
    │    - about.jsp: Technical overview
    │
    ▼
Controller Layer (Servlets)
    │    - TodoServlet: Handles all CRUD operations
    │
    ▼
Service Layer
    │    - TodoStorage: File-based storage service
    │
    ▼
Model Layer
    │    - Todo: Data model for todo items
    │
    ▼
Storage Layer
    │    - File System Storage (data/tasks.json)

Common Anti-patterns

  1. File System Dependencies: Direct file system access, hard coded paths, local file locking
  2. Local Caching: Non-distributed cache, file system persistence, no cache coordination
  3. Configuration Management: Properties files, hard coded values, no environment separation
  4. Logging Practices: File-based logging, local log rotation, no structured logging
  5. Code Style Issues: Inconsistent import ordering, missing documentation, non-standard formatting

Implementation Details

  1. Local File Storage: Tasks stored in data/tasks.json with direct file system access and no transaction support
  2. Embedded Cache: Local in-memory EhCache with disk persistence in data/cache/
  3. Local File System Logging: Logs written to data/app.log without rotation or centralization
  4. Local Configuration: Property files in src/main/resources with hard coded paths

Technical Stack

  • Runtime: Java 8+, JSP 2.3.3, Servlet API 3.1.0
  • Build: Maven 3.x
  • Dependencies: JSTL 1.2, EhCache 2.10.6, Jackson 2.15.3, SLF4J/Logback
  • Quality Tools: Maven Checkstyle Plugin with Google Java Style Guide

Project Structure

legacy-todo/
├── src/
│   └── main/
│       ├── java/          # Java source files
│       ├── resources/     # Configuration files
│       └── webapp/        # Web resources and JSP pages
├── data/                  # Runtime data directory
│   ├── tasks.json        # Todo items storage
│   ├── cache/            # EhCache storage
│   └── app.log           # Application logs
├── pom.xml               # Maven configuration
└── checkstyle.xml        # Checkstyle configuration
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