# Backend Development Guidelines

> Backend conventions for the JSP + Servlet + MySQL library-management system.

---

## Overview

The developer has established the backend architecture as a B/S Java web
application using JSP + Servlet, MySQL, Tomcat, and IDEA. Application source
code does not exist in this workspace yet, so package names, class names, and
table names below are illustrative project conventions for future code rather
than references to existing files.

Use a layered design:

```
JSP/CSS presentation -> Servlet controller -> Service/business -> DAO -> MySQL
```

Controllers handle request dispatch, parameter validation, and result return.
Services handle business workflows and permission checks. DAOs perform database
CRUD. MySQL stores books, categories, readers, borrowing records,
administrators, roles/permissions, and system logs.

---

## Guidelines Index

| Guide | Description | Status |
|-------|-------------|--------|
| [Directory Structure](./directory-structure.md) | Servlet, service, DAO, entity, and config organization | Project decision documented |
| [Database Guidelines](./database-guidelines.md) | MySQL tables, DAO CRUD, keys, and transactions | Project decision documented |
| [Error Handling](./error-handling.md) | Servlet validation, service failures, and safe responses | Project decision documented |
| [Quality Guidelines](./quality-guidelines.md) | Layer boundaries and review constraints | Project decision documented |
| [Logging Guidelines](./logging-guidelines.md) | System logs, key operations, and exception tracing | Project decision documented |

---

## Pre-Development Checklist

Before backend implementation, read:

- `.trellis/spec/backend/directory-structure.md`
- `.trellis/spec/backend/database-guidelines.md`
- `.trellis/spec/backend/error-handling.md`
- `.trellis/spec/backend/logging-guidelines.md`
- `.trellis/spec/backend/quality-guidelines.md`
- `.trellis/tasks/00-bootstrap-guidelines/research/project-requirements.md`

---

## Core Backend Modules

- Login and permission management for administrator, librarian, and reader
  roles.
- Book information management for create, update, delete, category maintenance,
  and inventory status.
- Reader information management for profiles, borrowing eligibility, and
  contact information.
- Borrowing and return management for borrow, return, renew, overdue handling,
  and automatic collection status updates.
- Book search and statistics for combined title, author, category, and ID
  search, borrowing rankings, inventory reports, and overdue reports.
- System maintenance and logs for key operation logs, data backup support, and
  exception tracing.

## Evidence

- `.trellis/tasks/00-bootstrap-guidelines/research/repo-scan.md` records that
  no application source code exists yet.
- `.trellis/tasks/00-bootstrap-guidelines/research/project-requirements.md`
  records the developer-provided stack, architecture, modules, and data model.

---

**Language**: All documentation should be written in **English**.