Invoicing and Order Processing System (Java Web Application)

A web application created for a small service company that needed a lightweight system for issuing sales documents and managing a basic database of customers, products, and orders – without using commercial SaaS platforms.

Functional scope

  • Product, customer, and order database,
  • Invoice generation (invoices/proforma invoices/corrections),
  • Automatic document numbering,
  • Registration of orders and related items,
  • Tax and order value calculations,
  • Document export to PDF,
  • Sales reports,
  • Simple role system (admin → data management, user → document issuing),
  • Database backups (SQLite file).

Technologies and Architecture

The application was built as a classic web application based on Java EE patterns:

  • Java (Servlets + JSP + JSTL) – application logic and controller layer,
  • JSP + JSTL – views and presentation layer,
  • SQLite relational database,
  • custom implementation of the DAO/ORM layer,
  • Bootstrap, HTML5, CSS3 – UI, layout, and responsiveness,
  • Servlet Filters – authorization and input validation,
  • MVC model – separation of layers, clear business logic architecture.

My role:

  • application architecture design,
  • implementation of the entire backend layer,
  • SQLite database structure and data mapping,
  • order, invoice, tax, and numbering logic,
  • front-end development based on Bootstrap,
  • testing and documentation.

    • The Result

    The company gained a lightweight, standalone tool that can be run locally or on any application server (Tomcat/Jetty), requiring no licenses, cloud configuration, or additional services. The system enables fast sales processing and invoice archiving without subscription fees.

     

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