Our RESTful web service

One common piece of software in use in the hospitality industry is a property management system (careful readers will notice the unfortunate acronym for these systems). It allows automating the operations of hotels and B&Bs. For the purpose of this book, we will build such a system using Spring. Each component of this system will expose a RESTful API that will be consumed by a simple web interface.

Tip

Designing effective Application Programming Interfaces is a topic that deserves its own treaty. It is beyond the scope of this book to discuss these concerns in detail. The main characteristics that one should bear in mind when designing APIs are: ease of use, consistency, exposing as little as necessary, extensibility, and forward compatibility.

Architecture

Our property management system will be formed of the four components, as illustrated in the following figure:

The four components are explained as follows:

• Inventory Service: This component provides the necessary functionality to manage and describe rooms and room types.
• Availability Service: This component lets users see what rooms are available on specific dates.
• Booking Service: This component will be responsible for taking bookings. It will rely on the Inventory Service and Availability Service components to validate bookings.
• Billing Service: Once a booking is made, this component will offer the ability to generate an invoice.

Data model

In this section, we will look at the data model that will support our web service. The following entity relationship diagram provides an overview of this model:

The entities that constitute our model are as follows:

• Room: This object represents the physical rooms that are part of our hotel. Rooms have a name and a description as well as photos.
• RoomCategory: Each room belongs to a category (for example, double room). Categories provide a description, and are linked to a pricing model.
• Pricing: This object encapsulates how rooms are priced (for example, a fixed price, or a sliding price based on the number of guests).
• Booking: The reservation of rooms is modeled on bookings. Bookings will capture the reserved room, dates, and contact details for guests.
• Invoice: This provides invoices to guests upon booking. They contain the relevant information regarding the booking, and the amount to be settled.

The data access layer will be implemented using Object-Relational Mapping (ORM) with Hibernate 4.3.8.

Tip

We will not delve into the specificities of Hibernate ORM in this book. However, documentation is available on Hibernate.org at http://hibernate.org/orm/.

In addition, for the purpose of simplifying the development and testing of our web service, we will use an embedded H2 database.

Note

Documentation about H2 can be found at http://www.h2database.com.

Hibernate supports H2 out of the box, so no specific setup is required to use it as our embedded database.

Tip

While an embedded database is great for development, it is not fit for a production deployment.