Distributed Bookstore

This application uses Java RMI and Jakarta XML Web Services to manage a distributed bookstore through Remote Method Invocations (RMI) and Remote Procedure Calls (RPC) respectively. There are three apps in this repository: the server, admin client and user client.

Architecture

The server has a dual-service architecture for showcasing two distinct types of remote communication in distributed systems:

1. Java RMI (Remote Method Invocation): Enables direct Java-to-Java interaction through a tightly-coupled, high-performance communication layer. The client uses this method for inter-process communication.
2. JAX-WS (SOAP/RPC): Makes administrative functions available from a wider range of platforms if necessary by exposing a standardized, interoperable web service endpoint. The admin client uses this method to communicate with the server.

User Client: Java RMI

The User Client connects to the server using Java RMI, allowing it to invoke methods on server-side objects as if they were local. The communication between the User Client and the Server follows a standard RMI layered architecture.

• Application Layer: Represents the User Client and the Server's service coordination logic.
• Stubs: Acts as a client's local representative or proxy for the remote object. In RMI, a stub for a remote object implements the same set of remote interfaces that a remote object implements.
• Skeletons: Responsible for dispatching the call to the actual remote object implementation.
• Remote Reference Layer: Determines how the remote object is invoked which could be determined based on replication, activation, reference behavior, etc.
• Transport Layer: Manages the low level network implementation.

Admin Client: JAX-WS (SOAP/RPC)

JAX-WS is the protocol is used by the Admin Client. This is more standardized and interoperable than RMI. An administrative contract (WSDL) is created between the server and the client. A dynamic proxy is established by the Admin to facilitate communication between server's web service endpoint and SOAP/XML.

1. WSDL to Java: The client uses the server's published WSDL (Web Services Description Language) to generate a Service Endpoint Interface.
2. Get Proxy: The client uses the generated service class to request a proxy instance that implements the RPCServiceInterface.
3. Invoke Method: When an admin function like createBook(book) is called on the proxy instance, the parameters (JAXB-generated class instances) are passed to it.
4. SOAP Request/Response: The proxy serializes the method call into a SOAP XML request and sends it to the server's Endpoint URL. The server processes the request and returns a SOAP response.
5. Return Value: The proxy deserializes the SOAP response back into a Java object and returns it to the client application.

Features

Area	User Client (RMI)	Admin Client (RPC)	Server
Core Function	Bookstore Browser	Inventory Management	Application & Data Engine
Data Rights	Read-Only	CRUD	System of Record
Book Operations	View, Search, Check Stock	Create, Update, Delete	Expose All Ops
Bulk Data	Not Supported	CSV Upload	Bulk Insert Endpoint
Protocol	RMI Consumer	SOAP/RPC Consumer	RMI & SOAP Provider
DB Access	None (via API)	None (via API)	Direct (JDBC)

GUIs

User Client (RMI)

For browsing and searching the book catalog.

Admin Client (RPC)

For managing the bookstore inventory (CRUD operations).

Project Setup

1. Clone the Repository

   git clone git git@github.com:shama-llama/distributed-bookstore.git
   cd distributed-bookstore

2. Build Modules

   # Build server
   mvn clean install -f bookstore-server/pom.xml
   
   # Build admin client
   mvn clean install -f bookstore-admin/pom.xml
   
   # Build user client
   mvn clean install -f bookstore-user/pom.xml

Database Setup

1. Install MariaDB

   sudo dnf install mariadb-server

2. Start MariaDB service

   sudo systemctl start mariadb

3. Secure Installation

   sudo mysql_secure_installation

4. Create Bookstore

   mysql -u root -p
   
   CREATE DATABASE bookstore DEFAULT CHARACTER SET utf8mb4 COLLATE     utf8mb4_unicode_ci;

5. Create Books

   USE bookstore;
   
   CREATE TABLE books (
       isbn VARCHAR(13) PRIMARY KEY,
       title VARCHAR(255) NOT NULL,
       author VARCHAR(255) NOT NULL,
       year INT NOT NULL,
       price DECIMAL(10,2) NOT NULL,
       quantity INT NOT NULL DEFAULT 0
   );

6. Update DB Configuration

   Edit bookstore-server/src/main/resources/db.properties:

   db.url=jdbc:mysql://localhost:3306/bookstore
   db.user=root
   db.password=root_password

Running the Application

1. Start the RMI Server

   cd bookstore-server
   mvn exec:java -Dexec.mainClass="rmi.RMIServer"

   The RMI server will start on port 1099.

2. Start the RPC Server

   cd bookstore-server
   mvn exec:java -Dexec.mainClass="rpc.RPCServer"

   The RPC server will start on port 8080.

3. Run the Admin Client

   cd bookstore-admin
   mvn exec:java -Dexec.mainClass="AdminClient"

4. Run the User Client

   cd bookstore-user
   mvn exec:java -Dexec.mainClass="UserClient"

Troubleshooting

• MariaDB must be running for the apps to work: sudo systemctl status mariadb.
• Change the database credentials in db.properties.
• Create the bookstore database and books table before running.
• Check if ports 1099 and 8080 are being used.
• Clear Maven cache if you're getting build errors: mvn clean.
• RPC server must be running when building admin client.

License

This project is licensed under the terms of the MIT open source license.