Question

Write a currency exchange service using Jini technology. This currency exchange service simply does one function: It exchanges the currency of one country to the currency of another country. The exchange rate can be dynamically loaded from an on-line resource or can be just statically loaded from a file. Create the public interface, service proxy, back-end interface and service implementation.

Short answer

Develop the public interface, service proxy, back-end interface, and service implementation using Jini technology.

Step-by-step solution

Define the Problem Scope

Begin by understanding the requirements. The task is to create a currency exchange service using Jini technology. This service must provide conversion between two different currencies, loading exchange rates dynamically from an online resource or statically from a file.

Create the Public Interface

Develop a public interface that clients can use to interact with the currency exchange service. The interface should include a method for exchanging currency, accepting parameters like the source and target currencies, and the amount to convert.

Design the Service Proxy

The service proxy acts as an intermediary between clients and the back-end service. Implement the proxy to translate client method calls into service requests and manage communication with the back-end components.

Develop the Back-End Interface

Create a back-end interface to define operations that the service will perform. This includes methods to connect to a data source for exchange rates and perform the currency conversion calculations.

Implement the Service Logic

Implement the service logic by creating classes based on the back-end interface. Load exchange rates either from an online API or a static file, and use them to compute conversion values for client requests.

Integrate Jini Technology

Deploy the service using Jini technology to enable lookup and discovery in the network. Ensure the service supports necessary Jini features like leasing and remote events for seamless integration.

Key concepts

Currency Exchange Service

At the heart of a currency exchange service is the ability to convert money from one country's currency to another. Jini technology can make this process more dynamic and efficient. The main task is to manage conversion rates, which can be sourced either online for real-time accuracy or from static files to save on data costs.
This service enables users to easily determine how much money they will receive when they exchange one type of currency for another. This is crucial for travelers, businesses, and investors who frequently deal with multiple currencies. Key features of a currency exchange service include:

• Dynamic updating of exchange rates from online resources, ensuring up-to-date conversions.
• Fallback on static files for constant rates to allow offline operations.
• Simple and user-friendly interface to prevent confusion over exchange processes.

With these capabilities in place, the service provides both accuracy and accessibility to users looking to perform currency conversions.

Service Proxy Design

Service proxy design plays an important role in connecting the client with the back-end service seamlessly. A proxy acts like a messenger, efficiently handling communication and data exchange between users and the service logic.
The service proxy's main task is to:

• Translate client interactions into valid service requests.
• Handle network communication effortlessly without user intervention.
• Provide a layer that can ensure security and validate incoming requests.

Designing a robust service proxy involves making sure it can deal with network interruptions, manage data effectively, and provide reliable connectivity to the back-end systems. For Jini technology, the proxy facilitates discovery and interaction with the service, making sure users or client applications can find and connect to the right service efficiently.

Interface Development

Interface development is all about creating a public interface that offers users a simple way to interact with the service. This interface doesn't show the complex operations behind the scenes. Instead, it provides clear and straightforward methods for using the currency exchange service.
When developing an interface for a currency exchange service, consider the following:

• Ensure methods are intuitive, like `convertCurrency(source, target, amount)`.
• Provide clear parameter definitions to avoid user mistakes.
• Implement error handling to manage incorrect or invalid requests gracefully.

For a Jini-powered service, the interface is crucial for offering interactions that are both easy to use and powerful, allowing clients to initiate currency exchanges with minimal fuss and maximum clarity.

Remote Service Implementation

Remote service implementation is the process of ensuring that the currency exchange service can be accessed from anywhere over a network. This means making sure the service is stable, reliable, and secure even when accessed from remote locations.
Key considerations in remote service implementation include:

• Implementing secure protocols to protect sensitive data during transmission.
• Ensuring the service is highly available and can handle concurrent requests without downtime.
• Integrating remote invocation technology like Jini to facilitate service discovery and use.

The purpose of using Jini technology is to support these remote interactions by providing essential features such as leasing and event notification. This expands the service's reach, allowing it to support a diverse range of client applications and environments, ensuring that users can access it anytime, anywhere.