State whether each of the following is true or false. If false, explain why. a) All methods of a web service class can be invoked by clients of that web service. b) When consuming a web service in a client application created in NetBeans, you must create the proxy class that enables the client to communicate with the web service. c) A proxy class communicating with a web service normally uses SOAP to send and receive messages. d) Session tracking is automatically enabled in a client of a web service. e) Web methods cannot be declared static. A user-defined type used in a web service must define both get and set methods for any property that will be serialized. g) Operations in a REST web service are defined by their own unique URIs. h) \(\mathrm{A}\) SOAP-based web service can return data in \(\mathrm{JSON}\) format.

The Simple Object Access Protocol (SOAP) is a fundamental web services protocol known for its structured communication method using XML-based messages. It follows a strict specification ensuring that messages are exchanged in a predefined way across different platforms and programming languages.

SOAP is designed for operations that are distributed and decoupled, making it a reliable choice for enterprise-level web services that require high security and transactional reliability. The protocol utilizes WSDL (Web Services Description Language) files for describing the available service methods, making it easier for clients to understand how to interact with the service.

A typical SOAP message includes an envelope structure with an optional header and a mandatory body containing the information or function call. SOAP messages are widely considered to have more overhead due to their verbose XML format but are favored when standardized, action-oriented messaging is required.

RESTful web services adopt a different architectural approach called Representational State Transfer (REST). Unlike SOAP, RESTful services use the HTTP protocol's standard methods such as GET, POST, PUT, and DELETE for communication.

These services are stateless, meaning that each request from a client to a server must contain all the information needed to understand the request, and no client context is stored on the server between requests. With REST, web services are designed around resources, which are identified using URIs. By using different HTTP methods, various operations can be performed on the resources, which allows for a more intuitive and flexible interface.

RESTful services often communicate in both XML and JSON formats, with JSON being especially popular in web applications due to its lightweight nature and compatibility with JavaScript. This approach is well-suited to the needs of modern, fast-paced web environments.

A web service proxy class acts as an intermediary between the client application and the web service. This proxy class provides a local representation of the web service, allowing the client to invoke methods as if it were calling a local object.

Generation of these proxy classes is typically handled by the IDE or a separate tool. NetBeans, for instance, automatically creates proxy classes, freeing developers from manually writing the boilerplate code required for communication with the web service.

The proxy class abstracts the complexity of handling network connections, marshalling and unmarshalling of data, and managing SOAP messages if SOAP protocol is used. It ensures that the client can interact with the web service in a strongly-typed manner, thereby simplifying the development process and enhancing maintainability.