Question

Fill in the blanks for each of the following statements: a) When messages are sent between an application and a web service using SOAP, each message is placed in a(n) ___. b) A web service in Java is a(n) ___ it does not need to implement any interfaces or extend any classes. c) Web service requests are typically transported over the Internet via the ___ protocol. d) To set the exposed name of a web method, use the __ element of the @WebMethod annotation. e) ___ transforms an object into a format that can be sent between a web service and a client.

Short answer

a) envelope; b) POJO; c) HTTP; d) operationName; e) serialization.

Step-by-step solution

Understanding SOAP Message Structure

SOAP (Simple Object Access Protocol) messages are typically placed inside an 'envelope.' This is the container where the headers and body of the message are defined, allowing structured communication between applications.

Identifying Java Web Service

In Java, a web service is often referred to as a 'POJO' (Plain Old Java Object). This is because Java web services do not need to implement any special interfaces or extend a specific class, allowing for more straightforward development.

Recognizing Web Service Transport Protocols

Web services are usually transported over the Internet using the HTTP (Hypertext Transfer Protocol). HTTP is a foundational protocol of the web that allows communication between clients and servers.

Customizing Web Method Names

In Java web services, the @WebMethod annotation is used to expose methods. To set a custom name for a web method, you use the 'operationName' element within this annotation.

Understanding Data Serialization

Serialization is the process that transforms an object into a format suitable for transport over a network. In web services, serialization usually refers to converting an object into XML or JSON that can be sent between client and server. This process is often simply termed 'serialization.'

Key concepts

SOAP Messages

SOAP, which stands for Simple Object Access Protocol, is an essential protocol used in web services for exchanging information between applications. Every SOAP message is encapsulated in an envelope. This envelope acts as a universal container, providing a standard framework to define the message's structure.
Within the SOAP envelope, you will find two primary parts:

• Header: This section contains optional metadata related to the message. It includes details on authentication, transactions, or other routing information essential for handling the message properly.
• Body: The core of the SOAP message where the actual data or instructions are contained. It provides the information intended for the receiving application or service.

These messages are designed to be platform-independent, ensuring communication across diverse systems. With XML as its base, SOAP messages are easily readable and structured, which makes it a reliable choice for enterprise solutions.

HTTP Protocol

HTTP, or Hypertext Transfer Protocol, is a vital part of web communication. It serves as the foundation for transferring data over the web, and it is widely used in transporting web service requests, such as those in SOAP.
Operating on a client-server model, HTTP allows a web browser (client) to request resources from a web server. The server processes these requests and sends back a response, which could be a web page, an image, or data from a web service.
HTTP supports multiple methods of communication, like:

• GET: Used to retrieve data from the server.
• POST: Sends data to the server to create or update resources.
• PUT: Updates existing resources on the server.
• DELETE: Removes resources from the server.

HTTP is stateless, meaning each request from a client is treated independently. This independence contributes to the scalability and efficiency of web services.

POJO (Plain Old Java Object)

A POJO, or Plain Old Java Object, is an uncomplicated Java object that does not require any pre-set conditions or frameworks. In Java web services, POJOs play a significant role as they provide a straightforward way to develop web services without adhering to strict conventions.
When you create a web service in Java using a POJO, you don't need to implement any specific interface or extend a superclass. This flexibility allows developers to focus on business logic without getting bogged down by complex setups.
POJOs in Java web services benefit from:

• Simplicity: The absence of restrictions makes POJOs easier to write and maintain.
• Reusability: They can be used across various applications, enhancing code reuse.
• Portability: Since POJOs aren't tied to specific frameworks, they can be easily transferred across different environments.

POJOs are instrumental in maintaining clean and efficient code, making them a popular choice for Java developers.

Serialization

Serialization is the crucial process that enables the transformation of an object's state to a format suitable for storage or transmission. In the context of web services, serialization often refers to converting an object into XML or JSON, both of which are lightweight and easily accessible formats.
This transformation is essential for web services, as it allows data to be efficiently shared and exchanged between different systems, be they client or server.
Key benefits of serialization include:

• Data Exchange: Facilitates seamless communication by presenting data in a universally understandable format.
• Persistence: Enables objects to be stored and retrieved later in their original state.
• Compatibility: Ensures that objects can be reconstructed across different programming environments.

Deserialization is the reverse process, where the formatted data is used to reconstruct the original object. Together, serialization and deserialization form the backbone of data interchange in web services.