Unlocking The Web – Navigating the World of Web Services

What is a Web Service?

At its core, a web service is a versatile software element facilitating interoperable machine-to-machine interactions across networks. These interactions are carried out using XML-based information exchange systems over the Internet, enabling seamless application-to-application communication using collection of standards or protocols.

 

Web Services in Simple Terms

In simpler terms, a web service encompasses fundamental functions:

  • Operates on a server system.
  • Connects over the internet or intranet networks.
  • Utilizes standardized XML messaging for communication.
  • Compatible with any operating system or programming language
  • Self-describes through standard XML language.
  • Discoverable through a straightforward location method

How Web Services Work

The functionality of web services is supported by key components, including:

  • Service Provider: Creates and offers specific services over the internet or a network. They publish the service, making it accessible to others who want to use it.
  • UDDI (Universal Description, Discovery, and Integration): Acts as a digital directory for web services, allowing service providers to list their services and providing a way for service consumers to discover and locate these services based on their descriptions and specifications.
  • WSDL (Web Services Description Language): A standardized language used to describe the interface and functionality of a web service. It provides a clear and structured way for service consumers to understand how to interact with a particular web service.
  • Web Service: A software component or application that can be accessed over the internet using standardized protocols. It allows different systems to communicate and share data or functionality, often over HTTP.
  • Service Consumer: An application that makes use of a web service. It sends requests to the service provider to access specific functions or retrieve data offered by the service.

Web Services Life Cycle

About WSDL

Imagine searching for a restaurant without knowing its location or menu. Similarly, WSDL (Web Services Description Language) acts as a map for web services. It guides the client to the service’s location and functionality, providing essential information on how to connect and interact with the web service.

  • Can you use a web service if you don’t know where it is? No, the client needs to know the location.
  • What else does the client need to know? The client needs to understand what the web service does.
  • How does the client learn these things? Through WSDL (Web Services Description Language).
  • What’s WSDL? WSDL is like a manual in XML format, detailing the web service’s location and capabilities.

WSDL Elements

WSDL includes elements such as <message>, defining data pieces for web service operations, <portType>, listing the operations offered, and <binding>, specifying communication details.

Web Service Types

SOAP (Simple Object Access Protocol)

SOAP operates by transferring XML data as SOAP Messages, consisting of an Envelope element, a header, a body, and an optional Fault element for reporting errors.

SOAP Message Components

   

The Envelope Element: 

Description: The Envelope is like a container for the SOAP message. It wraps everything in a SOAP message. 

Role: It tells the recipient that this is a SOAP message. 

The Header Element: 

Description: The Header is like a special instruction section. It can contain extra information that helps with processing the message. 

Role: It provides additional details or instructions for the message. 

The Body Element: 

Description: The Body holds the main content of the message. It contains the actual data or information being sent. 

Role: It carries the essential payload of the message. 

The Fault Element (Optional): 

Description: The Fault element is used to report errors if something goes wrong with the message. 

Role: It’s optional but helps in communicating issues or exceptions.

RESTful Web Services

REST (Representational State Transfer) is a scalable way to share data between applications over the web. It employs HTTP and involves resources, request verbs, request headers, request and response bodies, and response status codes.

REST Message Components  

Resources

  • Resources are like pieces of information or data, such as an employee record or a product listing. 
  • Each resource is identified by a unique URL, like http://application.url.com/employee/1234, where “/employee/1234” represents a specific employee’s record. 

Request Verbs: 

  • Request verbs are the actions you want to perform on resources. 
  • The most common verb is GET, which is used to read data from a resource. 
  • Other verbs include POST, PUT, DELETE. 

Request Headers:

  • Request headers are additional instructions sent with your request. 
  • They provide extra details about how the request should be handled. 
  • For example, headers might specify the format of the response or include authentication information.

Request Body:

  • The request body carries data sent with POST or PUT requests. It contains the information you want to add or modify in the resource. 
  • For instance, when adding a new employee, the request body would include their details, like name and contact information. 

Response Body: 

  • The response body is where the server provides the requested data. 
  • If you’re GETting employee details, the response body might contain that information in a format like XML or JSON.
  • It’s the heart of the server’s response to your request.

Response Status Codes:

  • Response status codes are like short messages from the server. They tell you how the server handled your request. 
  • For example, a 200 status code means “OK” and indicates a successful operation, while a 404 code means “Not Found” and suggests the requested resource doesn’t exist.

CICS Web Services

Introduction to CICS Web Services

CICS TS Server introduces a Web Service Support component enabling the transformation of traditional CICS programs into message-driven ‘services.’ This transformation allows these programs to be accessible to ‘service consumers’ within an enterprise.

Integration with Modern Technologies

CICS Web Services serve as a bridge between traditional mainframe systems and modern web-based applications. This integration facilitates the participation of mainframe applications in the world of web services, simplifying connections with other systems.

Exposing Mainframe Capabilities

CICS Web Services enable the exposure of functionalities and data stored in mainframe applications as web services. This means that applications, irrespective of their platform or technology, can access and utilize mainframe resources.

Standard Protocols

CICS Web Services typically use standard web protocols like HTTP and HTTPS for communication, ensuring interoperability and compatibility with a wide range of systems and programming languages.

Scalability and Accessibility

By enabling mainframes to provide web services, organizations can leverage robust and scalable mainframe resources to handle web-based workloads. This extension enhances the lifespan and value of existing mainframe investments.

Modernization

CICS Web Services play a pivotal role in modernizing legacy mainframe systems. They facilitate the gradual transition to more contemporary architectures and interfaces while leveraging existing mainframe assets.

CICS Web Services Flow

CICS Web Services Components

CICS Web Services involve components such as Service Provider, UDDI, WSDL, Web Service, and Service Consumer, working together to create a seamless web service environment.

CICS Set Up for Web Services

Setting up CICS for web services involves creating TCPIPSERVICE and PIPELINE resource definitions, installing them, generating the wsbind file using WSDL files, and publishing the WSDL files to service requester clients.

In conclusion, understanding web services, their types, integration with CICS, and the necessary configurations opens up a world of possibilities for seamless and modernized communication in today’s technologically diverse landscape.