UNIT 2

Web Services: Uses in Detail (With Examples)

What are Web Services?

Web Services are software applications that allow communication between different
applications over the internet or intranet using standard protocols like HTTP, XML,
SOAP, REST, etc.
Think of them as messengers that help two systems (even if they're built using different
languages or platforms) talk to each other.

Major Uses of Web Services (Explained Simply)

1. Application Integration
Web services connect different applications running on various platforms or written in
different programming languages.
Example:
A Java-based inventory system can send data to a .NET-based billing system using web
services.

2. Business-to-Business (B2B) Interactions

Companies use web services to share information with their partners, vendors, or suppliers
in real-time.
Example:
An e-commerce website can use web services to automatically place orders to its supplier
whenever stock is low.

3. Platform Independence
Web services enable interaction between software programs regardless of the platform
(Windows, Linux, Mac) or language (Python, Java, C#).
Example:
A Python app on Linux can consume a web service created in Java running on Windows.

4. Cloud Computing and SaaS

Most cloud-based services (like Google Drive, Dropbox, Microsoft 365) expose web
services (usually REST APIs) for communication.
Example:
A mobile app uses Google Maps Web Services to display location or calculate distance.

5. Mobile Applications
Mobile apps (iOS, Android) often use web services to fetch data from a server, like weather
updates, stock prices, or user details.
Example:
Swiggy or Zomato apps use web services to get restaurant listings, menu details, and track
orders.

6. IoT Integration
Web services help IoT devices send or receive data to/from a central server.
Example:
A smart thermostat uses a web service to get weather data or send temperature readings to
the cloud.

7. E-Governance and Public Services

Governments use web services to share data between different departments like health,
transport, taxation, etc.
Example:
The Aadhaar API (India) is a web service that banks and telecom companies use for identity
verification.

8. Banking and Financial Services

Used to fetch real-time data like account balances, perform transactions, or generate
statements securely.
Example:
UPI and Internet banking portals use web services to perform fund transfers or retrieve
account information.

9. Automated Data Sharing

Web services help in automated data exchange between servers, systems, or apps without
manual effort.
Example:
A weather forecast site updates its satellite data every 10 minutes using web services from a
government meteorology department.

10. Microservices Communication

Modern applications follow microservice architecture, where each module (authentication,
search, cart) uses web services (often REST APIs) to communicate.
Example:
Amazon's website uses hundreds of microservices; when you search, add to cart, or place an
order, each action involves web service calls.

Conclusion
Web services are the backbone of modern internet communication, enabling data sharing,
automation, cross-platform integration, and real-time collaboration across applications,
devices, and organizations. Their uses range from daily apps to enterprise-level systems and
even government services.

Basics of Web Services

What is a Web Service?

A Web Service is a software application that enables two machines or applications to
communicate with each other over the internet using standard protocols like HTTP,
XML, SOAP, or REST.

Think of it like a waiter:

Just like a waiter takes your order to the kitchen and brings back your food, a web service
takes a request from one app, processes it (maybe with help from a database or another app),
and returns the response.

Key Features of Web Services:

Feature Description

Interoperable Can work across different platforms and programming languages.

Standardized
Uses HTTP, XML, SOAP, REST etc.
Protocols

Applications can communicate without needing to know much about

Loosely Coupled
each other.
Feature Description

Reusable Web services can be used again and again in different apps.

Components of a Web Service

1. Service Provider
o The system that offers the web service (e.g., a weather service).
2. Service Requester
o The system or app that calls or uses the web service (e.g., a mobile app
showing weather updates).
3. Service Registry (optional)
o A place where services are listed and discovered, like a phone book for web
services (example: UDDI).

Basic Web Service Protocols

Protocol Purpose

HTTP Used to send/receive messages over the web.

XML/JSON Format for sending structured data.

SOAP A protocol for exchanging structured info using XML.

A lightweight, flexible alternative to SOAP using standard HTTP methods

REST
(GET, POST, etc.).

How Does It Work? (Simple Flow)

1. The Client (a browser or mobile app) sends a request to the web service.
2. The Web Service processes the request (possibly querying a database).
3. The web service sends a response back to the client.

Example:
A weather app requests today's temperature from a web service. The service fetches the data
and sends it back to the app.

Types of Web Services

Type Description

SOAP Web Services Use SOAP protocol and XML. Heavier and more secure.

RESTful Web Use standard HTTP methods. Lightweight, faster, and more popular
Services today.

Real-life Examples
• Login with Google/Facebook – uses web services to verify user identity.
• Online payment – uses web services to communicate between merchant site and
bank.
• Flight booking – combines data from airlines, travel sites using web services.

Summary

Concept Quick Note

Web Service A method to connect systems over the web.

Protocols HTTP, XML, SOAP, REST

Use Cases App integration, APIs, cloud, banking, e-commerce

Popular Type RESTful Web Services

Here's a clear and student-friendly explanation of the following Web Services concepts:
• SOAP
• UDDI
• Orchestrating Web Services
• Securing Web Services

1. SOAP (Simple Object Access Protocol)

Definition:
SOAP is a protocol used for exchanging structured information in web services using
XML over HTTP or other protocols.

Key Features:
 • Platform & language independent.
• Uses XML to format messages.
• Supports complex operations like authentication, transactions.
• Can work over HTTP, SMTP, TCP, etc.

How SOAP Works:

1. SOAP Request: Sent by the client (formatted in XML).
2. SOAP Processor: Reads and processes the request.
3. SOAP Response: Returned by the service provider (also in XML).

SOAP Message Structure:

<soap:Envelope>
<soap:Header> ... </soap:Header>
<soap:Body>
<getWeather>
<city>Delhi</city>
</getWeather>
</soap:Body>
</soap:Envelope>

2. UDDI (Universal Description, Discovery, and Integration)

Definition:
UDDI is a registry where businesses can list and discover web services. It acts like a
telephone directory for web services.

Key Elements:
• White Pages – Company info (name, address).
• Yellow Pages – Services grouped by category.
• Green Pages – Technical info (WSDL file location, binding info).

Purpose:
• Service providers register their services.
• Service consumers search and find services.
• Enables discovery and integration of services.
 Example:
An airline registers its flight availability service. A travel website finds and integrates it using
UDDI.

3. Orchestrating Web Services

Definition:
Orchestration is the process of combining multiple web services into a single workflow to
perform a business process.

Example:
Booking a hotel might involve:
1. Search for hotels
2. Check availability
3. Make payment
→ All these are individual web services orchestrated into one process.

Tools/Technologies Used:
• BPEL (Business Process Execution Language) – Describes workflows.
• WS-BPEL – Standard language for web service orchestration.

Use Case:
In an e-commerce system, placing an order can involve inventory check, payment gateway,
and shipment — all orchestrated behind one “Buy Now” button.

4. Securing Web Services

Why Security is Important?

Web services often exchange sensitive data (passwords, payments, personal info), making
security crucial.

Security Mechanisms:

Technique Purpose

HTTPS (SSL/TLS) Encrypts data during transmission.

A SOAP-based security standard. Adds security tokens, digital

WS-Security
signatures.

Authentication Validates user identity (API keys, OAuth, tokens).

Technique Purpose

Authorization Controls what a user can access.

Input Validation Protects against injections, malicious input.

Message
Ensures the message content is unreadable to unauthorized users.
Encryption

Example:
When logging into a banking app, the credentials are sent via HTTPS, validated using
authentication tokens, and access is granted based on authorization roles.

Here’s a detailed and student-friendly explanation of:

• Grid-Enabled Web Services
• Semantic Web of Web Services
These are advanced concepts that extend the basic ideas of web services with high-
performance computing and intelligent automation.

1. Grid-Enabled Web Services

Definition:
Grid-enabled web services integrate grid computing with web services to allow sharing of
distributed resources (like CPU, storage, data, etc.) over the web in a standardized way.

Think of it like combining the power of multiple computers across different locations
and making them work together via web services.

What is Grid Computing?

Grid computing is a system that uses a network of loosely connected computers to perform
large-scale tasks, like data analysis, simulations, etc.

How Web Services Fit In:

• Web services provide a standard interface to access grid resources.
• Enables clients to submit tasks, retrieve results, or query available resources over
the internet.
 Use Case Example:
A researcher submits a genome analysis task through a web portal.
The task is distributed across grid resources in universities worldwide.
Web services manage this communication and return results.

Technologies Used:
• OGSA (Open Grid Services Architecture)
• Globus Toolkit – a middleware for building grid-enabled services.

Benefits:
• Access to high computational power
• Scalable and reliable
• Ideal for scientific research, big data, financial modeling

2. Semantic Web of Web Services

Definition:
The Semantic Web of Web Services refers to enhancing web services with machine-
understandable meaning (semantics) so that they can be automatically discovered,
invoked, composed, and executed by software agents.

It’s like teaching web services to "understand" what they do, so machines can interact
with them intelligently and autonomously.

What is Semantic Web?

Semantic Web (by Tim Berners-Lee) is an extension of the web where data has meaning
(semantics) and can be processed by machines.

Why Add Semantics to Web Services?

Traditional web services only describe how to use them, not what they do.
Semantic web services include metadata that describes their purpose, inputs, outputs, and
conditions, making them:
• Discoverable
 • Composable
• Executable by agents

Core Technologies:

Technology Purpose

OWL-S (Ontology Web Language for

Describes web services in semantic terms.
Services)

Semantic annotations for WSDL (standard service

WSDL-S / SAWSDL
descriptions).

RDF, OWL Ontology languages used to describe semantics.

Use Case Example:

A travel app searches for a “hotel booking service”.
Using semantic metadata, it understands available services (even with different names like
"reserve accommodation").
It composes and executes them automatically.

Benefits:
• Automation of discovery and execution.
• Interoperability across different domains.
• Dynamic composition of services.

Summary Comparison Table

Feature Grid-Enabled Web Services Semantic Web of Web Services

Combines grid computing with Adds machine-readable meaning to

Main Idea
web services web services

Share distributed computing Enable automated service discovery &

Purpose
resources execution

Used In Scientific computing, simulations Intelligent apps, automation agents

Key
OGSA, Globus Toolkit OWL-S, RDF, SAWSDL
Technologies
Feature Grid-Enabled Web Services Semantic Web of Web Services

Benefit High performance Smart integration