Knowledge of Web Services

1. What are Web Services?

Web Services are software systems designed to support interoperable machine-to-machine communication over a network (usually the Internet). They enable different applications—written in different languages and running on different platforms—to communicate and share data with each other.

In simple terms: Web Services are like bridges that allow different software systems to "talk" to each other over the web.

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2. Why Should Business Analysts Understand Web Services?

Reason	Why It Matters
Requirement Gathering	Understand data flow between systems to capture accurate requirements.
Process Design	Design efficient workflows that involve system communication.
Communication with Developers	Speak clearly about integration needs and system interactions.
API and Data Mapping	Work with APIs to connect systems, define data mapping.
Testing and Validation	Validate whether systems exchange data as expected.

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3. Key Concepts of Web Services

Concept	Description
API (Application Programming Interface)	Set of rules that allows applications to communicate.
REST (Representational State Transfer)	Lightweight, fast web service using HTTP.
SOAP (Simple Object Access Protocol)	Protocol for web services using XML-based messages.
Endpoint	URL where the web service is accessed.
Request and Response	Communication model: client sends request, server responds.
JSON (JavaScript Object Notation)	Lightweight data format often used in REST APIs.
XML (eXtensible Markup Language)	Data format commonly used in SOAP services.

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4. Types of Web Services

Type	Description	Use Case
SOAP Web Services	Standard protocol, uses XML for messages.	Financial transactions, complex operations.
RESTful Web Services	Uses HTTP methods (GET, POST, PUT, DELETE).	Modern web apps, mobile apps, simple integrations.
JSON-RPC and XML-RPC	Remote procedure calls encoded in JSON or XML.	Lightweight services, internal system calls.

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5. How Do Web Services Work?

Basic Flow:

scssCopyEdit[Client System]  ---> (Request) --->  [Web Service/API]  ---> (Response) --->  [Client System]

Example:

• An eCommerce app (Client) requests order data.

• The Order Management System (Web Service) sends the order data back.

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6. HTTP Methods Used in REST APIs

HTTP Method	Purpose	Example
GET	Retrieve data.	GET /orders/123 (Fetch order #123 details)
POST	Create new data.	POST /orders (Create a new order)
PUT	Update existing data.	PUT /orders/123 (Update order #123)
DELETE	Delete data.	DELETE /orders/123 (Delete order #123)

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7. Sample REST API Call Example (JSON)

Request (GET Order Details):

vbnetCopyEditGET /orders/123 HTTP/1.1
Host: api.example.com
Authorization: Bearer <token>

Response (Order Data in JSON):

jsonCopyEdit{
  "order_id": 123,
  "customer_name": "John Doe",
  "items": [
    { "product": "Laptop", "quantity": 1, "price": 1000 }
  ],
  "status": "Shipped"
}

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8. SOAP Web Service Example (XML)

Request:

xmlCopyEdit<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope/">
  <soap:Body>
    <GetOrderDetails xmlns="http://example.com/orders">
      <OrderID>123</OrderID>
    </GetOrderDetails>
  </soap:Body>
</soap:Envelope>

Response:

xmlCopyEdit<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope/">
  <soap:Body>
    <Order>
      <OrderID>123</OrderID>
      <CustomerName>John Doe</CustomerName>
      <Status>Shipped</Status>
    </Order>
  </soap:Body>
</soap:Envelope>

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9. Benefits of Web Services

Benefit	Explanation
Interoperability	Connect different platforms and technologies.
Reusability	Use same service for multiple applications.
Scalability	Easily scale services independently.
Efficiency	Automate processes and reduce manual work.
Real-time Integration	Data is updated and shared instantly.

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10. Challenges and Considerations

Challenge	Consideration
Security	Ensure encryption, authentication, and authorization (e.g., OAuth2, API Keys).
Error Handling	Manage failed requests with proper error messages.
Data Privacy	Handle sensitive data carefully (GDPR, compliance).
Performance	Ensure services are fast and reliable.
Version Control	Manage changes in API versions over time.

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11. Common Tools for Working with Web Services

Tool	Purpose
Postman	Testing and documenting APIs.
Swagger (OpenAPI)	Designing, documenting, and testing APIs.
SoapUI	Testing SOAP and REST web services.
JMeter	Load testing APIs for performance.
Fiddler / Charles Proxy	Debugging web traffic and API calls.

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✅ Summary Table

Aspect	Key Takeaways
Definition	Systems that allow apps to communicate over the web.
Types	REST, SOAP, RPC.
Key Terms	API, Endpoint, Request/Response, JSON, XML.
HTTP Methods	GET, POST, PUT, DELETE.
Benefits	Interoperability, Efficiency, Scalability.
Challenges	Security, Error Handling, Performance.
Tools	Postman, Swagger, SoapUI.