What is WSDL in web services?

WSDL stands for Web Services Description Language, an XML document that describes the operations and endpoints of a SOAP web service.

Is WSDL used with REST APIs?

No. WSDL is primarily used with SOAP-based web services. RESTful services use OpenAPI/Swagger for documentation.

What is WSDL? | FullStackPrep.Dev

💡 Concept Name

WSDL (Web Services Description Language) – An XML-based language used for describing the functionality offered by a web service.

📘 Quick Intro

WSDL defines what a web service does, how to access it, and where it can be found. It enables tools to generate client/server stubs automatically.

🧠 Analogy / Short Story

Think of WSDL like a restaurant menu. It tells you what’s available (operations), the ingredients (input/output), and how to place an order (bindings).

🔧 Technical Explanation

📄 Written in XML format.
📌 Describes operations (methods), messages, and endpoints.
🔌 Supports binding protocols like SOAP or HTTP.
🔍 Used for contract-first web service development.
🧰 Tools like wsdl.exe, svcutil in .NET can generate code from WSDL.

🎯 Purpose & Use Case

✅ Enables client code generation for SOAP web services.
✅ Used in service registries for discovery and binding.
✅ Ensures strict service contracts in SOA environments.

💻 Real Code Example

<definitions name="CalculatorService"
             targetNamespace="http://example.com/calculator"
             xmlns="http://schemas.xmlsoap.org/wsdl/"
             xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
             xmlns:xsd="http://www.w3.org/2001/XMLSchema">

    <message name="AddRequest">
        <part name="a" type="xsd:int"/>
        <part name="b" type="xsd:int"/>
    </message>

    <message name="AddResponse">
        <part name="result" type="xsd:int"/>
    </message>

    <portType name="CalculatorPortType">
        <operation name="Add">
            <input message="tns:AddRequest"/>
            <output message="tns:AddResponse"/>
        </operation>
    </portType>
</definitions>

📝 MCQs

Q1. What does WSDL stand for?

Web SOAP Deployment List
Web Services Definition Language
Web Services Description Language
Wide Service Deployment Language

Q2. What format is WSDL written in?

YAML
JSON
XML
CSV

Q3. Which protocol is commonly associated with WSDL?

FTP
HTTP
SOAP
SMTP

Q4. What tool can generate code from WSDL in .NET?

dotnet-wsdl
xsd.exe
svcutil
cli-tool

Q5. What is defined inside WSDL's 'portType'?

Data types
Endpoints
Operations
Bindings

Q6. What section of WSDL describes the message types?

binding
port
service
message

Q7. Is WSDL used in RESTful APIs?

Yes
No
Sometimes
Only in ASP.NET Core

Q8. What file extension does WSDL usually have?

.xml
.soap
.wsdl
.xsd

Q9. Can a WSDL define multiple operations?

No
Yes
Only in SOAP 1.2
Only with .NET

Q10. What is the main role of WSDL?

Deploy services
Serialize JSON
Define service contract
Run test scripts

💡 Bonus Insight

Though WSDL is mainly used in SOAP-based services, understanding it helps in working with legacy systems and enterprise-level integrations.

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What is WSDL?