What is WSDL in Web Services ? Expert’s Top Picks | Free Guide Tutorial

• In this article you will get
• 1.Introducing WSDL
• 2.WSDL Enters
• 3.WSDL Ports
• 4.Operation Types
• 5.WSDL Messages
• 6.WSDL Bindings

Introducing WSDL

WSDL stands for a Web Services Description Language.WSDL is written in a XML.It is used to explain Web services.WSDL is also used to locate a Web services.WSDL is W3C recommendation.

WSDL Enters

A WSDL document is just simple XML document.It contains set of a definitions to explain a web service.WSDL document fulfills all above requirements:

Requirement 1: Where is service hosted?

Requirement 2: What protocol to use to talk to service?

Requirement 3: What are operations?

Requirement 4: What are parameters?

Requirement 5: What is data type of the messages?

WSDL Ports

The element is most important WSDL element.It explains a web service, the operations that can be performed, and messages that are involved.The element can be compared to function library (or a module, or a class) in the traditional programming language.

Operation Types

Type	Definition
One-way	The operation can receive the message but will not return response.
Request-response	The operation can receive the request and will return response.
Solicit-response	The operation can send request and will wait for response.
Notification	The operation can send message but will not wait for the response.
One-way operation type	The operation can receive message but will not return response.

WSDL Messages

The element explains the data elements of operation.Every message can consist of one or more parts.The parts can be compared to parameters of a function call in traditional programming language.

WSDL Types

The element explains the data type that are used by a web service.For maximum a platform neutrality, WSDL uses a XML Schema syntax to explain data types.

• Web service to be accessible to HTTP client, as well as to RMI client and a SOAP client.
• WSDL Bindings.
• The element explains the message format and protocol details for the each port.

Binding

Name:Can be anything

Type:Points to a port

Soap:Binding

Style:Rpc or document

Transport:Soap protocol to use

Operation:Explains each operation the service exposes

WSDL Bindings

The element offers specific details on how a portType operation will actually be transmitted over wire.The bindings can be made available by multiple transports, including the HTTP GET, HTTP POST, or SOAP.The bindings offer concrete information on what protocol is being used to transfer a portType operations.For SOAP protocol, binding is , and the transport is a SOAP messages on top of a HTTP protocol.WSDL 1.1 includes a built-in extensions for a SOAP 1.1.This enables to specify a SOAPspecific details, including the SOAP headers, SOAP encoding styles, and SOAPAction HTTP header.

The SOAP extension are elements include:

soap:binding

soap:operation

soap:body

Can specify a multiple bindings for single portType.

WSDL Services:

The element connects binding to an actual URL where a service is available.A service element explains a Web service as a collection of port elements.A port element explains a specific network address for binding.The sample below shows basic outline of a service that supplies address for a SOAP binding:

• The ServiceName sets a name of the service.
• The PortName sets a name of the specific address.
• The BindingRef refers to a name of a binding element.
• The BindingRef must be a namespace qualified if the targetNamespace for WSDL definitions element is not the same as a default namespace.

Conclusion

WSDL is an XML format for explaining network services as a set of endpoints operating on a messages containing either document-oriented or procedure-oriented information.The operations and messages are explained abstractly, and then bound to a concrete network protocol and message format to explain an endpoint.