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

1. Cloud Computing: 21
Basic Concept of WSDL Modeling
Prof Neeraj Bhargava
Vaibhav Khanna
Department of Computer Science
School of Engineering and Systems Sciences
Maharshi Dayanand Saraswati University Ajmer

2. 3.2 Modeling a Web Service
 The Web Services Description Language (WSDL) has
become an ad hoc industry standard for describing a Web
service
 Simple Object Access Protocol (SOAP) has become an ad
hoc industry standard for accessing a Web service.
 WSDL Version 2 and SOAP Version 1.2 are endorsed by the
World Wide Web Consortium (W3C).
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3. 3.2.1 Basic Concept of WSDL Modeling
 WSDL is “an XML format for describing network services as a
set of endpoints operating on messages containing either
document-oriented or procedure-oriented information”
(http://www.wsdl.org).
 It is created to define the public interface of a Web service,
including its functionalities and how to invoke them.
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4. 3.2.1 Basic Concept of WSDL Modeling
 A WSDL document defines the protocol bindings and
message formats required to interact with the Web services
listed in its directory.
 The supported operations and messages are described
abstractly, associated with a concrete network protocol and
message format.
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5. WSDL and SOAP (Interface and
Protocol)
 WSDL provides a notation to answer the following three
questions:
 What is the service about?
 Where does it reside?
 How can it be invoked? (i.e., what, where, and how)
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6. WSDL and SOAP (Interface and
Protocol)
 WSDL is often used in combination with SOAP and XML
schema to define a Web service over the Internet.
 A client program reads a WSDL document to understand
what it can do; data types used are embedded in the
WSDL file in the form of XML schema.
 The client then uses SOAP to actually invoke the
functions listed in the WSDL document.
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7. 3.2.1 Basic Elements of WSDL
 A Web service is defined as a set of
ports, each publishing a collection of
port types that bind to network
addresses using a common binding
mechanism.
 Every port type is a published
operation that is accessible through
messages.
 Messages are in turn categorized into
input messages containing incoming
data arguments and output messages
containing results.
 Each message consists of data
elements; every data element must
belong to a data type, either an XML
Schema Definition (XSD) simple type
or a XSD complex type.
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8. Sample Segment of a WSDL Document
 The tag portType defines “productPrice” as
the name of a port, and “getPrice” as the
name of an operation.
 The “getPrice” operation defines an input
message named “getPriceRequest” and an
output message “getPriceResponse.”
 The tag message defines the parameters
and associated data types of the input
message and the output message.
 Compared to traditional programming
language, “productPrice” maps to a
function library, “getPrice” maps to a
function with “getPriceRequest” as the
input parameters and “getPriceResponse”
as the return parameters.
<message name="getPriceRequest">
<part name="productid"
type="xs:string"/></message>
<message name="getPriceResponse">
<part name="value"
type="xs:string"/></message>
<portType name="productPrice">
<operation name="getPrice">
<input
message="getPriceRequest"/>
<output
message="getPriceResponse"/>
</operation>
</portType>
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9. Operation Types Defined in WSDL
 WSDL defines four types of operations: one-way, request-
response, solicit response, and notification.
 The one-way operation receives a message but does not
return a response message.
 The request-response operation receives a request and
returns a response.
 The solicit-response operation sends a request for a
response.
 The notification operation sends a message but does not
wait for a response.
 The request-response type is the most frequently used
operation type.
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10. Assignment
• What is WSDL. Explain the basic elements of
WSDL