SOAP vs. WSDL — What's the Difference?
By Tayyaba Rehman — Published on January 1, 2024
SOAP is a protocol for exchanging structured information in web services, while WSDL is an XML format for describing network services.
Difference Between SOAP and WSDL
Table of Contents
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Key Differences
SOAP, or Simple Object Access Protocol, is a standard protocol for sending and receiving web service requests and responses. WSDL, or Web Services Description Language, is used to describe the functionalities offered by a web service.
The role of SOAP is to define a standardized format for messages, ensuring that they can be understood in heterogeneous environments. WSDL complements SOAP by providing a machine-readable description of how the service can be called, what parameters it expects, and what data structures it returns.
A SOAP message is essentially an XML document that follows a specific schema, containing a header and a body that includes the request data. A WSDL file is an XML document that describes the service endpoint, its operations, and the message format required to communicate with it.
While SOAP deals with the communication part of a web service, defining how messages are transmitted, WSDL deals with the descriptive aspect, defining the service interface and structure. They often work together in web service architecture, with WSDL being used to generate SOAP messages.
Error handling in SOAP is standardized, with a specific element in the message structure dedicated to error messages. WSDL, on the other hand, defines what errors are possible in the context of a web service operation but does not handle the errors themselves.
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Comparison Chart
Definition
A protocol for message exchange in web services.
An XML format for describing network services.
Function
Defines message structure for communication.
Describes how to interact with the web service.
Usage
Used for sending and receiving requests/responses.
Used to detail operations and messages for clients.
Composition
An XML-based message protocol with envelope structure.
A descriptive document outlining service interfaces.
Relationship with Other Services
Independent of service description.
Often used to generate SOAP messages automatically.
Compare with Definitions
SOAP
A protocol for exchanging XML-based messages.
The web service uses SOAP to handle client requests.
WSDL
Defines operations, messages, and protocols for web services.
WSDL allows for automatic generation of client-side proxies.
SOAP
Can operate over multiple transport protocols like HTTP, SMTP.
SOAP messages can be sent via HTTP POST for web service operations.
WSDL
Abstracts the functionality of the web service from its implementation.
WSDL enabled the team to mock the service for testing without the actual implementation.
SOAP
Follows a strict structure with an envelope, header, and body.
The developer inspected the SOAP envelope for debugging purposes.
WSDL
Specifies the location of the service and the operations it offers.
Developers refer to the WSDL to know where and how to send requests.
SOAP
A cleansing agent, manufactured in bars, granules, flakes, or liquid form, made from a mixture of the sodium salts of various fatty acids of natural oils and fats.
WSDL
An XML document describing a web service's interface.
The client application parsed the WSDL to understand the service’s operations.
SOAP
A metallic salt of a fatty acid, as of aluminum or iron, that is not water soluble and may be used as a lubricant, thickener, or in various coating applications, ointments, or disinfectants.
WSDL
Used for automated tools to generate code for web service calls.
The WSDL file was essential for setting up the service stub in the development environment.
SOAP
(Slang) Money, especially that which is used for bribery.
SOAP
A soap opera.
SOAP
To treat or cover with or as if with soap.
SOAP
(Informal) To softsoap; cajole.
SOAP
(Slang) To bribe.
SOAP
(chemistry) A metallic salt derived from a fatty acid, commonly used in cleaning products.
SOAP
Some other substance, often a detergent or another surfactant, able to mix with both oil and water, used for cleaning.
I tried washing my hands with soap, but the stain wouldn't go away.
SOAP
(slang) Money, specially when used as a bribe.
SOAP
A soap opera.
SOAP
(countable) A solid masonry unit or brick reduced in depth or height from standard dimensions.
SOAP
(transitive) To apply soap to in washing.
Be sure to soap yourself well before rinsing.
SOAP
To cover, lather or in any other form treat with soap, often as a prank.
Those kids soaped my windows!
SOAP
To be discreet about (a topic).
SOAP
To flatter; to wheedle.
SOAP
A substance which dissolves in water, thus forming a lather, and is used as a cleansing agent. Soap is produced by combining fats or oils with alkalies or alkaline earths, usually by boiling, and consists of salts of sodium, potassium, etc., with the fatty acids (oleic, stearic, palmitic, etc.). See the Note below, and cf. Saponification. By extension, any compound of similar composition or properties, whether used as a cleaning agent or not.
The purifying action of soap depends upon the fact that it is decomposed by a large quantity of water into free alkali and an insoluble acid salt. The first of these takes away the fatty dirt on washing, and the latter forms the soap lather which envelops the greasy matter and thus tends to remove it.
This soap bubble of the metaphysicians.
SOAP
To rub or wash over with soap.
SOAP
To flatter; to wheedle.
SOAP
A cleansing agent made from the salts of vegetable or animal fats
SOAP
Money offered as a bribe
SOAP
Street names for gamma hydroxybutyrate
SOAP
Rub soap all over, usually with the purpose of cleaning
SOAP
Encapsulates call and response in web service communication.
SOAP ensures that the message format is understood across different platforms.
SOAP
Includes built-in error handling with fault elements.
The SOAP fault element provided clarity on the server error.
Common Curiosities
What does SOAP stand for?
SOAP stands for Simple Object Access Protocol.
What is WSDL used for?
WSDL is used to describe the services a web service provides and how to invoke them.
Does SOAP define service operations?
No, SOAP does not define operations; it's a protocol for message exchange.
What does WSDL stand for?
WSDL stands for Web Services Description Language.
Can SOAP be used without WSDL?
Yes, SOAP can be used without WSDL, but WSDL simplifies the interaction with the service.
Is WSDL necessary for a web service?
While not necessary, WSDL is highly recommended as it provides a clear contract for service interaction.
Does WSDL specify service implementation?
No, WSDL specifies the public interface, not the implementation details.
Can WSDL describe RESTful web services?
While possible, WSDL is typically used with SOAP services; WADL is more common for REST.
What is a SOAP envelope?
It's the root element of a SOAP message, containing the header and body.
Is SOAP tied to HTTP?
No, SOAP can work over various transport protocols like HTTP, SMTP, TCP, and more.
What type of operations can WSDL describe?
WSDL can describe both synchronous and asynchronous operations.
Can WSDL be used with protocols other than SOAP?
Yes, WSDL can be used to describe web services that use other protocols besides SOAP.
How does WSDL facilitate web service consumption?
WSDL allows automated tools to generate client-side code for service invocation.
Are SOAP messages always XML?
Yes, SOAP messages are always formatted as XML documents.
Is SOAP stateful or stateless?
SOAP can be both stateful and stateless depending on the service's design.
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Written by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
