1. Introduction
In this tutorial, we’ll compare SOAP and WSDL.
WSDL stands for Web Services Descriptive Language, whereas SOAP stands for Simple Object Access Protocol. We’ll investigate some valuable and exciting concepts related to SOAP and WSDL.
2. What Is a Web Service?
A web service is a standardized way of communicating between different software applications over the internet. It allows different systems, developed using different programming languages, to exchange data. The applications run on different platforms and seamlessly communicate with each other using web services.
Web services perform various tasks, such as data exchange, file transfer, business logic execution, and remote procedure calls. Other applications or services access them. Web services work both within an organization and across the internet.
Web services have two primary categories based on how they communicate – RESTful web services and SOAP-based web services. RESTful web services use a simpler architecture and rely on HTTP verbs to perform actions. SOAP-based web services use a more complex protocol for exchanging messages between systems.
3. What Is SOAP?
SOAP is a protocol for exchanging structured data between connected applications over the internet. With SOAP, developers can enable applications to invoke events on different operating systems.
The SOAP uses Extensible Markup Language or XML to communicate, authenticate and authorize. The HTTP protocols are enabled on all operating systems. Therefore, SOAP is able to communicate with web services and receive responses independent of language and platforms.
SOAP establishes a standard format for messaging. For example, it has a header part for message identification and a body part for the content of the message. It can transfer data over HTTP or HTTPS. Below is a sample skeleton of the SOAP XML file:
4. What Is WSDL?
Web Services Descriptive Language is for describing web services and their interfaces. It is an XML-based language. A WSDL document describes the various operations that a web service provides. It also provides information about the service’s protocols, such as SOAP.
WSDL provides a standard for service providers to state the basic format of requests to the service regardless of the technology and platform implementation.
World Wide Web Consortium defines WSDL as a standard XML document type. WSDL XML file is a means for communication between web service consumers and producers. Below is a sample skeleton of the WSDL XML file:
5. Difference Between SOAP and WSDL
Although SOAP and WSDL protocols are related to creating web services, they’re different, as described in the table below:
SOAP
WSDL
SOAP is a protocol used for exchanging structured information between systems over the internet
WSDL is a language used to describe web services and their interfaces
SOAP messages are in XML format
WSDL documents are in XML format
SOAP provides a framework for invoking remote procedures or exchanging data between different systems
WSDL provides a description of the operations provided by a web service
SOAP messages use various protocols, including HTTP, SMTP, and FTP
WSDL can describe the protocols of a web service, such as SOAP, HTTP, and SMTP
SOAP is based on a client-server architecture
WSDL describes the interfaces of web services that are accessed by clients
SOAP messages are dependent on the underlying protocol used for communication
WSDL is independent of any particular protocol
SOAP messages can use various programming languages, including Java, C#, and PHP
WSDL is created and parsed using tools such as WSDL editors, XML editors, and web service development kits
SOAP messages are compatible with various web services standards, including WSDL, UDDI, and XML Schema
WSDL can describe any web service that provides a SOAP interface
SOAP can enable communication between different systems
WSDL can describe the interfaces of web services that are accessed by clients
SOAP is more towards the message format and protocol for exchanging data
WSDL is more towards the description of the operations provided by a web service
6. Conclusion
In this article, we discussed the difference between WSDL and SOAP.
In summary, SOAP is a protocol for exchanging messages between systems. WSDL is a language for describing the interfaces of web services. SOAP messages use various protocols, and WSDL can describe the protocols of a web service.