Simple Object Access Protocol (SOAP) is a protocol used for accessing web services. SOAP is an XML-based protocol designed for exchanging structured information
between distributed applications.
SOAP was developed to enable communication between applications over HTTP, including across firewalls. It is platform-independent and relies on XML and HTTP to access services, servers, and objects.
What Is SOAP
SOAP (Simple Object Access Protocol) is an XML-based object invocation protocol. It allows programs running on different operating systems and written in different
programming languages to communicate with each other.
Because SOAP uses standard web protocols such as HTTP, it is well suited for distributed systems and enterprise-level integrations.
Main Components of SOAP
SOAP consists of three main parts:
SOAP Envelope
The SOAP Envelope defines the overall structure of a SOAP message. It specifies what is contained in the message and how it should be processed.
The envelope includes:
- Header – contains optional metadata and processing instructions
- Body – contains the actual message or request being sent
SOAP Encoding Rules
SOAP encoding rules define how application-defined data types are represented and exchanged in XML format.
An encoding rule specifies how data is serialized so that both sender and receiver understand the structure and meaning of the data.
SOAP RPC
SOAP RPC (Remote Procedure Call) defines a way to represent method calls and responses using XML messages.
SOAP RPC follows a request-response model:
- The request message invokes a remote method
- The response message returns the result of that invocation
Features of SOAP
SOAP provides several important features:
- Protocol independence
- Language independence
- Platform and operating system independence
How SOAP Works
SOAP enables programs to communicate with other programs using XML. The data to be sent is encapsulated inside an XML document and transmitted
to a remote system.
In simple terms, SOAP allows Java objects, COM objects, and applications written in other languages to communicate with each other in a standardized way.
A SOAP client is an application that creates an XML document containing the information required to invoke a method on a remote system.
A SOAP server listens for incoming SOAP messages, interprets them, and executes the requested operations.
SOAP Encoding Types
SOAP defines base-level encoding rules for representing data. These encodings fall into two categories:
Simple Encodings
Simple encodings include basic data types such as:
- Integers
- Floats
- Strings
- User-defined simple data types
- Enumerations
- Arrays of bytes
Compound Encodings
Compound encodings represent more complex data structures, including:
- Arrays
- Structures
Conclusion
SOAP is a powerful XML-based protocol designed for reliable communication between distributed systems. Its platform and language independence make it well suited for enterprise applications and service-oriented architectures.