What is SOAP API?

SOAP API (Simple Object Access Protocol API) is a protocol used for exchanging structured information in the implementation of web services. It relies on XML (eXtensible Markup Language) for message format and usually operates over HTTP or HTTPS.

Key Features of SOAP API

1. Protocol-Based: Unlike REST, which is an architectural style, SOAP is a protocol with strict standards. It defines a set of rules for structuring messages and uses XML for message formatting.

2. WSDL (Web Services Description Language): SOAP services are often described using WSDL, which provides a machine-readable description of how the service can be called, what parameters it requires, and what responses it can return.

3. Extensibility: SOAP allows for additional features such as WS-Security, WS-ReliableMessaging, and WS-AtomicTransaction, enabling it to support more complex enterprise-level applications.

4. Stateful Operations: SOAP can support both stateless and stateful operations, meaning it can maintain state across multiple calls if necessary.

5. Transport Protocols: While SOAP primarily uses HTTP/HTTPS, it can also operate over other protocols like SMTP, JMS, and more, making it versatile for various network environments.

Advantages of SOAP API

• Standardized Protocol: Its strict standards make it easier to understand and maintain across different systems.
• Security: Built-in features for security and transactions, making it suitable for enterprise applications that require reliability and security.
• Interoperability: SOAP APIs can be used across different platforms and programming languages due to its standardization.

Disadvantages of SOAP API

• Complexity: The protocol can be complex and heavyweight compared to REST, making it less suitable for simpler applications.
• Performance: Due to its reliance on XML and extensive standards, SOAP can be slower and consume more bandwidth than REST.

Conclusion

SOAP APIs are a powerful option for complex applications requiring strong security and transaction management, especially in enterprise environments. However, for simpler applications or services that need to be lightweight and flexible, REST APIs are often preferred.

For more detailed information, you can refer to these sources:

• IBM: What is SOAP?
• MuleSoft: SOAP API