SOAP and REST are two mechanisms for exchanging data on the Internet. For example, imagine that your internal accounting system is passing data to a customer’s accounting system in order to automate invoicing tasks. Both applications exchange data using an API that defines communication rules. SOAP and REST are two different approaches to API development. The SOAP approach is highly structured and uses the XML data format. REST is more flexible and allows applications to exchange data in multiple formats.
What are the similarities between SOAP and REST?
Many different programming languages, architectures, and platforms can be used to create applications. Sharing data between these different technologies is difficult because they have different data formats. Both SOAP and REST came into existence in an attempt to solve this problem.
SOAP and REST can be used to create APIs or communication points between different applications. The terms web service and API are used interchangeably. However, APIs are a broader category. Web services are a specific type of API.
The following are other similarities between SOAP and REST.
- Both protocols describe rules and standards for how applications create, process, and respond to requests for data from other applications;
- They both use the standardized Internet protocol HTTP to exchange information;
- They both support SSL/TLS for secure encrypted communication;
- You can use SOAP or REST to create secure, scalable, and fault-tolerant distributed systems.
When should I use SOAP and REST?
Before choosing between SOAP and REST, study the scenarios and requirements of API users. The following criteria are worthy of consideration.
Overall application design
Modern applications such as mobile and hybrid applications work better with REST APIs. REST provides scalability and flexibility to develop applications using modern architectural patterns such as microservices and containers. However, if you need to integrate or extend legacy systems that already have SOAP APIs built in, you may be better off continuing to use SOAP.
Security
Public APIs have lower security requirements and require more flexibility so that anyone can interact with them. Therefore, REST is the best choice when creating public APIs. Conversely, some private APIs for internal corporate tasks (e.g., reporting for compliance) may benefit from the tightened security measures in WS-Security of SOAP.
ACID Compliance
Do your API users require strict consistency and data integrity across the transaction chain? For example, financial transactions require the failure of an entire batch of data updates if even a single update fails.
SOAP has a built-in set of ACID properties. And SOAP may be better suited to meet high data integrity requirements. In this case, the REST API may need additional program modules to control state at the server or database level.