When developing APIs for applications there are a lot of things to consider and two terms that can be seen floating around this topic frequently are SOAP (Simple Object Access Protocol), and REST (Representational State Transfer), but what really are SOAP and REST? How do they differ and why should you build your application using one versus the other?
While on the surface SOAP and REST may appear to be similar, they are not really the same thing. SOAP is actually its own protocol, as represented by the “P”, that sends messages using other protocols such as HTTP and SMTP, while REST is an architectural style for a web services API. In fact, REST APIs can actually use SOAP in a similar fashion to how they can use HTTP.
So why exactly would one choose to use SOAP over REST or vice-versa? Each option has its benefits and drawbacks. For starters, SOAP is often a better option if the app in question needs higher levels of security, such as might be the case with a banking app. SOAP also has built-in ACID (Atomicity, Consistency, Isolation, Durability) compliance, which minimizes anomalies and protects database integrity by laying out exactly how transactions can interact with a database. One thing to note is that due to its more advanced nature, SOAP requires more bandwidth and resources to function, which can in turn lead to slower performance of the app or site using it.
REST, on the other hand, is known for being easy to use thanks to its use of HTTP and its use of a single uniform interface. REST is also optimized for use with the web and browsers thanks to its use of JSON for transferring data. In addition to this, REST is highly performant and scalable because it is built on a client-server principle, where data is passed back and forth in a communicative fashion that can be easily expanded as an application grows.
Both SOAP and REST are widely in use and experience using them is in high demand in the tech job market. While the popularity of REST has grown significantly, making it currently more widely in use than SOAP, the use of SOAP is very common within the world of enterprise-level application development and can offer benefits that sometimes outweigh the inherent ease of use and high-level performance of REST. For more info on SOAP and REST, check out these great resources: Making SOAP Requests, What is REST?