If a server is running on .net or PHP and you are building a web app with Ionic or using the more chic Svelte for example, or maybe you are going the traditional route and write a program in Fortran, because you know what, you are in the 2020’s and you are hipster developer looking for a challenge and wanting to feel like its the 1980’s, and newer programming language does not have the line by line procedural method that you so crave, in your horn rimmed glasses, with a cup of chai latte and avocado toast. But you know, to each his own.

Of course, the idea behind building all this, surely you need to be able to connect all of this together. But the question remains, how do you connect your back end server, built with a different implementation to your front end application, built with another totally completely different front end.

The answer, ladies and gents, is web services.

Web services have been around for a while and is part of the backbone of the modern web as we know it today. One can argue it is what kept the Internet going all around the world consistently on a daily basis. A key feature of web services is of course its ability to allow different software and applications to talk each other by adhering to a few standard protocols.

This would make it possible for a back end server built using Java through a framework like Spring Boot, to be able to communicate with a front end application built with Angular using TypeScript.

Two superstars of web services that is still being used to this day are SOAP (Simple Object Access Protocol) and REST (Representational State Transfer) API

While both SOAP and REST API serves the same purpose, here are 5 key differences between the two:

1. Messaging format: SOAP uses XML as its messaging format, while REST API can use a variety of formats including JSON, XML, and HTML. In my experiences, XML is not really a human friendly readable language, if compared to JSON. JSON is also lighter in terms of size if compared to XML.
2. Error handling: SOAP has a standardised error handling mechanism, while REST API typically uses HTTP error codes. With SOAP, it is easier to debug the errors since it follows a standard error handling mechanism to fix the error. With REST API, on the other hand, HTTP error codes, while vague, can also help you understand what is going on with your server, whether it is a problem with the connection (example: 404) or a problem with the server itself (500)
3. Performance: SOAP can be slower and more resource-intensive than REST API due to its use of XML and additional overhead. While resource intensive means a bigger server is needed, but it SOAP makes up for it by providing more functionality. REST API on the other hand, can be faster and more efficient for simple, lightweight applications or mobile devices
4. Transport protocol: SOAP uses HTTP, SMTP, or other protocols, while REST API uses HTTP only. With SOAP, you can use many other transport protocols to connect to your server, which could arguably mean that it is safer in terms of security. REST API on the other hand uses only HTTP, which makes it easier to integrate with other web based application which typically use HTTP for communication.
5. State management: SOAP is stateful, meaning that it maintains a session between the client and server, while REST API is stateless. SOAP servers maintaining connection could ensure that multiple requests and transaction between two nodes are reliable. REST API’s stateless nature means that ommunication can be faster and more scalable, since the server does not need to maintain session state.

SO there you go. Five key differences between SOAP and REST API. Is there a clear winner here? It depends on what sort of application you are planning to build, there is no clear answer. At the end of the day, while you sleep, just think about the magnitude of information travelling through web services, landing on originating from a different platform and landing in another different platform.

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