REST VS SOAP: Which is Best for You? (2020)

Introduction

When discussing Application Programming Interface (API) architectures, it is very common to compare REST VS SOAP. Both common paradigms, rest and soap are most commonly compared as similar fruits but in reality, are entirely different technologies and they cannot be compared on a low level. 

The main difference between REST and SOAP is that SOAP is protocol-based and REST is architectural style based. The REST API can use the SOAP protocol just as it uses the HTTP protocol. In a nutshell, they are boxed differently. Their functioning is very different and is also used in different scenarios.

Given that we now know the primary difference we can take a closer look at what each one is and what it entails. We can also discuss the pros and cons of using REST over SOAP  and it all depends on the requirement and the fit.

In this article let us look at:

1. What is REST?
2. What is SOAP?
3. Difference between SOAP and REST
4. Examples on SOAP and REST

1. What is REST?

The full form of REST is Representational State Transfer which was another standard made in response to the shortcomings of SOAP. It is a “web services” API based on URI’s ( Uniform Resource Identifier), HTTP protocol, and JSON data format that is compatible with all browsers. It also fixes problems with SOAP and provides a simpler method of accessing web services. One may choose to use REST owing to resource limitation, limited security necessities, browser client match, scalability, data scenario, and discoverability. A few key aspects of REST:

• It is all about simplicity.
• It facilitates client-server architectures and communication.
• It uses a single uniform interface.
• It is completely optimized for the web.
• It is well-known for performance and scalability.

2. What is SOAP?

The full form of SOAP is the Simple Object Access Protocol and is a standard-based web services access protocol. Designed by Microsoft, it is not a simple application. It has its protocol and has complex defining standards in comparison to REST. The already existing built standards are more complex but could benefit organizations that need additional features of security, transactions, and ACID ( Atomicity, Consistency, Isolation, Durability) compliance. Key aspects of SOAP include:

• It has tighter security.
• Retry or successful logic for dependable message functionality
• Built-in ACID compliance that protects the integrity of the database.

3. Difference between SOAP and REST

Let us now look at the key differences between REST API and SOAP API:

• SOAP is a protocol in comparison to REST which is an architectural style. An API is designed to picture certain aspects of the business logic on a server, SOAP users the service interface to do this whereas REST uses URI’s.
• REST API’s access a resource for data in comparison to SOAP API’s that perform operations. REST is more an architecture that is data-driven whereas SOAP is a standardized protocol that transfers structured information which is more function-driven
• REST allows many different data formats including HTML, plain text, JSON, and XML that helps to fit data and offer greater browser compatibility. SOAP on the other hand uses only XML.
• SOAP supports WS security that is great at a transporting level and more inclusive than SSL. It makes it more ideal for integration with enterprise-level security tools. REST supports SSL for end-to-end security and also uses the secure version of the HTTP protocol-HTTPS.
• SOAP needs more bandwidth and REST requires lesser resources. Overhead cost with SOAP is more while REST is lightweight as it is used for web services.
• Calls on REST can be cached whereas SOAP calls cannot be cached. Data can be marked as cacheable and can be reused by the browser without any initiation of request to the server. This saves time and resources
• REST and SOAP handle an application’s payload in different ways. The payload is data sent over the internet and requires more resources. REST uses HTTP and JSON that lightens the payload whereas SOAP uses XML. SOAP is coupled with the server to a slightly higher degree than REST. Being closely connected to the server makes it more difficult to make changes or updates. A client interacting with a REST API need not have a lot of knowledge of API but one interacting with a SOAP API would need complete knowledge before using it even before initiating an interaction.

For a large part, the advantages of REST over SOAP tend to get developers to turn to REST architecture for web services unless they find SOAP as a better choice for enterprise applications that are backed up by more resources, need additional security, and has more requirements.

4. Examples

When should one use SOAP? It is best for anything that needs formal contracts. Two common use cases for SOAP are:

1. Asynchronous operations that are time-specific and when different signals or preceding events trigger new events. REST is limited to HTTP and HTTPS which are not ideal communication protocols and delay operations. SOAP supports additional communication protocols. Asynchronous tasks are not ideal for simple tasks or very complex ones as it is difficult to maintain accurate timing.
2. Stateful operations need the performance of repetitive and chained tasks. For eg: the financial industry may need to retain client data in the server for future use. REST is stateless by default and does not save previous transactions but SOAP supports stateful operations.

When do you use REST? While REST can produce enough results ( not as the same as SOAP) through work from a professional developer, there are situations for which REST is geared to.

1. Limited bandwidth, low cost, and simple operations are the characteristics that let you write a simple URL to perform a basic and non-repetitive task. If you have limited bandwidth and limited resources, then REST can give faster results than SOAP.
2. Public API’s can be easily developed with REST as it is common and easy to find developers who understand it. Highly flexible, it brings a lot of options. Gmail is the best example of the REST API. It features public APIs from various developers for different purposes that include jobs, cryptocurrency, health, anti-malware, and even weather.

Conclusion

The bottom line is if one has to answer the question of REST vs SOAP, the answer is “depends on the requirement”. Each has its advantages and disadvantages. Selecting between REST v SOAP depends on the programming languages being used, environment, and most important your requirements. Choice of web services depends on the choice of protocol, budget, and maintenance costs. Thirdly irrespective of whether one chooses REST or SOAP, it is important to test the API.

SOAP and REST share similarities over the HTTP protocol. SOAP is more rigid in terms of a set of messaging patterns in comparison to REST. The rules in SOAP are very important as they can’t achieve any level of standardization without them. REST is more of an architectural style and does not require any processing as it is more flexible. Both REST and SOAP rely on well-set rules that need to be abided by the interest of exchanging information.

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