SOAP vs. REST: The Key Differences Between These API Styles 💻
- Engineering, Dev & IT
Learn the differences and similarities between SOAP and REST APIs for seamless web development. Also, discover what they are and their examples.
Web application development is on the rise, soaring to new heights in our increasingly digital world. As this landscape broadens, two protagonists — SOAP and REST APIs — take center stage, defining the narratives of countless applications. And understanding the interplay between these two is essential to build apps.
In this guide, we’ll compare SOAP versus REST APIs, including their differences and similarities, to help you make an informed choice. We’ll also look at some alternate APIs to help you elevate your development toolkit. But before we dive into these two, let’s explore APIs as a concept.
What are APIs? ⌨️
Short for application programming interfaces, APIs are mechanisms that allow two separate software components to communicate with each other through a set of protocols and definitions. Think of it as a translator between two languages or a waiter taking your order and conveying it to the kitchen.
APIs make it simple to share data sets, enabling tasks like the automation of marketing workflows and streamlining IT architectures. SOAP and REST are two of the most common API architectures.
What is SOAP? 💻
Simple object access protocol (SOAP) is an XML-based web service access protocol, meaning it uses XML to encode its messages and typically relies on other application layer protocols like hypertext transfer protocol (HTTP) or simple mail transfer protocol (SMTP) for message negotiation and transmission.
At its core, SOAP encapsulates messages in an XML envelope containing a header and a body. The header has information about the message (e.g., authentication, method type), and the body includes the actual message intended for the application.
The built-in standards carry more overhead, but they can be a significant factor for organizations that need more comprehensive features regarding transactions, security, and ACID (atomicity, consistency, isolation, and durability) compliance.
Example of SOAP API 🧼
In this example, SOAP requests an HTTP POST with an XML request body to find out user details. The request body is made up of an envelope and a SOAP body that holds the request parameters. The envelope is a type of SOAP wrapper that identifies the requested API.
We’re looking to fetch “Elizabeth’s” information:
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:sch="http://www.soapuserexample.com/xml/users">
<soapenv:Header/>
<soapenv:Body>
<sch:UserDetailsRequest>
<sch:name>Elizabeth</sch:name>
</sch:UserDetailsRequest>
</soapenv:Body>
</soapenv:Envelope>
The answer contains a SOAP envelope and SOAP body –– like the request. Here, the body represents the requested information about the user:
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
<soapenv:Header/>
<soapenv:Body>
<ns2:UserDetailsResponse xmlns:ns2="http://www.soapexample.com/xml/users">
<ns2:User>
<ns2:name>Elizabeth</ns2:name>
<ns2:age>32</ns2:age>
<ns2:address>Hooville</ns2:address>
</ns2:User
</ns2:UserDetailsResponse>
</soapenv:Body>
</soapenv:Envelope>
What is REST? 🖥️
Representational state transfer (REST) is a set of architectural principles providing a lighter-weight alternative to SOAP. It uses a stateless, client-server communication model where web services are treated as resources. Here, the APIs are based on uniform resource identifiers (URIs), of which a URL is a specific type, and HTTP.
REST APIs also generally use JSON for a data format, meaning instead of using XML, REST relies on a simple URL to make a request.
REST can use four different HTTP 1.1 verbs –– GET, POST, PUT, and DELETE –– to carry out tasks. This was created specifically for working with components such as media components and files.
Example of REST 🤩
REST APIs can be requested with any of the HTTP verbs. In this example, we’ll use a GET request to get a resource. A REST API accepts GET parameters from the URL.
GEThttps://restAPIexample.com/users?name=Elizabeth
Since REST APIs generally use the JSON data format, the user is represented as:
{
“name”: “Elizabeth”,
“age”: 32,
“address”: “Hooville”
}
Key differences between SOAP and REST APIs 🔑
When it comes to web services, REST and SOAP web services are two prominent protocols that front- and back-end developers often weigh against each other. While both serve as mediums to communicate over the internet, they come with distinct characteristics that set them apart:
Behavior 🤠
While REST is an architectural style that uses URIs to expose certain aspects of an application’s business logic on a server, SOAP is a protocol and uses a service interface. SOAP APIs are function-based, designed after the functions the API looks to expose, whereas REST APIs are data-based (created after the data).
Data formats 🌐
SOAP can only work with the XML format –– all data is passed in this format. REST, however, is more flexible and allows different data formats such as HTML, XML, JSON, and plain text, with the most preferred format being JSON for transferring data.
Security 🔐
REST is a better option for building public APIs, as public APIs demand greater flexibility and lower security requirements so anyone can interact with them. SOAP, on the other hand, supports WS-Security, and private APIs for internal organizational requirements may benefit from the tighter security measures with SOAP.
Bandwidth 💪
As SOAP messages consist of a lot of information (envelope-style), the amount of data transfer is typically a lot, highlighting SOAP’s higher bandwidth requirement. Conversely, REST messages are generally more lightweight.
Reliability 🥳
SOAP provides more reliability since error-handling logic has been built into it. However, REST, during communication failures, requires you to try again, making it less reliable.
Are there any similarities between SOAP and REST? 💯
Both SOAP and REST solve data-sharing challenges across various technologies via different data formats. But they possess a few similarities.
- Purpose: Both SOAP and REST serve as protocols to enable communication between applications over the web, especially in a distributed environment.
- Interoperability: They’re designed to be language- and platform-agnostic, ensuring applications written in different languages or on different platforms can communicate with each other.
- Usability: Both can be consumed by various clients, be it web, mobile, or other server-side applications.
How to choose between SOAP and REST 🤔
If you’re an independent web developer, you probably already know that every decision regarding tools and protocols directly impacts your efficiency, performance, and project success. And your choice between SOAP and REST is no different. Understanding the contexts in which each thrives can help you deliver optimal solutions to your clients, adding value to your freelance portfolio.
Situations for choosing REST API ⭐
- When there are fewer requirements for external libraries on the client side
- When there is lightweight communication needed using small payloads and HTTP
- When effective caching helps streamline processes
Situations for choosing SOAP 🌟
- When you require higher security on an enterprise level
- When you need built-in retry mechanisms or have requirements on ACID transactions that SOAP offers
- When you have to integrate with legacy systems already using the SOAP approach
Alternatives to SOAP and REST APIs 💡
While REST and SOAP have been the leading choices for building APIs, other alternatives are attracting developers’ attention. Here are two prominent examples:
- JSON: This open standard file format transmits data between several applications. JSON is a viable solution in several situations due to its simplicity and faster transmission of SOAP.
- GraphQL: Created by Facebook, this is a query language typically used to load data from a server to a client efficiently. GraphQL servers are available for languages such as C++, Python, and Javascript. It also uses HTTP and the JSON data format, like REST.
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