REST Vs. SOAP Web Services: What Are The Differences?

By Indeed Editorial Team

Published 8 November 2021

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

Representational state transfer (REST) has become the preferred choice for public application programming interfaces (APIs) and open-source work that allows other developers to connect and efficiently use the data. Both REST and SOAP (simple object access protocol) connect two applications via server-side data that are machine and human-readable. If you plan to build a program that depends on web services, knowing the difference between REST and SOAP can help you decide the suitable API for your project. In this article, we discuss the fundamental difference between REST and SOAP with examples, explore their advantages and outline some popular alternatives.

REST vs. SOAP web services

REST versus SOAP is an important decision developers make when creating application programming interfaces. Though both are API formats for accessing web services, both have some pros and cons. Here are some key differences between them:

SOAP is a protocol, whereas REST is an architectural style

SOAP employs a service interface to expose specific portions of an application's business logic on a server, whereas REST uses uniform resource identifiers (URIs) to do the same. You develop REST APIs after the data, whereas you can create SOAP APIs after the API's functionality. A SOAP API that exposes functionality to create a user, for example, might include a function called CreateUser in the SOAP body. Instead, a REST API exposes the uniform resource locator (URL) for users and a post request to that URL creates a user.

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REST APIs access a resource, whereas SOAP APIs perform an operation

REST is a more data-driven architecture, whereas SOAP is a standardised protocol for sharing structured data that is more function-driven. REST supports various data formats, including plain text, HTML, extensible markup language (XML) and JavaScript object notation (JSON), making it a better fit for data and increasing browser compatibility, whereas SOAP only supports XML. The format of the SOAP envelope includes header and body, whereas REST APIs are format neutral. While JSON is the most commonly used format, REST APIs can also accept XML, plain text and XML.

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REST and SOAP handle security differently

SOAP offers web services security (WSS), superior to secure sockets layer (SSL) in transport security and better suited for integration with enterprise-level security technologies. REST can use the secure version of the hypertext transfer protocol (HTTP), hypertext transfer protocol secure (HTTPS) and both support SSL for end-to-end security. While SOAP and REST APIs can encrypt their communication using HTTPS and SSL, SOAP provides an additional layer of WSS on the message level, ensuring that only the allowed server process can read it.

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SOAP requires more bandwidth compared to REST

Because of the envelope-style of payload transmission, SOAP has a little additional overhead by default. Developers primarily use REST for web services, as its lightweight nature is helpful in these situations. Compared to a REST request, a SOAP request contains more information. A SOAP API uses more bandwidth, which may affect systems that handle a lot of data.

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Caching benefit with REST API calls

The goal of caching is never having to generate the same response twice, which helps gain speed and reduce server load. REST provides an excellent caching infrastructure over HTTP GET methods and enables developers to mark response data as cacheable or non-cachable. SOAP often uses HTTP as the transfer mechanism. As HTTP post is an operation that always causes a state change, you cannot cache it at the HTTP level.

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REST and SOAP API handle payload differently

Using a SOAP API requires a particular client library with generated code. Soap is more intimately connected to the server than REST and has a lower abstraction layer. Less control over the interaction of two technologies means more abstraction. There is less complexity, and it is easier to update one without affecting the other. SOAP is tightly tied with the server, requiring a rigorous communication contract to make changes or updates. A client using a REST API does not need to understand it, whereas before communicating with a SOAP API, a client needs to know what it may use.

REST-based services are typically easier to implement than SOAP

REST can use JSON, which is easier to parse and process. Also, REST does not require you to have a service definition in place to provide a web service. You can simply define your service using web service description language (WSDL) with SOAP, and the processing and parsing of the SOAP-XML messages involve a more significant overhead.

Different transaction controls

SOAP has atomicity, consistency, isolation, durability (ACID) compliance transaction support, whereas REST does not. ACID is an enterprise-grade transaction quality and while exchanging sensitive information in enterprise architectures, the organisation prefers SOAP. Many common applications also require transaction ability, which is accepted by SOAP, whereas REST lacks it.

SOAP message example

The SOAP building blocks comprise a SOAP message which consists of an envelope element, a header and a body element. It can also contain an optional fault element. Here is an example of a SOAP message:

<span><span>xml version=<span>"1.0"</span><span>?></span></span>

<span><<span>soap:Envelope</span>
<span>xmlns:soap</span>=<span>"http://example.com/soap-envelope/"</span>
<span>soap:encodingStyle</span>=<span>"http://www.example.com/soap-encoding"</span>></span>

<span><<span>soap:Header</span>></span>
...
<span>soap:Header</span>></span>

<span><<span>soap:Body</span>></span>
...
<span><<span>soap:Fault</span>></span>
...
<span>soap:Fault</span>>
<span>soap:Body</span>>

<span>soap:Envelope</span>>

REST API example

You can call REST API with all of the HTTP methods like get, post, put and delete. An application implementing a REST API defines one or more URL endpoints with a domain, port, path or query string such as https://example.com/users?name=ramesh+sharma which returns data in JSON format. You can represent user details in JSON like:

{
<span>"name"</span>: <span>"Ramesh Sharma"</span>,
<span>"age"</span>: <span>25</span>,
<span>"gender"</span> : male,
<span>"address"</span>: <span>"New Delhi"</span>
}

Benefits of REST over SOAP

While SOAP allows you to access and manipulate items remotely, REST concentrates on the operations performed on those resources. When you do not need to map a group of things to the client correctly, REST is always preferable over SOAP. The transfer of object data requires a lot of bandwidth, making it difficult in areas with restricted network connectivity.

Another benefit is the REST protocol's simplicity when compared to SOAP. REST can use JSON, which makes things easier by standardising the serialisation and consumption of API payloads. The most significant benefit of JSON is its compatibility with JavaScript and the browser, which simplifies the creation of API-consuming rich applications.

Benefits of SOAP over REST

SOAP support WSS, which can be helpful if you need more robust security. It provides certain additional data privacy and integrity safeguards. SOAP also allows for identity verification via intermediaries rather than just point-to-point, like SSL.

Another benefit of SOAP is that it has built-in retry logic to compensate for lost communications. REST lacks an integrated message mechanism. If communication fails, the client must respond by retrying the communication. REST also lacks a standard set of rules. This means that both the service provider and the customer must know the content and context.

Popular alternatives to SOAP and REST

Here are some popular alternatives to SOAP and REST:

gRPC remote procedure call (gRPC)

gRPC is a modern, open-source, high-performance framework that can run in any environment. It can push messages in real-time and has excellent support for bi-directional streaming. gRPC compresses data into a binary format which makes it non-human readable, and it also has limited browser support. gRPC is most suitable for use-cases like real-time communication services, live streaming and multi-language environments.

Graph query language (GraphQL)

While REST focuses on resources and provides a set of endpoints around them to allow for multiple operations, GraphQL focuses on the data. It is more of a query language than an API. However, it includes all the tools needed to retrieve the searched data. One of the major benefits of GraphQL is the ability to dictate precisely what you need from the server and predictably receive that data.

Open data protocol (OData)

OData is a standardised API protocol that supports create, read, update, delete (CRUD) operations for creating and consuming data APIs. You can create OData APIs over existing HTTP and REST protocols. It provides a uniform and straightforward way to share data in a discoverable manner.

XML

XML is a markup language that gives great flexibility in marking up and sharing arbitrary data. It stores data in plain text format which is human readable. One of the biggest benefits of XML is that any application which can process XML can use your information, regardless of platform.

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