SOAP (Simple Object Access Protocol), is a standard messaging protocol defined by W3C(World Wide Web), for operating services like Window and Linux to communicate via HTTP and XML. SOAP supports XML data format and strongly follows standard messaging structure. As it is a protocol, it imposes built-in rules that increase its complexity and overhead, which can lead to longer page load times. However, these standards also offer built-in compliances that can make it preferable for enterprise scenarios. The built-in compliance standards include security, atomicity, consistency, isolation, and durability (ACID), which are set of properties for ensuring reliable database transactions. A SOAP message is an ordinary XML document containing the following elements:
An Envelope element that identifies the XML document as a SOAP message
A Header element that contains header information
A Body element that contains call and response information
A Fault element containing errors and status information
REST (Representational State Transfer) is an architectural style which is easy to use, it's not a protocol or a standard. Its most common use is to facilitate the use of Web services with a standardized, universal approach. These web services offer their web resources in a textual representation and allow them to be read and processed with a stateless protocol. The idea behind REST is to impose certain rules upon the API so that you get more performance, scalability, portability, and reliability. An API is considered to be RESTful if they follow these below architectural constraints
Client-server architecture: An API’s job is to connect two pieces of software without limiting their own functionalities. This objective is one of the core restrictions of REST: the client (that makes requests) and the server (that gives responses) stay separate and independent.
Statelessness: For an API to be stateless, it has to handle calls independently of each other. Each API call has to contain the data and commands necessary to complete the desired action.
Uniform Interface: A uniform interface between components so that information is transferred in a standardized form instead of specific to an application’s needs. This is described by Roy Fielding, the originator of REST, as “the central feature that distinguishes the REST architectural style from other network-based styles.”
Layered System: A layered system constraint, where client-server interactions can be mediated by hierarchical layers.
Cacheability: Cacheable data to eliminate the need for some client-server interactions.
Code on Demand: Code on demand, allowing servers to extend the functionality of a client by transferring executable code
SOAP vs REST comparison
Standards & Protocol
Strict standard protocol is followed for communication
It's an architectural style, so provides flexibility to implement the web service
Uses service interface to expose business logic
Uses resources (via URI) to expose business logic
Information exchange methods
supports XML only
multiple formats including JSON, HTML, XML
Uses security extension to provide end to end encryption during data exchange.
Relies on HTTP for security
Slow compared to REST since it uses more bandwidth and resources
Fast compared to SOAP since it uses less bandwidth and resources