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What is the difference between SOAP and REST web services

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In this tutorial we are going to learn about SOAP and REST web services.


  • SOAP stands for Simple Object Access Protocol whereas REST stands for Representational State Transfer.
  • SOAP is a protocol whereas REST is an architectural pattern.
  • SOAP uses service interfaces to expose its functionality to client applications while REST uses Uniform Service locators to access to the components on the hardware device.
  • SOAP needs more bandwidth for its usage whereas REST doesn’t need much bandwidth.
  • Comparing SOAP vs REST API, SOAP only works with XML formats whereas REST work with plain text, XML, HTML and JSON.
  • SOAP cannot make use of REST whereas REST can make use of SOAP.

SOAP Web Services

SOAP stands for Simple Object Access Protocol which relies exclusively on XML to provide messaging services.

Microsoft originally developed SOAP to take the place of older technologies that didn’t work well on the internet such as the distributed component object model and common object request broker architecture.

These technologies fail because they rely on binary messaging. The XML messaging that SOAP relies works better over the internet.

REST Web Services

REST stands for Representational state transfer is a software architectural style which uses a subset of HTTP. It is commonly used to create interactive applications that use Web services.

A Web service that follows these guidelines is called RESTful. Such a Web service must provide its Web resources in a textual representation and allow them to be read and modified with a stateless protocol and a predefined set of operations.

This approach allows interoperability between the computer systems on the Internet that provide these services. REST is an alternative to, for example, SOAP as way to access a Web service.

Many developers found SOAP cumbersome and hard to use. For example, working with SOAP in java scripts means writing a ton of code for a developer simply kills the time because you must create the required XML structure every time. Unlike SOAP, REST doesn’t have to use XML to provide response and you can find REST based web services that output the data in comma separated values.

Java script object notation and really simple syndications. The point is you can obtain the output you need in the form which is easy to parse within the language used within the application.

When to use REST?

One of the most highly debatable topics is when REST should be used or when to use SOAP while designing web services. Below are some of the key factors that determine when REST and SOAP API technology should be used for web services REST services should be used in the following instances

Limited resources and bandwidth – Since SOAP messages are heavier in content and consume a far greater bandwidth, REST should be used in instances where network bandwidth is a constraint.

Statelessness – If there is no need to maintain a state of information from one request to another then REST should be used. If you need a proper information flow wherein some information from one request needs to flow into another then SOAP is more suited for that purpose. We can take the example of any online purchasing site. These sites normally need the user first to add items which need to be purchased to a cart. All of the cart items are then transferred to the payment page in order to complete the purchase. This is an example of an application which needs the state feature. The state of the cart items needs to be transferred to the payment page for further processing.

Caching – If there is a need to cache a lot of requests then REST is the perfect solution. At times, clients could request for the same resource multiple times. This can increase the number of requests which are sent to the server. By implementing a cache, the most frequent queries results can be stored in an intermediate location. So whenever the client requests for a resource, it will first check the cache. If the resources exist then, it will not proceed to the server. So caching can help in minimizing the amount of trips which are made to the web server.

Ease of coding – Coding REST Services and subsequent implementation is far easier than SOAP. So if a quick win solution is required for web services, then REST is the way to go.

When to use SOAP?

SOAP should be used in the following instances

Asynchronous processing and subsequent invocation – if there is a requirement that the client needs a guaranteed level of reliability and security then the new SOAP standard of SOAP 1.2 provides a lot of additional features, especially when it comes to security.

A Formal means of communication – if both the client and server have an agreement on the exchange format then SOAP 1.2 gives the rigid specifications for this type of interaction. An example is an online purchasing site in which users add items to a cart before the payment is made. Let’s assume we have a web service that does the final payment. There can be a firm agreement that the web service will only accept the cart item name, unit price, and quantity. If such a scenario exists then, it’s always better to use the SOAP protocol.

Stateful operations – if the application has a requirement that state needs to be maintained from one request to another, then the SOAP 1.2 standard provides the WS* structure to support such requirements.

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