SOAP vs REST (differences)

Question

I have read articles about the differences between SOAP and REST as a web service communication protocol, but I think that the biggest advantages for REST over SOAP are:

1. REST is more dynamic, no need for creating and updating UDDI.

2. REST is not restricted to XML format. REST web services can send plain text, JSON, and also XML.

But SOAP is more standardized (Ex; security).

So, am I correct in these points?

Answer 1

Unfortunately, there are a lot of misinformation and misconceptions around REST. Not only your question and the answer by @cmd reflect those, but most of the questions and answers related to the subject on Stack Overflow.

SOAP and REST can't be compared directly, since the first is a protocol (or at least tries to be) and the second is an architectural style. This is probably one of the sources of confusion around it, since people tend to call REST any HTTP API that isn't SOAP.

Pushing things a little and trying to establish a comparison, the main difference between SOAP and REST is the degree of coupling between client and server implementations. A SOAP client works like a custom desktop application, tightly coupled to the server. There's a rigid contract between client and server, and everything is expected to break if either side changes anything. You need constant updates following any change, but it's easier to ascertain if the contract is being followed.

A REST client is more like a browser. It's a generic client that knows how to use a protocol and standardized methods, and an application has to fit inside that. You don't violate the protocol standards by creating extra methods, you leverage on the standard methods and create the actions with them on your media type. If done right, there's less coupling, and changes can be dealt with more gracefully. A client is supposed to enter a REST service with zero knowledge of the API, except for the entry point and the media type. In SOAP, the client needs previous knowledge on everything it will be using, or it won't even begin the interaction. Additionally, a REST client can be extended by code-on-demand supplied by the server itself, the classical example being JavaScript code used to drive the interaction with another service on the client-side.

I think these are the crucial points to understand what REST is about, and how it differs from SOAP:

• REST is protocol independent. It's not coupled to HTTP. Pretty much like you can follow an ftp link on a website, a REST application can use any protocol for which there is a standardized URI scheme.

• REST is not a mapping of CRUD to HTTP methods. Read this answer for a detailed explanation on that.

• REST is as standardized as the parts you're using. Security and authentication in HTTP are standardized, so that's what you use when doing REST over HTTP.

• REST is not REST without hypermedia and HATEOAS. This means that a client only knows the entry point URI and the resources are supposed to return links the client should follow. Those fancy documentation generators that give URI patterns for everything you can do in a REST API miss the point completely. They are not only documenting something that's supposed to be following the standard, but when you do that, you're coupling the client to one particular moment in the evolution of the API, and any changes on the API have to be documented and applied, or it will break.

• REST is the architectural style of the web itself. When you enter Stack Overflow, you know what a User, a Question and an Answer are, you know the media types, and the website provides you with the links to them. A REST API has to do the same. If we designed the web the way people think REST should be done, instead of having a home page with links to Questions and Answers, we'd have a static documentation explaining that in order to view a question, you have to take the URI stackoverflow.com/questions/<id>, replace id with the Question.id and paste that on your browser. That's nonsense, but that's what many people think REST is.

This last point can't be emphasized enough. If your clients are building URIs from templates in documentation and not getting links in the resource representations, that's not REST. Roy Fielding, the author of REST, made it clear on this blog post: REST APIs must be hypertext-driven.

With the above in mind, you'll realize that while REST might not be restricted to XML, to do it correctly with any other format you'll have to design and standardize some format for your links. Hyperlinks are standard in XML, but not in JSON. There are draft standards for JSON, like HAL.

Finally, REST isn't for everyone, and a proof of that is how most people solve their problems very well with the HTTP APIs they mistakenly called REST and never venture beyond that. REST is hard to do sometimes, especially in the beginning, but it pays over time with easier evolution on the server side, and client's resilience to changes. If you need something done quickly and easily, don't bother about getting REST right. It's probably not what you're looking for. If you need something that will have to stay online for years or even decades, then REST is for you.

Answer 2

A lot of these answers entirely forgot to mention hypermedia controls (HATEOAS) which is completely fundamental to REST. A few others touched on it, but didn't really explain it so well.

This article should explain the difference between the concepts, without getting into the weeds on specific SOAP features.

Answer 3

SOAP (Simple Object Access Protocol) and REST (Representation State Transfer) both are beautiful in their way. So I am not comparing them. Instead, I am trying to depict the picture, when I preferred to use REST and when SOAP.

What is payload?

When data is sent over the Internet, each unit transmitted includes both header information and the actual data being sent. The header identifies the source and destination of the packet, while the actual data is referred to as the payload. In general, the payload is the data that is carried on behalf of an application and the data received by the destination system.

Now, for example, I have to send a Telegram and we all know that the cost of the telegram will depend on some words.

So tell me among below mentioned these two messages, which one is cheaper to send?

<name>Arin</name>

or

"name": "Arin"

I know your answer will be the second one although both representing the same message second one is cheaper regarding cost.

So I am trying to say that, sending data over the network in JSON format is cheaper than sending it in XML format regarding payload.

Here is the first benefit or advantages of REST over SOAP. SOAP only support XML, but REST supports different format like text, JSON, XML, etc. And we already know, if we use Json then definitely we will be in better place regarding payload.

Now, SOAP supports the only XML, but it also has its advantages.

Really! How?

SOAP relies on XML in three ways Envelope – that defines what is in the message and how to process it.

A set of encoding rules for data types, and finally the layout of the procedure calls and responses gathered.

This envelope is sent via a transport (HTTP/HTTPS), and an RPC (Remote Procedure Call) is executed, and the envelope is returned with information in an XML formatted document.

The important point is that one of the advantages of SOAP is the use of the “generic” transport but REST uses HTTP/HTTPS. SOAP can use almost any transport to send the request but REST cannot. So here we got an advantage of using SOAP.

As I already mentioned in above paragraph “REST uses HTTP/HTTPS”, so go a bit deeper on these words.

When we are talking about REST over HTTP, all security measures applied HTTP are inherited, and this is known as transport level security and it secures messages only while it is inside the wire but once you delivered it on the other side you don’t know how many stages it will have to go through before reaching the real point where the data will be processed. And of course, all those stages could use something different than HTTP.So Rest is not safer completely, right?

But SOAP supports SSL just like REST additionally it also supports WS-Security which adds some enterprise security features. WS-Security offers protection from the creation of the message to it’s consumption. So for transport level security whatever loophole we found that can be prevented using WS-Security.

Apart from that, as REST is limited by it's HTTP protocol so it’s transaction support is neither ACID compliant nor can provide two-phase commit across distributed transnational resources.

But SOAP has comprehensive support for both ACID based transaction management for short-lived transactions and compensation based transaction management for long-running transactions. It also supports two-phase commit across distributed resources.

I am not drawing any conclusion, but I will prefer SOAP-based web service while security, transaction, etc. are the main concerns.

Here is the "The Java EE 6 Tutorial" where they have said A RESTful design may be appropriate when the following conditions are met. Have a look.

Hope you enjoyed reading my answer.

Answer 4

Difference between Rest and Soap

SOAP

1. SOAP is a protocol.
2. SOAP stands for Simple Object Access Protocol.
3. SOAP can't use REST because it is a protocol.
4. SOAP uses services interfaces to expose the business logic.
5. SOAP defines standards to be strictly followed.
6. SOAP requires more bandwidth and resource than REST.
7. SOAP defines its own security.
8. SOAP permits XML data format only.
9. SOAP is less preferred than REST.

REST

1. REST is an architectural style.
2. REST stands for Representational State Transfer.
3. REST can use SOAP web services because it is a concept and can use any protocol like HTTP, SOAP.
4. REST uses URI to expose business logic.
5. REST does not define too much standards like SOAP.
6. REST requires less bandwidth and resource than SOAP.
7. RESTful web services inherits security measures from the underlying transport.
8. REST permits different data format such as Plain text, HTML, XML, JSON etc.
9. REST more preferred than SOAP.

For more Details please see here

Answer 5

Among many others already covered in the many answers, I would highlight that SOAP enables to define a contract, the WSDL, which define the operations supported, complex types, etc. SOAP is oriented to operations, but REST is oriented at resources. Personally I would select SOAP for complex interfaces between internal enterprise applications, and REST for public, simpler, stateless interfaces with the outside world.

Answer 6

REST(REpresentational State Transfer)
REST is an architectural style. It doesn’t define so many standards like SOAP. REST is for exposing Public APIs(i.e. Facebook API, Google Maps API) over the internet to handle CRUD operations on data. REST is focused on accessing named resources through a single consistent interface.

SOAP(Simple Object Access Protocol)
SOAP brings its own protocol and focuses on exposing pieces of application logic (not data) as services. SOAP exposes operations. SOAP is focused on accessing named operations, each operation implement some business logic. Though SOAP is commonly referred to as web services this is misnomer. SOAP has a very little if anything to do with the Web. REST provides true Web services based on URIs and HTTP.

Why REST?

• Since REST uses standard HTTP it is much simpler in just about ever way.
• REST is easier to implement, requires less bandwidth and resources.
• REST permits many different data formats where as SOAP only permits XML.
• REST allows better support for browser clients due to its support for JSON.
• REST has better performance and scalability. REST reads can be cached, SOAP based reads cannot be cached.
• If security is not a major concern and we have limited resources. Or we want to create an API that will be easily used by other developers publicly then we should go with REST.
• If we need Stateless CRUD operations then go with REST.
• REST is commonly used in social media, web chat, mobile services and Public APIs like Google Maps.
• RESTful service return various MediaTypes for the same resource, depending on the request header parameter "Accept" as application/xml or application/json for POST and /user/1234.json or GET /user/1234.xml for GET.
• REST services are meant to be called by the client-side application and not the end user directly.
• ST in REST comes from State Transfer. You transfer the state around instead of having the server store it, this makes REST services scalable.

Why SOAP?

• SOAP is not very easy to implement and requires more bandwidth and resources.
• SOAP message request is processed slower as compared to REST and it does not use web caching mechanism.
• WS-Security: While SOAP supports SSL (just like REST) it also supports WS-Security which adds some enterprise security features.
• WS-AtomicTransaction: Need ACID Transactions over a service, you’re going to need SOAP.
• WS-ReliableMessaging: If your application needs Asynchronous processing and a guaranteed level of reliability and security. Rest doesn’t have a standard messaging system and expects clients to deal with communication failures by retrying.
• If the security is a major concern and the resources are not limited then we should use SOAP web services. Like if we are creating a web service for payment gateways, financial and telecommunication related work then we should go with SOAP as here high security is needed.

source1
source2