SOAP vs REST

SOAP : Great at Asynchronous processing and invocation, Formal contracts, Stateful operations
REST : Limited bandwidth and resources, Totally stateless operations, Caching situations

SOAP

• SOAP stands for Simple Object Access Protocol. REST stands for REpresentational State Transfer.
• SOAP is a XML based messaging protocol and REST is not a protocol but an architectural style.

• SOAP has a standard specification but there is none for REST.
• Whole of the web works based on REST style architecture. Consider a shared resource repository and consumers access the resources.

• Even SOAP based web services can be implemented in RESTful style. REST is a concept that does not tie with any protocols.
• SOAP is distributed computing style and REST is web style (web is also a distributed computing model).

• REST messages should be self-contained and should help consumer in controlling the interaction between provider and consumer(example, links in message to decide the next course of action). But SOAP doesn’t has any such requirements.

REST 

•  REST does not enforces message format as XML or JSON or etc. But SOAP is XML based message protocol.
• REST follows stateless model. SOAP has specifications for stateful implementation as well.

• SOAP is strongly typed, has strict specification for every part of implementation. But REST gives the concept and less restrictive about the implementation.
• herefore REST based implementation is simple compared to SOAP and consumer understanding.

•  SOAP uses interfaces and named operations to expose business logic. REST uses (generally) URI and methods like (GET, PUT, POST, DELETE) to expose resources.
• SOAP has a set of standard specifications. WS-Security is the specification for security in the implementation. It is a detailed standard providing rules for security in application implementation. Like this we have separate specifications for messaging, transactions, etc.

• Unlike SOAP, REST does not has dedicated concepts for each of these. REST predominantly relies on HTTPS.
•  Above all both SOAP and REST depends on design and implementation of the application.

Areas where SOAP based Web Services is a great solution:

Asynchronous processing and invocation: If application needs a guaranteed level of reliability

and security then SOAP 1.2 offers additional standards to ensure this type of operation. Things like

WSRM – WS-Reliable Messaging etc.

Formal contracts: If both sides (provider and consumer) have to agree on the exchange format

then SOAP 1.2 gives the rigid specifications for this type of interaction.

Stateful operations: If the application needs contextual information and conversational state

management then SOAP 1.2 has the additional specification in the WS* structure to support those things (Security, Transactions, Coordination, etc). Comparatively, the REST approach would make the developers build this custom plumbing.

Areas where Restful Web Services are a great choice:

Limited bandwidth and resources: Remember the return structure is really in any format
(developer defined). Plus, any browser can be used because the REST approach uses the standard GET, PUT, POST, and DELETE verbs. 
Again, remember that REST can also use the XMLHttpRequest object that most modern browsers support today, which adds an extra bonus of AJAX.

Totally stateless operations: If an operation needs to be continued, then REST is not the best
approach and SOAP may fit it better. However, if you need stateless 
CRUD (Create, Read, Update,and Delete) operations, then REST is suitable.

Caching situations: If the information can be cached because of the totally stateless operation of the REST approach, this is perfect.

Posted in: REST, SOAP, WebServices