Looking at the 2011 trends from ProgrammableWeb, the number of available APIs registered in their API Directory has once again doubled. What I find most interesting is that the REST web services now outnumber the SOAP web services by a factor of four.
Even Salesforce decided their original SOAP API could no longer stand alone and added a REST API in late 2010, acknowledging that REST is now the preferred choice for application integration due to easy implementation and deployment. Its lightweight nature is a good fit when creating mobile or web-based applications, both since the client app doesn’t need extensive libraries to be able to interact with the server and because SOAP has a much higher overhead in terms of bandwidth, which can negatively affect the perceived performance of the app.
Internally in many enterprises, SOAP is still used as the protocol over which the services in a service-oriented architecture (SOA) interact. However, despite the similarity of the acronyms, the components in a service-oriented architecture can just as easily interact using REST or other protocols. In fact, as many companies begin exploring hybrid integrations, leveraging the strengths of both in-house and cloud applications, it becomes crucial for any successful integration product to be able to consume both SOAP and REST web services.
In a hybrid world, the type safety of SOAP web services is of less importance, as the data transferred between cloud and in-house applications will most likely need to be validated and reformatted at the integration point anyway. Also, REST web services lend themselves easily to caching — riding on standard mechanisms — which can be important when the traffic between in-house systems and private and public clouds continues to increase.
My prediction is that in 2012, any CIO who is considering API-enabling an application — either to consume the service internally or to expose external APIs for partners and mobile or web applications — will be looking first and foremost at REST as the technology of choice.
By: Anne-Sofie Nielsen