Good day Gozni

The REST Service Type is a little more advanced than other Service Types according to the following documentation: REST - https://help.k2.com/onlinehelp/k2blackpearl/userguide/4.7/default.htm#ServiceBrokers/EndPoints/REST_Endpoint.htm.

Best,

Sunrise

REST provides superior performance, particularly through caching for information that’s not altered and not dynamic.

REST technology is generally preferred to the more robust Simple Object Access Protocol (SOAP) technology because REST leverages less bandwidth, making it more suitable for internet usage

Due to its independence. Due to the separation between client and server, the protocol makes it easy for developments across the various areas of a project to take place independently. In addition, the REST API adapts at all times to the working syntax and platform. This offers the opportunity to try several environments while developing.

Due to its scalability. This protocol stands out due to its scalability. Thanks to the separation between client and server, the product may be scaled by a development team without much difficulty.

Process instances are created explicitly.

REST allows a greater variety of data formats, whereas SOAP only allows XML.

You can educate yourself further here 

Enjoy.

Hi Gozni

You can use the REST service type and an advanced SmartObject to connect to a REST web service. For example, you have a REST service that exposes data from a store, and you want to create a SmartObject to use that data on a SmartForm. See link below on how to do it step by step

Ref:https://help.k2.com/onlinehelp/k2five/userguide/5.3/default.htm#How-Tos/AdvancedSmartObjects/REST/CreateAdvSmartObject-REST.htm

Regards

Elvis