REST Web Services

A REST (Representational State Transfer) Web service is a set of architectural principles by which you design Web services that focus on a system’s resources, including how resource states are addressed and transferred over HTTP by a wide range of clients written in different languages.

REST Web services support these key principles:

Provides an ID (structure-like URIs) for every resource
Links resources together
Uses standard HTTP methods
Supports resources with XML representation (Transfer XML)
Communicates statelessly

Representational State Transfer – when called, a representation of the resource is returned, which places the client application in a state. Traversing the returned URL accesses another resource, placing the client application into yet another state. Thus, the client application changes (transfers) states with each resource representation.

REST establishes a one-to-one mapping between mobile business object (MBO) create, read, update, and delete (CRUD) operations and HTTP methods:

Use POST to create a resource on SAP Mobile Server
Use GET to retrieve a resource
Use PUT to change or update the state of a resource
Use DELETE to remove or delete a resource

Example REST URIs include:

http://example.com/customers/1234
http://example.com/orders/2007/10/776654
http://example.com/products/4554
http://example.com/orders/2007/11
http://example.com/products?color=green

and this XML code fragment which links the resources together:

<order self='http://example.com/customers/1234' > 
   <amount>23</amount> 
   <product ref='http://example.com/products/4554' /> 
   <customer ref='http://example.com/customers/1234' /> 
</order>

With this representation, the standard HTTP GET method executes on the first resource:

http://example.com/customers/1234

Generic Interface Relationship
<interface> Resource: GET PUT POST DELETE	/orders: GET – list all orders PUT – unused POST – add a new order DELETE – unused
	/orders/{id}: GET – get order details PUT – update order POST – add item DELETE – cancel order
	/customers: GET – list all customers PUT – unused POST – add a new customers DELETE – unused
	/customers/{id}: GET – get customer details PUT – update customer POST – unused DELETE – delete customer
	/customers/{id}/orders: GET – get all orders for customer PUT – unused POST – add order DELETE – cancel all customer orders