Web Services Composition and Geographic Information - Geographical Information Systems: Trends and Technologies - page 136

a) Resource identifi cation through URI: each resource is identifi ed by
a URI, which basically represents the endpoint where the desired
resource is located.
b) Uniform Interface: the manipulation of resources is obtained through
a fi xed set of operations (create, read, update and delete) through
the usage of the standard HTTP PUT, GET, POST and DELETE
methods.
c) Self-descriptive messages: since resources are decoupled from their
actual representation, they can be accessed in more than one format
(e.g., PDF, JPEG, etc.).
d) Every interaction with a resource is stateless.
One of the advantages of the REST paradigm is the ease of development
(the services description, for example, does not rely on standards, such
as WSDL, it is more informal and human oriented) and the fact that the
required standards (such as HTTP) and related infrastructure are already
pervasive. Moreover, the possibility to choose lightweight data-interchange
formats, such as the JavaScript Object Notation (JSON) makes it easier to
optimize the performance of the service (Pautasso et al. 2008). Support for
caching or load balancing is also available.
The OGC growing interest towards the use of this paradigm to perform
distributed geoprocessing has led to the proposal of a new standard, the
GeoServices REST API briefl y summarized here. The proposed REST API
'provides a standard way for web clients to communicate
with geographic information system servers based on the
Representational State Transfer (REST) principles. Clients issue
requests to the resources on the server identifi ed by structured
URLs. The server responds with map images, text-based geographic
information, or other representations of resources that satisfy the
request.'
(Portele and Sankaran 2012)
This OGC candidate standard traces its roots to the ESRI GeoServices
REST Specifi cation Version 1.0 (ESRI 2010) originally developed by ESRI
and released in 2010 as a non-proprietary open specifi cation (Portele and
Sankaran 2012). An interesting aspect concerns the fact that this proposal
is based both on REST principles and on pragmatic considerations about
the effective support of the HTTP protocol by current web browsers or
environments. For example, the use of the HTTP POST method is needed
when the size of a URL is greater than 2048 characters, a quite common
event in the context of geographic information.