Java Reference
In-Depth Information
Note
SOAP-based web services are also known as
big web services
because they
are based on many specifications, such as the WS-I profiles mentioned earlier.
RESTful Web Services
SOAP-based web services can be delivered over various protocols such as HTTP,
SMTP, FTP, and the more recent Blocks Extensible Exchange Protocol —see
http://www.rfc-editor.org/rfc/rfc3080.txt
.
Delivering SOAP mes-
sages over HTTP can be thought of as a special case of a RESTful web service.
Representational State Transfer (REST)
isasoftwarearchitecturestylefordistributed
hypermedia systems
(systems in which images, text, and other resources are located
aroundnetworksandareaccessibleviahyperlinks).Thehypermediasystemofinterest
in a web services context is the World Wide Web.
Note
RoyFielding(oneoftheprincipalauthorsoftheHypertextTransferProtocol
[HTTP] specification versions 1.0 and 1.1, and cofounder of the Apache Software
Foundation) introduced and defined REST in his doctoral dissertation back in 2000.
(FieldingconceivedRESTasthearchitecturalstyleoftheWeb,althoughhewroteitup
long after the Web was a going concern.) REST is widely regarded as the solution to
what is considered to be the growing complexity of SOAP-based web services.
ThecentralpartofRESTistheURI-identifiableresource.RESTidentifiesresources
by their Multipurpose Internet Mail Extensions (MIME) types (such as
text/xml
).
Also,resourceshavestatesthatarecapturedbytheirrepresentations.Whenaclientre-
questsaresourcefromaRESTfulwebservice,theservicesendsaMIME-typedrepres-
entation of the resource to the client.
ClientsuseHTTP's
POST
,
GET
,
PUT
,and
DELETE
verbstoretrieverepresentations
ofresourcesandtomanipulateresources—RESTviewstheseverbsasanAPIandmaps
themontothedatabaseCreate,Read,Update,andDelete(CRUD)operations(see
ht-
for an introduction to CRUD).
Table 11-1
reveals this mapping.
