ations. Fortunately, there seems to be industry support for an integration of the WS-Transfer and WS-RF approaches, based on a WS-Transfer substrate—the WS-Resource Transfer specifications.

 

H T TP APPROACH

HTTP is an application protocol implementing a resource-oriented approach to building distributed systems. It has been described as an implementation of the REST

architectural style. Like WS-RF and WS-Transfer, HTTP implements a resource-oriented approach to building distributed systems. According to REST, a small set of verbs/operations with uniform semantics should be used to build hypermedia applications, with the Web being an example of such an application. The constraints applied

TABLE
1Key Characteristics of the Four Approaches

State represen-
tation schema
Address state
representation
Create
new state
Access
entire state
Get part
of state

WSDL
extensions
EPR ( WS-Addressing)

EPR (WS- URI Addressing) Create (WS-Transfer) Get (WS-Transfer)

URN

H TTP POST

GetResourcePropertyDocument (WS-ResourceProperties) GetResourceProperty, GetMultipleResourceProperties, QueryResourceProperties (WS-ResourceProperties) SetResourceProperties (WS-ResourceProperties) Set ResourceProperties, InsertResourceProperties, UpdateResourceProperties, DeleteResource-Properties ( WS-ResourceProperties) Subscribe (WS-Notification) SetTerminationTime (WS-resourcelifetime) Destroy (WS-ResourceLifetime) Well-defined error codes ( WS-BaseFaults + other specs) Yes Yes

H TTP GET

Update entire
state
Update, or add,
part of state

Put (WS-Transfer)

Not defined unless part of a state representation is exposed through a different URI (no semantics about the relationship are defined) H TTP PUT

Request
notification
Lease-based life-
time management
Destroy
state
Fault
modeling
RPC-
based
Open standards
process

Subscribe (WS-Eventing)

Subscribe (WS-Eventing)

Delete (WS-Transfer) SOAP faults

H TTP DELETE

H TTP fault codes

SOAP faults

No

No

Yes (OASIS)

Yes (W3C)

Already a standard

No need for new standards