OASIS Web Services Resource Framework (WSRF) Technical Committee
Statement of Purpose:
The purpose of the Web Services Resource Framework (WSRF) TC is to define a generic and open framework for modeling and accessing stateful resources using Web services. This includes mechanisms to describe views on the state, to support management of the state through properties associated with the Web service, and to describe how these mechanisms are extensible to groups of Web services.
Web services implementations are often stateless in that they maintain no dynamic state whose lifetime exceeds the processing of an individual message. The statelessness of Web service implementations is a valuable asset to their availability and ability to accommodate dynamic workloads.
Web service interfaces, on the other hand, often imply the need for some form of stateful interaction with the clients of the service. This may be manifest in a conversational style of use of a particular Web service interface in which some aspect of the result of one operation influences the execution of the next operation. The state in interactions with such interfaces is typically contained in or referred to from the messages that are exchanged with the target service. Inferences concerning the nature of the state may sometimes be made, but only in an application-specific fashion and not in a generic manner that can be exploited easily by tooling.
The goal of this TC is to define a set of royalty-free, related, interoperable and modular specifications that will allow the relationship between a Web service and state to be modelled in an explicit and standardized fashion. This will simplify the definition of new service interfaces and enable more powerful discovery, management and development tools. These specifications will be composable with other available Web services specifications enabling applications to access state with the qualities of service - for example security, transactions and reliability - provided for in those specifications.
Scope of Work:
The scope of this work is to define a framework within which Web services can access state in a consistent and interoperable manner, and an access pattern through which service requesters can interact indirectly with stateful resources through a Web service that encapsulates the state. The work of this TC will ensure that an architectural separation can be maintained between a stateful resource and the Web service that encapsulates it to promote the desirable loose coupling between service requestor and the stateless service provider and to provide a highly available and scalable means to interact with state.
This TC will define the means by which:
Web services can be associated with one or more stateful resources (named, typed, state components), the meaning of the term "stateful resource" and the context in which it operates.
Service requestors access stateful resources indirectly through Web services that encapsulate the state and manage all aspects of Web service based access to the state.
Stateful resources can be destroyed, through immediate or time based destruction.
The type definition of a stateful resource can be associated with the interface description of a Web service to enable well-formed queries against the resource via its Web service interface.
The state of the stateful resource can be queried and modified via Web service message exchanges.
Stateful resources can be aggregated for domain-specific purposes.
WSDL is an essential element of Web services architecture. The specifications produced by this TC will provide WSDL definitions for all normative message exchanges.
The benefits and results of this work will be a standard way for web services to access state leading to greater simplification in the definition of new Web service interfaces, better service interoperability and greater opportunity for tools vendors to provide means to manage Web service applications and resources.
Other contributions in addition to those listed above will be accepted for consideration without any prejudice or restrictions, and evaluated on their technical merit, as long as the contributions are within the scope of this charter.
Out of Scope:
The following topics are outside the scope of this TC:
Quality of service related policy enforcement on resource property access. The TC will not address security or transactions implications in the specifications it delivers.
The consideration of protocol-specific bindings.
Query and update of WS-Resource properties is within the scope of the TC, but general purpose XML document query and update, outside the context of managing stateful resources with Web services, is out of scope.
A normative factory pattern for the creation of WS-Resources.
List of Deliverables:
A revised WS-ResourceProperties specification. Committee Draft due within one year of the first meeting.
A revised WS-ResourceLifetime specification. Committee Draft due within one year of the first meeting.
A WS-ServiceGroup specification, which defines an interface to heterogeneous by-reference collections of Web services. Committee Draft due within one year of the first meeting.
A WS-BaseFaults specification, which defines a base fault XML type for use when returning faults in a Web services message exchange. Committee Draft due within one year of the first meeting.
These specifications will reflect refinements and changes made to, and by, contributions to the TC that are identified by members for additional functionality and semantic clarity within the scope of the TC charter. The titles and granularity of the specifications may change.
The anticipated audience for this work includes:
other specification writers that need stateful interaction patterns for Web services;
vendors offering web service products;
software architects and programmers who design and write distributed applications requiring the management of state.