Grid technologies have evolved through at least three distinct generations: early ad hoc solutions, de facto standards based on the Globus Toolkit (GT), and the current emergence of more formal Web services based standards within the context of the open grid services architecture (OGSA) (Foster, Kesselman, Nick, & Tuecke, 2002). The grid community has participated in, and in some cases led, the development of Web services specifications that address other grid require- ments. The Web services resource framework (WSRF) defines uniform mechanisms for defining, inspecting, and managing remote state, a crucial concern in many settings. WSRF mechanisms underlie work on service management (WSDM, in OASIS) and negotiation (Web services agreement, in GGF), efforts that are crucial to the grid vision of large-scale, reliable, and interoperable grid applications and services. Other relevant efforts are aimed at standardizing interfaces to data, computers, and other classes of resources.
A core unifying concept that underlies grids and agent systems is that of a service: an entity that pro- vides a capability to a client via a well-defined message exchange (Booth et al., 2003). Within third generation grids, service interactions are structured via Web service mechanisms, and thus all entities are services. However, while every agent can be considered a service (in that it interacts with other agents and its environment via message exchanges), we might reasonably state that not every grid service is necessarily an agent (in that it
may not participate in message exchanges that exhibit flexible autonomous actions).
While grid technologies provide the means for describing and grouping services, these higher level matchmaking, and discovery capabilities are not cur- rently part of grid infrastructure (Foster et al., 2002). Fortunately, this is an area where much work has been done in the space of agents, and incorporation of this technology would help a lot to improve this situation. This integration may have an impact on how state is represented and how services are organized.
concLuSIon
Current Web services, without any support from agents, still do provide the capability to seamlessly integrate different platforms. They provide an excellent choice for implementing distributed applications because they are architecturally neutral. Web services oper- ate using open, text-based standards, such as WSDL, UDDI, and SOAP, which enable components written in different languages and for different platforms to communicate.
Agent technology provides several advantages, which can be easily incorporated in existing Web services. The capability of agents to be autonomous, cooperate with other agents, be aware of the context in which they are invoked, and dynamically adapt to changes in the environment are some of the main advantages that agents have compared to current Web services. Agent-based Web services would provide clients with a fast, personalized, and intelligent service. This in turn will increase the percentage of returned customers because of higher satisfaction from services provided.
Instead of focusing on Web services separately from the agent technology, both technologies should be considered together. This approach makes it simpler to implement standards that organizations will have to follow which will lead to services that can be provided and consumed seamlessly.
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KEY tErMS
Agent-Based System: An agent-based system is
a system in which the key abstraction used is that of an agent. Agent-based system enjoys the following properties: autonomy, reactivity, pro-activeness, and sociability.
Grid: Grids provide an infrastructure for feder-
ated resource sharing across trust domains. Much like the Internet on which they build, current Grids define