Research On Grid Mobile Service And Its Transferring And Communication Mechanism

"Grid Service" is the key thought of OGSA which is an important architecture of Grid now. Described in OGSA, Grid Service is fixedly installed on the Grid node machine that can provide this service and has no mobility. This quiescent service results in many drawbacks such as continuous connection, waste of bandwidth, less intelligence and overloaded with services calling. After deep research on the framework and implementation of Grid Service, this paper brings up Grid Mobile Service conception. Grid Mobile Service is an extension and supplement to Grid Service. It refers to the up-to-date researches of mobile agent, adopts class serialization mechanism and dynamic class loading technologies. It is deployed at core service layer of grid system, giving service calling entrance to outside via mobile service interface, providing service encapsulation and mobility to local upper service layer or remote client.Based on analysis and contrast for distributed object, Web Service and SOAP, combined with the fact that Grid Service origins from Web Service, SOAP which is based on XML is used as the protocol for mobile service transferring and intercaction. SOAP2.1 version begins to support message with attachment. This makes it possible to transplant serialized dynamic class via SOAP. Using SOAP as protocol for transferring will give mobile service more heterogeneity, flexible and broad adaptability. The agent communication language KQML is used for interacting among mobile services. Mobile service adopts XML to encapsulate KQML primitives, uses SOAP to communicate with each other. RPC/RMI or message passing mode can be chose at interaction period according to its requirements. The demo program improved entrance function and communication module of mobile agent system—Aglets. It can run over grid host and web service host or run independently, supporting several transferring protocol including ATP(used by mobile agent), SOAP-Call(used by SOAP message) and GT3-RMI(used by Globus).Grid Mobile Service has great theoretic and practical values on consummating and improving the practicability and flexibility of Grid Service.