A DMVOCC-MVDA （distributed multiversion optimistic concurrency control with multiversion dynamic adjustment） protocol was presented to process mobile distributed real-time transaction in mobile broadcast environment...A DMVOCC-MVDA （distributed multiversion optimistic concurrency control with multiversion dynamic adjustment） protocol was presented to process mobile distributed real-time transaction in mobile broadcast environments. At the mobile hosts, all transactions perform local pre-validation. The local pre-validation process is carried out against the committed transactions at the server in the last broadcast cycle. Transactions that survive in local pre-validation must be submitted to the server for local final validation. The new protocol eliminates conflicts between mobile read-only and mobile update transactions, and resolves data conflicts flexibly by using multiversion dynamic adjustment of serialization order to avoid unnecessary restarts of transactions. Mobile read-only transactions can be committed with no-blocking, and respond time of mobile read-only transactions is greatly shortened. The tolerance of mobile transactions of disconnections from the broadcast channel is increased. In global validation mobile distributed transactions have to do check to ensure distributed serializability in all participants. The simulation results show that the new concurrency control protocol proposed offers better performance than other protocols in terms of miss rate, restart rate, commit rate. Under high work load （think time is ls） the miss rate of DMVOCC-MVDA is only 14.6%, is significantly lower than that of other protocols. The restart rate of DMVOCC-MVDA is only 32.3%, showing that DMVOCC-MVDA can effectively reduce the restart rate of mobile transactions. And the commit rate of DMVOCC-MVDA is up to 61.2%, which is obviously higher than that of other protocols.展开更多
Techniques for mining information from distributed data sources accessible over the Internet are a growing area of research.The mobile Agent paradigm opens a new door for distributed data mining and knowledge discover...Techniques for mining information from distributed data sources accessible over the Internet are a growing area of research.The mobile Agent paradigm opens a new door for distributed data mining and knowledge discovery applications.In this paper we present the design of a mobile agent system which couples service discovery,using a logical language based application programming interface,and database access.Combining mobility with database access provides a means to create more efficient data mining applications.The processing of data is moved to network wide data locations instead of the traditional approach of bringing huge amount of data to the processing location.Our proposal aims at implementing system tools that will enable intelligent mobile Agents to roam the Internet searching for distributed data services.Agents access the data,discover patterns,extract useful information from facts recorded in the databases,then communicate local results back to the user.The user then generates a global data model through the aggregation of results provided by all Agents.This overcomes barriers posed by network congestion,poor security,and unreliability.展开更多
基金Project(20030533011)supported by the National Research Foundation for the Doctoral Program of Higher Education of China
文摘A DMVOCC-MVDA （distributed multiversion optimistic concurrency control with multiversion dynamic adjustment） protocol was presented to process mobile distributed real-time transaction in mobile broadcast environments. At the mobile hosts, all transactions perform local pre-validation. The local pre-validation process is carried out against the committed transactions at the server in the last broadcast cycle. Transactions that survive in local pre-validation must be submitted to the server for local final validation. The new protocol eliminates conflicts between mobile read-only and mobile update transactions, and resolves data conflicts flexibly by using multiversion dynamic adjustment of serialization order to avoid unnecessary restarts of transactions. Mobile read-only transactions can be committed with no-blocking, and respond time of mobile read-only transactions is greatly shortened. The tolerance of mobile transactions of disconnections from the broadcast channel is increased. In global validation mobile distributed transactions have to do check to ensure distributed serializability in all participants. The simulation results show that the new concurrency control protocol proposed offers better performance than other protocols in terms of miss rate, restart rate, commit rate. Under high work load （think time is ls） the miss rate of DMVOCC-MVDA is only 14.6%, is significantly lower than that of other protocols. The restart rate of DMVOCC-MVDA is only 32.3%, showing that DMVOCC-MVDA can effectively reduce the restart rate of mobile transactions. And the commit rate of DMVOCC-MVDA is up to 61.2%, which is obviously higher than that of other protocols.
文摘Techniques for mining information from distributed data sources accessible over the Internet are a growing area of research.The mobile Agent paradigm opens a new door for distributed data mining and knowledge discovery applications.In this paper we present the design of a mobile agent system which couples service discovery,using a logical language based application programming interface,and database access.Combining mobility with database access provides a means to create more efficient data mining applications.The processing of data is moved to network wide data locations instead of the traditional approach of bringing huge amount of data to the processing location.Our proposal aims at implementing system tools that will enable intelligent mobile Agents to roam the Internet searching for distributed data services.Agents access the data,discover patterns,extract useful information from facts recorded in the databases,then communicate local results back to the user.The user then generates a global data model through the aggregation of results provided by all Agents.This overcomes barriers posed by network congestion,poor security,and unreliability.
