Request-Based Object Consistency Algorithm in
Content Distribution Networks
Chen Yan,Li Zengzhi,Liao Zhigang
(School of Electronics and Information Engineering, Xi'an Jiaotong University, Xi'an
710049, China)
Abstract: In order to ensure the object¡¯s novelty while increasing no more load to
Web servers and networks, a novel request-based object consistency algorithm (ROCA) for
content distribution networks is proposed, in which regarding every independent object as
a unit the duplication of servers is required and the newest version of the object
downloaded from Web servers is updated according to certain time interval. To determine
the frequency of the object¡¯s request the interest-measure of the object is defined and
the update policy of the object is decided based on it. For the object with higher
interest-measure the time slip-window method is utilized and the size of time window is
dynamically corrected in terms of the request and corrected instances of the object within
the previous time window. Trace-driven experiments show that ROCA algorithm can regulate
the update interval quickly according to the characteristics of the object. Compared with
traditional methods it has higher novelty of object and lower bandwidth wastage.
Keywords: content distribution network; object consistency; time slip-window