A Study on Advanced Network Information Filtering System

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HTTP proxy servers, the application level gateways which transfer HTTP messages between servers and clients, play an important role in efficient transmission of HTTP messages over wide area networks. This research aims at studying basic technologies for enhancing the current HTTP proxy servers systems with "advanced network information filtering" functions.The first year of the project focuses on the design and implementation of 'Common Filter Server' (CF server) which performs contents conversion of transit messages in cooperation with existing HTTP proxy servers. In our design of CF server, we assume DeleGate, a general-purpose application protocol gateway with unique contents conversion mechanism called CFI (Common Filter Interface), as cooperating proxy server and extend CFI function of DeleGate using a database of HTTP message header templates. Our CF server is implemented using script language Perl to confirm the interaction with popular HTTP clients. Future issues include cooperative operation between CF server and DeleGate, the speed up of the CF server, and consideration of application examples.The second year of the project focuses on the analysis of HTTP access logs. HTTP access log possibly contains rich information useful for cache server allocation or pairings of servers in collaborative caching. However, conventional methods suffer intractability of the analysis due to the hugeness of the data. In order to deal with the problem, LSI (Latent Semantic Indexing), an automatic indexing technique recently used in information retrieval, is adopted to large-scale HTTP log files and estimates the similarity between two Internet domains. Kullback-Leibler information criteria is applied in the pre-processing stage to summarize huge amount of log data utilizing the URL hierarchy. The effect of the summarization is demonstrated using actual HTTP log data.