Summary and Discussion

  In this thesis we have presented the Usenet News system and problems associated with its steady growth. These problems have been analyzed carefully. We have presented different solution strategies to solve these problems.

We have analyzed the current situation carefully and have shown that the News Cache solution requires the least modifications to existing Usenet News system and provides solutions to most of the problems. Table 10.1 shows the list of problems solved by the News Cache approach.

 

Tabelle 10.1: Usenet News problems solved by the News Cache

• The News Cache reduces the required network bandwidth necessary for the provision of Usenet News.
• The News Cache reduces the load on news servers caused by news clients.
• The News Cache provides a simple solution for the provision of local newsgroups.
• The News Cache is flexible enough to provide a possibility to read news offline from the news server.

 

We analyzed the requirements of the News Cache and have taken special care that existing software will not break with the introduction of the News Cache.

We have designed a database to store the various parts of the news database (active, overview and article database). For optimal performance, we developed a new container class library that stores its data on the file system implicitly using memory mapped files.

We showed the implementation of the News Cache and the interaction of the News Cache's various parts and presented a News Server Class Library that allows the development of other programs that need to access a news database or need to provide access to it.

We compared the News Cache with another news cache that came out while this thesis was under work. At the point of this writing this is the only other existing news cache.

We presented an evaluation of our News Cache in section 7.1 and have shown that the News Cache reduces the load of the news server. Even with a moderate use of the News Cache it reduces the load of the news server by those clients accessing news through the News Cache by $30\%$. With a wider use of the News Cache we expect better hit rates, because the number of users is usually higher than the number of read newsgroups. We expect that the News Cache can reduce the load caused to the news server by approximately $65\%$.