Experimental NEWS Distribution System
Dr. Mátyás Arató, Dr. Attila Kuki, Zsolt Lencse,
Department of Information Technology
Institute of Mathematics and Informatics
Lajos Kossuth University, Debrecen, Hungary
This paper is about developing a news distribution system. Since this system can provide concentrated information in special topics, it prevents users from the endless Web surfing. The main characteristics of this system are the followings. It is platform independent based on applications written in JAVA and on client server technology. It provides reliable multimedia news (sound video hypertext, picture) which is authenticated through digital signatures. It is a 3-tier client server application which replicates multimedia data from server to clients with news subscription facility. The system provides articles from standard database systems (current implementation on Lotus Notes) with all advantages of a database system over file systems. Data can serve as a source for statistical time series analysis performed by SAS and text processing. Special application fields: distributions of stock information, environment protection.
The Experimental MNEWS systems is a news distribution system which resolves some issues of current news distribution systems like USENET, Word Wide Web, etc. Current systems at the time of development had not much support for handling big volumes of multimedia data, access control or verification of source. Some had not much support on different platforms.
This facts lead us to define anew news distribution architecture over TCP/IP which may fulfil the requirements of small institutes or enterprises for distribution company data like stock information for statistical analysis.
The main design principles were to use as much standard technology as possible for openness and for fast implementation. Also we wanted to be absolutely platform independent at least on the client side. This lead us to define the following client-server architecture.
2. System architecture
This MNEWS architecture (see Figure 1) is a three tier client server architecture. At the top tier there is a Database System which stores multimedia articles such as hypertext, sound or video files. In former systems like USENET the articles were stores in file systems. As the system data grow, the high volume causes problems in management and handling of information.
The database systems has well know advantages over file systems in terms of
This is why we chose database system for article storage.
The articles will be placed in the database by a standard way for the particular database. In our implementation it is a form, which can be reached by a Notes client or a Web browser. An article record is digitally signed upon insertion for later source identification. An article record contains the news body, type information , depositor signature, time to live (expiration) , timestamp of the news. It also contains which particular users can reach it or it is open to public and it can be classified into a category. An article can be indirect which means it can be a reference to another piece of information. Indirect articles are implemented by URL references. The source identification is not reliable for those indirect articles which point out from the database.
The middle tier is the MNEWS server tier. The MNEWS servers can read the database articles from the database system by the help of the database’s own access protocol. For scalability there could be more MNEWS servers. The MNEWS server tier is the tier that should be changed when another base database system is chosen for article storage. The MNEWS servers can be installed on multiple network hosts.
The article displaying clients receive the articles not directly from the database but from a designated MNEWS server. The articles are distributed for the local system by the help of a special application protocol. The special replication protocol is implemented over TCP. The client can be interested in a special category of news which is set in a local configuration file along with the server address. The special protocol replicates those articles and categories to the client which are not in the local system and not expired. By the help of digital signature and the root key in the client the reader can be sure that the article replicated to the local system is from a reliable source. The user of the client can also get subscribed classified articles by the help of a simple password identification. The replication occurs pre-configured way at the client. Those articles whose time to live attribute is expired are removed from the local system automatically
The client is able to display several kind of multimedia articles such as text, html, sound and video.
Any modern database system can handle multimedia files and large objects on many platforms. In our current implementation we used Lotus Notes 4.5 database system which of course can be replaced without touching the implementation of another tier of the system.
The MNEWS servers are written in JAVA  for platform independence, so the database must be reached by JAVA code.
The digital signatures are implemented by standard MD5 hashes .
The client is also implemented as a JAVA application for platform independence. It was tested on Unix and Windows platforms so far.
A screenshot from the JAVA client can be seen in Figure 2 (see above).
By the usage of this system the users can get information from an identified reliable source by only specifying their interest categories and the news are automatically downloaded to their local systems, they don’t need to “hunt for news”.
NCTD - National Committee for Technological Development, Hungary
This research was also supported by the Hungarian Scientific Grant OTKA-16933
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