Designing And Implementation Of Special Email System For Ships

Since the middle of the 1980s, Internet has become the largest network and it is going up in the world the most quickly. Nowadays there have been 137 countries and regions connected together through Internet. On account of its unlimited geographical location, it realized the most wide rage resource share and gained the popularity. Almost all types of networks provide interfaces with Internet.. The development of Internet has led a new revolution.E-mail must be mentioned here because it is the most widely used service in Internet. The high efficiency and convenient information transmission make it replace the conventional paper medium mail and become the standard mode of synchronized communion. And E-mail is also a important measure to realize none-paper in handling official busyness.Email system in the land is quite developed. But for the people who sailing or work in the sea, it is not easy to use E-mail, because there lack perfect communication establishment and network basic which is familiar in the land.This thesis discusses how to construct an E-mail system in the ocean shipping from five aspects which are the choice of Email transmission means, the network configuration in general, the configuration of Email server and the design of client-end software. The first section introduces the background of this thesis , the object and the meaning. The second section simply described the composition of the system. The third section discusses the reason of adopting INMARSAT-B satellite communication system as the transmission measure in the special environment on the sea in detail. And through analyzing the performance of TCP in satellite network concludes that the sending data must be compressed in the satellite environment and provides a set of complete methods for designing email system on the sea. The fourth section presents the detailed design of client-end software and refers the improvement of the LZSS arithmetic by loading dictionary, simplifying each element of compressed pair-code and reducing complexity of the algorithm, finally applied the improved algorithm in Email system in sending and receiving process and realized the compression and decompression of email text and accessories. The last section makes a summary entirely and puts forward an object in future study.