Application of Memory-forwarding Model to Data Transmission System of CIMISS

In China Integrated Meteorological Information Sharing System (CIMISS) Project, the transmission time of data has put forward specific requirements. As one of the 14 categories of data, satellite data and products have more types, higher capacity, and more files amounts comparing with other conventional data files. As in recent years, the number of satellite data and products categories have gradually increased, meanwhile, the scope of applications of satellite data and products is being used more frequently in both weather forecast and research. Therefore, the satellite data transmission process calls for better timeliness.Considering the features of satellite data and products from users' aspects, the current satellite data receiving and forwarding process in National Meteorological Information Center (NMIC) is analyzed, and the limitation of existing procedure is figured out. In the existing satellite data forwarding process, the data receiving process is handled by standard FTP server, and data forwarding process uses standard FTP client. So it makes data receiving and forwarding flow, two relatively independent processes. The data receiving process is only responsible for the various data source reception, which only makes sure that all the arrived data and products could be recognized and transferred to data forwarding process successfully. Also, the data forwarding process only takes the responsibility to constantly scanning the sending directory to check out whether there is data or products to send. It may be concluded that there is no communication between data receiving process and data forwarding process, thus makes the total timeliness of data transmission lower than the ideal value.In order to solve or improve the situation, a new memory-forwarding model is proposed. In this model, by the memory sharing mechanisms, the data receiving process and forwarding process are combined as a unified whole, which has reduced the number of intermediate processing links. Based on memory-forwarding model, a unified procedure is designed by restructuring the FTP server transformation module. Through the development and testing of prototype systems, memory-forwarding model and unified procedure has been fully applied and achieved stage progress, and it will continue being validated and improved in further actual business system.