Data distribution is a common problem in observation missions. Data gathered by the satellite has to be distributed among different operational centers using different policies: as fast as possible, creating redundant copies, informing interest scientifics about the new available products, etc. All these policies have to be accomplished taking into account features such as:
Aforementioned features are desired by common distribution systems, but in observation missions it is necessary to deal with other specific problems:
Heterogeneity: When involving different centers in the distribution, flexibility is a desired feature. Every center can be managed using different policies. For example an observation center uses FTP to distribute data because during a past mission the infrastructure was thought to be FTP. But three other center uses HTTP, and other one uses HTTPS. A distribution system has to be flexible enough to deal transparently with heterogeneous protocols. We can also find heterogeneity at the data level, therefore a generic system not linked with a concrete set of protocols or information is desirable.
Redundancy: Data is fundamental. Using redundancy we increase the availability but in addition, we make information reliable. What happen if we try to download information from a server momentarily not working. In a redundant system other severs would be used in a transparent way, informing about the fallen server.
Communities of users: Small scientific communities are the last recipients of the information. These users will probably be interested in the same files and will want the information to be available as soon as it appears. This means that sets of files have to be downloaded by several users at the same time with no problems.