By having the physical connection between every system and the hub, the logical connections between any two
systems is feasible as shown by dotted lines in Fig. 3. Therefore any message generated in the ETD system of an
institute is delivered to both GANJ and SEMAT through this hub. The metadata of the article is stored in SEMAT
database while the full information including the full-text is stored in GANJ. Once the physical and logical
connections established, all systems need to communicate. Such a distributed environment introduces many issues
like latency, synchronization and partial failure of one system. A loose coupling using message passing mechanisms
has been preferred, with messaging protocols based on xml. Each message is issued by an authorized issuing system
which is the origin of the data. Each system sends the message to the hub where there is a message buffer.
Whenever the connection between the target system and the hub is alive, the messages are sent to the target system.