and heterogeneous. NoSQL databases are low-cost,
data, a few attempts to apply the NoSQL approaches, e.g. using
the key-value stores, have been made for clinical data storage
although the research effort is at an early stage. Despite
a relatively new technology, NoSQL is signi ficant in that it is a
common database approach for cloud computing and thus a
promising solution for cloud-based clinical systems.
On the other hand, XML is a well-known and robust markup
language designed to encode documents electronically and
represent the data in a structured way. It has been demonstrated