Design and Implementation of Middle Layer for Off-line Query Based on JSF and Hibernate Framework - Advanced Research on Computer Education, Simulation and Modeling - page 343

Fig. 2. The whole framework after adding the Middle Layer
In order to further understand the working principle of the Middle Layer, one ex-
ample will be analyzed in detail.
2 The Implantation of Middle Layer
2.1 Background
Food safety is a topic drawing prior attention of the society. As we all know, sub-
standard food can cause the serious harm to the human body. With this in mind, Food
Traceability System can track food information "from the origin to mouse". The core
of Food Traceability System is tracing, identifying, and linking the information flow
and real logistics to make all aspects of food traceable and identifiable.
In the food traceability system, due to regional differences in various aspects of the
circulation, the distributed database should be considered. So, the top-level database
and the underlying database are designed. The underlying database set at various su-
permarkets and other retail outlets is responsible for managing the purchasing-selling-
stocking data; while the top-level database is in charge of summarize data from each
underlying database for inquiring, aggregating and analyzing in the future.
In this paper, the query platform is built on the top-level database. If you feed a
source tracing code in, the system will show the detail information and every aspects
of this food's circulation information, in other words, one operation involves two ac-
tions: query detail information and circulation information.
2.2 Working Principle
First of all, the focus is the Middle Layer's working principles. In order to explain the
working principle more clearly, we should analyze the class diagram. The class
diagram of Middle Layer is shown in Figure 3: