Hydro4GE (Hy – dro – forge)

The most effective and efficient
system available for developing and maintaining web-based applications.

Designing a good database system can be quite difficult; coming into an existing system and having to learn its structure can be even more difficult. Database designers have diagrams to help ease a developer into the structure of an existing system. Those diagrams have either not enough system detail, such as an Entity Relationship Diagram (ERD), or too much system detail, such as a Referential Integrity diagram. We developed a visualization of the structure of a database that bridges the gap between these two types of diagrams by giving the details new developers need but without so much as to overwhelm them.

Inside Hydro4GE, tables are categorized as Primary, Secondary, Enumeration, or Relationship. The developer defines Primary tables as the most important tables. All tables not defined as Primary tables default to a Secondary table definition. Enumeration tables hold static data important to the underlying system, but not important to understanding the system. Therefore, HydroViz does not display Enumeration tables. Relationship tables represent a relationship between two or more tables. HydroViz draws Relationship tables by adding a field below each table that participates in the relationship. HydroViz marks Relationship tables with a dashed border to differentiate them from other items displayed with a table.

HydroViz can display four types of diagrams:

• Top Level: Displays all primary tables and relationships in which they participate.
• Secondary Level: In addition to primary tables, secondary tables are also displayed.
• Developer Defined Relationship Diagram(DDRD): The user decides which tables to display.
• Navigation Diagram: Displays the possible routes a user could take through the tables in the generated application.

In order to create DDRD’s we implemented an editing area inside of HydroViz dubbed “the pool”, wherein users have access to all the tables currently in their system. Developers drag and drop tables into and out of the two columns, and create as many DDRD’s as they want with custom names and color schemes. The system provides a set of default color schemes, but the developer can also define custom styles to associate with themselves or with a certain project.

HydroViz 2-column diagram

Here is an example of the two column display that HydroViz uses in Top Level, Secondary Level, and Developer Defined Diagrams. The display shows several tables and their relations with each other, including a few Relationship tables. The two column view simplifies the view but can become unwieldy for systems with large numbers of tables in a diagram. Hence, HydroViz also has another method of visualizing a system: a circle.

HydroViz circular diagram

In a circle diagram the same data is displayed as in a Top Level, Secondary Level, or Developer Defined Diagram, but in a much more space-efficient manner. HydroViz draws Relationship tables in the same manner as other tables, but marks them with a different color. Using a circle diagram, large systems with hundreds of tables can easily be visualized.

Navigation through the eventually generated application depends on the tables present in the system. HydroViz has the Navigation Diagram to show how a user can navigate through the system.

HydroViz navigation diagram

The Navigation Diagram is shown as a tree structure. The top of the tree is the table where the user starts. From that top table, a user can navigate to the connected tables on the level below, and to connected tables on the level below that, and so on down the tree. The example provided shows “Staff” as the top level table. The Navigation Diagram shows that the user can navigate to “Administration”, “Faculty”, or “Maintenance” from “Staff.” The user can then navigate from “Administration” to “Athletics”, from “Faculty” to “Course”, or from “Maintenance” to “Room”.

Visualization of database structure can ease a developer into an unfamiliar system, or help a developer realize the full potential of a familiar system. We hope visualization through HydroViz becomes a very heavily used feature of Hydro4GE.

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