Reverse Engineering : An insight into the process of reverse engineering databases

Lets first look into the definition of reverse engineering. Reverse engineering (RE) is the process of discovering the technological principles of a device, object or system through analysis of its structure, function and operation. Reverse Engineering is a very powerful technique for discovering the structures of databases. There are many tools available like Apache Cayenee,Oracle Designer etc. What I want to talk thorough here is the concept of reverse engineering and its relevance into enterprise application development. You must be knowing that in the 3 tier system of Enterprise Applications other than the business code in the middle tier a lot of coding goes into both data access and modification in the innermost layer. So an enterprise app could be seen as a concentric sperical shell of three layers with the ineermost core dedicated to database(say db2),its connections and data access. Once we have this core, i.e. we know exactly what data is to be delt with we could use a tool to map the database directly to code(POJO and DAO combination in case of EJB's) and then build the rest of the application on top of this. This is reverse of the actual front end to back end conceptuation we tend to do and is termed reverse engineering. Its a relatively fast and effective method wherein the focus is exactly on the application data, enabling us to build on both existing databases and our own data logic on any given scenario.

Design Phase - 3

Continuing further, we see the drawing of sequence diagram. Check the tutorial here. This diagram shows the various actors we have from our use case diagrams interact with the various classes in our class diagram. This UML specified the object to object message passing via various operations.

Design phase - 2

Continuing further from use cases, we reach the part of designing classes for the users and for different uses they do the system. Again on rational ROSE we've developed the following class diagram. (see this to learn how to draw class diagrams in UML). The next time I write about class diagrams, it would be expanded to its fullest possible extend. Catch a glipse of this to get a sneak peak on UML,

[caption id="attachment_18" align="aligncenter" width="497" caption="Class_diag_ver_1"][/caption]

Design phase - 1

After figuring out the host of technologies we reqire to our enterprise project and after our really long chat out at coffee day on 15th july Rahul and me immersed ourselves with design duties. He'll come around with the databases(DB2) soon with all the research work coming up from jan. Now into the tech stuff.

We used a trial version of IBM's ROSE to develop the following use case UML diagram. (see this to learn how to draw use case diagrams). After a few hours of pondering i've come up with the following use case view


[caption id="attachment_11" align="aligncenter" width="497" caption="UML_USE_CASE"][/caption]