Reverse engineering is a real Engineering
(This blog is dedicated to my Support Team: Amarnath, HariMohan, Prabhakaran, Vijay, Narayanbalaji)
Reverse engineering conjures an image of the "magic slot." We feed an unstructured, undocumented source listing into the slot and out the other end comes full documentation for the computer program. Unfortunately, the magic slot doesn't exist. Reverse engineering can extract design information from source code, but the abstraction level, the completeness of the documentation, the degree to which tools and a human analyst work together are highly variable
The abstraction level of a reverse engineering process and the tools used to effect it refers to the sophistication of the design information that can be extracted from source code.
Ideally, the abstraction level should be as high as possible. That is, the reverse engineering process should be capable of
ü Deriving procedural design representations (a low-level abstraction)
ü Program and data structure information (a somewhat higher level of abstraction)
ü Data and control flow models (a relatively high level of abstraction)
ü Entity relationship models (a high level of abstraction).
As the abstraction level increases, the software engineer is provided with information that will allow easier understanding of the program.
The completeness of a reverse engineering process refers to the level of detail that is provided at an abstraction level. In most cases, the completeness decreases as the abstraction level increases. For example, given a source code listing, it is relatively easy to develop a complete procedural design representation. Simple data flow representations may also be derived, but it is far more difficult to develop a complete set of data flow diagrams or entity-relationship models.
Completeness improves in direct proportion to the amount of analysis performed by the person doing reverse engineering. Interactivity refers to the degree to which the human is "integrated" with automated tools to create an effective reverse engineering process. In most cases, as the abstraction level increases, interactivity must increase or completeness will suffer.
If the directionality of the reverse engineering process is one way, all information extracted from the source code is provided to the software engineer who can then use it during any maintenance activity.
The reverse engineering process is represented in Figure below. Before reverse engineering activities can commence, unstructured (“dirty”) source code is restructured, so that it contains only the structured programming constructs.
This makes the source code easier to read and provides the basis for all the subsequent reverse engineering activities. The core of reverse engineering is an activity called extract abstractions. The engineer must evaluate the old program and from the (often undocumented) source code, extract a meaningful specification of the processing that is performed, the user interface that is applied, and the program data structures or database that is used.
Mailto: Shailendra.a@Avacorp.biz
