How is data understood through reverse engineering?

Reverse engineering forms an internal part of the whole software re- engineering process. To implement the reverse engineering properly in the re- engineering process one needs to understand the data through the reverse engineering.

In this article we have taken up the same topic i.e., “how is data understood through reverse engineering?” 

- When the reverse engineering is carried out, the main objective is always to recover the designs and specifications of the software system or application.

- With reverse engineering, the development is only understood and no changes are made to the software system or application. 

- For the reverse engineering process, the source of the software system or application is fed as the input. 

- If you go through the history of the reverse engineering, you will find some cases where the executable code is given as input for the reverse engineering process. 

- The reverse engineering though being in a great contrast with the re- engineering forms an internal part of it. 

- Reverse engineering serves the purpose of recovering system design and specifications in the software re- engineering process model. 

- These recovered designs and specifications are used by the engineers to understand the software system or application before they start re- organizing the whole structure.

- However, there have been cases in which the reverse engineering is not always followed by the re- engineering process. 

- There are three stages in reverse engineering process.

 1. System to be re- engineered is subjected to automated analysis.

 2. Then it is manually annotated.

 3. With the system information obtained, a whole set of new documentation is generated containing:

(a)  Program structure diagrams

(b)  Data structure diagrams and

(c)   Traceability matrices.

Activities in Reverse engineering

In reverse engineering the data is understood by the 3 basic activities that involved intense understanding efforts:

1. Understanding process: In order to understand the procedural abstractions as well as functionality analyze the source code on the level:

(a)  System

(b)  Program

(c)   Component

(d)  Statement and

(e)  Pattern

2. Understanding data: It analyzes the internal data structures and data base structure.

3. User interfaces: It analyzes the basic actions processed by the interface, system’s behavioral response to those actions and equivalency of the interfaces.

More about reverse engineering....

- The beginning of the reverse engineering process is marked with an analysis phase in which the analyzation is carried out with the help of automated tools in order to discover the structure of the software system or application. 

- But this stage itself does not suffice the purpose of recovering the whole structure. 

- Engineers then have to work on the program code and model and add the recovered information to this.

- The recovered information is maintained in form of a directed graph. 

- The engineers always make it a point to link the directed graph to the source code. 

- The directed graphs are compared with the code with the help of the information browser stores. 

- This graph helps in generating trace ability matrices and the data structures. 

- Tools that are used make it easy to navigate through the code. 

- After the complete generation of the design documentation, the information store is supplied with the additional information as a measure to re create the specifications systems. 

What is meant by Software Reengineering Process Model?

Software re- engineering process model is based up on the principles of the software re- engineering that was proposed by Chifosky in the year of 1990.  Before we discuss about the software re- engineering process model let us see what software re- engineering is.

What is Software Re-engineering?

- The software re- engineering is considered to be a process that alters a software system and thus reconstituting it in to a new form that is better than its previous form.

- The process of the re- engineering usually occurs after the software system or application has been reverse engineered. 

- The re- engineering is also carried out for the addition of the new functionalities or to correct the discovered faults and errors. 

- Sometimes this whole process is often collectively called as reverse engineering. 

But there is a subtle difference between the two! 

- The former process i.e., the reverse engineering is like an initial examination of the software system and the latter is like the subsequent modification. 

- Re- engineering of the software systems often comes in to play where there is an involvement of a legacy system. 

- In such cases the re- engineering can be considered to be a process that re- structures a legacy system in to a new system that is constituted of much better features and functionality and maintain the quality constraint.

Re- engineering is not a thing that can be achieved in an instant rather it takes a lot of time since there is a utilization of many information technological resources over the years. Therefore every organization requires a well defined strategy for carrying out the software re-engineering. 

Steps in Software re-engineering process model

The software engineering process model consists of the following steps:

1.Inventory analysis: Analysis of all the active applications listed in the inventory of an organization.

2.Document reconstruction: The software systems that are business critical are re- documented.

3. Reverse engineering

4. Code restructuring: It involves the analyzation of the source code and reviewed again.

5. Data restructuring: It begins with reverse engineering and ends with the review of all the data structures.

Scenario behind software re-engineering process

- Software re- engineering process serves the purpose of bringing up the poorly documented and poorly structured code to a standard that is maintainable and acceptable. 

- Let us see the scenario behind the need of re- engineering. 

- In a code that is poorly controlled and maintained, lies either a large number of files spread over a number of locations or consists of only a single file consisting of a very lengthy code.

- Observing these files, one could notice that the comments do not appear to have any relationship with the code itself and the associated documentation has become outdated or refers to the previous versions of that software system or application that has underwent many modifications since then which were left undocumented. 

- To say, an executable file does exists but many decisions have to be taken to run it. 

- At this point the identification of the actual objectives of the software re- engineering process becomes important. 

- There might be so many problems underlying those decisions that now can be easily addressed. 

- It is very important that before beginning with the re- engineering of the whole code that you check its correctness otherwise you will suffer a major set back if you would have been re- engineering the wrong code all the time. 

- At the end of the process the final code needs to be base-lined with the associated project log and the documentation.

- The re- engineered software system or application is brought to a well defined stage at which it can be considered to be ready for the release and also its future maintenance will be less arduous.

Data Restructuring - An activity involved in software re-engineering process model

Software re- engineering process model constitutes of the below mentioned 6 major  steps:

1. Inventory analysis
2. Documentation reconstruction
3. Reverse engineering
4. Code re- structuring
5. Data re- structuring
6. Forward engineering

In this article we have discussed about the 5^th stage of the software re- engineering process model i.e., the data re- structuring. 
Without a working code or an active flow of data a software system or application cannot be considered to be working. Therefore for the software systems and applications which have become outdated should be again brought up to the current acceptable software standards and data re- structuring is the one of the processes that can help in this regard. 


- This step of software re- engineering process model takes into consideration the restructuring of the data without making changes to the functionality of the software system or application. 
- With the re- structuring of data, the maintenance of the whole software system or application becomes so very easy. 
- The need to re- structure data arises when the data bases become too obsolete to be handled directly. 
- When the changes made to the data are confined only to the sub system, the data of the sub system needs to be re- structured. 
- The data re- structuring becomes even easier when the data re- structuring tools are easily available. 
- This step is carried out after the completion of the code re- structuring. 
- Unlike the previous re- structuring step, this step calls for a full cycle of reverse engineering. 
- The current structure of the data is dissected while defining the data models and the existing data models are run through a quality check or review test.
- So many of the legacy systems tend to make use of the global data structures and shared tables in order to save the memory space.
- Such shared data structures need to be converted in to objects like ADTs for restructuring. 

Benefits of Data Re-structuring

- One of the benefits of restructuring the data is that it certainly improves the quality of the software program or application. 
- Furthermore, it becomes easier to test and debug the software system or application along with a reduction in the efforts in the maintenance of the software and also the frustration of the developer is reduced. 
- As a bonus point, the productivity is also improved. 

Steps in Data Re-structuring

The re- structuring of the data involves the following steps:

1. Analysis of the source code of the application.
2. Redesigning of the data
3. Standardization of the data record.
4. Rationalization of the data name.
5. Translation of the file or data base.

Drawbacks of Data Restructuring

In spite of having so much plus points, the re- structuring does have some minus points which have been listed below:

1. Re- structuring does not improve the understandability of the data driven programs.
2. Re- structuring demands for heavy computations.
3. Re- structuring can lead to a loss of source code comments.
4. Restructuring does not helps with the problems with poor modularization i.e., the programs in which the components are wide spread through out the program.
5. Restructuring can lead to the loss of documentation.

From the discussion above, we can say the restructuring of data is a process that re –structures the source data in to the target data during the transformation process. 
Data re- structuring forms an integral part of the software re- engineering process model and therefore the above mentioned disadvantages of the data re- structuring are ignored. It is necessary that the data re- structuring is carried out after the code re- structuring since during the execution of the program, the code only handles the flow of the data. Therefore if the code itself has not been re- structured before re- structuring the data then the whole process does not makes any sense. 

Restructuring Concepts

Software restructuring modifies source code and/or data in an effort to make it amenable to future changes. In general, restructuring does not modify the overall program architecture. It tends to focus on the design details of individual modules and on local data structures defined within modules. Reasons for restructuring :

1. The current code would have reached a stage where it is impossible to do any more modifications without breaking something else.
2. The requirements have changed so much that the current architecture/design cannot handle it without a redesign.
3. The current application doesn’t/will not scale, perform well enough as it wasn’t designed to handle the current load/anticipated growth.
4. The folks who worked on the code are no longer there and nobody knows what the code really does.
5. You don’t really like the current way it is implemented and think that there is a better way to do it using framework X or library Y.

Code Restructuring :
It is performed to yield a design that produces the same function as the original program but with higher quality. In general, code restructuring techniques model program logic using Boolean algebra and then apply a series of transformation rules that yield restructured logic. A resource exchange diagram maps each program module and the resources that are exchanged between it and other modules. By creating representations of resource flow, the program architecture can be restructured to achieve minimum coupling among modules.

Data Restructuring :
Before data restructuring begins, a reverse engineering activity called analysis of source code must be conducted. Once the data analysis is done, data redesign commences. A data record standardization step clarifies data definitions to achieve consistency among the data item names or physical record formats within an existing data structure or file format. Another form of redesign, called data name rationalization ensures that all data naming conventions conform to local standards and that aliases are eliminated as data flow through the system. When restructuring moves beyond standardization and rationalization, physical modifications to existing data structures are made to make the data design more effective.