Towards architecture driven modernization

 

Architecture driven application modernization involves meta modeling and transformations of models that can help to optimize system evaluations costs by automating the modernization process of systems. This is done in three phases: reverse engineering, restructuring and forward engineering. Reverse engineering technologies can analyze legacy software systems, identify its widgets and their interconnection, reproduce it based on the extracted information, and create a representation at a higher level of abstraction. Some requirements for modernization tools can be called out here. It must allow extracting domain classes according to Concrete Syntax Tree meta-model and semantic graphical information, then analyze extracted information to change them into a higher level of abstraction as a knowledge-discovery model.

Software modernization approach becomes a necessity for creating new business value from legacy applications. Modernization tools are required to extract a model from text in source code that conforms to a grammar by manipulating the concrete syntax-tree of the source code. For example, there is a tool that can convert Java swing applications to Android platform which uses two Object Management Group standards: Abstract Syntax Tree for representing data extracted from java swing code in reverse engineering phase and Knowledge Discovery Platform-independent model. Some tools can go further to propose a Rich Internet Application Graphical User Interface. The three phases articulated by this tool can be separated into stages as: the reverse engineering phase which uses the jdt API for parsing the Java swing code to fill in an AST and Graphical User Interface model and the restructuring phase that represents a model transformation for generating an abstract KDM model and the forward phase which includes the elaboration of the target model and a Graphical User Interface.

The overall process can be described as the following transitions:

Legacy system  

–parsing->

AST Meta model

–restructuring algorithm->

Abstract Knowledge Model

--forward engineering->

GUI Metamodel.

The reverse engineering phase is dedicated to the extraction and representation of information. It defines the first phase of reengineering following the Architecture Driven Modernization process. It is about the parsing technique and representing information in the form of a model. Parsing can focus on the structural aspect of header and source files and then there is the presentation layer that determines the layout of the functionalities such as widgets.

The restructuring phase aims at deriving an enriched conceptual technology independent specification of the legacy system in a knowledge model KDM from the information stored inside the models generated on the previous phase. KDM is an OMG standard and can involve up to four layers: Infrastructure layer, Program Elements layer, resource layer and abstractions layer. Each layer is dedicated to a particular application viewpoint.

The forward engineering is a process of moving from high-level abstractions by means of transformational techniques to automatically obtain representation on a new platform such as microservices or as constructs in a programming language such as interfaces and classes. Even the user interface can go through forward engineering into a Rich Internet application model with a new representation describing the organization and positioning of widgets.

Automation is key to developing a tool that enables these transitions via reverse engineering, restructuring and forward engineering.