Section: Research Program
One important domain that is being investigated by the AtlanMod team is the reverse engineering of existing IT systems. We do believe that efficiently dealing with such legacy systems is one of the main challenges in Software Engineering and related industry today. Having a better understanding of these systems in order to document, maintain, improve or migrate them is thus a key requirement for both academic and industrial actors in this area. However, it is not an easy task and it still raises interesting challenging issues to be explored  .
We have shown how reverse engineering practices may be advantageously revisited with the help of the MDE approach and techniques, applying (as base principle) the systematic representation as models of the required information discovered from the legacy software artifacts (e.g. source code, configuration files, documentation, metadata, etc). The rise in abstraction allowed by MDE can bring new hopes that reverse engineering is now able to move beyond more traditional ad-hoc practices. For instance, a industrial PhD in partnership with IBM France aims to investigate the possibilities of conceptualizing a generic framework enabling the extraction of business rules from a legacy application, as much as possible, independently of the language used to code it. Moreover, different pragmatic solutions for improving the overall scalability when dealing with large-scale legacy systems (handling huge data volumes) are intensively studied by the team.
In this context, AtlandMod has set up within the past years and is still developing the open source Eclipse MoDisco project (see 5.2 ). MoDisco is notably being referenced by the OMG ADM (Architecture Driven Modernization) normalization task force as the reference implementation for several of its standard metamodels. It is also used practically and improved in various collaborative projects the team is currently involved in (e.g. FP7 ARTIST).
We have also opened a novel research line focused on integration of APIs into MDE. In the application of reverse engineering processes while modernizing software system it is very common to face the need of integrating Application Programming Intefaces (APIs). Indeed, building any application usually involves managing a plethora of APIs to access different software assets such as: basic infrastructures (e.g. operating system, databases, or middleware), general-purpose or domain specific libraries, frameworks, software components, web services, and even other applications. Thus, to promote the interoperability between the API and model technical spaces, we have developed API2MoL, which is an approach aimed at automating the implementation of API-MDE bridges. This new language allows defining mappings between the artefacts of a given API (e.g. API classes in object-oriented APIs) and the elements of a metamodel that represents this API in the MDE technical space. A mapping definition provides the information which is necessary to build a bridge for a concrete API specification and metamodel. Thanks to the API-MDE bridges automatically created, developers are liberated from having to manually implement the tasks of obtaining models from API objects and generating such objects from models. Therefore, API2MoL may improve the productivity and quality of the part of the MDE application that deals with the APIs.
Reverse engineering techniques have also been used in the context of the Web. In the last years the development of Web APIs has become a discipline that companies have to master to succeed in the Web. The so-called API economy requires, on the one hand, companies to provide access to their data by means of Web APIs and, on the other hand, web developers to study and integrate such APIs into their applications. The exchange of data with these APIs is usually performed by using JSON, a schemaless data format easy for computers to parse and use. While JSON data is easy to read, its structure is implicit, thus entailing serious problems when integrating APIs coming from different vendors. Web developers have therefore to understand the domain behind each API and study how they can be composed. We tackle this problem by developing a MDE-based process able to reverse engineer the domain of Web APIs and to identify composition links among them. The approach therefore allows developers to easily visualize what is behind the API and the connections points that may be used in their applications.