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As cloud computing allows improving the quality of software and aims at reducing costs of operating software, more and more software is delivered as a service. However, moving from a software as a product strategy to delivering software as a service hosted in cloud environments is very ambitious. This is due to the fact that managing software modernization is still a major challenge; especially when paradigm shifts, such as moving to cloud environments, are targeted that imply fundamental changes to how software is modernized, delivered, and sold. Thus, in addition to technical aspects, business aspects need also to be considered. ARTIST proposes a comprehensive software modernization approach covering business and technical aspects. In particular, ARTIST employs Model-Driven Engineering (MDE) techniques to automate the reverse engineering of legacy software and forward engineering of cloud-based software in a way that modernized software truly benefits from targeted cloud environments. Therewith, ARTIST aims at reducing the risks, time, and costs of software modernization and lowers the barriers to exploit cloud computing capabilities and new business models.

Abstract. Cloud computing has leveraged new software development and provisioning approaches by changing the way computing, storage and networking resources are purchased and consumed. The variety of cloud offerings on both technical and business level has considerably advanced the development process and established new business models and value chains for applications and services. However, the modernization and cloudification of legacy software so as to be offered as a service still encounters many challenges. In this work, we present a complete methodology and a methodology instantiation framework for the effective migration of legacy software to modern cloud environments. 1. Introduction. Nowadays, cloud computing [4] appears as one of the most popular and mature technological and business environments for engineering, hosting and provisioning software applications. A continuously increasing set of cloud-based solutions across the cloud stack layers [11] is available to application owners and developers to tailor their applications and exploit the advanced features of this paradigm for elasticity, high availability and performance. These solutions provide many benefits to new applications but they also introduce constrains to the modernization and migration of legacy applications. We consider legacy applications as software not developed for the Cloud and software in traditional architectural paradigms that cannot be scaled, cannot be measured and does not share resources beyond infrastructure (e.g. database, memory). Often the legacy applications follow monolithic architecture design approaches, implemented in technologies which may be deprecated or cannot easily deal with the notion of "as a Service" and are installed on owned infrastructures.The modernization and adaptation of legacy applications to cloud environments is a great challenge for all involved stakeholders, not only from a technical perspective, but also in business level with the need for adaptation of the business processes and models of the application which will be deployed on the Cloud and offered "as a service". In this paper, we present a novel model-driven [22] approach for the migration of legacy applications in modern cloud environments which covers all aspects and phases of the migration process, as well as an integrated framework that supports all migration process.Our motivation for this work is the requirements and challenges for the effective migration of legacy software on the Cloud as described in [9]. To this end, the proposed migration methodology considers the following aspects:• Unknown internal structure due to the complexity of the software and the data management processes.• Lack of knowledge for target environment where the application will be deployed and provisioned.

Nowadays Cloud Computing is considered as the ideal environment for engineering, hosting and provisioning applications. A continuously increasing set of cloud-based solutions is available to application owners and developers to tailor their applications exploiting the advanced features of this paradigm for elasticity, high availability and performance. Even though these offerings provide many benefits to new applications, they often incorporate constrains to the modernization and migration of legacy applications by obliging the use of specific development technologies and explicit architectural design approaches. The modernization and adaptation of legacy applications to cloud environments is a great challenge for all involved stakeholders, not only from the technical perspective, but also in business level with the need to adapt the business processes and models of the modernized application that will be offered from now on, as a service. In this paper we present a novel model-driven approach for the migration of legacy applications in modern cloud environments which covers all aspects and phases of the migration process, as well as an integrated framework that supports all migration process.