A Structured Legacy to SOA Migration Process and its Evaluation in Practice Ravi Khadka, Amir Saeidi, Slinger Jansen, Jurriaan Hage Department of Information and Computing Sciences, Utrecht University {r.khadka, a.m.saeidi, slinger.jansen, j.hage}@uu.nl Abstract—Legacy to Service-Oriented Architecture migration approaches have been extensively researched over the last decade, primarily to reuse the valuable business logic that resides within legacy applications. Interestingly, most of the proposed approaches fail to cover the complete process from the technological, organizational and business perspectives. This paper presents a structured six-phase process that covers both migration planning and execution, and does so by considering the aforementioned perspectives. Furthermore, within each of the six phases of the process, we present a rationale to justify the need of each phase, current practices within each phase, and challenges that require further attention. The proposed structured process is then evaluated by (i) migrating features of two simple yet representative applications to SOA, and (ii) by mapping activities reported in literature. Based on our findings, we believe that the proposed structured process is successfully fitting to capture the essence of the activities that are performed within the legacy to SOA migration domain by combining various perspectives. I. I NTRODUCTION One of the IT challenges faced by many enterprises is the maintenance of their legacy applications and migration of those applications to modern and flexible platforms. Legacy applications inherit various problems such as lack of up- to-date documentation, skilled manpower, resources of the legacy applications, and high maintenance costs [1]. Despite such problems, enterprises cannot simply remove/replace those applications as they are mission critical, implement the core business logic, and their failure can have a significant impact on business 1 . Thus, legacy applications present a dilemma: they are vitally important to the business, however maintaining them incurs unjustifiable expenses [2]. A viable solution to this dilemma is to migrate those systems into new technological environments in which the legacy features can be re-used. Service-Oriented Architecture (SOA) has gained significant attention from academic and industry as a promising ar- chitectural style enabling legacy applications to expose and reuse their functionalities [3]. A legacy to SOA migration not only aims at reducing maintenance costs [4], but also enables a higher Return on Investment (ROI) [5] and pro- motes flexibility to changing business needs [6]. With all these aforementioned benefits of SOA, several approaches to migrate legacy applications to SOA have been reported in academia [7], [8] and in industry [9], [10]. These approaches can be basically categorized into two aspects: (i) migration planning: to determine the migration feasibility based on 1 RBS IT Failure Cost Hits £175m: http://goo.gl/xpDjy technological and economical assessments, and (ii) migration execution: to develop a supporting technology so as to ex- pose legacy applications as a service and to provide service provisioning upon exposing the service. However, a legacy to SOA migration approach requires the consolidation of both the aforementioned aspects (i.e., migration planning and migration execution) [11]. Furthermore, legacy to SOA migration is not only a complex technical endeavor, but it also involves various organizational and business perspectives [5]. So, any legacy to SOA migration requires a structured process that can address these technical, organizational and business issues. The need of such a structured process has been argued by various researchers such as Kontogiannis et al. [6] and Lewis et al. [12], [13]. In this paper, we present a structured process that combines the migration planning and migration execution aspects of a legacy to SOA migration. The structured process is divided into two aspects (i.e., migration planning and migration im- plementation & management), each consists of three phases. For each phase, we present a rationale to justify the need for each phase, current practices for each phase, and challenges that require further attention. The proposed structured process is then evaluated by migrating features of two simple yet representative applications to SOA. To further validate the structured process, we selected 17 academic papers reporting legacy to SOA migration from 2000 to 2011 and mapped the activities described therein to the phases of the structured process. The paper makes the following contributions: • It presents a structured legacy to SOA migration process that consolidates migration planning and migration exe- cution aspects. • It identifies rationale, current practices and challenges for each phase of the proposed structured process. The rest of the paper is structured as follows: Section II describes the structured process with its phases and elaborates rationale, best practices and challenges of each phase. Sec- tion III presents two case studies to evaluate the proposed process and provides mapping of activities reported in the literature. In Section IV, we analyze and discuss our findings and finally, Section V concludes our research with an outlook to future work. II. THE STRUCTURED PROCESS Fig. 1 depicts the proposed structured legacy to SOA migra- tion process that includes six phases divided over two aspects: