From Legacy to Cloud: Risks and Benefits in Software Cloud Migration

Various factors need to be evaluated before moving on-premise software applications to the cloud. Considerations such as scale, legal constraints, and security play a key role in rearchitecting an application in a cloud-compliant way. However, the body of knowledge on relevant migration factors is mostly neglected in practice and scattered in the scientific literature. To make this knowledge accessible, we have conducted a systematic literature review. It identifies the relevant studies that describe measures and indicators for guiding software cloud migration. This chapter presents the results of the review, which include the collected factors, namely 40 benefits, 71 risks, and 72 general measures. All factors were classified into five categories: financial, organizational, technical, legal, and security-related. In Tables 9.7, 9.8 and 9.9 we present a selection (the complete list of factors is available online at http://tinyurl.com/h6rhhp6) of all factors (3 factors per category, if the category appears in the collected benefits, risks and general measures). The analysis of factors draws observations on the most relevant benefits, risks, and measures playing a role in contemporary cloud migration. Among them, security appears not to be the biggest inhibitor to cloud migration anymore thanks to matured Service Level Agreements (SLAs). In contrast, issues like post-migration costs and the potential impact of the migration on organization staff are gaining importance. These and similar findings, along with the list of factors, can help decision makers in assessing the risks and benefits of moving a software application to the cloud. The presented factors can also be used as a base for producing a more complete list of requirements for rearchitecting preexisting software and easing their migration to the cloud.