In this chapter, the author examines the migration process of a legacy system, as a software-as-a-service model, to the Web, and he looks at some of the reasons that drive this legacy system migration. As migration is often a multi-step process, depending on the legacy system being migrated, the author outlines several techniques and transformations for each step of the migration process in order to enable legacy systems, of different types, to be migrated to the cloud. Of particular interest are the different methods to handle data-intensive legacy systems to enable them to function in a cloud computing environment with reduced bandwidth. Unlike the migration of an unstructured legacy system to a locally-distributed desktop system, system migration to a cloud computing environment poses some unique challenges such as restricted bandwidth, scalability, and security. Part of this migration process is adapting the transformed legacy system to be able to function in such an environment. At the end of the chapter, several small case studies of legacy systems, each of a different nature successfully migrated to the cloud, will be given.
TopIntroduction
What is cloud computing? Cloud computing could be defined as an emerging paradigm of data and computation sharing over a scalable network of nodes (the “cloud”); these nodes include clients, data centers, and Web services (Mirzaei, 2009). Focusing on service provision, Betty defines cloud computing as Internet-based services and resources that are delivered to clients on-demand from a service provider (Beatty, 2009).
In order to access these services, these clients do not need expertise or control over the technology that they access; however, these clients are able to gain access to technology which both improves end-user productivity and is cost-effective (Mirzaei, 2009). For the service provider, these services consists of applications, such as payroll systems, with portals, which use standard interfaces and messages protocols, that can be accessed by clients (Schluting, 2010; Mirzaei, 2009). In addition to services, the providers supply resources to their clients such as servers, network, memory, CPU, and storage (Schluting, 2010).
This chapter describes the process of migrating a legacy system, often data-intensive, to a Web-based environment along with the challenges and possible solutions of such a migration. Unlike other users of cloud computing that utilise services supplied by other Web-based service providers in the “cloud”, this chapter focuses on enterprises that migrate their own legacy systems to the Web and provide services to their own clients using these migrated systems. In the chapter, several short case studies of legacy systems that were successfully migrated to the Web are given with an analysis of each migration.