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15.1. Project ScopeThe scope of Winterthur's SOA introduction is mainly defined by the requirements of innovative business-driven projects and the need to reuse existing mainframe applications. 15.1.1. BUSINESS IMPACTThe first pilot project to be implemented within the SOA was wincoLink, an interactive customer service of Winterthur Leben, the life insurance branch of Winterthur. It provided corporate customers with online access to all contracts and contained direct information about, for example, vested benefits. It also supported changes of contract information, such as the inclusion of new employees in a corporate contract or a change to address data. wincoLink was chosen as the pilot project because it not only was restricted to the passive browsing of static content but also involved user interaction. This provided Winterthur with the prestigious benefit of offering the first interactive life insurance Internet application. In addition, wincoLink promised significant cost-saving potential because it reduced Winterthur's customer support by enabling customers to access and change contract information directly, avoiding the need to go through Winterthur staff. In addition, wincoLink increased customer satisfaction because the online content available for inspection was always up-to-date. Finally, wincoLink offered the advantage of a restricted user group, namely corporate customers, which could be enlarged step by step. It was thus possible to increase the support organization and the necessary processes incrementally, while extending the user group in a parallel manner. In fact, the wincoLink project turned out to be ideal for collecting experiences associated with the SOA without any major risks. 15.1.2. TECHNOLOGY IMPACTThe focus of Winterthur's SOA is on the integration of existing host applications. One of the major incentives for the new architectural approach was the soaring cost for maintaining monolithic applications on the mainframe computer. In addition, Winterthur wanted to add new "sales" management channels to their IT infrastructure, in particular through the Internet and Intranet in order to make their applications and solutions widely available. In Winterthur's SOA, a service is defined as a set of operations granting access to a simplified business context or to enterprise information in the form of core business entities. Winterthur distinguishes three types of services (the terminology used for this distinction is Winterthur's):
In addition to these services, there are also application frontends, which, according to Winterthur's terminology, belong to the presentation layer:
Figure 15-1 shows the 3-tier architecture used by Winterthur (a more detailed architecture will be presented later in Section 15.3). This logical layering of the architecture, which is more or less standard for current Enterprise Systems, distinguishes between a presentation layer, an application layer, and the domain and data layers and is not to be confused with physical deployment. These layers are distributed according to non-functional requirements using one of the patterns illustrated in Figure 15-2. Figure 15-1. Winterthur's N-tier architecture.Figure 15-2. Example patterns for layer distribution.The initial implementation of the SOA and e-Platform focused mainly on offering reusable domain services on the mainframe computer. Its main purpose was to allow the applications to be implemented in the application layer and to use standardized interfaces to access data and functionality on the host. As we explain in more detail later on, CORBA was used to implement the domain services. Extensions of the e-Platform that include the necessary standards, processes, tools, and guidelines toward EJB, asynchronous messages and Web services are currently being defined. Figure 15-3 shows the services landscape of Winterthur with six top-level domains and their respective sub-domains. Winterthur uses these domains to structure their services and define degrees of decoupling. Whereas services within a sub-domain are not necessarily completely decoupled, there are no dependencies between services from different domainsthat is, decoupling is complete across domain boundaries. Figure 15-3. Winterthur's Non Life Applications (NLA) services landscape 2003.One reason for this "mixed" approach is that decoupling is both costly and risky at times. It is therefore reasonable to place an initial limit on the degree of decoupling and choose a rather coarse-grained structure, as illustrated by the top-level domains in Figure 15-3. These top-level domains constitute the main application groups offered by Winterthur and provide a clear intermediate structure for which service contracts and application frontends can be designed. According to the SOA philosophy underlying Winterthur's e-Platform, services provide given functionality as coarse-grained operations. To capture this functionality, technology-independent service contracts are established. These contracts are published in a repository and contain interface definitions and descriptions of data elements used. From the SOA's point of view, services are completely defined by these contractsthat is, a service constitutes a black box with respect to all internal aspects of the service implementation and is not visible in the contract. This black box approach allows a rather effective decoupling of clients and servers in addition to the transparent location of service implementations. Currently, 66 services are in production, another 21 are under development, 26 are in the test phase, and 3 additional services are planned for the near future. Every service contains one to three operations. |
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