Section 15.4. Lessons Learned, Benefits, and Perspectives

15.4. Lessons Learned, Benefits, and Perspectives

The introduction of the SOA has already delivered substantial benefits. The development of new applications has been significantly simplified due to the flexible nature of the implemented services and the resulting reusability.

What is particularly noteworthy is the fact that Winterthur has achieved these benefits by using very simple and basic SOA concepts: service orientation, explicit contracts, reused policies, and a descriptive but concise repository. Winterthur did not employ any advanced SOA concepts, such as service composition or distributed transactions.

One of the major success factors was the efficient process established at Winterthur to ensure reusability of developed services and e-Platform blueprints. However, it also became clear that designing services with focus on reusability generates a considerable overhead. It transpired that only one in three or four services was actually used by more than one application. Additional new application frontends, however, are enhancing the reuse rate. A further lesson was learned: design focused solely on reuse can lead to overly fine-grained services (e.g., to have an overview of a customer or a contract, you might have to call many fine-grained services to get all information related to an overview). Performance will be less than optimal if the service is accessed remotely, which leads to performance-optimized remote services that internally called fine-grained services accessed by local interfaces. The same fine-grained services can be easily encapsulated by a CORBA interface and called by a remote client. Further optimization was found in the so-called "multiple" services. Rather than retrieve a single contract or person through a single key, a whole list of business entities can be obtained with a single remote call using a list of keys.

Also due to performance issues related to remote communication, both domain layer services using CORBA and in some cases application layer services^[3] were implemented on the host.

^[3] Process-centric services according to the terminology of this book.

One way of minimizing the overhead caused by reusability is to explicitly distinguish between public and private services. Only the former are designed with reusability considerations in mind, whereas the latter are to be used solely by the application for which they were originally developed.

Apart from these qualifications, however, the reuse of implemented services was rather successful. All applications using host data are migrating to use them through the newly developed services. The SOA has therefore become the cornerstone of Winterthur's IT integration.

Another major benefit is the widespread use of the repository. The information available in the repository turned out to be an excellent documentation of the already implemented functionality. In contrast to traditional documentation that quickly becomes complex and voluminous, the information contained in the repository is very concise. This is mainly due to the fact that the information to be published in the repository is restricted to essential facts required to adequately use the service in applications. On the other hand, the simple fact that the repository imposes a standardized format also contributes to its usability and offers an advantage over traditional documentation, which is usually crudely structured.

The development of Winterthur's SOA and its underlying e-Platform still continues. The main direction of enhancements concerns the removal of platform limitations, in particular regarding the SOA support of message-type communication, EJBs, and Web services.

Whereas emphasis has been on host applications in the beginning, focus now shifts to the application layer and non-host applications. Because the application layer is largely based on EJBs, the main task is to extend the SOA standards, guidelines, and processes that are currently based on synchronous CORBA to encompass EJBs, asynchronous messages, and Web services.

Another area of extension concerns workflows. To date, workflows are not explicitly modeled and supported in the e-Platform. They are only contained in the dynamic models of use case realizations developed in the design phase. The integration of workflows to support specification, automatic execution, monitoring, and optimization of workflows is currently under investigation.

These extensions will be defined by different long-term Winterthur IT sub-strategies such as the Swiss Insurance IT Platform definition, Integration strategy, Solution Delivery Process, and the Technical Platform.