Design and Implementation of a service-oriented Information System Architecture based on a Case Study

In today’s companies changes happen very fast. On the one hand more and more new technologies are arising, on the other hand business processes have to change because of mergers and acquisitions, new regularities, changing customer requirements and so forth. As business processes are supported by information technology, information technology has to cope with both types of changes. From a business perspective on-demand adaptation of information technology to business is required. Service-oriented architecture (SOA) is currently discussed as an opportunity to better adapt to those changes.

According to Gartner's hype cycle for emerging technologies SOA already crossed the peak and is now in the trough of disillusionment. But SOA is far from being unfashionable as it would be expected during this phase. There is still high media coverage and a lot of SOA books have been published recently or will be published during the next months. What is true, however, is that the expectations are getting more realistic and people start to think about the real benefits. This is probably due to the fact that companies experienced, that implementing an SOA is not as fast and easy as the marketing hype might have given the impression.

Although the hype surrounding SOA is immense, the concept is still in its early childhood with regards to concrete implementations. According to a survey conducted by Experton Group only three percent of 110 German enterprises, all with over 100 Employees, have a SOA based solution in place. Besides high costs expected from migration to SOA the lack of SOA know-how is identified as a main reason. As the survey reveals 45 percent of the interviewed enterprises have nearly no knowledge or no knowledge about SOA at all. Another 38 percent have only basic knowledge.

The lack of knowledge is confirmed by a survey from the research company Quocirca, which found out, based on a sample size of 1500, that 30 percent of respondents have absolutely no knowledge about SOA and 25 percent have only minimal knowledge. Similar results are found among enterprises using SAP software. The results of an online survey conducted by the German speaking SAP User Group (DSAG) shows that 64 percent of 344 enterprises are just a little or not at all familiar with enterprise SOA and only every fifth enterprise has developed a platform strategy. Furthermore, enterprise SOA is still a topic of the IT department, although it would be relevant for the management and other departments as well. The president of the user group concludes that, instead of theory, more trainings and practical case studies would have to be offered by SAP.

As with SOA 2.0 already the following hype is announced, it makes sense to refrain from SOA marketing efforts as far as possible and to bring more clarity into current SOA and enterprise SOA discussions. To achieve this objective, the thesis examines the topic from different views. The first view is a vendor-neutral, theoretical view on general SOA concepts. The second view is targeted to enterprise services architecture (ESA), also called enterprise service-oriented architecture (ESOA), which is a SOA blueprint from SAP. The third view finally provides a practical case study. It examines based on a small scenario how to implement a service-oriented architecture using SAP technology.

SOA is intended to close the gap between IT and Business. In the same way this thesis does not focus on one side or the other but brings aspects of both disciplines together. For example business process design will be part of the thesis in the same way as Web services and developer tools. However, this also means that the field of research is very broad and an in depth discussion is not always possible. To counterbalance this fact, references to further information will be provided as often as possible.

The thesis introduces service-oriented architecture (SOA) as an information system architecture that promotes agility, reusability and business relevance of applications. SAP's enterprise service-oriented architecture (ESOA) is discussed as a reference architecture for realizing the benefits of SOA at an enterprise level.

During the case study a business process is designed according to the requirements of a specified scenario. From the functional model a technical model is deduced and then all layers of an enterprise SOA are implemented using SAP NetWeaver technology. Starting from service-enablement of Enterprise JavaBeans, entity services and application services in CAF Core are developed. Those services are used in Visual Composer to model user interfaces and flows with included service calls. The Visual Composer iViews are then passed to the process layer and linked with Guided Procedures to a complete process that involves several roles.

Table of Contents:

Chapter 4., SAP's Enterprise Service-Oriented Architecture: The previous chapter described the general principles of SOA and topics related to it. This chapter will supplement SAP's view of a service-oriented architecture and explain the meaning of enterprise services architecture, the blueprint introduced by SAP in 2003. The terms „enterprise services architecture“ (ESA) and „enterprise service-oriented architecture“ (enterprise SOA/ESOA) are used as synonyms in this chapter because SAP began to promote the term enterprise service-oriented architecture in the second quarter 2006 and SAP press releases, articles and books use both terms without stating any differences.

In a newly published book, Bönnen and Herger state that whereas ESA focuses mainly on service-enablement of applications and SAP solutions, the Enterprise SOA concept goes one step further. The main differentiator is the capability to take existing services and combine them to build new applications, so-called composite applications. But this probably rather reflects a focus shift in current development activities than a real difference in terminology or concepts as composite applications have always been an important part of the ESA blueprint.

Chapter 4.1, Fundamentals of Enterprise Service-Oriented Architecture: SAP introduced its new enterprise services architecture (ESA) blueprint in 2003 but there is still confusion about what it is and how it differentiates from the general SOA concept. In fact, SAP itself „has had a difficult time helping customers and partners fully understand the ESA roadmap, and how it is fundamentally different from just adopting SOA technologies.

One reason might be that it really requires a change in the way of thinking (SOA has also caused much confusion), another one that the ESA roadmap has been set up as a vision several years in advance and is still not fully completed, so customers and partners had to believe in the vision without being able to make real prove points for themselves. However, the question remains whether ESA is only fundamentally different from adopting SOA technologies or whether it is also fundamentally different from SOA as a concept.

Chapter 4.1.1, Basic Concepts of Enterprise SOA: Campbell and Mohun state that ESA is a completely new architectural blueprint for SAP. It contains both a technology aspect based on industry-driven SOA and related IT trends, as well as an enterprise business dimension built from SAP's Solution Maps and the company's deep horizontal and vertical process knowledge. This leads to an important aspect. It is helpful to keep in mind that SAP is primarily a solution provider.

As such the company is offering solutions and best practice processes for whole industry segments and for many years already. With ESA, SAP is restructuring its own solution landscape. So in contrast to other vendors in the SOA field, SAP is not only delivering technology but also solutions which follow the principles introduced by the ESA roadmap. The fundamental premise of Enterprise Services Architecture is the abstraction of business activities or events, modeled as enterprise services, from the actual functionality of enterprise applications. Aggregating Web services into business-level enterprise services provide more meaningful building blocks for the task of automating enterprise-scale business scenarios. Enterprise services allow IT organizations to effciently develop composite applications, defined as applications that compose functionality and information from existing systems to support new business processes or scenarios.

There are three main points in this statement: Firstly, enterprise services are used for automating business scenarios. Secondly, enterprise services are an abstraction from the actual functionality of enterprise applications. And finally composite applications are a means of developing efficient applications based on enterprise services. Enterprise services are introduced as an aggregation of Web services. Fritz states that „enterprise services are simply Web services that provide enterprise-level business functionality. They may range from very simple lookup services (like finding a company's location or product offerings) to more complex and composite services - but what they have in common is that they're highly integrated into your process or application“.

Figure 4.1 shows an enterprise service Cancel Order which aggregates several Web services to offer more business value. The order cancellation results in several internal steps implemented through Web services, including for example a rollback of inventory, a shipment cancellation and a planning adjustment. Enterprise services follow clear semantics, which are defined at different levels. The basic elements are global data types. They become the „semantic vocabulary of an enterprise and a basis for describing business objects and defining the phrases (or messages, technically speaking) that are exchanged by consumers and providers“.

Regarding to the second point, abstraction from actual functionality, it is quite obvious that SAP cannot rebuild its whole application suite in one go following the enterprise services concept. So a large initiative called service-enabling has been started to create enterprise services based on existing functionality of systems like ERP, CRM, SCM and so forth. Of course, new functionality will be developed already with the enterprise services concept in mind and therefore offer even more flexibility.

The first service-enabled enterprise services have been delivered a few month ago and many more will follow. The ESA Preview System on SDN provides an overview of available and planned services.