Chapter EIGHT. The Enterprise Services Repository and the Enterprise Services Inventory

In many ways, the Enterprise Services Repository is the heart of ESA. The Enterprise Services Repository is the design-time repository of service objects for ESA. Before we unpack that more technical definition, let's frame the Enterprise Services Repository and Enterprise Services Inventory in simpler terms.

A repository is essentially a container, as shown in Figure 8-1. According to Wikipedia, a repository is a central place where data is stored and maintained. SAP offers the containerthe Enterprise Services Repositoryand its contentsthe enterprise service descriptions defined in the Enterprise Services Inventory (see Figure 8-2)as part of the SAP NetWeaver platform.

What is an inventory ? It's a detailed list of all items that a company has in stock. The Enterprise Services Inventory is a set of services that SAP has provided to its customers. The initial version of the Enterprise Services Inventory includes some 500 enterprise services. Additional services will be added to the Enterprise Services Inventory over time by SAP and by customers and partners participating in the Enterprise Services Community (which is discussed in Chapter 6).

Figure 8-1. A repository and its contents

Figure 8-2. A simplified view of the Enterprise Services Repository and the Enterprise Services Inventory, which it contains

By providing not only the containerthe Enterprise Services Repositorybut also the contentsthe enterprise services themselvesSAP's approach to service-oriented architecture (SOA) can be seen as dramatically different from that of its competitors. Of course, the Enterprise Services Repository is further enriched with services that your organization may add for your own use. You might also choose to submit the services you create to the Enterprise Services Community for possible inclusion in the Enterprise Services Inventory offered to all customers.

In the first part of this chapter, we will talk about the Enterprise Services Repository; later in this chapter, we'll cover the Enterprise Services Inventory.

Before we delve deeper into the Enterprise Services Repository, however, let us make it perfectly clear: the Enterprise Services Repository, simplified graphics aside, does not contain the services themselves. The service definitions are what reside in the Enterprise Services Repository; the implementation of the services is stored in the development environments (more on that topic in Chapters 15 and 16). What the Enterprise Services Repository includes, however, is vital. It includes everything we need to design services using a model-based approach, reusing data types, message types, and entire operations if desired.

The Enterprise Services Repository is still evolving. As we move through the chapter, we will describe where the Enterprise Services Repository is today, and, where relevant, we will provide you with a glimpse of its future direction. The Enterprise Services Repository is evolving quickly, and it's quite possible that by the time you are actively using it in your own ESA implementation, these features of the future will be a current reality. Having a more complete concept of the Enterprise Services Repository from the outset will help you form your ESA strategy.

In this chapter, we'll describe the Enterprise Services Repository from a number of angles. We'll talk about the nature of the Enterprise Services Repository, its roots, its advantages, and what is in it. Finally, we'll look at the Enterprise Services Inventory: a collection of services that SAP provides to help users get started on the path to ESA adoption.