Mastering Enterprise SOA with SAP NetWeaver® and mySAP™ ERP

Chapter 11. Developing Enterprise Services

To move toward an ESA-based landscape and architecture, one of the important steps is to figure out how to service-enable existing applications and build new applications or components that are service-enabled. Existing assets include any application that currently solves a business problem. A typical system landscape consists of SAP, third-party ISV packages, and custom-developed systems. This chapter provides details on service-enablement of both SAP and non-SAP systems. Once service-enabled, the services can become enterprise services by adding the artifacts to the Enterprise Services Repository (ESR). Concepts surrounding SAP’s Enterprise Services Infrastructure are also explained in this chapter.

SAP promotes two approaches to the development of Web Services–enabled interfaces: inside-out and outside-in. In the inside-out approach, you start with existing application functionality and then expose it as services. This is fairly easy to do when you have current interfaces, APIs, objects with public methods, integration schemas, and so forth. In fact, many IDEs offer tools and wizards to create Web Service interfaces based on this content. You will see how the SAP development environments support these capabilities for ABAP and Java developers later in the chapter.

Basically, current system implementations drive the details of how services are defined and created with the inside-out approach. This can limit your flexibility in terms of ...