Find and Validate Enterprise Services for Reuse 
Questions Answered
Which role do composite applications play in Enterprise SOA?
What is an enterprise service?
What options do I have when reusing existing services?
What kind of framework does SAP provide for customers to find and test enterprise services?
Which role does the Services Registry play?
What kind of infrastructure and tools are publicly available to discover enterprise services provided by latest solutions of SAP Business Suite?
Introduction
In the Enterprise SOA, you must distinguish between one or more service providers on one side and a wide range of service consumers on the other. The service providers generally offer certain business functions as services and publish their interfaces. Consumers use several services that may be provided by multiple service providers to create new functions. At this point, composite applications come into play. Composite applications use exactly this service-oriented architecture to fill the gaps that standard solutions can not cover. They sit on top of existing enterprise solutions and reuse their functionality to shape new collaborative business processes. To implement such innovative business processes, composite applications only run against well-defined interfaces with well-defined business semantics.
What Is an Enterprise Service?
An enterprise service is a callable entity that provides business functionality and is published by SAP in the Enterprise Services Repository. |
This definition however includes the following characteristics:
Enterprise services are based on the Web service standards so that they can be consumed by all Web service clients, however they also incorporate some non-technical aspects.
Enterprise services
Are structured according to the harmonized enterprise model based on Global Data Types (GDTs), business objects, and interface patterns
Safeguard interface stability
Are well-documented
Are based on open standards (XML, WSDL, SOAP and so on).
Reusing Existing Business Functionality
The basic concept around the composites is to make extensive reuse of existing functions and thus minimize the effort required for new development – as far as possible. However, the amount of reusabilty you will able to achieve depends on the needs of your composite application. In general, you have several options:
Complete reuse of existing services:
You use the services as they are.
Wrapping service interfaces:
Based on an existing service, you can, for instance simplify the service interface so that the service is tailored to the needs of your composite application. In this case CAF comes into play. CAF provides an abstraction layer between the application and the service interfaces. Whenever service adoption is needed you just have to modify the CAF layer, not the application.
Enhancement of existing enterprise services.
SAP’s Infrastructure for Finding and Testing Enterprise Services
There is an extensive infrastructure and utilities available to find, evaluate, and test enterprise services that is delivered by SAP to expose its proven business functionality:
ES Workplace
Even if your company does not yet have the ES Repository installed, you can benefit from service descriptions and check the content. These descriptions are made available in the global repository ES Workplace and are published in the SDN. Therefore, ES Workplace is the central source of information from which customers and non-customers can explore enterprise services that SAP delivers in the latest releases of SAP Business Suite. The ES Workplace provides a publicly available Services Registry so that you are able to test a real implementation of the enterprise services that you discover in a hosted environment.
Services Registry
The Services Registry (SR) is a directory for all service definitions and service endpoints available within your SOA landscape. The SR acts like yellow pages and offers development-relevant information about services provided in that landscape, with references to relevant WSDL metadata for the service and to the locations of the callable service endpoints. It is comprised of two major components: a UDDI v3 server (OASIS standard) and a classification service (SAP standard). The registered services are classified using semantic-rich classification systems to enable the browsing of services by classification. In addition, you can publish new service definitions of the back-end services to Services Registry. By publishing in the Services Registry, you can organize a huge number of services provided by multiple back-end systems centrally in your landscape.
Enterprise Services Repository
The Enterprise Services Repository (ES Repository) is a central place within your SOA landscape where enterprise service definitions are modeled, stored, and maintained. ES Repository provides metadata for enterprise services that supply common business functionality. While designing composite applications, you can use this central modeling and design environment to investigate which services in your local landscape exist, what their interface definitions look like, and - if necessary - which gap your own development has to fill.
Activities
You have different options to find and evaluate enterprise services delivered by SAP:
Explore and test services provided with ES Workplace in the SDN
Access the publicly available ES Workplace in the SDN:
Find and test services available centrally in your landscape using the Services Registry.
More information: Discovering Services in the Services Registry
Use the Enterprise Services Repository to investigate what the service definitions look like.
While developing composite applications, you can use the ES Repository to investigate which services exist and how they meet the requirements of your composite application.
More information: Working with Enterprise Service Definitions Delivered by SAP