Dear Sara,
In a nutshell, 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.Typically enterprise services are high-level components that take more granular Web services and aggregate them into reusable elements with business value. For example, take the service Cancel Purchase Order. An elementary Web
service like Delete Purchase Order would simply lead to the deletion of a purchase order in the corresponding
database. However, if the stated goal is “cancel purchase order,” the service has to become a more far-reaching enterprise service that handles this process end-to-end, and therefore has to trigger a number of follow-up actions, including:
=> Check against production orders
=> Check against a corresponding billing process
=> Update of inventory/warehouse information Or consider the Credit Limit Check
service, which at first glance seems to be quite simple. Normally, this service is one ingredient of the Order Creation service. But typically, credit checking is
really a more elaborate composite service.
5 Key Principles of ESA
1. Abstraction — hiding confusing details
2. Modularity — breaking down complexity, resulting in reusable pieces
3. Standardized connectivity — enabling flexible composition of services to
create bigger processes and scenarios
4. Loose coupling — allowing for separate evolution of the various components
without breaking any points of integration
5. Incremental design — enabling changes to composition and configuration
without affecting the interior of components, and vice versa
<b>Service Oriented Architecture (SOA)</b>
A service-oriented architecture (SOA) is a collection of services that communicate with each other. Communication can involve either simple data passing or it can involve two or more services coordinating some activity. Some means of connecting services to each other is needed.
A service is a function that is well-defined, self-contained, and does not depend on the context or state of other services.
The communication is initiated by the a service consumer that sends a service request message to a service provider. The service provider returns a response message to the service consumer. The request and subsequent response connections are defined in a way that is understandable to both the service consumer and service provider. The connections are defined by Web services. A service provider can also be a service consumer.
<b>Enterprise Service Architecture (ESA)</b>
Enterprise Services Architecture (ESA) is SAPs open architecture for adaptive business solutions. ESA creates a gradual path to flexible, service-centric system landscapes and allows a non-disruptive transition of existing applications and architecture for more flexibility and value.
The fundamental premise of ESA is the abstraction of business activities or events, modelled as enterprise services, from the actual functionality of enterprise applications. Aggregating Web services into business-level enterprise services provides more meaningful building blocks for the task of automating enterprise-scale business scenarios. Enterprise services allow IT organizations to efficiently develop composite applications.
Hope it was usefull..
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