Consuming Services with the Services
Registry
The Services Registry is the central entry point for service consumers. Each consumption tool implements the Services Registry to:
· Find the entities needed
· Use the reference provided by the Services Registry to retrieve the concrete metadata from a separate location
The high-level process flow of a service consumption can be described as follows:
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1. The consumer queries the Services Registry using taxonomies to find the services to use.
2. The Services Registry delivers the reference to the metadata.
3. The consumer / consumption tool retrieves the metadata using this reference from the following destinations:
¡ Enterprise Services Repository for modeled design time entities
¡ Backends for service definitions (= service implementations)
¡ Backends for service endpoints (=configured services)
The following sections describe the processes of the lifecycle of a client application with the Services Registry.
The prerequisite for consumer application developers to be able to find services is that the services are published in the Services Registry.
Service Definition
A service definition can be a service interface modeled in the ES Repository. The service interface structure and the data types it uses can be downloaded in a standard way from the ES Repository through a port-type WSDL document.
A service definition can also be implemented on a backend/provider system. Its description can be accessed through a WSDL file located on the provider system. A service definition can have design-time features, such as the minimum level of authentication that is necessary to invoke the methods of the service definition.
The service definition can have design-time classification data such as deployment units, process components, business scenarios.
Service Endpoint
A service endpoint is a service definition with endpoint information.
Development Cycle
The entire development cycle is done in the following steps:
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1. The developer starts searching for services.
All relevant classification systems and their values, as well as grouped classification systems are retrieved.
The developer can use them as value helps in search criteria so that the developer can filter or browse through service definitions based on a process component, for example.
The UI for discovering of service definitions is explained in the section Searching and Browsing Service Definitions.
2. After the developer has entered the search criteria, a search request is executed and a result list is displayed.
The developer can choose the service he or she would like to use and decide which provider system and deployment unit to get it from, provided it is available more than once.
3. The URLs are retrieved for the WSDL and WS Policy documents for the service selected.
The developer creates or chooses an already existing logical destination.
More information: Configuration of Web Services and Web Service Clients
4. The documents required for generation of a WS proxy definition are downloaded directly from the provider system through a separate metadata connection.
5. The developer creates the WS proxy.
Information about the service is retained in the proxy definition metadata for future references.