Swordfish Documentation: Architecture: Dynamic Endpoint Resolution
In Swordfish the relationship between components using a service (consumers) and components providing a service (providers) need not be static. Using dynamic endpoint resolution a consumer can look up a provider based on a service interface and a policy (a list of non-functional capabilities and requirements) from a service registry (a database of existing service providers and their policies).
Swordfish supports the connection to different service registries in order to allow dynamic endpoint resolution. This flexibility is realized through the service registry plugin. The Service Registry Plugin consists of the following components:
- ServiceResolver - resolves information about the service endpoints for specified service using endpoint document providers and endpoint extractors
- EndpointDocumentProvider - is responsible for retrieval of service description from different kinds of location. Different implementations of the EndpointDocumentProvider can be used to get the service descriptions from local filesystem or from a remote registry.
- EndpointExtractor - extracts endpoint parts (e.g. endpoint address, transport protocol) from the service description representation. At the same time multiple endpoint extractors can be registered in the system, each suitable for processing one type of service description document (e.g. extractor for WSDL 1.1 based service descriptions, extractor for WSDL 2.0 and so on).
Main component classes
The endpoint resolution process is described by the following scenario:
- ServiceResolver gets all EndpointDocumentProviders registered at runtime and chooses one with the highest priority. The chosen provider is then queried for service description documents corresponding to the specified service interface. All found documents are returned from provider as collection of the ServiceDescription objects where each ServiceDescription represents one raw description document.
- ServiceResolver gets all registered EndpointExtractors and uses them to extract endpoint description information from received ServiceDescriptions. At this step it also performs policy trading which allows to exclude non-matching service descriptions from the extraction process. Extracted endpoint descriptions are grouped as collection of EndpointDescription objects and returned to caller.
- org.eclipse.swordfish.core.api, org.eclipse.swordfish.core.resolver (core interfaces)
- org.eclipse.swordfish.plugins.resolver.backend.base (basic implementations for endpoint descriptions and WSDL extraction)
- org.eclipse.swordfish.plugins.resolver.backend.local (resolve endpoints using the local file system)
- org.eclipse.swordfish.plugins.resolver.backend.remote (resolve endpoints using a Swordfish Service Registry)