---+ 5th Provider Service Proposal
---++++ General strategy
Treat a provider service as a local MessageBrokerService.

---++++ Files
   * *Shared Core Schema* : http://ww3.bgbm.org/viewcvs/viewcvs.cgi/*checkout*/schemas/protocol/newprotocolCore.xsd
   * *Provider Service Schema* : http://ww3.bgbm.org/viewcvs/viewcvs.cgi/*checkout*/schemas/protocol/newprotocolProvider.xsd

---++++ Details
   * optionally listing addressed datasources in the header. If none is mentioned the request should by default be passed on to all available local datasources.
   * All requests are passed on to the requested datasources. EXCEPT:
   * A PingRequest is never relayed to other services and will always be answered directly by the ProviderService.
   * A ProviderService should have its own metadata added to the individual metadata responses of a DatasourceService
   * A ProviderService does not have any additional capabilities (just pooling datasource capabilities responses).
   * Use the same way to call providers:
   * Using a single POST or GET parameter called "request" which contains either the XML message or an URL pointing to the XML message. 
   * Use the same error handling strategy:
   * use common Error Codes and prefixes for classification of codes.