Taking Care – Error Handling - Applied SOA Patterns on the Oracle Platform - page 481

The structure of these messages must be associated with logs' structures in order
to minimize mappings and transformations on logging APIs and EJBs.
Fault handling sequence diagram in Agnostic Composition Controller
In the preceding sequence diagram, which is the consolidated view of all our SOA layers
and frameworks around the agnostic composition controller, starting from the left (north-
bound), we can identify generic EH rules as follows:
1. First, we start with the error in Application Adapter 1 (Active Poller), stating
Service-Legacy wrapper cannot extract data . The reason why
an active service adapter cannot connect to the endpoint data source is because
DB is offline and Queue is unavailable. Information will be provided to the Error
Handler when the common resolution operation "Retry predefined number of
times" (configured on ABCS/ OSB, depending on adapter realization), failed last
time. Error Manager (ErM) will initiate the process of sending an acknowledg-
ment message to the Legacy Application (if it can accept it, either human or ma-
chine readable) and activate data extraction using Dual Protocol again if it's avail-
able. Technically, ErM cannot do much about this error on the north side, even if
poller is a complex BPEL process that assembles data from various data sources
over a prolonged amount of time into a consolidated ABO. This scenario just sig-
nifies that the source is not available and business composition cannot be initi-