Maintaining the Core – Service Repository - Applied SOA Patterns on the Oracle Platform - page 341

stract and agnostic because they are predefined in the business and/or GU do-
main. This is also a way to provide trade-off reusability for time to market. The
borderline is where the EBO for the Composition controller is implemented in the
Message Container as the payload <any> or within the Message Container
namespace. It could be acceptable to have an alternative approach in this type of
realization.This causes a positive impact on reusability. Maintainability is signi-
ficantly increased. Performance could be potentially less than that in a direct cod-
ing approach, but it can be easily justified through the resizing of compositions.
This is attainable through configuration. Reliability can also be negatively im-
pacted as we have implemented some single points of failure here, but caching
and redundant implementation can solve this problem just as easily.
3. The transactional part of an extracted configuration persisted in the Message Con-
tainer and Process Header (execution plan, set of transactional variables, or rout-
ing slip). Process Header will be propagated end-to-end to the adapter framework
before the ultimate receiver. This positively impacts all characteristics.
4. EBS in ESB will use PH values for Transformation (enrichment), Validation, Fil-
tering, and the Invocation service, or its ABCS. A minimal number of lookups is
allowed as this layer must be a good performer. However, if necessary, Java cal-
louts to the MDBs (such as RE MDB) are allowed. This approach is in alignment
with the Delivery Factory pattern, where groups of adapters to the ultimate re-
ceiver can be abstracted through the factory layer. Grouping is usually done by
MEP and the transport protocol. This positively impacts all characteristics.
The Cross-domain Utility layer
Apparently, even in a decentralized enterprise, some domain-specific services can be util-
ized between dissimilar domains. First, this could be completely agnostic Utility Services.
Of course, their utilization across different domains will be carefully evaluated using per-
formance numbers derived from their usage statistics and SLA declarations. Demands
could be too high for the installation of a single utility service, and we should use redund-
ant implementation in order to address it. Nevertheless, this is the same service, and we
did not reinvent it. We just discovered it and added a new service node.
Entity services are also good candidates for cross-domain implementation. For instance,
the Customer entity service (usually from OSS/BSS) can provide vital information for au-
thentication and authorization purposes to all other services in the enterprise. Let's take a
close look:
• Lookups types in use : 1-5