Explanation/Reference:
C: Logical Data Representations
Message and data formats should be based on logical representations of business objects rather than native applicationdata structures.
D: Providing consumer representations and reading from and writing to multiple source systems leads to the issue of data format transformations. For a very small number of source systems, point-to-point transformations can be used by the SOA Services.
However, this approach becomes untenable as the number of source systems increases.
Thus, a better approach is to create a normalized format for the data entities and then provide transformations to and from the normalized format for each source system.
Normalized Data Formats
Data transformations are to and from normalized formats.
Normalized data formats facilitate composition and reduce the number of transformations that must be created and maintained.
F: Binary data formats would be awkward.
Incorrect answers:
B: A canonical data representation that spans the enterprise can be used but is not required. A federated approach to data normalization is also possible.
Note: It should be noted that a single canonical data model for the entire enterprise is not required to successfully employ normalized data formats. Rather a federated approach to normalization can be used.
For example, in a large enterprise each functional domain could create a normalized format.
Transformations between the domain formats would then be created for SOA Services that span domains.
E: Database normalization (e.g. third normal form) is a specific type of data normalization that is used in relational databases. It does not apply here.
G: The Data Normalization Layer provides a standardized format for data entities. Each EIS stores data in its own (usually proprietary) format. This layer transforms the data to a form that is readily consumable by the upper layers in the architecture.
The key capabilities provided by this layer include:
* Logical Data Model - The logical data model provides an "enterprise" view of data entities. The logical data model for an enterprise frequently incorporates industry standard data formats (e.g. HR-XML, HL7, IATA).
* Data Aggregation
* Data synchronization
* Data caching
Reference: Oracle Reference Architecture, Service-Oriented Integration, Release 3.0