This second article of this
series briefly covers the Oracle Warehouse Builder architecture, and how it
adapts to the industry standards.
Some of the typical steps or
phases that are part of the datawarehouse life are:
- Designing
the DW model and the physical structures.
- Identifying
the source(s). (Database systems, flat files etc.)
- Designing
the extraction, transformation and loading processes (ETL).
- Identify
and manage the changes in source definitions.
- Manage
and upgrade the target warehouse structures.
- Integration
with other business intelligence tools, such as reporting tools etc.
- Importing
or exporting Metadata
to facilitate data exchange between different tools (openness).
- Design
and establish a metadata-reporting environment.
The above-mentioned steps may
span multiple and often disparate systems, resources and even functional areas,
which give rise to significant complexities. In order to facilitate integration
between systems quickly and easily, the Object Management Group (OMG) provides a
standard, the Common Warehouse Metamodel
(CWM) that allows for the interoperability of
enterprise applications. Many ETL vendors (including Oracle)
support the CWM standard that aids in faster implementation cycles.
In
order to prototype the ETL design process (or any phase in the DWLC) with a
tool, it is necessary to understand the tool architecture and the method in
which it supports or aids in the design, development, implementation and
management of the phases or standards mentioned above.
Familiarity with DWLC phases and
the CWM goal, will lead to a better understanding of Oracle warehouse builders
architecture and components that will be used for prototyping and also in evaluating
the suitability of other ETL tools in your specific environment.
The OWB architecture
The OWB architecture is shown in Figure 1 below. The core concept in the OWB architecture
is OWB repository, which is stored in the Oracle database server. The basic
architecture is comprised of two components.
- The design time component
- The runtime component.
Together, the repository and the
components facilitate design, development and implementation of all phases of
DWLC as can be inferred from the figure.
Design time component
The OWB design time component
provides a highly scalable metadata repository, design editors and metadata
reporting tools that enable creating and publishing metadata.
The metadata repository contains
design objects like source definitions, library based and custom
transformations etc.
Some of the editors include:
- Module
editors
The module editors define the source/target modules and editing modules (containers
or collection of the DW objects).
- Object
editors
The object editors include the
table editor, dimension editor, fact editor etc. that enable you to edit object
properties.
- Mapping
editor
The mapping editor primarily enables
you to design and configure how the data gets loaded into the target data
warehouse, and is used to design a graphical representation of the relation
between the data source objects that are used to populate the data warehouse
target objects.
The editor provides a set of
operators that you can include with the mappings along with standard or custom
transformations if required, such as key look, generating sequence etc. It
also enables validation and generation of the code used to populate the data warehouse
target.
- Code
editor
The code editor enables editing or customizing OWB generated code.
The design time browser also
enables viewing various reports that include custom reports in addition to the
lineage, impact analysis and summary reports.
Runtime component
The OWB runtime component includes
the runtime repository and the audit viewer, which enables you to view the
runtime information of the ETL jobs that were executed using Oracle tools such
as Oracle Enterprise manager (OEM). These jobs are created in the OEM
repository when they are registered with the OEM in the mapping editor.
Integrators
OWB is capable of extracting data
from various sources including Flat files, SAP R/3, other Oracle sources, other
database sources such as DB2, and older OWB version repositories.
The integrators are components
that facilitate the extraction from non-Oracle systems such as SAP R/3
integrator or in such cases as from an older version OWB repository; it
provides the MDL (Meta Data Loader) utility for extraction of the metadata.
Bridges
This component enables transfer of
the metadata from OWB to other Oracle tools such as Oracle Discoverer, OLAP
etc., thus supporting the OMG CWM standards.
Metabase
This intermediate layer provides
services to all producers (source) and consumers (targets, Oracle tools) of
data. Services include multi-user and locking service, generation and
validation services etc.
API's and SDK
From OWB 9.0.3.x onwards Oracle
provides fully documented public Java API's and SDK that enable developers to programmatically
manipulate the metadata such as performing batch operations on the metadata
without having to use the OWB client GUI tools (which are also written in Java
and make use of these APIs).
The OMB (Oracle MetaBase) Plus
utility enables developers to use the OMB scripting language which gives
greater power and flexibility to extend the features of OWB such as a greater
control in integrating with other business intelligence products.
Figure 1
Click for larger image
Conclusion
Part 3 in the series will cover a simple prototype
implementation of ETL design using OWB.
References:
Oracle
Warehouse Builder portal
Oracle
warehouse builder collateral library
OWB
documentation
The OMG data warehousing
resource page
Intelligent
Enterprise article by Vijay Saradhi & Martin Simoneau
Gartner
Report on OWB Jan 2003
Pervious
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