Chapter 3. Application Integration pattern 39
? Completeness of the application interfaces
? Conformity of the participating applications to the EAI data and interface
model.
Tight coupling versus loose coupling
What is the level of independence between the application implementation and
the EAI interface? How likely is it that changes to the application will require
changes to the interface or changes to the integration approach? The degree of
invasiveness not only affects the application adapter. It can also affect the
integration hub processing and even require changes to the partner application.
The further across the application integration topology a change ripples, the
more expensive this change will be. The degree of invasiveness is often
described in terms of coupling (loose coupling versus tight coupling) or black box
versus white box approach.
Ideally, the less invasive the integration, the more successful the integration will
be in the long-term. This is the primary reason for the use of messaging based
integration to isolate as much of the integration processing from any
application-specific dependencies. EAI best practices should be employed to
ensure that the integration is as non-invasive as possible.
However, EAI projects will vary in the level of independence available based on
the completeness of the participating applications functionality and interfaces.
For environments with heavy application-specific processing required, it is best
to implement these using a sophisticated integration broker component
supported by easy to use application development tools. This ensures that future
extensions to the integration can be implemented quickly and easily.
3.2.6 What's next
If you have determined that the Application Integration pattern is appropriate for
use in your solution, the next step is to select an associated Application pattern
based on your specific Business & IT drivers.
If the Application Integration pattern is not appropriate for your development
efforts, review the Business patterns to determine which pattern best addresses
your e-business needs.
3.3 Application patterns
Application patterns for Application Integration can be broadly categorized as
either Process-focused or Data-focused. These two categories enable different
types of integration functionality.
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