Databases Reference
In-Depth Information
However, the move to a client server greatly increased the complexity of monitoring
the solution. Moving processing off the central system and into the client meant
that it was now necessary to monitor the health of components in the client and that
the client was more complex than the terminals used in the previous generation.
A particular problem in this environment was the unexpected interactions that
different applications in the client could have with each other.
The problems of monitoring and managing the distributed client applications led
to pressure to move the processing back into the data centre, which led to a third
generation of solution architectures based around web/application servers and
web browsers.
This led to a further complication of the security infrastructure, as applications now
had to maintain links from many different clients and ensure that they enforced
appropriate access controls on each individual client. It did, however, simplify the
management environment by bringing the application back into the managed data
centre environment. However, the end-to-end environment was now more complex
to manage due to there being multiple tiers rather than a single tier, and problems in
any one tier would impact the entire service offered by an application.
The move to service-oriented architectures can be thought of as a natural progression
from the web deployment model, but with the additional complication that
applications are now composed from services provided by many individual service
providers, potentially on different machines. In some circumstances, the service may
be provided outside the company by another company. In the next section, we will
examine the management and security challenges that SOA brings.
Added complications of SOA environment
The SOA environment makes it harder to enforce a consistent security policy. It also
has a number of moving parts that must be managed. Let us consider each of these
challenges in turn.
