Database Reference
In-Depth Information
Chapter 15
Optimize Distributed Workload
Business systems' infrastructure has become seriously fragmented and diverse, increasing its complexity and making
it insecure, fragile, and difficult to maintain. The complexity of compounded functionality changes that have been
implemented over the years has made it harder and less productive to implement any further changes. The business
rules and functionalities that have been built into the application have made organizations think twice before
rewriting these systems to be easily manageable. Reinventing several years of development and business knowledge
that have gone into these business systems has been a huge investment that organizations are seldom interested in.
The growth toward a more loosely coupled composite solution has brought into existence a new wave in the
technology architecture that focuses on functionality in the enterprise system as a service. For example, the dot-com
and Internet-based solutions had brought the web services into existence. Whereas web services provided loose
coupling at the interface level, the business systems did not propagate this architecture to the middle and database
tier of the enterprise systems. The new wave is to take this service-oriented approach across the entire stack of the
business or enterprise system.
Therefore, services are geared toward integrating systems not from an enterprise perspective but from a business
values perspective, that is, by taking a coarse-grained step into a business transaction and grouping components that
belong to its transaction boundaries. Thus service-oriented architecture (SOA) should design and build business
services that easily and effectively plug into real business processes to deliver a composite business application.
Service Framework
The concept of services is not new in Oracle. Oracle introduced services in Oracle Database Version 8i, where client
load balancing used services. Although client load balancing continues to be supported in Oracle Database 12c, the
concept of services has as improved significantly. Apart from the database being a single service that applies to all
instances in the cluster, several different types of services can now be created that will help in workload management
across instances. A service is a group of related tasks within the database with common functionality, quality
expectations, and priority definitions. Examples of services could be payroll, accounts payable, order entry, and so on.
Some of the advantages of using services are the following.
Manageability
The legacy systems where one large application provides all business functions for an organization implemented as
a single system image brought about complexity in its management and administration. When slow performance
was noticed, one large monolithic application made troubleshooting and performance diagnosis difficult as well as
not knowing which module or functional area in the application was the cause of the problem. However, services
enable each workload to be managed in isolation and as a unit. This is made possible because services can span one
or more instances of a RAC environment. Load balancing and other features available to the database service can be
implemented at a more controlled and functional level.
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