WebSphere Extended Deployment is built on features of autonomic
computing in the dynamic operations environment. With these features the application
server environment can expand and contract as the business demands. Using
the autonomic managers in the WebSphere Extended Deployment environment, dynamic
operations can make logical decisions based on business goals.
The dynamic operations environment has the following components:
- Operational policy
- An operational policy is a business, or performance objective that supports
specific goals for specific requests. Operational policies include service
and health policies. A service policy defines a business goal and an importance
and contains one or more transaction classes. For a given work class, a rule
condition maps to a transaction class which belongs to a service policy to
further classify its workload by more specific criteria. This mapping gives
the work class its goal. The service policy contains the business goal requirements
and the work class contains the work description upon which the service policy
is applicable. The combination of these policies is read by the dynamic operations
environment to make decisions on HTTP, SOAP, JMS and IIOP work requests.
- Node groups
- Within WebSphere Extended Deployment, the relationship between applications
and the nodes on which they run is expressed in terms of an intermediate construct
called a node group. A node group is a pool of computing power, inside
of which one or more dynamic clusters is created. The computing power represented
by a node group is divided among its dynamic cluster members. This distribution
of resources is modified autonomically in accordance with business goals to
compensate for changing workload patterns.
- Dynamic clusters
- A dynamic cluster is an application deployment target that is expandable
and contractible, as needed by the dynamic operations environment. Dynamic
cluster instances are created on nodes that are members of the node group
that is associated with the dynamic cluster.
- Autonomic request flow manager
- The autonomic request flow manager has numerous functions:
- Limits concurrency to avoid overloading the current set of WebSphere Application
Server instances for a given flow and to manage the competition between deployment
targets that compete for node resources.
- Controls the rate of release requests from the queues.
- Sends signals to the placement controller. The signals indicate the computing
power allocation that best optimizes the performance results given the operational
policy and currently offered load.
- Supplies information to the Tivoli Intelligent Orchestrator about the
computing power that is currently available in and ideally needed by each
node group.
- Dispatches requests out of the queues based on weights (one weight per
queue, not one per class). Class weights are set by the administrator (manual
mode) or autonomically by the controller components of the autonomic request
flow manager (automatic mode).
- On demand router
- The on demand router (ODR) is a type of proxy server in WebSphere Extended
Deployment that decides where HTTP requests are routed. The ODR also determines
if enough application resources are available to support the work received
from the flow control manager. When spikes occur in work requests that require
application manipulation, the ODR starts and stops instances of applications
accordingly, if the environment is running in the on demand mode.
- Dynamic workload manager
- The autonomic request flow manager classifies and prioritizes requests
to application servers based on the demand and policies. The dynamic workload
manager then distributes the requests among the nodes in a node
group to balance the work.
- Application placement controller
- The application placement controller is an autonomic manager in the dynamic
operations infrastructure that supports the fluid mobility of applications
within a dynamic cluster. The application placement controller adds application
instances when the work is more than can be handled by the current application,
and stops application instances when there are too few requests for the number
of started applications.
- Health controller
- The health controller constantly monitors the defined health policies.
When a condition specified by a health policy is not met in the environment,
the health controller assures that the configured actions are taken to correct
the problem.
- Tivoli Intelligent Orchestrator
- The Tivoli Intelligent Orchestrator is an optional piece of the dynamic
operations environment. A WebSphere Extended Deployment environment with Tivoli
Intelligent Orchestrator integration supports the ability to dynamically allocate
additional hardware to the environment.
- EWLM
- The enterprise workload manager (EWLM) manages sub-goals and resource
allocations for the larger environment which contains WebSphere Extended Deployment.