WebSphere Application Server V7.0: Concepts ... - IBM Redbooks

Cluster workload management
Workload management, implemented by the usage of application server clusters,
optimizes the distribution of client processing requests. WebSphere Application
Server can handle the workload management of servlet and EJB requests.
(HTTP requests can be workload-managed using tools like a load balancer.).
Use of a HTTP traffic-handling device such as IBM HTTP Server is highly
recommended. This is a simple and efficient way to front-end the WebSphere
HTTP transport.
The server-weighted round robin routing policy ensures a balanced routing
distribution based on the set of server weights that have been assigned to the
members of a cluster. In the case of horizontal clustering where each node
resides on a separate server system, the loss of one server system will not
disrupt the flow of requests, because the deployment manager is only used for
administrative tasks. The loss of the deployment manager would have no impact
on operations and primarily affects configuration activities. You can still use
administration scripts to manage your WebSphere Application Server
environment.
Workload management for EJB containers can be performed by configuring the
Web container and EJB containers on separate application servers. Multiple
application servers can be clustered with the EJB containers, enabling the
distribution of enterprise bean requests between EJB containers on different
application servers.
Workload management on the z/OS platform introduces a finer granularity, as
well as the usage of real-time performance data, to decide on which member a
transaction should be processed, instead of using a static round robin procedure.
About Workload Manager and Sysplex Distributor: Workload management
is achieved by using the Workload Manager (WLM) subsystem in combination
with the Sysplex Distributor (SD) component of z/OS. The Sysplex Distributor
receives incoming requests through a Dynamic Virtual IP address, and asks
WLM to which cluster member the request should be transmitted. WLM knows
how well each cluster member is achieving its performance goals in terms of
response time. It chooses the one that has the best response time to process
the work.
It is possible to classify the incoming requests in their importance. For example,
requests coming from a platinum customer will be processed with higher
importance (and therefore faster), than a silver ranked customer.
82 WebSphere Application Server V7.0: Concepts, Planning, and Design