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

You can also choose that EJB requests are preferably routed to the same host as
the host of the requesting EJB client. In this case, only cluster members on that
host are chosen (using the round-robin weight method). Cluster members on
remote host are chosen only if a local server is not available.
When planning for clustering, determine the number of application servers and
their physical location. Determine the server weights to assign for application
servers based on considerations such as system stability and speed. When
creating the cluster, consider using the prefer local setting to ensure that when a
client (for example, a servlet) calls an EJB, WLM will attempt to select the EJB on
the same system as the client, eliminating network communication.
7.4.5 Scheduling tasks
WebSphere Application Server provides a Scheduler service that can be used to
schedule actions to happen with the following frequencies:
► Only once
► Some time in the future
► On a recurring basis
► At regular intervals
It can also receive notifications about task activity. Scheduler tasks can be stored
in a relational database and can be executed for indefinite repetitions and long
time periods. Scheduler tasks can be EJB-based tasks or they can be triggered
using JMS.
The Scheduler service can be a tool in workload management by scheduling
maintenance tasks such as backups, cleanups, or batch processing during
off-peak hours.
When a task runs, it is executed in the work manager associated with the
scheduler instance. You can control the number of actively running tasks at a
given time by configuring schedulers with a specific work manager. The number
of tasks that can run concurrently is set by the Number of alarm threads
parameter on the work manager.
Chapter 7. Performance, scalability, and high availability 245