Workload management
Workload management (WLM) optimizes the distribution of client requests. Incoming client requests are distributed to the application servers, enterprise beans, servlets, and other objects that can most effectively process the requests. Workload management also provides failover support, which improves application availability. WLM configurations use clusters, transports, and replication domains to improve availability. To use workload management, install WebSphere Application Server Network Deployment.
- A client refers to any servlet, Java application, or other program or component that connects the end user to the application.
- A cluster is a logical group of application servers, or cluster members, that work together to process client requests. For more information on clustering, see Clusters and cluster members.
- Transports, such as remote HTTP, route data between the components of the configuration.
- A replication domain is a collection of replication entry instances, which transfer data within WebSphere Application Server. For more information on replication domains and replication entries, see Replication.
Workload management is automatically enabled for all of the application servers in a cluster when you start the cluster. You do not need to perform any additional configuration.
Workload management provides several advantages that enhance the availability of your enterprise applications.
- Workload balancing WebSphere Application Server can distribute processing tasks according to the capacities of each machine in the configuration.
- Failover support WLM configurations can redirect client requests when one or more servers fail.
- Scalability WLM allows you to scale your system to process a higher client load than a single-server configuration. Use clustering to add additional instances of servers, servlets, and other objects to the configuration.
- Transparent maintenance You can configure multiple cells with a load balancing product such as Network Dispatcher. Load balancing allows for transparent maintenance and upgrade of application servers and the machines on which the servers run.
- Centralized administration Clustering and the Network Deployment deployment manager allow you to administer several application servers simultaneously.
The following topics provide more information about workload management:
Workload management for enterprise beans and application servers
Enterprise beans can participate in WebSphere Application Server workload management. This topic provides information about how enterprise beans participate in workload management. It also describes the differences in how WLM handles stateful and stateless session beans.Workload management for stand-alone Java application clients
Application clients can use workload management to distribute requests to multiple application servers. This topic describes how to design Java application clients to participate in workload management.Workload management selection policies and affinities
In an application server cluster, workload management distributes client requests among the available application servers. This topic describes the selection policies that determine how WLM distributes requests. It also provides information on transaction affinity and server affinity, which can affect how requests are distributed.Runtime exceptions and failover strategies for workload management
This topic describes runtime exceptions that the workload management service can throw, and strategies that the workload management client uses in the event of a failure.Tune a workload management configuration
This topic provides tips for improving the performance of workload management.Replication
WebSphere Application Server clusters use replication to share data among multiple application servers. This topic describes replication, replication entries, and replication domains.