1.4.3 Operations Using a Load-balancing Cluster Consisting of Multiple HCSC Servers
A Service platform enables you to configure a system that can cluster multiple HCSC servers to distribute workload using a load balancer or CTM, so that the execution requests of service modules are not concentrated on one specific HCSC server. This configuration is called a load-balancing cluster configuration. In this manual, both load balancers and CTMs are referred to collectively as load balancers.
The following figure shows a configuration in which HCSC servers are clustered (load-balancing cluster configuration):
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![[Figure]](GRAPHICS/ZC010505.GIF)
The load-balancing cluster configuration enables you to add, change, or remove the HCSC servers that constitute the load-balancing cluster without having to stop operations.
The load balancer used in a load-balancing cluster configuration accepts only service modules execution requests issued to a standard synchronous reception (Web Services or SessionBean). It cannot accept a service module execution request issued to a standard asynchronous reception (MDB (WS-R) or MDB (database queue)). Note that the choice of load balancer used depends on the standard synchronous reception, that is, either Web Services or SessionBean, to which service module execution requests are to be sent. For details about which load balancer should be used, see "2.5 Environment setup to change HCSC server to load balancing cluster configuration".
- Important note
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With a load-balancing cluster configuration, asynchronous execution requests (MDB (WS-R)/MDB (database queue)) issued via a load-balancing cluster cannot be accepted, but direct asynchronous execution requests issued to individual HCSC servers (MDB (WS-R)/MDB (database queue)) can be accepted. Make sure that you set the destination of the service requester in the HCSC server to which the service module execution request is to be sent. If the destination is set for a load-balancing cluster configuration, the service module execution request may not be processed correctly. Therefore, specify settings in such a manner that the load balancer will not accept a service module execution request to a standard asynchronous reception (MDB (WS-R)/MDB (database queue)).