IBM SG24-6526-00 manual Performance requirements, Constrained performance, Application settings

Figure 5-23 Advanced tab of the Enterprise Bean panel

Performance requirements

We have not yet determined precise guidelines for sizing these applications. Our standard tests normally use a test harness that emulates a specified number of users entering orders. A 20 second think time is used. For example, the simulated users wait for 20 seconds between creating the order header and the first line, then wait another 20 seconds between this line and the next, etc. You need to estimate whether this is similar to your usage or whether your users are likely to be enter data faster or slower than this.

For our simulated users, approximately 8 CPW is required per user. For 30 such users, a CPW of 240 is required. This assumes that sufficient memory is available. Insufficient memory constrains performance so that a system with insufficient memory may not support as many users as its CPW would imply.

Constrained performance

WebSphere has many time limits that are intended to detect and clear up failed transaction and applications. If the system can cope with the workload and it is tuned reasonably, then the default settings are normally acceptable. However if performance is poor, then there is a danger that a transaction or application exceed a time limit and be cancelled even if it has not failed.

Application settings

These limits are specified on the Advanced page of the Application Server panel.

Transaction time out

This parameter defaults to 120 seconds, that is two minutes. This means that if a transaction (one method call) has not completed in two minutes, it is cancelled by WebSphere.

132Geac System21 commerce.connect: Implementation on the iSeries Server