IMS Connectivity in an On Demand Environment: A Practical Guide to IMS Connectivity

Chapter 11. IMS Connect Extensions 193

Figure 11-20 Candidate list for a single transaction

Step 1 in the diagram shows the incoming message request. Step 2 shows that TX1 has a

transaction affinity of datastores IMP1, IMT1, and IMD1. Step 3 shows that IMD2 has a

datastore affinity of datastores IMD1 and IMD2. Step 4 shows the intersection of transaction

affinity and datastore affinity as IMD1. The message is routed from IMD2 to the new target

datastore of IMD1.

11.3.2 Workload balancing

Workload balancing allows IMS Connect Extensions to redirect incoming transaction

requests to one of multiple IMS datastores, thereby balancing the transaction workload

across multiple IMS systems, ensuring both availability and responsiveness for the remote

client.

Workload balancing uses a weighted rotate algorithm that considers the processing capacity

of a datastore. Datastores with greater capacity receive more transactions. Basic rotation is

achieved by assigning each datastore an equal weighting value. You specify the relative

weighting of each datastore during the datastore definition process. See Figure 11-19 on

page 192. The Capacity weight rating field accepts values in the range of 1 to 100.

If the workload balancing option on the system definition is set to Active and IMS Connect

Extensions identifies that a datastore is no longer available, the datastore is not used to

process incoming message requests.

Figure 11-21 on page 194 illustrates workload balancing. The figure shows an IMS system

containing eight datastores and assumes an incoming message request running TX1 on

datastore IMD1 and that the definitions for both TX1 and IMD1 have transaction routing set to

Active.