CICS IPIC workload distribution

From V3.0.59.0, IBM® z/OS® Connect supports workload distribution of requests across a group of CICS® regions, using a single connection reference.

You can configure a group of IPIC connections for a single connection reference to enable requests to be distributed across the group of connected CICS regions, in a round robin sequence. For example, for a connection group of 3 CICS regions, "A, B, C", requests are distributed as follows:
A, B, C, A, B, C, .....
There is also the option to specify a weighted distribution across the CICS regions. A weighted distribution is configured by specifying the relative number of requests to be sent to each connection in the group. For example, for a connection group of 3 CICS regions, "A, B, C", with request ratios "4, 2, 3", requests are distributed as follows:
A, B, C, A, B, C, A, C, A
For more information on configuring workload distribution, see Configuring IPIC workload distribution.

If a CICS connection is lost, that connection is removed from workload distribution until the connection is re-established. IBM z/OS Connect attempts to re-establish the connection at a regular interval specified by the connectionRetryInterval attribute on the zosconnect_cicsIpicConnection element. This attribute is applicable only when the connection is in a connection group. If all connections have been lost and there is a request ready to be sent, an attempt is made to re-establish a connection immediately, without waiting for the connection retry interval to expire.

When a request fails because the CICS connection is lost during the request send, or a request is rejected because the connection is closing, the request is retried to another CICS region in the group.

A CICS connection reference, whether it is specified in the service archive file or overridden by a policy at runtime, can reference either an individual connection defined by a zosconnect_cicsIpicConnection element or a connection group defined by a zosconnect_cicsConnectionGroup element. An IPIC connection element can be included in more than one connection group. An IPIC connection that is included in a group can also be referenced directly by a request, outside of workload distribution.

The following example demonstrates a weighted workload distribution across two LPARs combined with a round robin distribution across a set of 3 CICS regions on each LPAR.

<zosconnect_cicsConnectionGroup id="cicsConn" cicsConnectionRefs="lparA, lparB" connectionRatios="3,2"/>

<zosconnect_cicsConnectionGroup id="lparA" cicsConnectionRefs="cicsConnA, cicsConnB, cicsConnC"/>
<zosconnect_cicsConnectionGroup id="lparB" cicsConnectionRefs="cicsConnD, cicsConnE, cicsConnF"/>

<zosconnect_cicsIpicConnection id="cicsConnA" host="9.1.2.123" port="1110"/>
<zosconnect_cicsIpicConnection id="cicsConnB" host="9.1.2.123" port="1111"/>
<zosconnect_cicsIpicConnection id="cicsConnC" host="9.1.2.123" port="1112"/>
<zosconnect_cicsIpicConnection id="cicsConnD" host="9.1.2.156" port="2120"/>
<zosconnect_cicsIpicConnection id="cicsConnE" host="9.1.2.156" port="2121"/>
<zosconnect_cicsIpicConnection id="cicsConnF" host="9.1.2.156" port="2122"/>