CICSPlex® SM’s workload management (WLM) function provides you with the capability to control where your work requests are run, in order to optimize performance and workload throughput. WLM uses the CICSPlex SM dynamic routing program EYU9XLOP to route work requests to the most suitable target region from a predefined set of target regions.
In a CICSplex or BTS-set, resources such as transactions and programs required in one region may be owned by another. For example, you may have a terminal-owning region (TOR) that requires access to transactions owned by an application-owning region (AOR).
You can specify the location of a resource when you are designing your system. Then, requests of a specific resource are always routed to the same region. Typically, the location of the resource is specified in the installed resource definition. This is known as static routing.
With dynamic routing, the location of the resource is decided at run time. In CICSPlex SM, the decision on where to run a piece of work is made by the user-replaceable dynamic routing program (called the dynamic transaction routing program in previous releases). The user-replaceable program EYU9XLOP creates the environment necessary for CICSPlex SM-based dynamic routing, and sets up the run-time environment.
The dynamic routing program can route:
In CICSPlex SM, dynamic routing is managed by the Workload Manager component of CICSPlex SM.
The CICS regions involved in dynamic routing may act as one or more of the following:
For dynamic transaction routing, the requesting region and the routing region are typically TORs, and the target region is typically an AOR.
For inbound DPL client requests, the requesting region and the routing region are typically TORs, and the target region is typically an AOR.
For EXEC CICS START commands associated with a terminal, the requesting region is typically an AOR, the routing region is typically a TOR, and the target region is typically an AOR.
For peer-to-peer DPL requests, EXEC CICS START commands that are not associated with a terminal, for CICS business transaction services processes and activities, and for Link3270 bridge requests, the requesting region, routing region, and target region are typically AORs.
For enterprise bean invocations, the requesting region is typically the external client code (but can be Enterprise JavaBean code in another CICS region) that invokes the enterprise bean, the routing region is a CICS listener region, and the target region is typically an AOR.
There are two possible dynamic routing models:
The traditional hub model is shown in Figure 17. This is the model used for the dynamic routing of transactions, EXEC CICS START commands associated with a terminal, and inbound client DPL requests. The request is initiated in the requesting region, typically a TOR, which also acts as the routing region. The request is routed to a target region, selected from the specified target group, where the program is executed.
The "hub" model is hierarchical, in which routing is controlled by one region (the routing region, that is, the TOR). Normally, a routing program runs only in the routing region. This model has the advantage of being relatively simple to implement. For example, compared with the distributed model, there are few inter-region connections to maintain. The disadvantages of the hub model are:
The distributed model is shown in Figure 18. This is the model used for the dynamic routing of EXEC CICS START requests that are not related to a terminal, enterprise bean and BTS activities, and Link3270 bridge requests. Each CICS system in the target group may act as a requesting region, routing region, and target region. A distributed routing program runs in each region.
The advantage of the distributed model is that there is no single point of failure. The disadvantages are:
CICSPlex SM’s dynamic routing program supports:
CICSPlex SM’s WLM function is of particular benefit in those enterprises that are running CICS/ESA on Parallel Transaction Servers (PTSs), because CICSPlex SM can route work throughout the sysplex.
With WLM in your enterprise, you have:
For full details, see CICSPlex System Manager Managing Workloads.
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