Two routing models

There are two possible dynamic routing models.

The "hub" model

The "hub" is the model that has traditionally been used with CICS® dynamic transaction routing. A routing program running in a TOR routes transactions between several AORs. Usually, the AORs (unless they are AOR/TORs) do no dynamic routing. Figure 14 shows a "hub" routing model.

Figure 14. Dynamic routing using a "hub" routing model. One routing region (the TOR) selects between several target regions.
 The picture shows a terminal-owning region (TOR) connected to four application-owning regions (AORs). A dynamic routing program runs in the TOR and balances transaction requests across the AORs. The TOR is both the requesting region and the routing region. Each of the AORs is a possible target region.

The "hub" model applies to the routing of:

The "hub" model is a hierarchical system--routing is controlled by one region (the TOR); normally a routing program runs only in the TOR.

Advantage of the "hub" model

It is a relatively simple model to implement. For example, compared to the distributed model, there are few inter-region connections to maintain.

Disadvantages of the "hub" model

The distributed model

In the distributed model, each region may be both a routing region and a target region. A routing program runs in each region. Figure 15 shows a distributed routing model.

Figure 15. Dynamic routing using a distributed routing model. Each region may be both a routing region and a target region.
 The picture shows four CICS regions. Each region is connected to all the other regions. A distributed routing program runs in each region. Each region may be a requesting region, routing region, or target region. It is a peer-to-peer model.

The distributed model applies to the routing of:

The distributed model is a peer-to-peer system--each participating CICS region may be both a routing region and a target region. A routing program runs in each region.

Advantage of the distributed model

There is no single point-of-failure.

Disadvantages of the distributed model

Related concepts
What is dynamic routing?
Two routing programs
CICS transaction routing
Defining indirect links for transaction routing
Related tasks
Defining remote resources for transaction routing
Application programming for CICS transaction routing
Related reference
Appendix A. Intercommunication rules and restrictions checklist
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