IBM SC34-7012-01 manual Example What to do next Relationships between processing units

vProgress transaction, to check on progress through the application. Such a function could be used after a transaction failure or after an emergency restart, as well as at any time during normal operation. For example, it could be designed to find the correct restart point at which the terminal user should recommence the interrupted work. This would be particularly relevant in a pseudo-conversation.

vCatch-up function, for entering data that the user might have been forced to accumulate by other means during a system failure.

2.Specify the files and databases that can be accessed in each processing unit. Of the files and databases that can be accessed, specify those that are to be updated as distinct from those that are only to be read.

3.Specify how to apply the updates for those files and databases that can be updated by an application processing unit. Factors to consider here include the consistency and the immediacy of updates.

a. Specify which, if any, updates must happen in step with each other to ensure integrity of data. For example, in an order-entry application, it might be necessary to ensure that a quantity subtracted from the inventory file is, at the same time, added to the to-be-shipped file.

b. Specify when newly entered data must or can be applied to the files or databases:

vThe application processing unit updates the files and databases as soon as the data is accepted from the user.

vThe application processing unit accumulates updates for later action; for example, by a later processing unit within the same application or a batch application that runs overnight. If you choose the batch option, make sure that there is enough time for the batch work to complete the number of updates.

Use the above information when deciding on the internal design of application processing units.

4.Specify what data needs to be passed from one application processing unit to another. For example, in an order-entry application, one processing unit might accumulate order items. Another separate processing unit might update the inventory file. Clearly, there is a need here for the data accumulated by the first processing unit to be passed to the second. Use this information when deciding what resources are required by each processing unit.

Example

What to do next

Relationships between processing units

Specify what data needs to be passed from one application processing unit to another.

For example, in an order-entry application, one processing unit may accumulate order items. Another, separate, processing unit may update the inventory file. Clearly, there is a need here for the data accumulated by the first processing unit to be passed to the second.

This information is needed when deciding what resources are required by each processing unit (see “Mechanisms for passing data between transactions” on page 145).

142CICS TS for z/OS 4.1: Recovery and Restart Guide