Business Application Services (BAS) is an alternative to resource definition online (RDO) that enables you to manage CICS® resources in terms of the business application to which they belong, rather than their physical location in the CICSplex. A business application can be any set of resources that represent a meaningful entity in your enterprise. Within the application, you can group together resources of a particular type and define the run-time characteristics of that group. At run-time, you can refine the selection of resources to be installed by using a filter expression, and you can change the resource attributes by using an override expression.
RDO is the traditional CICS method of defining resources to CICS systems. With RDO, resource definitions are tied to a single group and groups that are processed sequentially from a group list. Any duplicate definition found later in the process overrides any earlier one. In addition, the very nature of the definitions that RDO requires and the extent to which they are available to multiple CICS systems can prove limiting. RDO has several disadvantages in a CICSPlex® SM environment:
BAS enables you to view and manage your resources in terms of their use in your business, and independently of their physical location. This topic introduces the basic concepts of the BAS function.
Once your CICS resources are defined to CICSPlex SM, you can monitor and control resources in terms of their participation in a named business application, rather than their physical location in the CICSplex. Logically-related resources can be identified and referred to as a set, regardless of where they actually reside at any given time.
Sets of definitions can be reused and associated with any number of other logical associations of resources that reflect your business needs, rather than your system configuration.
If you set the scope to be your application, any operation or monitoring views will display only those resources that satisfy your selection criteria. This gives you the power to control precisely how those resources are managed.
With BAS, you can have multiple versions of the same resource. Each time you create a new definition for the same resource and the same name, BAS allocates a new version number. Note that a new version number is not created if you update the resource. You can specify a specific version of a resource definition by its version number.
Version support allows you to develop resource definitions as your business applications develop. You can then have, for example, a single version of a resource in multiple groups, or multiple versions of the resource throughout the CICSplex. Note that you can install only one version of a resource in a CICS system at one time.
RDO definitions are held in a CICS System Definition (CSD) file. BAS resources are held on a central data repository that is accessed by all the CICS systems in the CICSplex.
The CICSPlex SM data repository (EYUDREP) serves as the central repository for all your CICS resource definitions. This minimizes the number of resource definitions you need for your CICSplex by:
The traditional method of defining links between CICS systems is to use RDO to define connections and sessions between each CICS system. For each pair of CICS systems, there are four definitions: two connections and two sessions. Each connection and session is unique for a given pair of CICS systems.
With BAS, communications links are created dynamically from model
connection and session resource definitions. You define connections and sessions
that describe the nature of the link. The BAS system link (SYSLINK) object
is used to create the link between two CICS systems, by specifying the connection
and session definitions to be used. The connection and session definitions
can be used by any number of system link definitions that share the same characteristics.
For more information see "Establishing CICSPlex connectivity" and "Accessing
the SYSLINK view" and CICSPlex System Manager Administration.
Resources that are defined to CICSPlex SM must still be installed in the appropriate systems, either by CICS or by CICSPlex SM. You can use BAS to install your resources either automatically, at CICS initialization, or dynamically, while a system is running. A single resource can be installed in multiple CICS systems either locally or remotely, as appropriate.
You can use BAS in two ways:
You can use either or both of these forms, depending on the situation and degree of precision you require.
The simplest form is the migration form using resource descriptions. You create resource definitions and resource groups, and associate them with one or more resource descriptions. It is the resource description that defines the logical scope for the resources. The resources are assigned to specific CICS systems and you therefore still need separate definitions for a resource that is local to one system and remote to another. This approach to BAS is similar to using RDO, in that the resource description is analogous to the group list. You in effect create a version of your CSD on the CICSPlex SM data repository. Though this is a good position from which to establish your CICSPlex SM resources environment, you cannot take advantage of all the facilities offered by BAS.
To take advantage of the facilities offered by BAS to manage your resources in terms of the business application rather than location, you need to use resource assignments. A resource assignment selects resources of a particular type from a group, and assigns them to the appropriate CICS system. A resource assignment is associated with a resource description. The resource description then no longer functions like a group list, but becomes a user-defined, logical set of resources, such as an application.
Using resource assignments allows you to manage your individual resources and change their attributes for individual systems, or to suit special circumstances. You can:
The BAS approach to the management of resources offers several advantages over RDO: