IMS Environments: Overview
The Adapter for IMS supports two environments that connect
to IMS databases:
-
IMS DBCTL. The recommended environment used by most
IMS sites.
-
IMS XMI. A legacy IMS BMP environment that is still used
at some IMS sites.
DBCTL and the XMI Server are mutually exclusive for any one server
configuration.
Advantages of IMS DBCTL
The advantages of using DBCTL include the following:
-
Direct communication between your application and IMS. Your task
establishes its own connection to IMS by loading and calling the
DBCTL subsystem when needed. It then issues DL/I calls directly
to IMS. This implementation eliminates the need for a batch job
(the XMI server), running in an additional address space.
-
Enhanced security. You have access to standard security
systems through the standard SAF interface. The SAF interface is
supported by security products such as RACF, CA-TOP SECRET, and
CA-ACF2. Before allowing access to a particular PSB, the system
verifies that the user is authorized to read the PSB.
-
Dynamic PSB selection and switching within your application. When you
have Access Files, you do not have to issue a command to select
a PSB, so the selection is transparent to your application.
-
Sharing of PCBs between applications. Multiple users
can share the same PCBs, reducing the number of duplicate PCBs in
a PSB and minimizing overhead.
-
IMS SET ? query command. DBCTL enables you to view current
settings (PSB, IMSSEC, IMSCLASS, IMSMODE, IMSPZP) by issuing the
IMS SET ? query command.
-
Read/write capabilities. XMI can only be used to retrieve
data.
-
Creation of Master and Access files using the Web Console. For
the XMI Server environment, while the Master File can be created
from the Web Console, the WebFOCUS view of the PSB (called the FOCPSB)
must be created manually (as described in Creating Supplementary Metadata in the IMS XMI Server Environment).
Note: Environment preparation and configuration steps
vary by environment. Be certain to follow the instructions for your
environment.