| |
NOMAD
Interface To IMS |
 |
The NOMAD IMS Interface is a powerful tool for unlocking the information held
in IMS databases.
 |
|
 |
| |
 |
Benefits |
|
|
|
 |
Companies battling application backlogs with
traditional programming languages will find that NOMAD's comprehensive
fourth-generation language reduces coding and significantly improves user
productivity. |
 |
|
|
|
Companies planning to migrate from IMS to DB2
will welcome NOMAD's long-standing relational history and experience in
supporting DB2. |
|
|
 |
|
 |
For all these companies, the NOMAD IMS Interface delivers the resource
control, security and seamless access to multiple data sources needed for their
productive use of IMS data.
Using the IMS Interface
Schema Generation
The NOMAD IMS Interface is easy to use. NOMAD's Schema language is used to
describe an IMS database. NOMAD provides an automated IMSSCHEM facility that
retrieves the necessary information from the IMS libraries and the Interface
Control file and generates a skeletal NOMAD Schema.
The user then edits the Schema file, adding additional NOMAD attributes such as
headings and display formats, allocates the dataset and compiles the Schema. The
user can then access this data with no knowledge of IMS structure.
Access to Multiple File Types
You can define a database that contains descriptions of multiple file types so
that your database can, for example, contain NOMAD files, IMS files, DB2 tables
and VSAM files. You always have a consistent view of the data, because NOMAD
retrieval and analysis commands operate identically on all supported file types,
and there are no special sub-environments to access.
Interface Facilities
Centralized Data Definition Control The Schema, NOMAD's internal data
dictionary, provides data validation checks, security constraints, null values
and display and internal formats.
Automatic Data Synchronization NOMAD protects the integrity of your data by
checking the NOMAD definition against the definition of the file you are
accessing (IMS, DB2, etc.) and denies access if there is a mismatch. This is an
important capability for preventing corruption of databases, or, in the case of
a read-only interface, of reporting incorrect information.
Important Security Features Complete control of the data-down to the item
level-is provided with NOMAD's powerful security features, which can be combined
with any in-house security package. In addition, users such as a Database
Administrator (DBA) can create a control file tailored to specific needs. This
file can control password access, the number of simultaneous users and the limit
on DL/I calls generated without interruption by a specific user.
Audit Facility for Tracking Data Access and Security Violations The IMS
Interface automatically tracks all attempted connections (successful or not) and
writes them to a NOMAD database where they can be easily queried. Other captured
information includes databases accessed, userids and accounts with time stamps,
number of DL/I calls, number of positioning commands (FIRST record, NEXT record,
LOCATE, etc.) and use of the NOMAD SELECT command, which performs efficient data
screening.
Optionally, the IMS DIAGNOSE command causes the interface to track each DL/I
command code and Segment Search Argument (SSA) in the audit file. These DIAGNOSE
records are time-stamped when passed to IMS and again when data is returned.
This is a useful feature in performance tuning.
With this information, the efficiency of IMS access by NOMAD users can be
monitored to help achieve better resource control.
Query and Control Commands The NOMAD IMS Interface provides special commands for
database allocation, server quiescence, server shutdown and database activity
monitoring.
The number of records retrieved for NOMAD and the number of DL/I calls initiated
by a single request are also controllable. This ensures a fairer distribution of
database access to users requesting simultaneous retrieval. In addition, the DBA
can set limits on the number of accesses both DL/I calls and record limits by an
individual user, thus avoiding inadvertent attempts to withdraw huge amounts of
data.
NOMAD for the Production Environment
The NOMAD IMS Interface has many performance features as well as two modes of
operation to facilitate use in a production environment.
Resource Efficiency Facilities
NOMAD has several facilities for improving the efficiency of data retrieval.
These include the SELECT command, TEST clause and &INSTANCE_LIMIT
variable.
|
|
|
|
| |
|
|
NOMAD SELECT Command. This command enables you to
apply selection criteria to the data accessed for all subsequent reports until
the SELECT is changed or removed. With this facility, it is not necessary to
remember to append an "IF" or a "WHERE" clause to each NOMAD
command. NOMAD handles the data screening automatically for all
operations. |
|
|
|
|
|
TEST Clause This clause is useful to test report
output without accessing all of the possible records. It retrieves only the
designated number of records before returning control to the user. |
|
|
|
|
|
&INSTANCE_LIMIT This variable controls the
number of instances retrieved by any NOMAD retrieval command to prevent runaway
requests. It can be set either in the user's access profile or used
interactively. |
|
|
|
|
|
|
Optional Selection Strategies
The IMS Interface provides the option of using either IMS or the NOMAD IMS
Interface to screen data retrieved when screening on non-key fields.
User Exits for Extra Flexibility The NOMAD IMS Interface provides a series of
user exits. These programs can be used to communicate with external security
packages, to further control access to the IMS database or to have additional
data screening performed by IMS.
Multi- or Single-User Mode
The Interface can be used in either single- or multi-user mode, based on
installation requirements and user need for data.
|
|
|
|
| |
 |
Multi-User Mode |
|
In multi-user mode, all users share a single copy
of the interface. This mode is implemented using IBM's Cross Memory Services
(CMS). Advantages of this mode include maximum security, since the interface
resides in the Control Region; fewer BMP (Batch Message Processor) regions;
minimal overhead to bring up new users; and minimal impact on the CSA (Common
Storage Area). When the NOMAD IMS Interface is run in multi-user mode with the
NOMAD MVS Session Manager, further efficiency is achieved from multiple users
sharing the same address space outside TSO. |
|
|
|
|
Single-User Mode |
|
In this mode, a copy of the interface resides in
each user's region, so CMS is not needed for communication. This method can
provide savings of up to 40% in CPU and elapsed time requirements. With this
method, the user is also less likely to exceed the limits of the address space
when large amounts of data are retrieved.
Use of single-user mode is specified at database access time, so installations
can make multi-user mode the default and allow single-region access to selected
users. |
|
|
|
|
|
|
The Interface Environment
The NOMAD IMS Interface executes as an interactive program providing
read-only access to IMS databases. The Interface can be used with IMS databases
being updated through IMS/DC, CICS or IMS Batch. The interface runs under ISPF,
TSO, MVS Batch or TSO Batch. When run as a batch program under the Batch Message
Processor, it provides flexibility for maintaining databases while reporting is
performed.
Additionally, in combination with the NOMAD MVS Session Manager, which allows
multiple users to share the same address space outside TSO, access from CICS and
VTAM is supported.
|
|
Learn
More |
|
To find out more about how Select Business Solutions can help you either Contact
Us, or visit our Product Resources area for all the latest related
downloads.
|
|
|
