Download IMS (Information Management System) – IBM

IMS (Information Management System) – IBM Hierarchical database management system.
Origins: 1965 – IBM and NASA partnership - Apollo program
It has 2 components: IMS DB and IMS TM – IMSDB (DBMS – organize data); IMSTM
(message based transaction processor).
Database Management System is a collection of programs for storing, organizing,
selecting, modifying and extracting data from a database.
Transaction Management System – provides users of a network with access to
applications running under IMS to perform online real time transactions.
Interface – DL/I for both IMS DB and TM. IMS resources are accessed by functions
called DL/I calls. Other interfaces: SNA (System Network Architecture), TCP/IP, DRA
(Database Resource Adapter) and products like Websphere MQ.
Programming Languages supported: COBOL, PASCAL, C, Java, Assembler, REXX,
PL/I
Operating System: Runs on z/OS in a parallel sysplex environment, where multiple IMS
systems can run and share data as well as queues, for workload balancing and protection
from IMS outages.
Advantages:
1. Speed - Hierarchical database; IMS (Fast Path) – highest transaction per second
database access solution
2. Accessibility – Can be accessed from any platform
3. Integrated – Open standards- Customers can connect to IMS applications using
products of choice – IMS Connect
4. Scalability – high performance, availability, and high storage capacity
5. Self Managing capabilities – XRF (Extended Recovery Facility) and RSR
(Remote Site Recovery) – takeover support
6. MSC (Multiple Systems Coupling) – balancing workload and prevent outages
Disadvantages:
Due to hierarchical structure, data need to be in a specified format, so that no changes are
foreseen in the architecture. Unable to handle complex relationships.
Architecture:
IMS runs on z/OS and uses several address spaces. Primary address space is the CTL
(control region), and other address spaces called dependent regions. The CTL can be
initiated through a start command or by submitting JCL (Job Control Language)
Within the CTL, the CSL (Common Service Layer) manages the address spaces like OM
(Operations Manager), RM (Resource Manager) and SCI (Structured Call Interface).
They perform system management tasks.
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Dependent address spaces include; MPR (Message Processing Region), IFP (IMS Fast
Path), Batch Message Processing, JMP (Java Message Processing), JBP (Java Batch
Processing), and DBT (DBCTL Thread).
IMS separate address spaces include:
DBRC (Database Control Recovery) – required – provides access to RECON datasets
and managing IMS logs; DLISAS - performs most DB access functions, and CQS
(Common Queue Server) – manages data objects on a z/OS coupling facility on behalf of
multiple clients.
Various configurations of IMS:
1. DB/DC (both IMS DB and TM)
2. DBCTL (only IMS DB)
3. DCCTL (only IMS TM)
BOOKS:
Customization Guide: customize IMS functions to fit the specific needs of the
installation – writing exit routines to change functionality.
CQS: IMS runs in a parallel sysplex shared queues environment. CQS receives,
maintains, and distributes data objects from a shared queue that resides in a coupling
facility
BPE: Common system service base upon which various components or interfaces are
built like CSL and CQS