Oracle Mainframe Re-hosting Solutions – Part Two


This article is part two of a two part series describing Oracle’s mainframe re-hosting solutions.  You can read part one of this series here.

Oracle Solution Overview

As a leading provider of enterprise software and hardware, Oracle can help mainframe customers to implement different modernization options:   Re-engineering, Packaged Application and Re-hosting, in this paper, our discussion is focused on the Oracle Mainframe Re-hosting solution.

High-Level Architecture Comparison

Oracle re-hosting solution is based on Oracle software stack and hardware, it provides a solid platform for enterprise core applications.  Below is a high level architecture comparison picture.


On this picture, by mainframe compatible stack we mean a set of technologies on open systems that can run your mainframe applications with little to no change – in order to minimize the risk and cost of migration.  Oracle provides a mainframe-compatible set of capabilities to preserve CICS, IMS, and batch application logic and data intact.  Through this picture and details below, you can see the maturity of the Oracle re-hosting solution.

OS Layer

IBM Mainframe is based on MVS then evaluated to Z/OS; Z/OS is a mix of MVS and USS (Unix Sub System Service).

Oracle solution is based on Linux, Solaris or all other major UNIX platforms.

TPM Middleware Layer

Starting on the bottom with CICS or IMS TM (two major IBM mainframe transaction processing monitors) – that host mostly COBOL business logic, but sometimes PL/I, C, Assembly or even 4GLs.

On the red stack Oracle provides Tuxedo and Tuxedo’s application runtime for CICS and IMS that supports re-hosted business logic with the same CICS or IMS programming model.  The result – same CICS or IMS TM applications, but in a more scalable, elastic, flexible environment, and with a rich set of integration adapters and extension capabilities. The CICS or IMS transactions are running as Tuxedo services and can be accessed and exposed through web services, JCA, Oracle Service Bus, .Net clients, etc.

Database Layer

On DB layer, from IBM mainframe side, there are VSAM files, IMS/DB, DB2,IDMS, etc.

Oracle provides solutions for different type of databases to meet customer requirement:

  • VSAM to Oracle DB conversion and migration
  • DB2 to Oracle DB conversion and migration
  • IMS DB to Oracle DB conversion and migration, also ODBA adapter to remotely access IMS DB
  • Data migration is an important part of our re-hosting solution, not just DB2 to Oracle migration, but also automated migration of VSAM and pre-relational databases to Oracle DB.  We also support COBOL file system for migrating record sequential files, VSAM, etc.

Batch Environment Layer

IBM batch environment is based on JCL as script language, JES as runtime component, job scheduler and print service.

Oracle provides different component to support migration mainframe batch job processing:

  • Translate JCL script to Unix KSH script
  • A full runtime based on Tuxedo to schedule, execute and monitor batch job execution
  • A very scalable, distributed, parallel batch execution runtime environment
  • Tuxedo ART for Batch provides JES-compatible job management and control, JCL functions and standard utilities, as well as integration with third party components like Syncsort, LRS printing, etc.  Tuxedo ART for Batch provides everything a batch job needs to feel at home, even though it’s no longer running on the mainframe.  We can even support existing enterprise schedulers or provide an Oracle scheduler.

UI Presentation Layer

The final layer is the user interface for the online applications.  On IBM mainframe, typically it’s 3270 green screens displayed on tn3270 emulator or a custom fat client on Windows connecting to CICS or IMS.

Oracle provides 3270 support in Tuxedo ART for CICS, BMS and IMS MFS screens, so it can just plug-and-play with your existing tn3270 emulators.  Oracle can also support conversion of 3270 screens to JSP pages running in Web UI, and can also provide integration libraries for custom clients on .Net or other environments.  Oracle solutions can also support MQ-initiated transactions and other means to run online applications.

Re-hosting Tool Overview (Tuxedo ART Workbench)

One of strong points of Oracle’s re-hosting solution is Tuxedo ART workbench tool; it is a tool with a set of configurable rules to automatically convert source code, data scheme, JCL script, data content from mainframe to open systems.  The automatic conversion avoids human error during conversion phase and assures a good quality of target software asset, and also saves time to User Acceptance Test (UAT).

Workbench Workflow Overview


The Tuxedo ART Workbench is built to help accelerate re-hosting projects, by automating the code and data migration and supporting an industrialized, repeatable methodology.  It’s been created on a sophisticated foundation of advanced language processing technology that has been used for many years in large migration projects.

On the left side of the diagram is the source environment – the mainframe.  On the right is the target environment – an open systems platform with Oracle Tuxedo and its Application Runtimes for CICS, IMS, and Batch and an Oracle Database.  In the middle is the migration environment with the Re-hosting Workbench.

The workbench environment is where all of the application’s assets – COBOL programs, copybooks, BMS screens, JCL, DB2 DDL, etc. are processed.

  • You begin by collecting these assets on the mainframe, transferring them to the workbench environment, and typically loading them into a source control system.
  • The Cataloger parses all of the source objects, calculates dependencies and generates meta-data. It also produces reports to indicate any missing objects or unused ones.
  • Following the Cataloguer, data migration tools for files and DB2 tables are run and then code migration tools for COBOL and JCL.
  • The COBOL and JCL tools apply sophisticated language processing to adapt COBOL code between compiler dialects, transform JCL, adapt SQL calls for differences between DB2 and Oracle, etc.
  • For data migration, the  File and DB2 migrator generate the target schema, including Oracle DDL, and a complete set of data migration tools – including  unload JCL, transcoding and reload programs, SQL*Loader control scripts, etc. to automate data reloading.
  • To facilitate configuration management, generation of system configuration files for Tuxedo, CICS, IMS, and batch, and simplified deployment process.
  • Customers can add their own scripts to do specific processing step.
  • Tuxedo ART workbench can be used by two ways:  UNIX command line mode and Eclipse IDE graphical environment.


Re-hosting Runtime Component (Tuxedo ART Workbench)

Below is a picture to show, from run time perspective, different components:

  • Different components of Tuxedo Art runtime
  • Possibility of integration with Open system technology and SOA architecture
  • Possibility of integration with existing mainframe software components


 Why Tuxedo Based

From architecture and concept perspective, Tuxedo is a transaction processing system which is designed after IBM IMS and CICS. It combines the good design points of IMS and CICS, but is based on Open System platforms with a native distributed architecture.  It provides all IMS, CICS Transaction manager features from an application perspective.

For this reason, all IMS and CICS applications can easily migrate to Tuxedo system keeping same processing logic and data integrity, and take all advantage of open system platforms.

How Tuxedo Based Solutions Meet Mainframe RASP

There is a myth that only mainframe platform can provide enterprise application RASP (Reliability, Availability, Scalability, Performance).  But with the progress made from open system software and hardware during last decennial this myth is breaking.

Combining Oracle mainframe re-host solution based on Tuxedo and Exalogic Elastic Cloud is truly a Game Changer.  The massively scalable, elastic foundation running Oracle Tuxedo with cloud-ready capabilities is a perfect target platform for migrated mainframe applications.

Over the years, some customers have hesitated because of the complexity and the cost of migration.  With Tuxedo ART we have responded to this challenge. The Application Runtimes for CICS, IMS, and Batch minimize change, but enable higher agility through the openness and extensibility they provide and through the rich SOA capabilities which provide powerful integration options. The Workbench delivers extreme accuracy and very high productivity.  It is wrapped in an automated process that reliably supports migration of very large applications with faster ROI. Bringing these attributes together with the robustness, performance, scalability of Tuxedo on Exalogic truly makes this solution a Game Changer.

This gives mainframe customers the key they’ve been waiting for.  You can now open the door to the future of your mainframe applications.

In this future, you can maintain and extend Mainframe RASP at a fraction of the mainframe cost

  • Improve scalability with massive, elastic, horizontal scale-out
  • Improve availability with rolling upgrades, active/active HA/DR

You can also enable strategic evolution of these vital applications

  • Easily integrat in SOA, extend with Java
  • Re-architect selected components as business needs evolve
  • Unlock access to legacy non-relational data to the enterprise

With Oracle Tuxedo ART and Exalogic, the future of the mainframe application has arrived.

CICS Runtime

Tuxedo ART CICS runtime is a set of Tuxedo servers to simulate IBM CICS core features to assume transparency of IBM CICS applications after the conversion by Tuxedo ART workbench.


  • 3270 Terminal Server for tn3270 UI using CICS BMS maps and terminal management
  • ART CICS Servers in Tuxedo application grid contain CICS functions, provide EXEC CICS APIs, and execute COBOL logic:
    • Managing sending and receiving of BMS maps
    • Implementing all CICS transactions and services (LUW, TSQ, TDQ, File access, DPL, Sync/Async transactions)
    • Implementing CICS system transactions, including SignOn/SignOff for authentication
    • Managing explicit (XC Query Security) and implicit authorizations
    • Managing COBOL services execution: invoking first programs for CICS transactions, COBOL runtime errors trapping, trace service
    • Managing database connections and commit/rollback, XA (2PC) services
    • Managing VSAM access and operations
  • Tuxedo system servers and gateways provide  underlying application server functions: cluster management, request routing, health monitoring, restarts, fail-over, load balancing, transaction  management, communication channels and gateways (ATMI, CICS, IMS, SOAP/HTTP web services, Java/JCA, .Net, ESB, etc.), protocol conversion

Batch Runtime

Tuxedo ART BATCH runtime is a set of Tuxedo servers to simulate IBM JES core features to assume transparence of IBM batch application after the conversion by Tuxedo ART workbench:

  • Batch Management
  • Duplicates JES functions – job queues, classes, priorities, initiators, etc.
  • Supports standard job control – job submit, hold, cancel, purge.
  • Provides distributed initiators for cluster-wide execution (configurable by job classes)
  • Publishes job-related events (state changes) to Tuxedo Event Broker, which can trigger notifications, service calls, CLI actions
  • Supports job control via command line client – can be used interactively, or via scheduler to submit and control jobs
  • Duplicates mainframe batch functions, supports expected JCL behavior, provides IBM-compatible utilities, integrates external utilities

VSAM Conversion

Oracle proposes two VSAM conversion options:

  • Oracle Database, this is the recommended solution
  • Unix VSAM

During the whole VSAM to Oracle database conversion, there are two parts:

  • Program source conversion, this task is accomplished by Workbench tool. It will transform VSAM Access operation to SQL statements
  • Existing data conversion, this task includes several steps:
    • Migrate z/OS files (VSAM, QSAM, GDG) to the target platform as ISAM files or ORACLE tables
    • Prerequisites:
      • Establish the Physical/Logical mapping
      • Determine files to be migrated/unloaded
      • Ensure that file references are consistently converted in various programs
      • Re-create the significant COBOL descriptions
    • Process:
      • Unload the physical files (if necessary) and transfer them to target
      • Transcode (using EBCDIC-to-ASCII conversion) and reload
      • Translation into Relational Schema

DB2 Conversion

During the IBM DB2  to Oracle DB conversion, there are two parts:

  • Program source conversion, this task is accomplished by Workbench tool, it includes:
    • All SQL statement converted from BD2 to Oracle DB
    • Conversion of DB2 Objects into Oracle Objects and migration of the Table Data from Z/OS to the target platform
    • All SQL objects (except physical concepts, such as storage group & table space) are converted.
    • Common data types fully supported (incl. DATE and TIME, CLOB/BLOB, but not XML) as well as comments on Tables and Columns
  • Existing data conversion, this task includes several steps:
    • Unload DB2 tables using generated JCL
    • Text code conversion (using EBCDIC-to-ASCII conversion)
    • Reload using Oracle SQL*Loader utility

IMS DB Conversion

Oracle provides two solutions for existing IMS DB due to its specificity.

  • With our partner solution, Migrate IMS DB to Oracle DB, it can be summarized as below:
    • Normally, one IMS Segment is migrated as one Table in the relational database
    • For multi-segment DBD, columns are added in a child table with borrowed keys from the parent
    • Most IMS DBDs contain only the key and index information, the actual data attributes are defined in COPYBOOKs used by the COBOL application. The migration tools parse the COPYBOOKs to help define Oracle DDL using the actual data types (e.g., Numeric, Decimal, Date, Character etc.), presenting a truer picture of the data in the target relational database.
  • With IBM ODBA (Open DabaBase Access) interface, Oracle provides a IMS DB ODBA adaptor. It allows COBOL IMS DB application to run on Tuxedo ART IMS runtime to access mainframe IMS DB transparently.

Web UI

With our partners, Oracle Tuxedo ART provides the possibility to convert BMS map based 3270 screen applications to Web based applications.

Methodology and Project Management

Oracle re-hosting solutions include not only technical components but also the methodology and project management capabilities.  The picture below shows the main steps for a re-hosting project.


How to begin your mainframe modernization journey?  Oracle offers a road map to modernization that starts with a discovery process.  This typically involves an in-depth discovery session with our mainframe migration experts to help us:

  • understand your objectives, needs, and constraints
  • diagnostic into your applications dependencies and mainframe technologies
  • evaluate potential pilot options
  • discuss and narrow some choices for target architecture
  • determine best integration approaches and strategy for switch-over

You can contact your Oracle account representative to arrange this.

Following the discovery session, we provide a report with our findings, capturing the key aspects of the current environment, and providing a strategic modernization road-map with tactical recommendations.  The report will also include the details of the recommended modernization approach, description of the target architecture options, detailed technology road-map, ROI analysis of the migration and specific plans (budget, time, etc.) for the suggested pilot migration and planned deliverables.


For the people want to know more detail about Oracle Re-hosting solution, below link will provides more detail and more actualized information:

Oracle Tuxedo general product information

Tuxedo ART Workbench Documentation

Tuxedo ART CICS and Batch Documentation

Tuxedo ART IMS Documentation


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