Introduction

This chapter introduces the OpenFrame OSI (Online Server type I) system and its components and describes its entire structure.

1. OSI System Overview

OpenFrame OSI is one of many products that make up OpenFrame (a rehosting solution). It allows online applications running in a mainframe to run in an open system (Unix).

The following questions may arise when considering migration of applications running in an existing mainframe, to an open system.

  • How can the open system provide the same performance and reliability as the existing Mainframe ?

  • How easily can migration be performed ?

OSI addresses these two issues by using Tmax TP-Monitor and the migration tool.

To solve performance and reliability issues, OSI uses the Tmax engine (a TP-monitor) which has proven reliability and performance in open systems. Therefore, OSI enjoys the following benefits of Tmax.

  • Convenient process management

    In OSI, user-created processes are managed by Tmax from start-up to shut-down and use the various monitoring information that Tmax provides. This allows processes to be conveniently managed.

  • Large-scale transaction

    Tmax contains built-in scheduling and service queue management functions for large-scale transaction processing.

    Tmax is suitable for mission-critical systems in an open environment. OSI, which is based on Tmax, also reliabliy supports large-scale transactions.

  • Unrestricted integration in an open environment

    Integration is not the most important issue arising immediately after rehosting from an IBM mainframe to an open system environment. However, there are many cases in which systems in operation have to be extended or integrated with other systems. In these situations, Tmax seamlessly integrates with commercial TP-monitors such as Tuxedo which conforms to a different X/Open DTP model, and therefore OSI has an excellent advantage over other rehosting solutions.

    This feature of Tmax allows an easy extension of business applications written with OSI. Furthermore, it can also saemlessly integrate with the web environment by linking with JEUS (TmaxSoft’s Web Application Server).

OSI provides various tools to manage applications in an open system in the same way as in a mainframe, by migrating user programs and their associated resources. An interface similar to DL/I is provided to allow user programs operating in Mainframe’s IMS/DC, MPP (Message Processing Program) and BMP (Batch Message Processing) to run in the same way in OSI.

For more information about MPP and BMP in OSI, refer to OSI User Server (Dependent Region).

2. OSI System Components

OSI is composed of two modules: the OSI system server (system servers such as the schedule server and command server) which is responsible for the important functions of the OSI system and the OSI user server (user servers such as the MPP and BMP servers) which runs user applications.

  • OSI System Server (Control Region)

    A system module required for operating the OSI system.

    The functions of the OSI system servers include: message scheduling, message queue management, message transformation via MFS, DB integration, and system and user command processing.

  • OSI User Server (Dependent Region)

    Users run user application programs by starting the processes (in the Tmax server) themselves through JCL or by executing the "/START REGION" command.

    1. The MPP server is provided under the name of OSIMPPSVR, and the BMP server is provided as the osibmpsv module.

    2. Starting from the current version, TN3270 Gateway is not supported by OSI, but replaced by OpenFrame Gateway, which provides all the existing features. For more information, refer to OpenFrame Gateway Administrator’s Guide.

3. OSI System Structure

Generally, running application programs requires a base system for operating these programs in terms of both system server and user server. The OSI structure for such base system is as follows:

figure 1 1
OSI Structure

The system server (Control Region) is a region corresponding to the OSI system module and contains various configurations including the server which is required for running application servers and application programs in the OSI system itself. The user server (Dependent Region) is a part of the OSI user module and divided into two types of aplication server provided in the OSI system: MPP and BMP. The OSIOMSVR (Online Manager) server is required for activating both system server and user server. The OSI system also includes the system engine area, Online Core (Tmax).

3.1. OSI System Server (Control Region)

The OSI system server (control region) consists of two servers: the schedule server (osisschd) and command server (osicmdsv). Both servers are provided under the type of Tmax UCS server.

  • Schedule Server (osisschd)

    Determines the integrity of the requested message (determines whether the message is valid), stores (backup) and passes (forwarding) the message at the same time. In the current version, the schedule server only checks for the message’s integrity and forwards the message to its destination. In the case of a message received from the terminal (screen), a data transformation through MFS is performed and then the message is sent to the MPP server.

    Classification Description

    Message storage and forwarding

    Backs up the requested message to the Message Queue (MQ) table, and then forwards the message to the MPP or command server, or to the emulator connecting to OpenFrame Gateway, depending on the type of the destination (command, transaction…​)

    MFS transformation

    Unifies the data format defined in the screen information and application, between MPP and TN3270 emulator (OpenFrame Gateway is present in between), and converts data with different code pages, from ASCII to EBCDIC or the other way round.

  • Command Server (osicmdsv)

    Processes all commands required for operating the OSI system.

    For more information about the commands processed by the command server, refer to OpenFrame OSI Command Reference Guide.

3.2. OSI User Server (Dependent Region)

Operating user-written application programs requires a user to prepare a dedicated server module during the system configuration phase, in addition to the default system module provided by OSI. A user-prepared server module means, conceptually, the region corresponding to the OSI user server (dependent region) of IMS/DC. Generally, at least one user module is prepared for each of the dependent regions which have been run in the IBM mainframe.

The following describes the user servers used in operating OSI.

Classification Description

MPP User Server

Corresponds to an MPP region in IMS/DC. OSI runs MPP servers at the level of message classes. Therefore, an MPP user server features up to one-to-four correspondence per MPP region running in the existing IMS/DC.

BMP User Server

Allows user programs running in the BMP region of IMS/DC to be managed.

The process for preparing the user server can be started by using JCL or the OSI command. For more information about relevant user server environment configurations, refer to User Server Configuration.

3.3. OSIOMSVR

OSIOMSVR is a server for starting and stopping the OSI system and MPP user servers. If you execute JCL or the "/START REGION" command, OSIOMSVR internally stores information about the regions required for startup to the database and then starts servers through tmboot. If you execute "/STOP REGION" or "/CHECKPOINT FREEZE", OSIOMSVR deletes the regions information that has been internally stored in the database, and then shuts down servers through tmdown.

OSIOMSVR must be booted ahead of the regions and can be started or stopped along with the OpenFrame core (Tmax/Base/Batch) servers by using the osiboot or osidown tool.

The BMP user server must be directly started/stopped without using OSIOMSVR.

3.4. OSIMQSVR

OSIMQSVR is a server allowing connection with IBM Websphere MQ and providing the Queue Trigger Monitor feature, which can be enabled by specifying a certain option but does not affect the system behavior if disabled.

The following describes different MQ interfaces (MQI) used by OSIMQSVR.

Name Description

MQCONN

Connects to an IBM MQ queue manager.

MQOPEN

Enables access to an object.

MQGET

Gets messages from a local queue that has been opened by MQOPEN.

MQPUT

Sends messages to a local queue that has been opened by MQOPEN.

MQCLOSE

Disables access to an object.

MQDISC

Disconnects from an IBM MQ queue manager.

For more information about how to configure and use the Queue Trigger Monitor feature of OSIMQSVR, refer to OpenFrame Configuration Guide.

3.5. OpenFrame Gateway

OpenFrame Gateway (OpenFrame GW) is found between the OSI system server (control region) and TN3270/TN3270E emulators, or between terminals that are connected through web browsers. OpenFrame GW is a server that sends transaction requests to the OSI system server (control region) and manages information about terminal connections and system servers (control region). It is also referred to as VTAM (Virtual Terminal Access Method) Gateway.

The following are the main functions of OpenFrame GW.

  • Supporting TN3270 protocol

  • Managing the Application Identifier (APPLID) information (APPLID indicates a terminal connecting to OpenFrame GW and the OSI system server (control region). )

  • Supporting IP-LU mapping

For more information about how to configure and use OpenFrame GW, refer to OpenFrame Gateway Administrator’s Guide.