1 Introduction to Oracle Procedural Gateway for APPC

1.1 Overview of the Gateway

The Oracle Procedural Gateway for APPC extends the Remote Procedural Call (RPC) facilities available with the Oracle server. The gateway enables any client application to use PL/SQL to request execution of a remote transaction program (RTP) residing on a host. The gateway provides RPC processing to systems using the SNA APPC (Advanced Program-to-Program Communication) protocol and to IMS/TM systems using TCP/IP support for IMS Connect. This architecture allows efficient access to data and transactions available on the IBM mainframe and IMS, respectively.

The gateway requires no Oracle software on the remote host system. Thus, the gateway uses existing transactions with little or no programming effort on the remote host.

• For gateways using SNA only: The use of a generic and standard protocol, APPC, allows the gateway to access a multitude of systems. The gateway can communicate with virtually any APPC-enabled system, including IBM Corporation's CICS on any platform, IBM Corporation's IMS and APPC/MVS, and Computer Associates' IDMS. These transaction monitors provide access to a broad range of systems, allowing the gateway to access many datastores, including VSAM, DB2 (static SQL), IMS, IDMS, ADABAS and others.

  The gateway can access any application capable of using the CPI-C API, either directly or through a TP monitor such as CICS.

1.2 Features of the Gateway

The Oracle Procedural Gateway for APPC provides the following benefits:

• Fast interface

  The gateway is optimized so that remote execution of a program is achieved with minimum network traffic. The interface to the gateway is an optimized PL/SQL stored procedure specification (called the "TIP" or "transaction interface package") precompiled in the Oracle Integrating Server. Because there are no additional software layers on the remote host, overhead occurs only when your program executes.

• Location transparency

  Client applications need not be operating system-specific. For example, your application can call a program in a CICS Transaction Server for z/OS. If you move the program to a CICS region on AIX, then you need not change the application.

• Application transparency

  Users calling applications that execute a remote transaction program are unaware that a request is sent to a host.

• Flexible interface

  You can use the gateway to interface with existing procedural logic or to integrate new procedural logic into an Oracle Integrating Server environment.

• Oracle server integration

  The integration of the Oracle server with the gateway enables the gateway to benefit from existing and future Oracle features. For example, the gateway can be called from an Oracle stored procedure or database trigger.

• Transactional support

  The gateway and the Oracle Integrating Server allow remote transfer updates and Oracle server updates to be performed in a coordinated fashion.

• Wide selection of tools

  The gateway supports any tool or application that supports PL/SQL.

• PL/SQL code generator

  The Oracle Procedural Gateway for APPC provides a powerful development environment, including:

  • a data dictionary to store information relevant to the remote transaction

  • a tool to generate the PL/SQL Transaction Interface Package, or TIP

  • a report utility to view the information stored in the gateway dictionary

  • a complete set of tracing and debugging facilities

  • a wide set of samples to demonstrate the use of the product against datastores such as DB2, IMS, IDMS, CICS, and ADABAS

• Site autonomy and security

  The gateway provides site autonomy, allowing you to do such things as authenticate users. It also provides role-based security compatible with any security package running on your mainframe computer.

• Automatic conversion

  Through the TIP, the following conversions are performed:

  • ASCII to and from EBCDIC

  • remote transaction program datatypes to and from PL/SQL datatypes

  • national language support for many languages

• TCP/IP support for IMS Connect

  This release of the gateway includes TCP/IP support for IMS Connect, giving users a choice of whether to use an SNA or TCP/IP communication protocol. IMS Connect is an IBM product which allows TCP/IP clients to trigger execution of IMS transactions. The gateway can use a TCP/IP communication protocol to access IMS Connect, which triggers execution of IMS transactions. There is no SNA involvement with this configuration.

  Related to this new feature of the gateway is:

  • The gateway mapping tool. This release of the gateway includes a tool (pg4tcpmap) whose purpose is to map the information from your SNA Side Profile Name to the TCP/IP host name and Port Number. For more information about the pg4tcpmap tool, refer to Chapter 6 of this guide and to Chapter 10 of the Oracle Procedural Gateway for APPC Installation and Configuration Guide regarding configuration of the gateway using TCP/IP.

    Note:

    When your communications protocol is TCP/IP, only IMS is supported as the Online Transaction Processor (OLTP).

1.3 Terms

The following terms and definitions are used throughout this guide:

Gateway Initialization File

This file is known as initsid.ora and it contains parameters that govern the operation of the gateway. If you are using the SNA protocol, refer to Appendix A, "Gateway Initialization Parameters for SNA Protocol" in the Oracle Procedural Gateway for APPC Installation and Configuration Guide for more information. If your protocol is TCP/IP, refer to Appendix B, "Gateway Initialization Parameters for TCP/IP Communication Protocol" in the Oracle Procedural Gateway for APPC Installation and Configuration Guide.

Gateway Remote Procedure

The Oracle Procedural Gateway for APPC provides prebuilt remote procedures. In general, the following three remote procedures are used:

• PGAINIT, which initializes transactions

• PGAXFER, which transfers data

• PGATERM, which terminates transactions

Refer to Appendix B, "Gateway RPC Interface" in this guide and to "Remote Procedural Call Functions" in Chapter 1 of the Oracle Procedural Gateway for APPC Installation and Configuration Guide for more information about gateway remote procedures.

tg4pwd

tg4pwd is a utility which encrypts passwords that are normally stored in the gateway initialization file. Passwords are stored in an encrypted form in the password file, making the information more secure. Refer to "Passwords in the Gateway Initialization File" in the security requirements chapter of the Oracle Procedural Gateway for APPC Installation and Configuration Guide for detailed information about how the tg4pwd utility works.

pg4tcpmap Tool

This tool is applicable only when the gateway is using TCP/IP support for IMS Connect. Its function is to map SNA parameters (such as Side Profile Name) to TCP/IP parameters (such as OLTP host name, IMS Connect port number and IMS destination ID).

PGA (Procedural Gateway Administration)

PGA is a general reference within this guide to all or most components comprising the Oracle Procedural Gateway for APPC. This term is used when references to a specific product or component are too narrow.

PGDL (Procedural Gateway Definition Language)

PGDL is the collection of statements used to define transactions and data to the PGAU.

PL/SQL Stored Procedure Specification (PL/SQL package)

This is a precompiled PL/SQL procedure that is stored in Oracle Integrating Server.

UTL_RAW PL/SQL Package (the UTL_RAW Functions)

This component of the gateway represents a series of data conversion functions for PL/SQL RAW variables and remote host data. The types of conversions performed depend on the language of the remote host data. Refer to Appendix D, "Datatype Conversions" in this guide for more information.

UTL_PG PL/SQL Package (the UTL_PG Functions)

This component of the gateway represents a series of COBOL numeric data conversion functions. Refer to "NUMBER_TO_RAW and RAW_TO_NUMBER Argument Values" in Appendix C of this guide for supported numeric datatype conversions.

Oracle Integrating Server

This is any Oracle server instance that communicates with the gateway for purposes of performing remote procedural calls to execute remote transaction programs (RTP). The Oracle Integrating Server can be on the same system as the gateway or on a different system. If it is on a different system, then Oracle Net is required on both systems. Refer to Figure 1-2, "Gateway Architecture Featuring SNA or TCP/IP Protocol" for a view of the gateway architecture.

OLTP (Online Transaction Processor)

OLTP is any of a number of online transaction processors available from other vendors, including CICS Transaction Server for z/OS, IMS/TM, and IDMS-DC.

PGAU (Procedural Gateway Administration Utility)

PGAU is the tool that is used to define and generate PL/SQL transaction interface packages (TIPs). Refer to Chapter 2, "Procedural Gateway Administration Utility" in this guide for more information about PGAU.

PG DD (Data Dictionary)

This component of the gateway is a repository of remote host transaction definitions and data definitions. PGAU accesses definitions in the PG DD when generating TIPs. The PG DD has datatype dependencies because it supports the PGAU and is not intended to be directly accessed by the customer. Refer to Appendix A, "Procedural Gateway for APPC Data Dictionary" in this guide for a list of PG DD tables.

RPC (Remote Procedural Call)

RPC is a programming call that executes program logic on one system in response to a request from another system. Refer to "Gateway Remote Procedure" in Appendix C of the Oracle Procedural Gateway for APPC Installation and Configuration Guide, and to Appendix B, "Gateway RPC Interface" in this guide for more information.

RTP (Remote Transaction Program)

A remote transaction program is a customer-written transaction, running under the control of an OLTP, which the user invokes remotely using a PL/SQL procedure. To execute a remote transaction program through the gateway, you must use RPC to execute a PL/SQL program to call the gateway functions.

TIP (Transaction Interface Package)

A TIP is an Oracle PL/SQL package that exists between your application and the remote transaction program. The transaction interface package, or TIP, is a set of PL/SQL stored procedures that invoke the remote transaction program through the gateway. TIPs perform the conversion and reformatting of remote host data using PL/SQL and UTL_RAW/UTL_PG functions.

Figure 1-1 illustrates where the terminology discussed in the preceding sections applies to the gateway's architecture.

Figure 1-1 Relationship of Gateway and Oracle Integrating Server on Windows

Description of "Figure 1-1 Relationship of Gateway and Oracle Integrating Server on Windows"

1.4 Examples and Sample Files for the Gateway

The following sample files and examples are referred to for illustration purposes throughout this guide. There are different example and sample files for a gateway using the SNA protocol than for a gateway using TCP/IP for IMS Connect.

Examples and Sample Files for Gateway Using SNA

For gateways using the SNA communication protocol, this guide uses a CICS-DB2 inquiry as an example. Transaction Interface Packages (TIPs) pgadb2i.pkb and pgadb2i.pkh send an employee number, empno, to a DB2 application and receive an employee record, emprec.

The CICS-DB2 inquiry sample and its associated PGAU commands are also available in the %ORACLE_HOME%\pg4appc\demo\CICS directory. The sample CICS-DB2 inquiry used as an example in this chapter is in files pgadb2i.pkh and pgadb2i.pkb. Refer to the README.doc file in the same directory for information about installing and using the samples. It can be found in the %ORACLE_HOME%pg4appc\demo\CICS directory.

Examples and Sample Files for Gateway Using TCP/IP

If your gateway is using the TCP/IP communication protocol, this guide uses an IMS inquiry as an example. Transaction Interface Packages (TIPs) pgtflip.pkh and pgtflip.pkb send input to IMS, through IMS Connect, and receive the flipped input as the output.

The IMS inquiry sample (FLIP) and its associated PGAU commands are located in the %ORACLE_HOME%\pg4appc\demo\IMS directory. The sample IMS inquiry used as an example for a gateway using TCP/IP is located in files pgtflip.pkh and pgtflip.pkb.

Refer to the README.doc file for more information about installing and using other IMS samples. It can be found in the %ORACLE_HOME%\pg4appc\demo\IMS directory.

1.5 Architecture of the Gateway

The architecture of Oracle Procedural Gateway for APPC consists of several components:

1. Oracle Integrating Server

   Refer to the configuration chapter appropriate to your communications protocol in the Oracle Procedural Gateway for APPC Installation and Configuration Guide for a description of the various methods for establishing the gateway-Oracle Integrating Server relationship.

   The Oracle Integrating Server can also be used for non-gateway applications.

2. The gateway

   Oracle Procedural Gateway for APPC must be installed on a server that can run the required version of the operating system.

3. An OLTP (online transaction processor)

   The OLTP must be accessible from the gateway using your SNA or TCP/IP communication protocol. Multiple Oracle Integrating Servers can access the same gateway. A single system gateway installation can be configured to access more than one OLTP.

   • For gateway using TCP/IP for IMS Connect: The only OLTP that is supported through TCP/IP is IMS through IMS Connect.The OLTP must be accessible to the system using the TCP/IP protocol. Multiple Oracle Integrating Servers can access the same gateway. A single system gateway installation can be configured to access more than one OLTP. Multiple IMS can be accessed from an IMS Connect. If you have a number of IMS Connect systems available, any of these may be connected to one or more IMS systems.

Figure 1-2 illustrates the architecture of the Oracle Procedural Gateway for APPC using SNA or TCP/IP, as described in the previous section.

Figure 1-2 Gateway Architecture Featuring SNA or TCP/IP Protocol

Description of "Figure 1-2 Gateway Architecture Featuring SNA or TCP/IP Protocol"

1.6 Starting the Gateway

Because the gateway does not have background processes and doesn't need a management utility such as Oracle Enterprise Manager, you needn't "start" the gateway. Each Oracle Integrating Server user session that accesses a particular gateway creates an independent process on Windows that runs the gateway server and executes either the SNA or ­TCP/IP functions to communicate with an OLTP, depending upon your protocol.

1.7 Communication With the Gateway

All of the communication between the user or client program and the gateway is handled through a transaction interface package (TIP) which executes on an Oracle Integrating Server. The TIP is a standard PL/SQL package that provides the following functions:

• declares the PL/SQL variables that can be exchanged with a remote transaction program;

• calls the gateway packages that handle the communications for starting the conversation, exchanging data and terminating the conversation;

• handles all datatype conversions between PL/SQL datatypes and the target program datatypes.

The Procedural Gateway Administration Utility (PGAU), provided with the gateway, automatically generates the TIP specification.

The gateway is identified to the Oracle Integrating Server using a database link. The database link is the same construct used to identify other Oracle server databases. The functions in the gateway are referenced in PL/SQL as:

function_name@dblink_name 

1.8 Remote Procedural Call Functions

The Oracle Procedural Gateway for APPC provides a set of functions that are invoked by the client through remote procedural call (RPC). These functions direct the gateway to initiate, transfer data with, and terminate remote transaction programs running under an OLTP on another system.

Table 1-1 lists the remote procedural call functions and the correlating commands that are invoked in the gateway and remote host.

1.9 Overview of a Gateway Using SNA

If you are using the SNA communication protocol, read the following sections to develop an understanding of how the gateway communicates with the Oracle Integrating Server and with the mainframe, as well as transaction types unique to your gateway and writing TIPs.

1.10 Simple Gateway Communication With the Oracle Server (SNA)

This section describes simple communication between the mainframe and the Oracle Integrating Server on a gateway using the SNA communication protocol. The Oracle Procedural Gateway for APPC lets you write your own procedures to begin transferring information between the Oracle Integrating Server and a variety of programs on an IBM mainframe, including IBM CICS, IMS, and APPC/MVS.

For an illustration of the communications function of the Oracle Procedural Gateway for APPC, refer to %ORACLE_HOME%\pg4appc\demo\CICS\pgacics.sql, which is a simple sample communication between the Oracle server and CICS Transaction Server for z/OS. Executing the simple PL/SQL procedure pgacics.sql causes the Oracle Integrating Server to invoke the procedural gateway, which uses SNA to converse with the FLIP transaction in CICS. These steps are described in detail in Section 1.10.1, "Steps to Communication Between Gateway and Mainframe, Using SNA". Note that you will already have compiled and linked the stored procedure when you configured the gateway.

1.10.1 Steps to Communication Between Gateway and Mainframe, Using SNA

The following steps describe the Windows-to-mainframe communications process illustrated in Figure 1-3, "Communication Between the Oracle Server and the Mainframe, Using SNA" when your communication protocol is SNA to communicate between the gateway and the mainframe:

1. From SQL*Plus, execute pgacics; this invokes the PL/SQL stored procedure in the Oracle Integrating Server.

   C:\> sqlplus <userid>/<password>@<database_specification_string>
   SQL> execute pgacics('==< .SCIC htiw gnitacinummoc si yawetag ruoy ,snoitalutargnoC >==');
   
   

2. The pgacics PL/SQL stored procedure will start up the gateway. The gateway will start up communication with CICS Transaction Server for z/OS through SNA and will call FLIP.

3. FLIP processes the input, generates the output and sends the output back to the procedural gateway.

4. Finally, the procedural gateway will send the output back to the PL/SQL stored procedure in the Oracle Integrating Server. The result is displayed in SQL*Plus:

   ==> Congratulations, your gateway is communicating with CICS. <==
   PL/SQL procedure successfully completed.
   
   

   Figure 1-3, "Communication Between the Oracle Server and the Mainframe, Using SNA" illustrates the communications process described in steps 0 through 4 in the previous section.

Figure 1-3 Communication Between the Oracle Server and the Mainframe, Using SNA

Description of "Figure 1-3 Communication Between the Oracle Server and the Mainframe, Using SNA"

1.11 Writing TIPs to Generate PL/SQL Programs on Gateway Using SNA

Most transactions using SNA communication protocol are much larger and more complex than the simple sample pgacics.sql file referred to in Figure 1-3, "Communication Between the Oracle Server and the Mainframe, Using SNA". Additionally, communication with a normal-sized RTP (remote transaction program) would require you to create an extremely long PL/SQL file. Oracle Procedural Gateway for APPC's PGAU function generates the PL/SQL procedure for you.

The following is a brief description of the four steps necessary for you to generate a TIP. Refer to Chapter 3, "Creating a TIP" for detailed information about this procedure, and refer to Chapter 2, "Procedural Gateway Administration Utility" for more information about PGAU.

All parameter names in this section are taken from a file called pgadb2i.ctl in the %ORACLE_HOME%\pga4appc\demo\CICS directory.

C:\> pgau
PGAU> CONNECT<userid>/<password>@<database>_specification_string>
PGAU> @pgadb2i.ctl

C:\> sqlplus<userid>/<password>@<database_specification_string>
SQL> @pgadb2i.pkh;
SQL> @pgadb2i.pkb;

C:\> sqlplus <userid>/<password>@<database_specification string> 
SQL> @pgadb2id.sql
SQL> execute db2idriv('000320');

1.12 Overview of a Gateway Using TCP/IP

If you are using the TCP/IP communication protocol, read the following sections to develop an understanding of how the gateway communicates with the Oracle Integrating Server and with the mainframe, as well as transaction types unique to your gateway and writing TIPs.

1.13 Simple Gateway Communication with the Oracle Server (TCP/IP)

This section describes simple communication between IMS and the Oracle Integrating Server whenTCP/IP for IMS Connect is being used as the communication protocol between the gateway and the remote host (IMS). The Oracle Procedural Gateway for APPC lets you write your own procedures to begin transferring information between the Oracle Integrating Server and I/O PCB programs on IMS.

For an illustration of the communications function of the gateway using TCP/IP for IMS Connect, refer to %ORACLE_HOME%\pg4appc\demo\IMS\pgaims.sql file.

Executing the simple PL/SQL procedure pgaims.sql causes the Oracle Integrating Server to invoke the gateway, which uses TCP/IP to converse with the sample transaction FLIP in IMS. The communication steps that take place when you execute the PL/SQL procedure are described in detail in Section 1.13.2, "Steps to Communication Between the Gateway and IMS, Using TCP/IP". Note that you will already have compiled and linked the stored procedure when you configured the gateway.

1.13.2 Steps to Communication Between the Gateway and IMS, Using TCP/IP

The following steps describe the Windows-to-IMS on a mainframe communications process, as illustrated in Figure 1-4 when your communication protocol is TCP/IP:

1. From SQL*Plus, execute pgaims.sql; this invokes the PL/SQL stored procedure in the Oracle Integrating Server.

   C:\> sqlplus <userid>/<password>@<database_specification_string>
   SQL> execute pgaims 'snoitalutargnoC';
   
   

   The pgaims.sql stored procedure will start up the gateway.

2. The gateway which has the APPC information will call the mapping table (PGA_TCP_IMSC). The mapping table will map the information so that it will have the host name (TCP/IP address) and the port number.

   Note:

   Rather than insert, delete or update the PGA_TCP_IMSC mapping table manually, you should use the pg4tcpmap tool to do so. You may use the select statement to query the rows.

3. When the gateway has the port number and host name, it will initiate communication with IMS through TCP/IP, and will call FLIP through IMS Connect.

4. FLIP processes the input, generates the output and sends the output back to the gateway.

5. Finally, the gateway will send the output back to the PL/SQL stored procedure in the Oracle Integrating Server. The result is displayed in SQL*Plus:

   Congratulations
   PL/SQL procedure successfully completed.
   
   

Figure 1-4, "Communication Between Oracle Server and Mainframe, Using TCP/IP" illustrates the communications process described in the previous Steps 0 through 5.

Figure 1-4 Communication Between Oracle Server and Mainframe, Using TCP/IP

Description of "Figure 1-4 Communication Between Oracle Server and Mainframe, Using TCP/IP"

1.14 Writing TIPs to Generate PL/SQL Programs on Gateway Using TCP/IP

Most transactions are much larger and more complex than the simple sample pgaims.sql file referred to in Figure 1-4, "Communication Between Oracle Server and Mainframe, Using TCP/IP". Additionally, communication with a normal-sized RTP (remote transaction program) would require you to create an extremely long PL/SQL file. Oracle Procedural Gateway for APPC's TIP function generates the PL/SQL procedure for you.

The following is a brief description of the four steps necessary for you to generate a TIP. Refer to Chapter 3, "Creating a TIP" for detailed information about this procedure, and refer to Chapter 2, "Procedural Gateway Administration Utility" for more information about PGAU.

All parameter names in this section are taken from a file called pgtflip.ctl in the %ORACLE_HOME%\pga4appc\demo\IMS directory.

C:\> cd %ORACLE_HOME%\pg4appc\demo\IMS
C:\> pgau
PGAU> CONNECT userid/password@database_specification_string
PGAU> @pgtflip.ctl

C:\> sqlplus userid/password@database_specification_string
SQL> @pgtflip.pkh;
SQL> @pgtflip.pkb;

C:\> sqlplus <userid>/<password>@<database_specification string> 
SQL> @pgtflip.sql
SQL> execute pgtflipd('hello');