Oracle Procedural Gateway® for APPC Installation and Configuration Guide 10g Release 2 (10.2) for UNIX Part Number B16209-01 |
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This appendix describes the gateway initialization file location and lists the gateway initialization parameters supported by Oracle Procedural Gateway for APPC, specifically for the SNA protocol. These parameters are fully documented in Chapter15, "Migrating An Existing Gateway Instance to a New Release Using SNA Protocol". In addition, this appendix contains sample listener.ora
and tnsnames
files for a gateway using SNA.
This appendix contains the following sections:
The parameter file for the gateway is located in the $ORACLE_HOME/pg4appc/admin
directory and is called init
sid.
ora
.
This section covers various aspects of the gateway initialization file in the following sections:
AppendixA, "Sample listener.ora file for a Gateway Using SNA"
AppendixA, "Sample tnsnames.ora file for a Gateway Using SNA"
Note:
Theinit
sid.
ora
file contains both SNA and TCP/IP parameters. You must modify these files with suitable parameters.The PGA parameters control the APPC interface portion of the gateway. PGA parameters are specified using the SET
gateway initialization parameter. For example:
SET pga_parm=value
where:
pga_parm
is one of the PGA parameter names in the list that follows
value
is a character string with contents that depend on pga_parm
Table A-1 provides a list of PGA parameters and their descriptions.
Table A-1 PGA Parameters for Gateway Using SNA
Parameter | Description |
---|---|
where:
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PGA transaction capability. This controls whether updates are allowed through the gateway. The following are valid values:
The default is |
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Incoming APPC
The default is |
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The Oracle Net service name for the Oracle server in which the gateway maintains its transaction log. This parameter can be from 1 to 255 characters long. This parameter is required only when There is no default value. |
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The Oracle password to be used by the gateway when connecting to the Oracle server specified by the There is no default value. |
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The Oracle user ID to be used by the gateway when connecting to the Oracle server specified by the There is no default value. |
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The password to be used by the gateway when allocating an APPC conversation with the transaction specified by the There is no default value. |
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The TP name of the transaction installed in the OLTP for commit-confirm FORGET and RECOVERY processing. The TP name can be from 1 to 64 characters long. For CICS Transaction Server for z/OS, the TP name is limited to four characters. For IMS/TM, the TP name is limited to eight characters. Other OLTPs might have other limits on the length of the TP name. This parameter is required only when The default value is |
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The user ID to be used by the gateway when allocating an APPC conversation with the transaction specified by the There is no default value. |
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APPC conversation security option. This controls what security parameters are sent to the OLTP in the FMH-5 at conversation allocation. The following are valid values:
The default is For further information on these options, refer to Chapter 14, "Security Requirements". |
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(AIX only parameter) |
Action to take on receipt of a SIGDANGER signal from the system indicating a shortage of paging space. The following is a valid value:
The default is |
PGA trace level. This controls tracing output written to stderr (the target of the The default is 0, indicating no tracing. Any value between 1 and 255 will turn tracing on. |
When choosing a setting for the PGA_CAPABILITY
parameter, take care to ensure that the correct setting is used based on what the remote transaction programs will be doing.
The READ_ONLY
setting should always be used when the remote transaction programs are read-only, that is, when the remote transaction programs perform no database updates. READ_ONLY
should never be used when the remote transaction programs perform database updates. For example, if the READ_ONLY
setting is chosen and if a remote transaction program invoked by the gateway performs updates to a foreign database, then Oracle Integrating Server does not provide any integrity protection for those updates. Furthermore, the READ_ONLY
mode enables a gateway transaction to be part of a distributed transaction that might update several other databases. If the gateway invokes a remote transaction program that performs updates in this situation and if a failure occurs, then the database updated by the remote transaction program is not synchronized with the other databases.
In cases where the remote transaction programs perform updates to foreign databases, there are two options for the value of PGA_CAPABILITY
:
SINGLE_SITE
COMMIT_CONFIRM
Each of these options provides protection against data integrity problems by allowing COMMIT
and ROLLBACK
requests to be forwarded to the remote transaction program and by informing Oracle Integrating Server about the distributed update and recovery capabilities of the gateway. The particular option depends on the design of the remote transaction programs and on the capabilities of the OLTP (online transaction processor) where they execute.
If the OLTP has LU6.2 SYNCLEVEL 1 or 2 support, then the COMMIT_CONFIRM
capability provides limited two-phase commit between the Oracle Integrating Server and the OLTP, with the restriction that no other commit-confirm site (gateway or Oracle) can be part of the distributed transaction. If it is not possible to use COMMIT_CONFIRM
, then the SINGLE_SITE
capability provides update capability between Oracle Integrating Server and the OLTP, with the restriction that only the OLTP can perform updates and no updates can occur on the Oracle side.
Each of the PGA_CAPABILITY
options for update control imposes specific requirements on the remote transaction program and on the OLTP. For COMMIT_CONFIRM
capability, these requirements are discussed in detail in Chapter 5, "Implementing Commit-Confirm," of the Oracle Procedural Gateway for APPC User's Guide. Also refer to Chapter12, "Configuring the OLTP for Commit-Confirm" in this guide. For SINGLE_SITE
capability, the remote transaction program is responsible for performing the required tasks in response to COMMIT
and ROLLBACK
requests received from the gateway on behalf of the Oracle Integrating Server. The gateway uses the APPC CONFIRM
and SEND_ERR
requests to implement COMMIT
and ROLLBACK
, respectively. On receipt of a CONFIRM
, the remote transaction program must perform COMMIT
processing and then respond to the gateway with an APPC CONFIRMED
response. On receipt of SEND_ERR
, the remote transaction program must perform ROLLBACK
processing.
Because the distributed transaction capability of the Oracle Integrating Server is affected by the PGA_CAPABILITY
option used by the gateway, it is desirable to separate inquiry and update applications by using different gateway instances for each. One gateway can be defined with PGA_CAPABILITY
set to READ_ONLY
and others with PGA_CAPABILITY
set to SINGLE_SITE
or COMMIT_CONFIRM
.
This allows read-only transaction programs to participate in distributed transactions under the control of the Oracle Integrating Server. For example, data from DB2 can be retrieved through the READ_ONLY
gateway by an inquiry-only remote transaction program and can then be used as input to database updates on the Oracle Integrating Server, all in one Oracle transaction. A SINGLE_SITE
gateway can be used only for accessing remote transaction programs which perform updates to foreign databases outside the scope of the Oracle Integrating Server control. Data can be read from any databases accessible to the Oracle Integrating Server, and that data can be used to perform updates through the gateway.
When it is necessary to update resources on both the Oracle side and the OLTP side, a COMMIT_CONFIRM
gateway can be used, provided that the OLTP and the remote transaction programs are set up to implement commit-confirm.
All that is necessary to set up multiple gateway instances is to set up the following for each instance:
An entry in the listener.ora
file defining the sid
of the gateway instance
An entry in the tnsnames.ora
file defining an alias to be used to connect to the gateway instance defined in listener.ora
A database link in Oracle Integrating Server that specifies the alias defined in the tnsnames.ora
file in its USING
parameter
Note that the gateway instances can share one common directory structure and use the same executables.
For example, to set up two gateways, PGAI and PGAU (for inquiry and update use, respectively), the following steps are required:
Define two aliases in tnsnames.ora
that connect to the two new sid
s, PGAI
and PGAU
.
Define two database links in Oracle Integrating Server, one connecting to PGAI and the other connecting to PGAU.
Finally, create the initialization files initPGAI.ora
and initPGAU.ora
.
In initPGAI.ora
, set PGA_CAPABILITY
to READ_ONLY
, and in initPGAU.ora
, set PGA_CAPABILITY
to SINGLE_SITE
or COMMIT_CONFIRM
. Then, use the PGAI gateway for inquiry-only transactions, and use the PGAU gateway for update transactions.
The same steps can be used to set up additional gateway instances.
When deciding on the setting for the PGA_CONFIRM
parameter, it is important to understand the effects of each setting. First, keep in mind that this parameter affects only those conversations running at SYNCLEVEL 1. The default setting, PGA_CONFIRM
=
REJECT
, is correct for most applications. With this setting, the gateway generates an error if a CONFIRM
request is received from the remote transaction program. If you have a remote transaction that uses CONFIRM
to verify that data was received by the gateway, then you must use PGA_CONFIRM
=ACCEPT
to allow the gateway to respond to those incoming CONFIRM
requests with CONFIRMED
responses. You must be aware that the gateway sends CONFIRM
requests to the remote transaction when the Oracle application has sent a COMMIT
request. For the COMMIT
processing to work correctly, the remote transaction must be written to perform its local commit processing whenever a CONFIRM
request is received from the gateway, and respond to the gateway with CONFIRMED
after the commit processing has successfully completed. If an error occurs during commit processing, then the remote transaction must respond to the gateway with SEND_ERR
to indicate that the commit failed.
One special case for the use of PGA_CONFIRM
=ACCEPT
is with IMS/TM version 7. When using the "implied APPC" support that is provided by IMS/TM version 7, conversations that run at SYNCLEVEL 1 are handled differently than conversations that run at SYNCLEVEL 0. IMS/TM automatically generates CONFIRM requests after each APPC SEND
when the conversation is at SYNCLEVEL 1. On the gateway side, if PGA_CONFIRM
=ACCEPT
is not specified, then the CONFIRM
requests sent by IMS/TM result in errors generated by the gateway. Using PGA_CONFIRM
=ACCEPT
alleviates this problem, allowing the gateway to respond to incoming CONFIRM
requests with CONFIRMED
responses. The only limitation with running this way is that the implied APPC support provided by IMS does not notify the application when a CONFIRM
request is received from the gateway. This means that the gateway cannot use CONFIRM
to implement COMMIT
, thereby disabling the use of COMMIT
and ROLLBACK
to control updates on the IMS side of the conversation.
LISTENER = (ADDRESS_LIST = (ADDRESS= (COMMUNITY= TCP.world) (Host = bay) (PROTOCOL= TCP) (Port= 2621) ) (ADDRESS= (COMMUNITY= TCP.world) (Host = bay) (PROTOCOL= TCP) (Port= 2623) ) ) SID_LIST_LISTENER = (SID_LIST = (SID_DESC = (SID_NAME = PGA) (ORACLE_HOME = /oracle/pga/10.2) (PROGRAM = pg4asrv) ) )
ORA920 = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = bay.us.oracle.com)(PORT = 1521)) ) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = ORA920.bay) ) ) PGA = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = bay)(PORT = 2621)) ) (CONNECT_DATA = (SID = PGA) ) (HS = OK) )