10g Release 1 (10.1) for Solaris Operating System (SPARC)
Part Number B10527-01
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| Oracle® Transparent Gateway for Informix Administrator's Guide 10g Release 1 (10.1) for Solaris Operating System (SPARC) Part Number B10527-01 |
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After installing the gateway, perform the following tasks to configure the gateway for Informix:
Perform the following tasks to configure the Oracle Transparent Gateway for Informix.
The gateway system identifier (SID) is an alphanumeric character string that identifies a gateway instance. You need one gateway instance, and therefore one gateway SID, for each Informix database you are accessing. The SID is used as part of the file name for the initialization parameter file. The default SID is tg4ifmx.
You can define a gateway SID, but using the default of tg4ifmx is easier because you do not need to change the initialization parameter file name. However, if you want to access two Informix databases, you need two gateway SIDs, one for each instance of the gateway. If you have one Informix database and want to access it sometimes with one set of gateway parameter settings, and other times with different gateway parameter settings, you can do that by having multiple gateway SIDs for the single Informix database.
The initialization parameter file must be available when the gateway is started. During installation, the following default initialization parameter file is created:
$ORACLE_HOME/tg4ifmx/admin/inittg4ifmx.ora
where $ORACLE_HOME is the directory under which the gateway is installed.
If you are not using tg4ifmx as the gateway SID, you must rename the initialization parameter file using the SID you chose in Task 1. This default initialization parameter file is sufficient for starting the gateway, verifying a successful installation, and running the demonstration scripts.
In the initialization parameter file, specify the Informix connection as follows:
HS_FDS_CONNECT_INFO=database_name@server_name
If you specify only database_name, omitting server_name, the gateway binds to the database residing on the local Informix server (as specified in the environment variable INFORMIXSERVER).
Additionally, set the Informix environment variable, as follows:
SET INFORMIXDIR=ifmx_clt_dir
A number of initialization parameters can be used to modify gateway behavior. You might want to change the initialization parameter file later to meet system requirements.
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See Also:
Appendix D, "Heterogeneous Services Initialization Parameters" and the Oracle Database Heterogeneous Connectivity Administrator's Guide for more information about customizing the initialization parameter file. |
The gateway requires Oracle Net Services to provide transparent data access. After configuring the gateway, configure Oracle Net Services to work with the gateway.
Oracle Net Services uses the TNS listener to receive incoming connections from a Oracle Net Services client. The TNS listener and the gateway must reside on the same machine.
The TNS listener listens for incoming requests from the Oracle database server. For the TNS listener to listen for the gateway, information about the gateway must be added to the TNS listener configuration file, listener.ora. This file is located in $ORACLE_HOME/network/admin, where $ORACLE_HOME is the directory under which the gateway is installed.
The following entries must be added to the listener.ora file:
The Oracle database server accesses the gateway using Oracle Net Services and the TCP/IP protocol adapter. The following is the syntax of the connect descriptor entry in the listener.ora file:
LISTENER= (ADDRESS= (PROTOCOL=TCP) (HOST=host_name) (PORT=port_number))
where:
To direct the TNS listener to start the gateway in response to incoming connection requests, add an entry to the listener.ora file with the following syntax:
SID_LIST_LISTENER= (SID_LIST= (SID_DESC= (SID_NAME=gateway_sid) (ORACLE_HOME=oracle_home_directory) (PROGRAM=tg4ifmx) (ENVS=LD_LIBRARY_PATH=ifmx_clt_dir/lib:ifmx_clt_dir/lib/esql:
oracle_home_directory/lib) ) )
where:
If you are already running a TNS listener that listens on multiple database SIDs, add only the following syntax to SID_LIST in the existing listener.ora file:
SID_LIST_LISTENER= (SID_LIST= (SID_DESC=. . ) (SID_DESC=. . ) (SID_DESC= (SID_NAME=gateway_sid) (ORACLE_HOME=oracle_home_directory) (PROGRAM=tg4ifmx) (ENVS=LD_LIBRARY_PATH=ifmx_clt_dir/lib:ifmx_clt_dir/lib/esql:
oracle_home_directory/lib) ) )
The TNS listener must be started to initiate the new settings, as follows:
/bin where the gateway is installed. If you have the Bourne or Korn Shell, enter the following:
$ PATH=$ORACLE_HOME/bin:$PATH;export PATH
If you have the C Shell, enter the following:
$ setenv PATH $ORACLE_HOME/bin:$PATH
$ lsnrctl stop
$ lsnrctl start
$ lsnrctl status
The following is an example of output from a lsnrctl status check:
LSNRCTL for Solaris: Version 10.1.0.0.0 - Production on 28-NOVEMBER-2003 10:16:17
Copyright (c) 1991, 2001, Oracle Corporation. All rights reserved.
Connecting to (ADDRESS=(PROTOCOL=TCP)(HOST=204.179.99.15)(PORT=1551))
STATUS of the LISTENER
----------------------
Alias listener
Version TNSLSNR for Solaris: Version 10.1.0.0.0 - Production
Start Date 28-NOVEMBER-2003 10:16:17
Uptime 0 days 2 hr. 10 min. 25 sec
Trace Level off
Security OFF
SNMP OFF
Listener Parameter File /users/oracle/gateway/network/admin/listener.ora
Listener Log File /users/oracle/gateway/network/log/listener.log
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=204.179.99.15)(PORT=1551)))
Services Summary...
Service "tg4ifmx" has 1 instance(s).
Instance "tg4ifmx", status UNKNOWN, has 1 handler(s) for this service...
The command completed successfully
In this example, tg4ifmx is the default SID value assigned during installation. You can use any valid ID for the SID, or keep the default.
Before you use the gateway to access Informix data you must configure the Oracle database server to enable communication with the gateway over Oracle Net Services.
To configure the server you add connect descriptors to the tnsnames.ora file. You cannot use the Oracle Net Services Assistant or the Oracle Net Services Easy Config tools to configure the tnsnames.ora file. You must edit the file manually.
For the Oracle database server to access the gateway, it needs a service name entry or a connect descriptor name entry in the tnsnames.ora file to tell the Oracle database server where to make connections. By default, this file is in $ORACLE_HOME/network/admin, where $ORACLE_HOME is the directory in which the Oracle database server is installed. The tnsnames.ora file is required by the Oracle database server accessing the gateway, but not by the gateway.
Edit the tnsnames.ora file to add a connect descriptor for the gateway. The following is an example of the Oracle Net Services entries using TCP/IP protocol needed for the Oracle database server to access the gateway:
connect_descriptor= (DESCRIPTION= (ADDRESS= (PROTOCOL=TCP) (HOST=host_name) (PORT=port_number) ) (CONNECT_DATA= (SID=gateway_sid)) (HS=OK))
where:
| Parameter | Meaning |
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connect_descriptor |
is the description of the object to connect to as specified when creating the database link, such as tg4ifmx.
Check the
Note: The |
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is the TCP protocol used for TCP/IP connections. |
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host_name |
specifies the machine where the gateway is running. |
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port_number |
matches the port number used by the Oracle Net Services TNS listener that is listening for the gateway. The TNS listener's port number can be found in the |
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gateway_sid |
specifies the SID of the gateway and matches the SID specified in the |
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specifies that this connect descriptor uses the Oracle Heterogeneous Services option. |
Any Oracle client connected to the Oracle database server can access Informix data through the gateway. The Oracle client and the Oracle database server can reside on different machines. The gateway accepts connections only from the Oracle database server.
A connection to the gateway is established through a database link when it is first used in an Oracle session. In this context, a connection refers to the connection between the Oracle database server and the gateway. The connection remains established until the Oracle session ends. Another session or user can access the same database link and get a distinct connection to the gateway and Informix database.
Database links are active for the duration of a gateway session. If you want to close a database link during a session, you can do so with the ALTER SESSION statement. The database and application administrators of a distributed database system are responsible for managing the necessary database links that define paths to the Informix database.
The tasks for configuring the gateway to access multiple Informix databases are similar to the tasks for configuring the gateway for a single database. The configuration example assumes the following:
Configuring the gateway for additional Informix databases is similar to configuring it for one database, and involves the following:
A separate instance of the gateway accesses the different Informix databases. Each instance needs its own gateway System ID (SID). For this example, the gateway SIDs are chosen for the instances that access the Informix databases:
Create an initialization parameter file for each instance of the gateway by copying the original initialization parameter file, $ORACLE_HOME/tg4ifmx/admin/inittg4ifmx.ora, twice, naming one with the gateway SID for db2 and the other with the gateway SID for db3:
$ cd $ORACLE_HOME/tg4ifmx/admin
$ cp inittg4ifmx.ora inittg4ifmx2.ora
$ cp inittg4ifmx.ora inittg4ifmx3.ora
Change the value of the HS_FDS_CONNECT_INFO parameter in the new files.
For inittg4ifmx2.ora, enter the following:
HS_FDS_CONNECT_INFO=db2@inf74_sun
For inittg4ifmx3.ora, enter the following:
HS_FDS_CONNECT_INFO=db3@inf74_sun
Set the Informix environment variables in both of the new initialization parameter files, as follows:
For inittg4ifmx2.ora, enter the following:
SET INFORMIXDIR=ifmx_clt_directory
For inittg4ifmx3.ora, enter the following:
SET INFORMIXDIR=ifmx_clt_directory
The ifmx_clt_directory specified is the directory where the client library is installed.
Add two new entries to the TNS listener configuration file, listener.ora. You must have an entry for each gateway instance, even when multiple gateway instances access the same database.
The following example shows the entry for the original installed gateway first, followed by the new entries:
SID_LIST_LISTENER= (SID_LIST= (SID_DESC= (SID_NAME=tg4ifmx) (ORACLE_HOME=oracle_home_directory) (PROGRAM=tg4ifmx) (ENVS=LD_LIBRARY_PATH=ifmx_clt_dir/lib:ifmx_clt_dir/lib/esql:
oracle_home_directory/lib) ) (SID_DESC= (SID_NAME=tg4ifmx2) (ORACLE_HOME=oracle_home_directory) (PROGRAM=tg4ifmx) (ENVS=LD_LIBRARY_PATH=ifmx_clt_dir/lib:ifmx_clt_dir/lib/esql:
oracle_home_directory/lib) ) (SID_DESC= (SID_NAME=tg4ifmx3) (ORACLE_HOME=oracle_home_directory) (PROGRAM=tg4ifmx) (ENVS=LD_LIBRARY_PATH=ifmx_clt_dir/lib:ifmx_clt_dir/lib/esql:
oracle_home_directory/lib) ) )
If the listener is already running, use the lsnrctl command to stop the listener and then start it with the new settings, as follows:
$ lsnrctl stop
$ lsnrctl start
Add two connect descriptor entries to the tnsnames.ora file. You must have an entry for each gateway instance, even if the gateway instances access the same database.
The following Informix example shows the entry for the original installed gateway first, followed by the two entries for the new gateway instances:
old_db_using=(DESCRIPTION= (ADDRESS= (PROTOCOL=TCP) (PORT=1541) (HOST=gtwhost)) (CONNECT_DATA= (SID=tg4ifmx)) (HS=OK)) new_db2_using=(DESCRIPTION= (ADDRESS= (PROTOCOL=TCP) (PORT=1541) (HOST=gtwhost)) (CONNECT_DATA= (SID=tg4ifmx2)) (HS=OK)) new_db3_using=(DESCRIPTION= (ADDRESS= (PROTOCOL=TCP) (PORT=1541) (HOST=gtwhost)) (CONNECT_DATA= (SID=tg4ifmx3)) (HS=OK))
The value for PORT is the TCP/IP port number of the TNS listener that is listening for the gateway. The number can be found in the listener.ora file used by the TNS listener. The value for HOST is the name of the machine on which the gateway is running. The name also can be found in the listener.ora file used by the TNS listener.
Enter the following to create a database link for the tg4ifmx2 gateway:
SQL> CREATE PUBLIC DATABASE LINK IFMX2 CONNECT TO 2 user2 IDENTIFIED BY password2 USING 'new_db2_using';
Enter the following to create a database link for the tg4ifmx3 gateway:
SQL> CREATE PUBLIC DATABASE LINK IFMX3 CONNECT TO 2 user3 IDENTIFIED BY password3 USING 'new_db3_using';
After the database links are established you can query the new Informix databases, as in the following:
SQL> SELECT * FROM ALL_USERS@IFMX2;
or
SQL> SELECT * FROM ALL_USERS@IFMX3;
You can perform the following configuration tasks:
The gateway supports the following transaction capabilities:
By default, the gateway runs in COMMIT_CONFIRM transaction mode. When the Informix database is updated by a transaction, the gateway becomes the commit point site. The Oracle database server commits the unit of work in the Informix database after verifying that all Oracle databases in the transaction have successfully prepared the transaction. Only one gateway can participate in an Oracle two-phase commit transaction as the commit point site.
To enable the COMMIT_CONFIRM transaction mode, create a recovery account and password and create a log table. The log table, called HS_TRANSACTION_LOG, is where two-phase commit transactions are recorded.
For the gateway to recover distributed transactions, a recovery account and password must be set up in the Informix database. By default, both the user name of the account and the password are RECOVER. The name of the account can be changed with the gateway initialization parameter HS_FDS_RECOVERY_ACCOUNT. The account password can be changed with the gateway initialization parameter HS_FDS_RECOVERY_PWD.
"Task 2: Customize the Initialization Parameter File" for information about editing the initialization parameter file. For information about HS_FDS_RECOVERY_ACCOUNT and HS_FDS_RECOVERY_PWD, see Appendix D, "Heterogeneous Services Initialization Parameters".
See Also:
When configuring the gateway for two-phase commit, a table must be created in the Informix database for logging transactions. The gateway uses the transaction log table to check the status of failed transactions that were started at the Informix database by the gateway and registered in the table.
The table, called HS_TRANSACTION_LOG, consists of two columns, GLOBAL_TRAN_ID, data type CHAR(64) NOT NULL and TRAN_COMMENT, data type CHAR(255).
You can use another name for the log table, other than HS_TRANSACTION_LOG, by specifying the other name using the HS_FDS_TRANSACTION_LOG initialization parameter.
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See Also:
Appendix D, "Heterogeneous Services Initialization Parameters" for information about the HS_FDS_TRANSACTION_LOG initialization parameter. |
Create the transaction log table in the user account you created in "Task 1: Create a Recovery Account and Password". Because the transaction log table is used to record the status of a gateway transaction, the table must reside at the database where the Informix update takes place. Also, the transaction log table must be created under the owner of the recovery account.
To create a transaction log table use the tg4ifmx_tx.sql script, located in the directory $ORACLE_HOME/tg4ifmx/admin where $ORACLE_HOME is the directory under which the gateway is installed, as follows:
If you have the Bourne or Korn Shell, enter the following:
$ DELIMIDENT = y; export DELIMIDENT
If you have the C Shell, enter the following:
$ setenv DELIMIDENT y
$ cd $ORACLE_HOME/tg4ifmx/admin
$ dbaccess database_name tg4ifmx_tx.sql
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 Copyright © 2002, 2003 Oracle Corporation. All Rights Reserved. |
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