C
Using Oracle Application Server Containers for J2EE Plug-in

This appendix explains how the Oracle Application Server Containers for J2EE (OC4J) plug-in enables you to use third party HTTP listeners to access servlets running in OC4J J2EE within Oracle Application Server. OC4J Plug-in works with Sun ONE Web Server Enterprise Edition, version 4.1 and 6.0, and Microsoft Internet Information Server (IIS), version 4.0 or 5.0.

It also contains information about using mod_oc4j in a non-Oracle Apache.

Topics discussed are:

Overview

OC4J Plug-in provides functionality for third party HTTP listeners similar to that provided by mod_oc4j for Oracle HTTP Server. In Releases 2 (9.0.2) and 2 (9.0.3), Oracle Application Server Proxy Plug-in provided third party listener support. However, the proxy plug-in provides reverse proxy functionality where requests must pass through both the third party listener and Oracle HTTP Server before reaching OC4J. For efficiency or administrative reasons, you may choose to not run Oracle HTTP Server in addition to the third party listener.

OC4J Plug-in is a shared library that can be loaded into IIS, or Sun ONE HTTP listener. It provides functionality to route requests directly from a third party listener to OC4J in the same manner mod_oc4j routes requests from Oracle HTTP Server to OC4J. Thus, requests for OC4J can be directly routed from IIS or Sun ONE to one or more OC4J JVMs using the AJP or AJP over SSL protocol.

Note:

Proxy Plug-in and SSO Plug-in are certified to work with the entire Oracle Application Server stack, such as Oracle Application Server Forms Services, Oracle Application Server Reports Services, and Oracle Application Server Wireless. However, OC4J Plug-in is only certified to run customer applications. For example, you cannot route requests from Sun ONE using OC4J Plug-in to an OC4J container where Oracle Application Server Forms Services is running.

See Also:

Figure C-1 illustrates how the OC4J Plug-in routes requests directly from a third party listener to OC4J.

Figure C-1 OC4J Plug-in for IIS and Sun ONE

Text description of the illustration opii.gif

Downloading and Installing OC4J Plug-in

The plug-in is distributed on the OracleAS Repository Creation Assistant/Utilities CD, which is included in your Oracle Application Server CD Pack.

The plug-in consists of a single shared library for either IIS or Sun ONE. The file is called opii.dll for IIS, and opii.so for Sun ONE.

Configuring OC4J Plug-in on Sun ONE

Place the opii.so file in a directory such as /sunone/opii.so, where it is readable by the Sun ONE listener. The following examples assume that Sun ONE is installed in a directory called /sunone, and that the instance being configured exists under /sunone/https-mymachine.

Add the following lines at the end of /sunone/https-mymachine/magnus.conf:
```
Init fn="opii_init" log_file="/sunone/https-mymachine/logs/opii.log"
  log_level=error server_defs="/sunone/https-machine/config/opii.conf"
Init fn="opii_child_init" LateInit=yes
```
where, log_file points to a file where OC4J Plug-in messages will be logged and server_defs points to an OC4J Plug-in configuration file.

See Also:
"OC4J Plug-in Configuration File"
Make the following modifications to /sunone/https-mymachine/obj.conf:
1. Add the following line before any ObjectType line:
```
ObjectType fn=opii_objecttype
```
2. Add a Service line, such as:
```
Service Type="oracle/opii" fn="opii_service" UserOutPutStreamSize = 8192
```
If you want to enable the OC4J status page, which is equivalent to the URL /oc4j-service in mod_oc4j for Oracle HTTP Server, then make the following two changes to obj.conf:
1. Add the following line at top of obj.conf:
```
NameTrans fn=assign-name from="/oc4j-service" name="opii-status"
```
2. Add the following section at the end of obj.conf:
```
<Object name="opii-status">
```
```
      Service fn="opii_status_service" UseOutputStreamSize=8192
```
```
</Object>
```

Configuring OC4J Plug-in for IIS

Perform the following steps to configure OC4J Plug-in for IIS:

Edit your registry to create a new registry key named HKEY_LOCAL_MACHINE\SOFTWARE\Oracle\OPII
Specify the exact location of your configuration file with the name server_defs, and a value pointing to the location of your configuration file, for example d:\opii\opii.conf.

See Also:
"OC4J Plug-in Configuration File"
(Optional) Specify a log_file and log_level:
1. Add a string value with the name log_file, and the desired location of the log file, for example, d:\opii\plugin.log.
2. Add a string value with the name log_level, and a value for the desired log level. Valid values are debug, inform, error, and emerg.
3. If you want to enable the OC4J Plug-in status page, a page equivalent to mod_oc4j /oc4j-service URL, add a string value with the name status_uri and a value like /oc4j-service.
Using the IIS management console, add a new virtual directory to your IIS Web site with the same physical path as that of opii.dll. Name the directory opii and give it execute access.
Using the IIS management console, add opii.dll as a filter in your IIS Web site. The name of the filter should be opii and its executable must point to the directory contain opii.dll, for example, d:\opii\opii.dll.

Restart IIS (stop and then start the IIS server), ensuring that the filter is marked with a green arrow pointing up.

Note:

To restart IIS, you must stop all of the IIS services through the control panel, or restart the computer. This is the only way to ensure that the .dll is reloaded. Restarting IIS through the management console is not sufficient.

Integrating Generic Apache with Oracle Application Server

In Oracle Application Server, 10g (9.0.4), you can integrate generic Apache with Oracle Application Server. In doing so, you can route requests from generic Apache to OC4J in the same manner as routing requests using Oracle HTTP Server and mod_oc4j.

Using Oracle Notification Service (ONS), the communication method utilized between mod_oc4j and OC4J, you can load mod_oc4j into a generic Apache instance and use it in a static routing configuration without requiring any other Oracle infrastructure. In combination with mod_onsint and ONS, mod_oc4j can utilize the same dynamic configuration and failover options that are available when using Oracle HTTP Server.

See Also:

"mod_onsint"

This section discusses the following topics:

Integration Requirements

mod_oc4j and mod_onsint require the following open source software packages to be included in generic Apache builds that will be integrated with Oracle Application Server:

Enhanced API (EAPI) provided as part of mod_ssl. EAPI provides a context mechanism that is used extensively by mod_onsint and mod_oc4j to share information and function callbacks between modules without introducing link time dependencies. EAPI is provided by configuring Apache with mod_ssl.

Note:
mod_ssl does not need to be loaded at runtime as it is the integration of EAPI provided by mod_ssl that is important.

See Also:
http://www.modssl.org
(UNIX only) mm shared memory library. The mm library is used on UNIX platforms to share routing information between all of the child processes that make up an Apache instance on UNIX. This library is not necessary on Windows platforms since the Apache architecture on Windows uses a single multi-threaded process instead of many single-threaded processes.

See Also:
http://www.ossp.org/pkg/lib/mm/

Note:
mod_oc4j is supported in Apache versions 1.3.x only. It is not supported in Apache 2.0.x versions.

Generic Apache Files

Four libraries need to be accessible by the generic Apache instance that is going to be integrated with Oracle Application Server. If mod_oc4j is used in a static configuration and mod_onsint is not used, then you need only two libraries.

On UNIX, the four files and their locations within an ORACLE_HOME are:

$ORACLE_HOME/Apache/Apache/libexec/mod_oc4j.so
$ORACLE_HOME/Apache/Apache/libexec/mod_onsint.so
$ORACLE_HOME/opmn/lib/libons.so
$ORACLE_HOME/lib/libdms2.so

On Windows, the four files and their locations within an ORACLE_HOME are:

%ORACLE_HOME%\Apache\Apache\modules\ApacheModuleOc4j.dll
%ORACLE_HOME%\Apache\Apache\modules\ApacheModuleOnsint.dll
%ORACLE_HOME%\opmn\bin\onsclient.dll
%ORACLE_HOME%\bin\yod.dll

It is easiest if the binaries for the two modules are copied into the same location as the other modules in the generic Apache installation (libexec on UNIX, and modules on Windows), although this is not a requirement. Full paths can be used if you want to place the binaries elsewhere. The dms and ons libraries do not need to be in any specific location, but they must be in the your LD_LIBRARY_PATH on UNIX, and the PATH on Windows. On UNIX, this is most easily accomplished by editing the apachectl script used to start the generic Apache instance to set the LD_LIBRARY_PATH appropriately. On Windows, this is most easily accomplished by placing the appropriate directory into the System environment variable PATH. However, if more than one generic Apache instance is running on the same machine, then some other mechanism might be needed.

Setting Up a Static Configuration with mod_oc4j

A simple configuration can be constructed using generic Apache and only mod_oc4j. This configuration is very similar to the functionality provided by mod_jserv.

See Also:

"mod_jserv"

In this configuration, the host and port of all OC4J instances must be statically configured. There is no automatic registration of new JVMs, nor are failed JVMs ever removed from the routing table used by mod_oc4j. The advantage of this configuration is its simplicity, including the fact that it does not require the availability of other Oracle Application Server infrastructure components, such as ONS. Following is an example of such a configuration. This configuration loads mod_oc4j and provides routing of all requests starting with /j2ee/ to two different JVMs, both located on the same machine, one at port 3001, and the other at port 3002:

LoadModule oc4j_module libexec/mod_oc4j.so
Oc4jMount /j2ee/* ajp13://localhost:3001,ajp13://localhost:3002

On Windows, change the line used to load mod_oc4j to the following:

LoadModule oc4j_module modules/ApacheOc4jModule.dll

On UNIX, this implies that the mod_oc4j.so file will be copied into the libexec directory within the Apache installation. On Windows, it means that the ApacheOc4jModule.dll file will be copied to the modules directory within the Apache installation.

Setting Up a Dynamic Configuration with mod_oc4j and mod_onsint

In order to provide full mod_oc4j functionality including dynamic detection of new JVMs and Oracle Application Server installations, mod_oc4j must be combined with mod_onsint.

In order to utilize mod_onsint and mod_oc4j, ORACLE_HOME must be set to point to an Oracle Application Server instance where OPMN is running. On UNIX, this can be accomplished by adding the setting of ORACLE_HOME to the apachectl script used to start the generic Apache instance. On Windows, this is most easily accomplished by setting ORACLE_HOME as a System environment variable.

The following configuration shows how to load the modules and mount /j2ee to the OC4J instance, myinstance, running within the Oracle Application Server cluster, mycluster.

LoadModule oc4j_module libexec/mod_oc4j.so
LoadModule onsint_module libexec/mod_onsint.so
Oc4jMount /j2ee/* cluster://mycluster:myinstance

Any allowable Oc4jMount syntax available from within Oracle HTTP Server is available when used with generic Apache. This configuration supports all of the same routing and availability features that mod_oc4j offers when running within Oracle HTTP Server, including dynamic discovery of new OC4J processes and instances as they are added and failover of both stateless and session based requests.

Integrating with Oracle Process Manager and Notification Server

Oracle Process Manager and Notification Server (OPMN) can be configured to provide process management, such as starting, stopping, and restart capability for a generic Apache installation. To do this, the Apache instance must have mod_onsint configured. It should have the standard Apache directory layout, that is, the directory structure created by doing a standard Apache 1.3 installation. To configure OPMN to manage this Apache instance, the following changes must be made to opmn.xml:

In the module section add the GENERIC_APACHE module-id to the configuration for libopmnohs, such as:

<module path="$ORACLE_HOME/opmn/lib/libopmnohs"> 
  <module-id id="OHS"/> 
  <module-id id="GENERIC_APACHE"/> 
</module>

In the HTTP_Server section, you must set the module to GENERIC_APACHE and set an apache-home, such as:

</ias-component>
  <ias-component id="HTTP_Server"> 
    <process-type id="HTTP_Server" module-id="GENERIC_APACHE"> 
      <module-data> 
        <category id="start-parameters"> 
          <data id="apache-home" value="/private/my/path/to/APACHE"/> 
        </category> 
      </module-data> 
    <process-set id="HTTP_Server" numprocs="1"/> 
  </process-type> 
</ias-component>

You can configure either an Oracle HTTP Server instance or a generic Apache instance into any opmn.xml. Configuring both in the same opmn.xml is currently not supported.

See Also:

"opmn.xml"

OC4J Plug-in Configuration File

When you set up the OC4J Plug-in in the third party listener, the configuration file points at a server_defs file, or the OC4J Plug-in configuration file. This file defines the OC4J instances that the OC4J Plug-in communicates with. It has the same syntax as the mod_oc4j file for Oracle HTTP Server. For example, a configuration file that contains only the following line

Oc4jMount /j2ee/* ajp13://localhost:3000

routes any requests to URLs that begin with/j2ee/ to the OC4J instance that has an AJP listener on the localhost interface on port 3000.

All of the Oc4j* directives defined for mod_oc4j also work for OC4J Plug-in. In additional to these directives, the OC4J Plug-in-specific directives Oc4jOracleHome can be used in place of setting the ORACLE_HOME directive in the environment for the third party listener. An ORACLE_HOME value is required if you want to use the dynamic functionality of the OC4J Plug-in.

The dynamic routing functionality of the OC4J Plug-in provides the same Oc4jMount syntax as mod_oc4j for routing to OC4J instances that are managed by OPMN. Accordingly, you can mount OC4J instances or clusters instead of just pointing at the host and port of a single JVM. In order to accomplish this, the OC4J Plug-in must be able to communicate with an ONS daemon on the same machine. If Oracle Application Server is installed on the same machine as the OC4J Plug-in, then this can be accomplished simply by setting either ORACLE_HOME in the environment, or setting the Oc4jOracleHome directive to point to the location of the ORACLE_HOME, and ensuring that the third party listener is running as the same user as Oracle Application Server, or root on UNIX.

See Also:

"Running Oracle HTTP Server as Root"

If Oracle Application Server is not installed on the same machine, then the standalone ONS daemon must be installed. OC4J Plug-in supports all the mod_oc4j functionality, including AJP over SSL and use of port tunneling.

See Also:

"Understanding Port Tunneling"