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Introduction to Oracle9i Application Server

This chapter provides a general discussion of the Oracle9i Application Server (Oracle9iAS) characteristics in comparison to those of Oracle Application Server. It includes a mapping of Oracle Application Server components to their equivalent functionality in Oracle9iAS. The topics include:

• What is Oracle9i Application Server?

• Oracle Application Server Component Migration Options

• Enterprise Services Migration

What is Oracle9i Application Server?

Oracle9iAS provides full support for the Java 2 Enterprise Platform (J2EE), XML, and emerging Web services standards. With Oracle9iAS you can simplify information access for your customers and trading partners by delivering enterprise portals, which can be customized and accessed from a network browser or wireless devices. It allows you to redefine your business processes, and integrate your applications and data sources with those from your customers or partners. You can deliver tailored customer experiences via real-time personalization, and assess and correlate Web site traffic patterns using Oracle9iAS integrated business intelligence services.

You can also implement a centralized management, security, and directory framework to manage and monitor all of your distributed systems and diverse user communities. Oracle9iAS allows you to save on Web site infrastructure by deploying your fast, scalable Internet applications through built-in Web caching, load balancing and clustering capabilities.

See Also: Oracle9i Application Server Concepts in Oracle9iAS documentation library for additional information on Oracle9iAS

Before proceeding to migration, you must have successfully deployed the Oracle9iAS product and have worked with the examples provided in respective sections of Oracle9i Application Server Concepts and other related documentation.

Oracle Application Server Component Migration Options

Table 1-1 presents Oracle Application Server components and their corresponding functionality in Oracle9iAS. During the migration process, you must migrate these Oracle Application Server components to their closest corresponding components in Oracle9iAS. Please refer to the reference chapters presented in Table 1-1 for detailed discussions on specific components.

Table 1-1 Comparison of Application Components

Oracle Application Server Component	Closest Oracle9i Application Server Equivalent Component	Reference
JWeb application	Oracle9iAS Container for J2EE (OC4J) application	Chapter 2
JServlet application	OC4J application	Chapter 2
LiveHTML application	Apache SSI and JavaServer Page (JSP) applications	Chapter 3
Perl application	mod_perl application	Chapter 3
CWeb application	Custom Apache Modules, Common Gateway Interface (CGI), FastCGI, Java Naming and Directory Interface (JDNI), and PL/SQL Callouts	Chapter 3
PL/SQL application	mod_plsql application	Chapter 3
ECO/Java application	OC4J application	Chapter 4
EJB application	OC4J application	Chapter 4
JCORBA application	OC4J application	Chapter 4

Enterprise Services Migration

This section discusses enterprise services and characteristics of a Web site of concern to administrators and developers. It describes scalability, availability, fault tolerance, load balancing, administration, security, and the third-party Web server support in Oracle Application Server. It also describes whether migrating your Web site from Oracle Application Server to Oracle9iAS affects these characteristics.

Overview

Oracle Application Server consists of three layers, the HTTP listener layer, the server layer, and the applications layer. The HTTP listener layer consists of listeners, the adapter interface, and the dispatchers. The server layer provides a common set of components for managing applications. These components include load balancing, logging, automatic failure recovery, security, directory, and transaction management components. The application layer consists of applications, cartridges, and cartridge servers. When a request arrives, the dispatcher routes the request to the application server layer, and if a cartridge instance is available, the request will be serviced by that instance. Otherwise, a new instance will be created.

See Also: Oracle Application Server Overview and Glossary for details on Oracle Application Server.

In Oracle9iAS, Oracle HTTP Server handles load-balancing, routing servlet requests to OC4J through mod_oc4j, single sign-on authentication and security context propagation through mod_osso and SSL. OC4J consists of pure J2EE containers for running JSPs, Servlets, and Enterprise JavaBeans (EJBs), and provides J2EE container services. Both the Oracle HTTP Server and OC4J perform the same functions as three layers in Oracle Application Server.

Scalability

You can deploy Oracle Application Server in single or multiple-host environments. You can configure the Oracle HTTP Server and OC4J for single or clustered-host environments.

HTTP Server

In Oracle Application Server, each listener accommodates a maximum number of concurrent connections. This number varies based on operating system restrictions. To distribute the request load on a site, you can create multiple listeners, each listening on a different TCP port.

For Oracle9iAS on UNIX platforms, Oracle HTTP Server creates a pool of child processes ready to handle incoming client requests during the start-up. As the requests load increases, the server spawns new processes for subsequent requests. The initial and maximum size of the pool, and the minimum or maximum number of spare server processes is configured with the StartServers, MaxClients, MinSpareServers and MaxSpareServers directives, respectively.

For Oracle9iAS on Windows platforms, Oracle HTTP Server runs as a multi-threaded process. The number of simultaneous connections is configured with the ThreadsPerChild directive, which is analogous to both the StartServers and MaxClients directives for UNIX.

You can configure Oracle Application Server through the Node Manager. For Oracle9iAS, you can configure Oracle HTTP Server using Oracle Enterprise Management (OEM) graphical user interfaces (GUIs), or by manually editing the http.conf file.

See Also: Oracle HTTP Server Administration Guide and Oracle9i Application Server Administrator's Guide in the Oracle9iAS Documentation Library

OC4J Container

In Oracle Application Server, as the number of requests increases, the system creates new cartridge servers and new instances.

In Oracle9iAS Oracle HTTP Server, mod_oc4j receives requests from the server and routes them to the OC4J servlet container.

See Also: Oracle9iAS Containers for J2EE User's Guide in the Oracle9iAS Documentation Library

Refer to Chapter 2, "Migrating JWeb & JServlet Applications to OC4J" and Chapter 4, "Migrating EJB, ECO/Java and JCORBA Applications" for Migration of Oracle Application Server components to Oracle9iAS OC4J.

Availability and Fault Tolerance

When a component, such as a listener or a cartridge server fails, Oracle Application Server detects the failure and restarts the failed component, and restoring any preserved state information, when possible.

In Oracle HTTP Server, if there is more than one HTTP server host, or more than one OC4J host, when one of the hosts stops, the system will still function as long as one HTTP server and one OC4J are running, provided that J2EE components have been deployed against the cluster of OC4J instances. Any Oracle HTTP Server instance can route a request to any OC4J instance. Maintaining routing information in cookies eliminates single point of failure.

Load Balancing

Oracle Application Server allocates system resources and prioritizes requests based on two types of load balancing methods, priority-based method and minimum or maximum-based method.

In priority mode, the system manages and allocates resources automatically, based on the priority level you set for your applications and cartridges. The number of processes, threads, and instances is automatically determined based on the request load and priority level of the application and components.

In minimum or maximum mode, you set the number of instances, threads and client parameters for each cartridge at the cartridge level.

In Oracle HTTP Server, you can define the number of hosts and a logical set of these hosts in your configuration file. The system assigns incoming requests to OC4J instances.

Configuration of an instance determines whether the instance is part of a cluster. If an OC4J instance may be part of one cluster, all of its configured components are implicitly part of that cluster. A cluster can contain one or more instances. Each installation can have only one instance. There can be many installations on one host.

Administration

Oracle Application Server provides GUI tools and built-in support for administering and monitoring your site, listeners, and applications. The configuration data from the Oracle Application Server Manager tool is stored in various configuration files.

In Oracle HTTP Server, you can perform site administration and maintenance using OEM through GUIs, or through a set of configuration files. Table 1-2 presents configuration files for the Oracle Application Server HTTP listener and Oracle HTTP Server. The configuration files between two servers are significantly different.

See Also: Oracle9i Application Server Administrator's Guide and Oracle HTTP Server Administration Guide in the Oracle9iAS Documentation Library

Table 1-2 Configuration Files

Oracle Application Server HTTP Listener	Oracle9iAS Oracle HTTP Server
owl.cfg - list of registered listeners and their configuration settings	httpd.conf - primary (or sole) server-wide configuration file (You can choose to maintain file location and translation information in srm.conf, and security information in access.conf, or to maintain all directives in one file.)
site.app - site configuration file	(no equivalent)
svlistenerName.cfg - listener configuration file	(no equivalent)
wrb.app - process and cartridge configuration file	(no equivalent)
resources.ora - configuration file for the ORB	(no equivalent)

Security

You must convert the certificate from Oracle Application Server to Oracle9iAS.

Migrating Certificates

Oracle9iAS contains two migration tools, pconvert and ssl2ossl (Unix) or osslconvert (Windows). You can take the following two steps to migrate from the Oracle Application Server certificate to an Oracle9iAS certificate or wallet.

1. Convert the Oracle Application Server private key to an Oracle9iAS private key using the conversion tool, pconvert. The full path to the tool is:
   • (UNIX) ORACLE_HOME/Apache/Apache/bin/pconvert

   • (Windows) ORACLE_HOME\Apache\Apache\bin\pconvert.exe

   The syntax for running pconvert is:
   pconvert -s oas_private_key_file -d ias_private_key_file

   For example:
   prompt> pconvert -s privkey.der -d iaskey.pem

   Generate an Oracle9iAS wallet file using the Oracle Application Server certificate file and the ias_private_key file that you obtained from step 1 with the conversion tool, ssl2ossl or osslconvert. The full paths to the tools are:

   • (UNIX) ORACLE_HOME/Apache/Apache/bin/ssl2ossl

   • (Windows) ORACLE_HOME\Apache\Apache\bin\osslconvert.exe

   The syntax for running ssl2ossl on Unix is:

   ssl2ossl -cert oas_certificate_file

            -key ias_private_key_file

            -wltpass password_for_wallet

            -certpass password_for_oas_certificate_file

            -chain oas_certificate_chain_file

            -capath oas_certificate_authority_path

            -cafile oas_certificate_authority_file

            -wallet wallet_full_path

            -ssowallet yes/no

            -validate yes/no

   The syntax for running osslconvert on Windows is:

   osslconvert.exe -cert oas_certificate_file

                   -key ias_private_key_file

                   -wltpass password_for_wallet

                   -certpass password_for_oas_certificate_file

                   -chain oas_certificate_chain_file

                   -capath oas_certificate_authority_path

                   -cafile oas_certificate_authority_file

                   -wallet wallet_full_path

                   -ssowallet yes/no

                   -validate yes/no

   Table 1-3 summarizes the parameters and their associated requirements for the ssl2ossl or osslconvert conversion tool.

   Table 1-3 Summary of ssl2ossl or osslconvert Tool Parameters

   Parameter	Description	Requirement
   cert	your Oracle Application Server certificate file	required
   key	the ias_private_key_file you just obtained from step 1	required
   certpass	the password for the certificate	optional
   wltpass	the password for the wallet	optional
   chain	the Oracle Application Server certificate chain file	optional, but of chain, capath, or cafile, at least one of these parameters are required.
   capath	the Oracle Application Server certificate authority path	optional, but of chain, capath, or cafile, at least one of these parameters are required.
   cafile	the Oracle Application Server certificate authority file	optional, but of chain, capath, or cafile, at least one of these parameters are required.
   wallet	the full path of your wallet file	optional, but the default path is: ORACLE_HOME/Apache/Apache/conf/ssl.wlt/0
   ssowallet	with a value of either yes or no	optional, the default value is no
   validate	with a value of either yes or no - If yes, then the tool will not generate a wallet. - If no, the tool will generate a wallet.	optional, the default value is no.

   See Also: Oracle9i Application Server Security Guide in the Oracle9iAS Documentation Library for details on ssowallet and other security information

Third-Party Web Server Support

Oracle9iAS uses Oracle HTTP Server and Oracle Application Server uses HTTP Server as their Web listeners. However, many companies only use Microsoft Internet Information Services (IIS) or iPlanet as their corporate standard Web server.

Both Oracle Application Server and Oracle9iAS support the third-party Web servers, such as IIS and iPlanet.