Oracle9i Application Server Migrating from Oracle Application Server Release 2 (9.0.2) Part Number A95108-01 |
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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:
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.
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.
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.
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.
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.
In Oracle9iAS, Oracle HTTP Server handles load-balancing, routing servlet requests to OC4J through mod_oc4
j, 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.
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.
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.
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.
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.
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.
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.
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.
You must convert the certificate from Oracle Application Server to Oracle9iAS.
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.
pconvert
. The full path to the tool is:
pconvert
is:
pconvert -s oas_private_key_file -d ias_private_key_file
prompt> pconvert -s privkey.der -d iaskey.pem
ias_private_key
file that you obtained from step 1 with the conversion tool, ssl2ossl
or osslconvert
. The full paths to the tools are:
/Apache/Apache/bin/ssl2ossl
\Apache\Apache\bin\osslconvert.exe
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
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.
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.
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