2.2 Oracle Application Server Infrastructure

   

Shadow processes such as OPMN, DCM, and DMS, and configuration management tools such as Oracle Enterprise Manager, depend on a repository of configuration data. This repository is part of what is known as the Oracle Application Server Infrastructure . The OracleAS Infrastructure may consist of a simple file-based repository, or may be as complex as a database repository with an LDAP server.

2.2.1 OracleAS Infrastructure Components

The OracleAS Infrastructure is divided into two parts :


OracleAS Metadata Repository

Holds Oracle Application Server configuration information and other component information in a collection of schemas


Oracle Identity Management

Contains several subcomponents that work together to provide a seamless Single Sign-on facility

In addition, the Application Server Control tool and a group of shadow processes can be considered a part of the overall OracleAS Infrastructure.

2.2.1.1 OracleAS Metadata Repository

The OracleAS Metadata Repository is either operating system file-based or an Oracle database. The Java Edition of Oracle Application Server uses a file-based repository for DCM. The Portal/Wireless Edition and the BI/Forms Edition always use an OracleAS Metadata Repository in an Oracle database.

If Oracle Application Server is clustered (a topic described later in this chapter) and a file-based repository is being used, one of the clustered Oracle Application Server instances is designated as a central repository . This designation isn't necessary if a database repository is being used.

The OracleAS Infrastructure installation normally clones a new Oracle database to use as a database repository. During the installation process, it is possible to use an existing database instance for the OracleAS Metadata Repository, instead of creating a new one. However, specifying an existing instance has an impact on the use of the OracleAS Backup and Recovery Tool, described in Chapter 3.

2.2.1.2 Oracle Identity Management

Oracle Identity Management is a term used with Oracle Application Server 10 g that encompasses all the components used to support enterprise-style security in Oracle Application Server. All these components depend on the OracleAS Metadata Repository:


Oracle Internet Directory

Provides an LDAP directory for security principals (login information)


Oracle Directory Provisioning Integration Service

Allows the LDAP directory to import and replicate data between homogeneous or heterogeneous types of LDAP servers


Oracle Delegated Administration Services

Allows regional administrators and users to update directory information in the Oracle Internet Directory


OracleAS Single Sign-On

Supports the Single Sign-on capability for all Oracle Application Server applications


OracleAS Certificate Authority

Provides an infrastructure for creating and maintaining SSL certificates

Chapter 4 describes Oracle Application Server security in greater detail.

2.2.2 Application Server Control

The web-based Oracle Enterprise Manager 10 g tool used to monitor and control Oracle Application Server is known as Application Server Control . Application Server Control is actually an Oracle Application Server application that is installed with the OracleAS Infrastructure and with each individual application server home. The tool has a graphical user interface and is used to manage individual instances of Oracle Application Server. Other portions of the overall Oracle Enterprise Manager 10 g product handle management of the database and a grid of computing resources.

Oracle Enterprise Manager stores component configuration data in the Metadata Repository. Doing so simplifies the management for multiple Oracle Application Server instances when Oracle Application Server clusters are being used.

Chapter 3 describes Oracle Enterprise Manager 10 g , Application Server Control, and Grid Control, as well as other Oracle Application Server management tools, in more detail.

2.2.3 Shadow Processes

Oracle Application Server has many different components, and some deployment architectures may have more than one instance of any one of these components. To keep the burden of monitoring, managing, and coordinating the interaction between these components from being too overwhelming, Oracle Application Server includes three shadow processes, shown earlier in Figure 2-1:

  • Oracle Process Manager and Notification Server

  • Distributed Configuration Management

  • Dynamic Monitoring Service

These shadow processes also use the OracleAS Metadata Repository. DCM updates component configuration files so that they will match the values in the repository. OPMN uses the repository to identify what components should be started and monitored . DMS stores runtime statistics in the repository.

2.2.3.1 Oracle Process Manager and Notification Server

The Oracle Process Management and Notification Server monitors the health of the individual components in an Oracle Application Server architecture. OPMN monitors and manages all Oracle Application Server components, with the exception of the following:

  • The repository database, if used

  • The listener for the database

  • The Application Server Console

If a particular component becomes unavailable, OPMN automatically restarts it. OPMN also informs any dependent component that a component isn't available. For example, suppose that a request for a Java application comes into an Oracle HTTP Server. It is passed to the mod_oc4j module, which passes the request to an OC4J process. If the OC4J process goes down, OPMN lets the mod_oc4J process know that it should prevent any additional requests from being routed to the failed process. In this way, OPMN simplifies management while making the entire set of Oracle Application Server components highly available.

2.2.3.2 Distributed Configuration Management

For high availability and scalability, you can create clusters of Oracle Application Server components (Oracle HTTP Server and OC4J) and OracleAS Web Cache. The Distributed Configuration Management service coordinates configuration information across all members of a cluster.

DCM automatically replicates base configuration information to a new member of a cluster. It also propagates changes to any of this information to all members of a cluster. In addition to this base information, each cluster member also has some individual configuration parameters of its own, such as port numbers for the instance.

You can also use DCM to make a backup of your configuration files that can be used to restore these crucial files in the event of corruption.

DCM is invoked through the Application Server Control tool or via the dcmctl command-line tool.

2.2.3.3 Dynamic Monitoring Service

Oracle Application Server uses the Dynamic Monitoring Service to collect information about the performance of some of its components. DMS uses sensors to measure various types of durations or simply the occurrence of different types of events. DMS periodically collects the information from these sensors and compiles it into metrics. You can access these metrics using a variety of different tools. The most commonly used is dmstool , a command-line tool for presenting DMS metrics. The metrics may also be accessed in different portions of the Application Server Control tool.

DMS sensors are built into Oracle Application Server Containers for J2EE, so metrics are automatically provided for all applications that run in an OC4J container. You can add sensors to any application you deploy on Oracle Application Server through a DMS API, so the use of DMS is completely extensible. You can also turn off DMS to save the small amount of overhead incurred.

   


Oracle Application Server 10g Essentials
Oracle Application Server 10g Essentials
ISBN: 0596006217
EAN: 2147483647
Year: 2004
Pages: 120

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