Oracle Web Cache Component Characteristics Oracle Web Cache Process Monitoring Oracle Web Cache Startup and Shutdown Lifecycle

9-14 Oracle Fusion Middleware High Availability Guide Figure 9–3 shows an overview of how reverse proxy Web caching works. Oracle Web Cache has an IP address of 144.25.190.241 and the application Web server has an IP address of 144.25.190.242. The steps for browser interaction with Oracle Web Cache are as follows: 1. A browser sends a request to a Web site named www.company.com:80. This request in turn generates a request to Domain Name System DNS for the IP address of the Web site. 2. DNS returns the IP address of the load balancer for the site, that is, 144.25.190.240. 3. The browser sends the request for a Web page to the load balancer. In turn, the load balancer sends the request to Oracle Web Cache server 144.25.190.241. 4. If the requested content is in its cache, then Oracle Web Cache sends the content directly to the browser. This is called a cache hit. 5. If Oracle Web Cache does not have the requested content or the content is stale or invalid, it hands the request off to application Web server 144.25.190.242. This is called a cache miss. 6. The application Web server sends the content to Oracle Web Cache. 7. Oracle Web Cache sends the content to the client and stores a copy of the page in cache. A page stored in the cache is removed when it becomes invalid or outdated. Figure 9–3 Web Server Acceleration

9.3.1.1 Oracle Web Cache Component Characteristics

An Oracle Web Cache system component consists of two performance-oriented native processes, the cache server process and the admin server process. The cache server Application Web Server IP Address: 144.25.190.242 IP Address: 144.25.190.241 Oracle Web Cache Web Browser DNS Server 1 2 3 4 7 3 4 7 6 5 www.company.com:80 = 144.25.190.240 Load Balancer IP Address: 144.25.190.240 Configuring High Availability for Web Tier Components 9-15 process handles client requests serving content back to the client. The admin server process provides administration, configuration, and monitoring capabilities.

9.3.1.2 Oracle Web Cache Process Monitoring

You manage the cache and admin server processes withOracle Process Manager and Notification Server OPMN using the Fusion Middleware Control, Oracle Web Cache Manager, or the opmnctl utility, as described in the Oracle Fusion Middleware Administrators Guide for Oracle Web Cache.

9.3.1.3 Oracle Web Cache Startup and Shutdown Lifecycle

OPMN is responsible for the direct start, stop, restart, and monitoring of the cache server and admin server processes. Anytime the Oracle Web Cache configuration is statically modified, you must stop and restart Oracle Web Cache processes: The executable for the cache process is webcached, and the executable for the admin server process is webcachea. These executables reside in the following directories: UNIX ORACLE_HOMEwebachebin Windows ORACLE_HOME\bin When you stop Oracle Web Cache, all objects are cleared from the cache. In addition, all statistics are cleared. After you configure Oracle Web Cache, restart Oracle Web Cache. In addition, if you change the administrator password, restart the admin server. To restart Oracle Web Cache, use one of the following tools: ■ Use Fusion Middleware Control or the opmnctl command-line utility to restart the cache or admin server processes. ■ Use Oracle Web Cache Manager to restart the cache server process. You must restart both the cache server and admin server processes if you modified one of the following configuration settings: ■ Administration port properties ■ Trusted subnets ■ User and group ID information See the Oracle Fusion Middleware Administrators Guide for Oracle Web Cache for further information about starting and stopping Oracle Web Cache.

9.3.1.4 Oracle Web Cache Request Flow