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10g Release 2 (10.1.2) for Microsoft Windows (64-Bit) on Intel Itanium
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17 Oracle Application Server Web Cache

This chapter describes the issues associated with Oracle Application Server Web Cache (OracleAS Web Cache). It includes the following topic:

17.1 Configuration Issues and Workarounds

This section describes configuration issues and their workarounds for OracleAS Web Cache. It includes the following topic:

17.1.1 "Page Cannot be Displayed" Error During Login

You will receive a "Page Cannot be Displayed" error during SSL-enabled Single Sign-on login to an SSL-enabled midtier application when using Microsoft Internet Explorer version 5 or version 6. In this scenario, OracleAS Web Cache is a reverse-proxy for OracleAS Single Sign-On. Both OracleAS Infrastructure and OracleAS Web Cache Midtier are SSL enabled and using the same authentication certificate. Refreshing the browser displays the authenticated application page.

To work around this issue, do not use OracleAS Web Cache as a reverse proxy. Route all client requests directly to the midtier instance of Oracle HTTP Server and disable session in the ssl.conf file.

To fix the problem, apply Oracle Application Server 10g Release 2 (10.1.2) Patch Set 2 ( to your instance of Oracle Application Server 10g. Then apply the one-off fix for Bug 4700543 for version

17.1.2 "Authentication Required" Error When Monitoring the OracleAS Web Cache Invalidation Port

In the Oracle Application Server Enterprise Deployment Guide, section 8.3.7, "Completing the Configuration", provides the following URL for monitoring the invalidation port 9401:

When you use this URL, configure the load balancing router to send an HTTP request to the invalidation port instead of TCP ping, which is usually the default.

17.1.3 Configuring the Load Balancer with the Ping URL for the Invalidation Port

When configuring a load balancer to use OracleAS Web Cache, you specify the OracleAS Web Cache servers and the URL to ping each cache server to check the status of the cache. You specify the same ping URL as you configured for the auto-restart mechanism. The default ping URL is /_oracle_http_server_webcache_static_.html, but is configurable, as described in section "Task 3: Configure Auto-Restart Settings" of Chapter 8, "Setup and Configuration," of the Oracle Application Server Web Cache Administrator's Guide.

In addition to the auto-restart ping URL, some load balancers can route invalidation traffic. For these load balancers, you can configure with the ping URL to check the health of the invalidation port. The ping URL for invalidation is /x-oracle-cache-invalidate-ping. This URL is not configurable.

17.1.4 DNS Round Robin in Front of an OracleAS Web Cache Cluster

In a multi-node configuration featuring an OracleAS Web Cache cluster, a further OracleAS Web Cache can be used on the front end as a software load balancer. Front end refers to the OracleAS Web Cache instance having its IP address mapped to the virtual hostname of the whole system, and defined within the OracleAS Web Cache configuration itself.

Alternatively, DNS-based load balancing or a full hardware load balancer can be used to front the OracleAS Web Cache cluster. With a DNS-based solution, the virtual hostname of the system is stored in DNS only, and the DNS server flips between the IP addresses of the front-end OracleAS Web Cache cluster members.

There are limitations with both the OracleAS Web Cache and DNS load-balancing solutions, and a full hardware load balancer is recommended for production systems.

17.1.5 Patch Available for Configuring OracleAS Web Cache Solely as a Software Load Balancer or Reverse Proxy

In previous releases, you could configure OracleAS Web Cache solely as a software load balancer or reverse proxy in place of hardware load balancers.

By applying a patch to this release, you can now configure OracleAS Web Cache as software load balancer or reverse proxy even in front of an application using Edge Side Includes (ESI) or in front of another OracleAS Web Cache forming a cache hierarchy. A typical OracleAS Portal deployment, for example, has a built-in OracleAS Web Cache used for ESI assembly.

To use OracleAS Web Cache in this mode, download an Automated Release Update (ARU) for bug 4569559 from OracleMetalink:

See Also:

Section "OracleAS Web Cache Solely as a Software Load Balancer or Reverse Proxy" in Chapter 8, "Setup and Configuration," of the Oracle Application Server Web Cache Administrator's Guide

17.1.6 Reloading Issue with Cache Operations Success Message in OracleAS Web Cache Manager with Internet Explorer Browser

When you submit a successful operation in the Cache Operations page (Operations and then Cache Operations) in OracleAS Web Cache Manager, a Success message box appears. When you click OK to acknowledge the message, on versions of Internet Explorer running on Macintosh, the Success dialog box reloads the OracleAS Web Cache Manager interface into the message box itself.

17.2 Documentation Errata

This section describes documentation errata. It includes the following topics:

17.2.1 Running webcached with Root Privilege

In section "Running webcached with Root Privilege" in Chapter 8, "Setup and Configuration" of the Oracle Application Server Web Cache Administrator's Guide the following text is displayed:

"On UNIX, you must configure webcached to run with root privilege in the following cases:

  • There are more than 1,024 file descriptors being used for connections to OracleAS Web Cache."

The above text is then followed with a section with configuration steps titled, "Configuring Root Privilege for Privileged Ports and More than 1,024 File Descriptors".

The listed information and section about configuring more than 1,024 File Descriptors is incorrect. Specifically:

  • OracleAS Web Cache does not require root privilege to have more than 1,024 file descriptors

  • In the Oracle Application Server Installation Guide, the file descriptor (nofile) requirement for the non-root oracle user is 65536.

17.2.2 Additional Site Configuration

Both the Oracle Application Server Web Cache Administrator's Guide and online help for Application Server Control Console and OracleAS Web Cache Manager specify that when configuring sites, you specify site definitions, followed by creating ordered mappings of sites to origin servers.

Because OracleAS Web Cache resolves a request first to a site definition, and then to the first matching site-to-origin server mapping, the order in which you configure the site definitions is also important. The documentation and the online help do not specify that the site definitions themselves must be ordered.

For example, consider site definitions configured in this order:

Because is a superset of, OracleAS Web Cache will match requests for to site definition rather than In addition, OracleAS Web Cache will use the site-to-server mapping for

To avoid this problem, you would have to configure the site definitions in the following order: