Oracle9iAS Web Cache Release Notes Release 2 (9.0.2) for Windows Part Number A97397-01 |
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May 2002
Part No. A97397-01
This document summarizes the differences between Oracle9iAS Web Cache and its documented functionality.
This section describes general issues and their workarounds for Oracle9iAS Web Cache. It contains the following sections:
Oracle9iAS Web Cache uses 2 KB for the access log buffer size and the following for cached documents:
To change the default value, add the DOCHEADERBUFFERSIZE
attribute with the new default size as its value to the <CACHE>
element in the internal.xml
file. For example:
<CACHE DOCHEADERBUFFERSIZE="20480"
.../>
To change the default value, add the MAXRESPONSEHEADERSIZE
attribute with the new default size as its value to the <MISCELLANEOUS>
element in the internal.xml
file. For example:
<MISCELLANEOUS MAXRESPONSEHEADERSIZE="8192" ... />
To change the default value, add the DOCBUFFERSIZE
attribute with the new default size as its value to the <CACHE>
element in the internal.xml
file. For example:
<CACHE DOCBUFFERSIZE="65536"... />
If the HTTP response body is less than 4 KB, then Oracle9iAS Web Cache uses a 4 KB buffer size.
The internal.xml
file is located in the ORACLE_HOME
\webcache
directory on Windows.
Oracle9iAS Web Cache Manager does not enforce the same level of consistency checking upon receiving configuration input that Oracle9iAS Web Cache does upon starting up. Therefore, there may be instances where configuration changes are accepted by the Oracle9iAS Web Cache Manager, but Oracle9iAS Web Cache does not start up with the resulting configuration.
This is especially a problem when the admin
server process is shut down (with the webcachectl stop
or webcachectl stopadm
command) after applying invalid configuration changes. In that case, the admin
server process will not be able to start up, and the Oracle9iAS Web Cache Manager will become inaccessible.
To remedy this problem:
webcache.xml
file to Oracle Support Services to troubleshoot the invalid configuration entry. The webcache.xml
file is located in the ORACLE_HOME
\webcache
directory on Windows.
webcachectl reset
command to restore to the previous version of the configuration. webcachectl
is located in the ORACLE_HOME
\bin
on Windows.
Oracle Application Server, when used specifically with the Oracle Web Listener, strictly enforces virtual-host checking using the Host
request header, that is sent by almost all browsers. The Host
header contains the string "hostname:port
" where hostname
and port
are as entered in the location bar of the browser, even if the hostname
in the location bar is an IP address. If the Oracle Web Listener receives a Host
header that does not match an entry in the Host Name
and Port
columns of the Network
section of the configuration (corresponding to the [Multiport]
section in the sv*.cfg
configuration file for the listener), it returns an HTTP error code 400 indicating that the request did not specify a valid virtual host.
This limitation applies to the following deployments:
Network
section. The port number in the Host
header does not matter.
To make an Oracle Web Listener recognize and accept a Host
header, a corresponding entry must be added to the Network
section for that listener. When you add an entry with host name h1 and port p1
, h1
is only used to match incoming Host
headers and does not otherwise effect the operation of the listener. h1 does not need to be a DNS host name of the computer. However, p1
is used as a port that the Oracle Web Listener tries to listen on. Hence there should be no other process on the computer listening on port p1
.
Oracle9iAS Web Cache does not change the Host header that it receives as part of a request when relaying that request to the application Web server.
If you set up Oracle9iAS Web Cache to listen on port 1100 on a computer with DNS host name m1
and the Application Web Server is on computer m2
on port 80, and you use a browser to access http://m1:1100/
, the Host
header received by Oracle9iAS Web Cache is "Host: m1:1100
". This is exactly the Host
header that will be received by the application Web server.
If you are using Oracle Application Server with the Oracle Web Listener as your application Web server, this means that the Host
header sent to Oracle9iAS Web Cache must be recognized by the Oracle Web Listener, that is, there must be a corresponding entry in the Network
section.
If you are using Oracle9iAS Web Cache's host name and port directly in your browser, and if Oracle9iAS Web Cache and the Oracle Web Listener are on the same computer, the Oracle Web Listener will need to accept Oracle9iAS Web Cache's host name and port number in the Host
header, and for that to occur Oracle9iAS Web Cache's port number needs to be in the Network
section of the Listener's configuration. This would mean that both Oracle9iAS Web Cache and the Oracle Web Listener will try to listen on that port, which is not possible. See Section 1.3.2, "Entries for Network".
When you are using your browser to connect directly to Oracle9iAS Web Cache, ensure that Oracle9iAS Web Cache and the Oracle Web Listener are not on the same computer.
To deploy Oracle9iAS Web Cache and the Oracle Web Listener on the same computer, there has to be a port-translating switch between the browser and Oracle9iAS Web Cache that translates the port number to which the browser connects to Oracle9iAS Web Cache's listening port.
For example, assume that Oracle9iAS Web Cache is listening on port 7777 on computer m1.aaa.com
, and Oracle Web Listener is the application Web server listening on port 80 on the same computer m1.aaa.com
. In this example, the user enters http://www.aaa.com/
in the browser. The browser will attempt to connect to port 80 on www.aaa.com
. www.aaa.com
should be resolved through DNS to the switch, which should redirect requests for www.aaa.com
on port 80 to computer m1 on port 1100. Note that the Host header will be: "Host: www.aaa.com:80
". Oracle9iAS Web Cache will forward requests as needed to computer m1 port 80, that is, the Oracle Web Listener. For the Oracle Web Listener to accept this Host
header, you will need to have added an entry to Network
containing host name www.aaa.com
and port 80. See Section 1.3.2, "Entries for Network" for how this can done on computer m1
.
If you want Oracle9iAS Web Cache to handle a large number of concurrent HTTP requests, you may need to tune TCP/IP settings for your operating system, such as the maximum TCP/IP connection queue length.
In particular, if you run stress tests against Oracle9iAS Web Cache and continuously open more TCP/IP connections from one client computer to Oracle9iAS Web Cache, you may experience periodic oscillation of throughput. This is usually caused by the TCP/IP TIMED_WAIT
state of the operation system. In real world deployments, this is not an issue since it is unlikely that a single client will generate a huge number of connections. You can adjust the setting of the TIMED_WAIT
state by modifying the value of the TcpTimedWaitDelay
parameter in the registry at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
.
In case of denial of service attack, availability problems usually arise in the network layer in your operating system. For example, if one client generates large number of connections, TCP/IP connection problems generally arise in your operating system.
This section describes configuration issues and their workarounds for Oracle9iAS Web Cache. It contains the following sections:
To start initial Oracle9iAS Web Cache configuration:
From the command line, enter webcachectl start
.
http://
web_cache_hostname
:4000/
administrator
.
Oracle9iAS Web Cache Administration and Deployment Guide (available at
See Also:
http://otn.oracle.com/products/ias/web_cache/
) for complete configuration coverage
Oracle9iAS Web Cache uses two configuration files: webcache.xml
and internal.xml
. The Oracle9iAS Web Cache Manager writes its configuration information to the webcache.xml
file. Oracle9iAS Web Cache uses internal.xml
file. These files are located in the ORACLE_HOME
\webcache
directory on Windows. Do not edit these configuration files manually, except in the cases described in these Release Notes, or when directed to do so by Oracle Support Services. Improper editing of these configuration files may cause problems in Oracle9iAS Web Cache.
In past releases, the following attributes required manual modification of the internal.xml
file:
KEEPALIVE_TIMEOUT
attribute specifies the time, in seconds, for Oracle9iAS Web Cache to keep a connection open to the browser after it has returned a response.
OSRECV_TIMEOUT
attribute specifies the time, in seconds, for the origin server to generate a response to Oracle9iAS Web Cache.
In this release of Oracle9iAS Web Cache, these attributes have been merged into the Oracle9iAS Web Cache Manager (webcache.xml
). During migration, these modifications are not preserved. If you modified these attributes, you have two choices. You can:
internal.xml
, and copy the changes to the appropriate place in webcache.xml
.
If you are upgrading an existing Oracle9iAS Web Cache installation, the passwords for administration and invalidation are reset. The user name and password for administration is administrator
/administrator
and the user name and password for invalidation is invalidator
/invalidator
. You can change both passwords in the Security page (General Configuration > Security) of Oracle9iAS Web Cache Manager.
By default, Oracle9iAS Web Cache is configured to use the following default TCP ports:
If these ports are in use, then the installation procedure attempts to assign other port numbers from a range of possible port numbers.
The Oracle HTTP Server is configured to use the following default ports:
At the end of installation, Oracle9iAS Web Cache will attempt to start. If there are port conflicts, then Oracle9iAS Web Cache may fail to start.
If the definition of Oracle home in the webcache.xml
configuration file is different than the definition of Oracle home in your environment, Oracle9iAS Web Cache may fail to start.
For example on Windows, if the Oracle home is configuration as C:\home\oracle_home_ias
during the installation, then that configuration is written to the ORACLEHOME
attribute in the webcache.xml
file. However, if the registry specifies ORACLE_HOME
parameter as C:\oracle\oracle_home_ias
and you invoke the webcachectl start
command to start Oracle9iAS Web Cache, then Oracle9iAS Web Cache will fail to start. In this case, you may see a message similar to the following:
The description for Event ID ( 1 ) in Source ( Oracle9iAS-Web-Cache ) cannot be found.The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer.The following information is part of the event: Cannot open log files because NULL socket indicates problem.
You can remedy this situation by modifying the webcache.xml
file to match the registry settings located in HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE
so that the definitions are identical. (In the webcache.xml
file, you modify the ORACLEHOME
attribute of the CACHE NAME
element. In a cluster environment, there is more than one CACHE NAME
element, one for each cluster member. Be sure to modify the correct element.)
[Reference Bug: 2286732]
By default, peer requests between two members of a cache cluster are not logged in the access log. Only client requests to the cluster are logged. Peer request logging can be enabled for individual cache cluster members by adding the ACCESSLOGIGNOREPEERREQUEST
attribute to the MISCELLANEOUS
element in the internal.xml
configuration file.
The valid values for this attribute are:
The default value is YES
.
The following example shows the MISCELLANEOUS
element with peer-to-peer logging enabled:
<MISCELLANEOUS
ERRORLOGFILE="C:/my_oracle_home/webcache/logs/event_log"
ACCESSLOGIGNOREPEERREQUEST="NO"/>
[Reference Bug: 2364139]
The DAVOraWebCacheReadOnly
parameter, if specified in the httpd.conf
file, does not work in this release.
As a workaround, use the <LimitExcept>
directive in the httpd.conf
file, as described in the OraDAV module configuration chapter of the Oracle HTTP Server Administration Guide. Applying access restrictions to a location for all methods except GET
, HEAD
, and OPTIONS
requests will essentially achieve the goal of using the DAVOraWebCacheReadOnly
parameter. However, a caveat is that end users will always be restricted to GET
, HEAD
, and OPTIONS
requests, even when Oracle9iAS Web Cache is not being used.
[Reference Bug: 2312620]
This section describes issues specific to Windows. It contains the following sections:
Oracle9iAS Web Cache permits only five concurrent users on Windows NT Workstation. If you require more than five concurrent users, then consider using a Windows NT Server, such as Windows NT or Windows 2000.
XML parsing errors related to not being able to read the webcache.xml
file are displayed to the Event Viewer rather than to the screen in Windows NT.
[Reference Bug: 2277346]
This section describes security limitations for Oracle9iAS Web Cache. It contains the following sections:
Oracle9iAS Web Cache does not cache login requests or authenticated pages that use mod_sso
static directives. To ensure that responses for those pages using dynamic directives with mod_sso
are not cached, add the Surrogate-Control: no-store
response-header field to identify the page as non-cacheable.
When configured with HTTPS listening ports, Oracle9iAS Web Cache is unable to forward browser certificates to origin servers. If browsers are using certificate-based single sign-on authentication, do not use Oracle9iAS Web Cache. This restriction will be lifted in a future release of Oracle9iAS Web Cache.
If a wallet contains a user certificate as a trustpoint for an origin server, then a core dump will occur when the user connects to the origin server. Oracle Corporation recommends not adding user certificates to trustpoints in the Oracle wallet but instead install the certificate authority (CA) signers' certificate as a trustpoint.
Oracle Corporation plans to resolve this issue in the next release.
[Reference Bugs: 2295542 and 2295884]
When using the Oracle9iAS Web Cache Manager online help, refer to the Oracle9iAS Web Cache Administrator's Guide for updated information on the following topics:
Oracle is a registered trademark, and Oracle9i is a trademark or registered trademark of Oracle Corporation. Other names may be trademarks of their respective owners.
Copyright © 2002 Oracle Corporation.
All Rights Reserved.
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