URL rewrite tags
Resin 3.1

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Resin's <rewrite-dispatch> tag allows configuration for URL aliasing, rewriting, dispatching, and redirection.

<rewrite-real-path> configures an alias for files located on the filesystem.

<and>
child of when, unless

Contains one or more conditions and evaluates to true if all of the contained conditions evaluate to true, false if any of the contained conditions does not evaluate to true.

auth-type
child of when, unless

Evaluates to true if the authorization mechanism used in the request is the given value. The comparison is always case insensitive.

If the auth-type is not "none", or if the auth-type of the request is not "none", a Cache-Control header containing "private" is added to the response.

auth-typeBASIC, CLIENT-CERT, DIGEST, FORM, or NONErequired
send-varySend a Vary header containing "Cookie" as part of the responsetrue
cookie
child of when, unless

Evaluates to true if the value of a cookie with a given name matches a regular expression regexp, false if it does not or if the cookie does not exist.

The Vary header of the response is updated to include "Cookie", which indicates to the browser and any intervening proxy cache that the response varies based on the submitted value of cookies.

cookieName of the cookierequired
regexpThe regular expression to matchoptional
send-varySend a Vary header containing "Cookie" as part of the responsetrue
disable-at

Cron syntax for specifying a time or times that that the rule should be disabled. In conjunction, enable-at and disable-at provide a means for scheduling the enablement of a rule.

<dispatch>
child of rewrite-dispatch, match

If <dispatch> matches the current URL, the rest of the items in the enclosing rewrite-dispatch are not considered and the request passes immediately to normal servlet evaluation. <dispatch> is often used to specify URLs which should be handled normally before a more general pattern which modifies the URL.

For example, the following pattern uses <dispatch> to handle images and *.php files normally, but forward's all other requests to /index.php.

Mediawiki dispatch in resin-web.xml
<web-app xmlns="http://caucho.com/ns/resin">

 <rewrite-dispatch>
   <dispatch regexp="\.(php|gif|css|jpg|png)"/>
   <forward regexp="^" target="/index.php"/>
 </rewrite-dispatch>

</web-app>
disable-atA cron syntax time specification for triggering disablement of the rulenone
enable-atA cron syntax time specification for triggering enablement of the rulenone
enabledFalse to start with the rule initially disabledtrue
nameA name to use for registering a JMX mbean with type=RewriteRuledo not register an mbean
regexpA regexp that must match the URLoptional
whenA condition which must evaluate to trueoptional
unlessA condition which must not evaluate to trueoptional
enable-at

Cron syntax for specifying a time or times that that the rule should be enabled, see <disable-at/>.

enabled

Set's the initial state of the rule, default is true. In conjunction with name, an initial enabled value of "false" is valuable for rules which are to be turned on and turned off at runtime.

<forbidden>
child of rewrite-dispatch, match

<forbidden> sents a 403 forbidden message to the browser for a matching URL.

Forbidding a directory
<web-app xmlns="http://caucho.com/ns/resin">

 <rewrite-dispatch>
   <forbidden regexp="^/protected"/>
 </rewrite-dispatch>

</web-app>
disable-atA cron syntax time specification for triggering disablement of the rulenone
enable-atA cron syntax time specification for triggering enablement of the rulenone
enabledFalse to start with the rule initially disabledtrue
nameA name to use for registering a JMX mbean with type=RewriteRuledo not register an mbean
regexpA regexp that must match the URLoptional
whenA condition which must evaluate to trueoptional
unlessA condition which must not evaluate to trueoptional
<forward>
child of rewrite-dispatch, match

<forward> rewrites the current URL, forwarding it to the target using the servlet forward() call. Because <forward> is internal, it will have better performance than a <redirect> when the target URL is on the same server, the browser will not know that the underlying resource has moved.

Forwarding to a new URL
<web-app xmlns="http://caucho.com/ns/resin">

 <rewrite-dispatch>
   <forward regexp="^/old" target="/new"/>
 </rewrite-dispatch>

</web-app>
disable-atA cron syntax time specification for triggering disablement of the rulenone
enable-atA cron syntax time specification for triggering enablement of the rulenone
enabledFalse to start with the rule initially disabledtrue
nameA name to use for registering a JMX mbean with type=RewriteRuledo not register an mbean
regexpA regexp that must match the URLoptional
targetThe target of the the forewardrequired
whenA condition which must evaluate to trueoptional
unlessA condition which must not evaluate to trueoptional
header
child of when, unless

Evaluates to true if the value of a header with a given name matches a regular expression regexp, false if it does not or if the header does not exist.

The Vary header of the response is updated to include the header name which indicates to the browser and any intervening proxy cache that the response varies based on the submitted value of the header.

headerName of the headerrequired
regexpThe regular expression to matchoptional
send-varySend a Vary header containing the header name as part of the responsetrue
<gone>
child of rewrite-dispatch, match

<gone> sents a 410 gone response to the browser for a matching URL.

Hiding a directory
<web-app xmlns="http://caucho.com/ns/resin">

 <rewrite-dispatch>
   <gone regexp="^/protected"/>
 </rewrite-dispatch>

</web-app>
disable-atA cron syntax time specification for triggering disablement of the rulenone
enable-atA cron syntax time specification for triggering enablement of the rulenone
enabledFalse to start with the rule initially disabledtrue
nameA name to use for registering a JMX mbean with type=RewriteRuledo not register an mbean
regexpA regexp that must match the URLoptional
whenA condition which must evaluate to trueoptional
unlessA condition which must not evaluate to trueoptional
<import>
child of rewrite-dispatch, match

<import> loads rules from an external xml file.

Importing rules from an external file
<web-app xmlns="http://caucho.com/ns/resin"
         xmlns:resin="http://caucho.com/ns/resin/core">

  <rewrite-dispatch>
    <import path='/WEB-INF/rewrite-maintenance.xml' enabled="false"/>
    <import path='/WEB-INF/rewrite-rules.xml'/>
  </rewrite-dispatch>

</web-app>
An external file containing rules
<rewrite-dispatch xmlns="http://caucho.com/ns/resin"
                  xmlns:resin="http://caucho.com/ns/resin/core">

   <dispatch regexp="\.(css|gif|jpg|pdf|png)"/>

   <forward regexp=".*" target="/maintenance.html"/>

</rewrite-dispatch>

Changes to the external file are checked for at a frequency determined by dependency-check-interval or when the update() operation of the mbean is invoked. If an error occurs when loading the modified file, the contents of the old file are used until the errors are corrected or the server is restarted. The log file will contain details for the error, and the RedeployError property of the mbean wil contain a description of the error.

Each <import> registers an mbean of type RewriteImport, with a full a name like "resin:Host=default,WebApp=/,name=Foo,type=RewriteRule" and an interface of com.caucho.management.server.RewriteImportMXBean. It provides the update(), start() and stop() operations. The update() operations forces an immediate check for modifications to the external file.

disable-atA cron syntax time specification for triggering disablement of the rulenone
dependency-check-intervalThe frequency with which to check the external file for changesThe dependency-check-interval of the environment
enable-atA cron syntax time specification for triggering enablement of the rulenone
enabledFalse to start with the rule initially disabledtrue
nameA name to use for registering a JMX mbean with type=RewriteImportthe value of path
optionalIf false, do not require that the path existstrue
pathA path to an external xml filerequired
<load-balance>
child of rewrite-dispatch, match

<load-balance> forwards requests from a web-tier server to a cluster of app-tier servers for load-balancing. Load balancing provides scalability by splitting load among many application servers and increases reliability by avoiding servers which are upgrading or restarting.

In the following example, the web-tier load-balances all traffic to a cluster of backend application servers. Because the web-tier has a proxy cache, static pages and cached pages will be served directory from the web-tier.

<load-balance> requires Resin Professional.

Load balancing to an app-tier
<resin xmlns="http://caucho.com/ns/resin">

  <cluster id="app-tier">
    <server id="app-a" address="192.168.3.1">
    <server id="app-b" address="192.168.3.2">
    ...
  </cluster>

  <cluster id="web-tier">
    <server id="web-a" address="192.168.2.1">
      <http port="80"/>
    </server>

    <cache/>

    <host id="">
      <web-app id="/">

        <rewrite-dispatch>
          <load-balance regexp="" cluster="app-tier"/>
        </rewrite-dispatch>

      </web-app>
    </host>

</resin>
clusterThe cluster that gets the matching requestsrequired
disable-atA cron syntax time specification for triggering disablement of the rulenone
enable-atA cron syntax time specification for triggering enablement of the rulenone
enabledFalse to start with the rule initially disabledtrue
nameA name to use for registering a JMX mbean with type=RewriteRuledo not register an mbean
regexpA regexp that must match the URLoptional
sticky-sessionsWhether or not sessions should be stickytrue
strategyThe load balancing strategy, `round-robin' or `least-connection'least-connection
whenA condition which must evaluate to trueoptional
unlessA condition which must not evaluate to trueoptional
locale
child of when, unless

Evaluates to true if the value of the Locale matches a regular expression, false if it does not. The comparison is always case insensitive.

The Locale is a normalization of the value of the Accept-Language header. For example "fr" remains "fr" and "FR-CA" becomes "fr_CA". If the request does not include the Accept-Language header then the Locale is the default Locale for the server.

<web-app xmlns="http://caucho.com/ns/resin"
         xmlns:resin="http://caucho.com/ns/resin/core">

  <rewrite-dispatch>
    <forward regexp='^/' target='/fr/'>
      <when locale="^fr"/>
    </forward>

    <forward regexp='^/' target='/en/'/>
  </rewrite-dispatch>
</web-app>
localeRegular expression to matchrequired
send-varySend a Vary header containing "Accept-Language" as part of the responsetrue
local-port
child of when, unless

Evaluates to true if the value of the request's local port is the specified value, false if it does not. The local port is the port that Resin has bound to and has used to receive the request.

local-portThe local port to match.required
method
child of when, unless

Evaluates to true if the http method used in the request is the given value. The comparison is always case insensitive. Common methods include HEAD, GET, POST, DELETE, OPTIONS, PUT, and TRACE, although a method by any name may be used by a client.

methodThe method to match.required
<match>
child of rewrite-dispatch, match

<match> provides a way to group more specific rules based on the url. The contents of the <match> are any rule, and they are considered only if the regexp of the <match> is satsified and the match is enabled.

Judicious use of <match> will provide better performance in situations where there are many rules and some of them contain when or if conditions.

<match> also provides a convenient way to group a set of rules that can be enabled or disabled using an mbean. If the name attribute is specified for the <match> then an mbean with a name like resin:Host=default,WebApp=/,name=name,type=RewriteRule is registered and the start() and stop() operations are available.

The documentation for <rewrite-dispatch> provides a table of all rules. In addition to the rules that can be contained within <match>, the following configuration tags are available.

disable-atA cron syntax time specification for triggering disablement of the rulenone
enable-atA cron syntax time specification for triggering enablement of the rulenone
enabledFalse to start with the rule initially disabledtrue
nameA name to use for registering a JMX mbean with type=RewriteRuledo not register an mbean
regexpA regexp that must match the URLoptional
whenA condition which must evaluate to trueoptional
unlessA condition which must not evaluate to trueoptional
<moved-permanently>
child of rewrite-dispatch, match

<moved-permanently> sends a HTTP 301 moved permanently response to the browser, indicating that the resource has moved.

Forwarding to a new virtual host
<web-app xmlns="http://caucho.com/ns/resin">

  <rewrite-dispatch>
    <moved-permanently regexp="^/(foo)" target="http://$1.bar.com"/>
  </rewrite-dispatch>

</web-app>
disable-atA cron syntax time specification for triggering disablement of the rulenone
enable-atA cron syntax time specification for triggering enablement of the rulenone
enabledFalse to start with the rule initially disabledtrue
nameA name to use for registering a JMX mbean with type=RewriteRuledo not register an mbean
regexpA regexp that must match the URLoptional
whenA condition which must evaluate to trueoptional
unlessA condition which must not evaluate to trueoptional
name

A rule can be given a name, which causes a JMX mbean to be registered. The mbean has a name like "resin:Host=default,WebApp=/,name=Foo,type=RewriteRule" and an interface of com.caucho.management.server.RewriteRuleMXBean. It provides the start() and stop() operations.

<not>
child of when, unless

Contains one or more conditions and evaluates to true only if none of the contained conditions evaluate to true, false if any of the contained conditions evaluate to true.

<or>
child of when, unless

Contains one or more conditions and evaluates to true if any of the contained conditions evaluate to true, false only if all of the contained conditions evaluate to false.

<not-found>
child of rewrite-dispatch, match

<not-found> sents a 404 not found to the browser for a matching URL.

Hiding a directory
<web-app xmlns="http://caucho.com/ns/resin">

 <rewrite-dispatch>
   <not-found regexp="^/protected"/>
 </rewrite-dispatch>

</web-app>
disable-atA cron syntax time specification for triggering disablement of the rulenone
enable-atA cron syntax time specification for triggering enablement of the rulenone
enabledFalse to start with the rule initially disabledtrue
nameA name to use for registering a JMX mbean with type=RewriteRuledo not register an mbean
regexpA regexp that must match the URLoptional
whenA condition which must evaluate to trueoptional
unlessA condition which must not evaluate to trueoptional
query-param
child of when, unless

Evaluates to true if the value of a query parameter with a given name matches a regular expression regexp, false if it does not or if the parameter does not exist.

Form parameters submitted in the body of a POST are not available for the comparison performed by query-param.

query-paramName of the parameterrequired
regexpThe regular expression to matchoptional
<real-path>
child of rewrite-real-path

<real-path> maps a URL to a filesystem path inside a <rewrite-real-path tag.

The source path is a URL, the target path is a real filesystem path.

/images located outside of /var/www
<web-app xmlns="http://caucho.com/ns/resin">

  <rewrite-real-path>
    <real-path regexp="^/images" real-path="/usr/local/share/images"/>
  </rewrite-real-path>
<redirect>
child of rewrite-dispatch, match

<redirect> sends a HTTP 302 redirect response to the browser, indicating that the resource has moved.

Forwarding to a new virtual host
<web-app xmlns="http://caucho.com/ns/resin">

  <rewrite-dispatch>
    <redirect regexp="^/(foo)" target="http://$1.bar.com"/>
  </rewrite-dispatch>

</web-app>
disable-atA cron syntax time specification for triggering disablement of the rulenone
enable-atA cron syntax time specification for triggering enablement of the rulenone
enabledFalse to start with the rule initially disabledtrue
nameA name to use for registering a JMX mbean with type=RewriteRuledo not register an mbean
regexpA regexp that must match the URLoptional
whenA condition which must evaluate to trueoptional
unlessA condition which must not evaluate to trueoptional
remote-addr
child of when, unless

Evaluates to true if the remote address of the client matches the specified ip address.

A Cache-Control header containing "private" is added to the response.

Forbidding admin access to clients outside of the local network
<web-app xmlns="http://caucho.com/ns/resin"
         xmlns:resin="http://caucho.com/ns/resin/core">
  <rewrite-dispatch>
    <forbidden regexp='^/foo'>
      <unless remote-addr="192.168.2.1/24"/>
    </forbidden>

  </rewrite-dispatch>
</web-app>
remote-addrAn IP address, optionally followed by a / and a number of bits to match.required
remote-user
child of when, unless

Evaluates to true if the user is authenticated and has the specified name.

If there is a current user, a Cache-Control header containing "private" is added to the response.

remote-userA user name.required
send-varySend a Vary header containing "Cookie" as part of the responsetrue
<rewrite>
child of rewrite-dispatch, match

<rewrite> rewrites the current URL, continuing processing of the <rewrite-dispatch> tags. <rewrite> can be used as an intermediate rewriting stage for more complicated patterns.

<rewrite-real-path>
child of web-app

<rewrite-real-path> configures an alias for the getRealPath() call, i.e. an enhancement to the <path-mapping> tag.

The source path is a URL, the target path is a real filesystem path.

/images located outside of /var/www
<web-app xmlns="http://caucho.com/ns/resin">

  <rewrite-real-path>
    <real-path regexp="^/images" real-path="/usr/local/share/images"/>
  </rewrite-real-path>
<rewrite-dispatch>
child of server, host, web-app

<rewrite-dispatch> evaluates the child tags in order. The first matching tag dispatches the request. If no children match, the request uses the standard servlet handling.

The child tags rewrite and dispatch based on regexp patterns.

Mediawiki dispatch in resin-web.xml
<web-app xmlns="http://caucho.com/ns/resin">

 <rewrite-dispatch>
   <dispatch regexp="\.(php|gif|css|jpg|png)"/>
   <forward regexp="^" target="/index.php"/>
 </rewrite-dispatch>

</web-app>
<dispatch>Dispatch the request immediately and do not process any more rules
<forbidden>Send a 403 Forbidden response to browser and do not process any more rules
<forward>Rewrite the URL and internally forward the request without processing any more rules
<forbidden>Send a 410 Gone response to the browser and do not process any more rules
<import>Import rules from an external file
<load-balance>Forward requests to another instance or instances of Resin and do not process any more rules
<match>Group more specific rules
<moved-permanently>Send a 310 Moved Permanently response to the browser and do not process any more rules
<redirect>Send a 302 Moved response to the browser and do not process any more rules
<rewrite>Rewrite the current URL and continue processing rules
<set>Set a property of the request or response and continue processing rules
secure
child of when, unless

<secure> specifies a condition for the ssl status of the request. If secure is true, then the request must be using ssl for the rule to match. If secure is false, then the request must not be using ssl for the rule to match. If secure is not specified, the ssl status of the request is not considered when testing if the rule matches.

secure example
<web-app xmlns="http://caucho.com/ns/resin">
  <rewrite-dispatch>
    <redirect regexp='^/foo' target='/secure'>
      <when secure='true'/>
    </redirect>

    <redirect regexp='^/foo' target='/insecure'>
      <when secure='false'/>
    </redirect>

    <redirect regexp='^/bar' target='/public'/>
  </rewrite-dispatch>
</web-app>
http://localhost:8080/foo/index.html
  --> redirect to /insecure/index.html

https://localhost:8080/foo/index.html
  --> redirect to /secure/index.html

http://localhost:8080/bar/index.html
  --> redirect to /public/index.html

https://localhost:8080/bar/index.html
  --> redirect to /public/index.html
server-name
child of when, unless

Evaluates to true if the value of the request's server name matches the specified regexp, false if it does not. The comparison is always case insensitive. The server name is the name that the client has used to connect to the server and may not be the name of the actual server that is hosting Resin.

Most potential problems that can be solved by server-name are more efficiently solved using virtual hosts and the host-alias tag.

server-nameA regular expression to match.required
server-port
child of when, unless

Evaluates to true if the value of the request's server port is the specified value, false if it does not. The server port is the port that the client has used to connect to the server and may not be the actual port that Resin is bound to.

server-portThe server port to match.required
<set>
child of rewrite-dispatch, match

<set> is used to set properties of the request or response before continuing on to the next rule. The properties are maintained after the rewriting is complete, for example a request that becomes secure because of <set> will continue to be regarded as secure when the request eventually reaches a jsp or servlet.

Making the request secure in response to a header from a hardware load balancer
<web-app xmlns="http://caucho.com/ns/resin">

  <rewrite-dispatch>
    <set request-secure="true">
      <when header="X-SSL-cipher"/>
    </set>

    <forward regexp="^/checkout" target="https://hogwarts.com/checkout">
      <when secure="false"/>
    </forward>

  </rewrite-dispatch>

</web-app>
disable-atA cron syntax time specification for triggering disablement of the rulenone
enable-atA cron syntax time specification for triggering enablement of the rulenone
enabledFalse to start with the rule initially disabledtrue
nameA name to use for registering a JMX mbean with type=RewriteRuledo not register an mbean
regexpA regexp that must match the URLoptional
request-character-encodingSets the character encoding of the request, used for parsing POST data, request.setCharacterEncoding(value)none
request-secureSets the value of request.isSecure()none
response-character-encodingSets the value of the character encoding sent for the response with response.setCharacterEncoding(value). If a Content-Type is not set either with a set rule, or by some other process involved in servicing the request, this has no effect.none
response-content-typeSets the value of the content type sent for the response. If the final destination is a file with a corresponding mime-mapping, the mime-mapping will override the content-type set herenone
whenA condition which must evaluate to trueoptional
unlessA condition which must not evaluate to trueoptional
<unless>

Contains a condition that further refines the match of the enclosing tag beyond the information provided by the url. If the condition does not evaluate to true, then the enclosing tag is applied.

See <when> for a description of possible conditions.

user-in-role
child of when, unless

Evaluates to true if the user is authenticated and in the specified role. The special role of '*' means any role.

If the current user is any role, a Cache-Control header containing "private" is added to the response.

user-in-roleA role name.required
send-varySend a Vary header containing "Cookie" as part of the responsetrue
<when>

Contains a condition that further refines the match of the enclosing tag beyond the information provided by the url. If the condition evaluates to true, then the enclosing tag is applied.

<and>A subgroup of conditions that must all pass
auth-typeEvaluates to true if the authorization mechanism used in the request is the given value
cookieEvaluates to true if a cookie exists and matches an optional regexp
headerEvaluates to true if a request header exists and matches an optional regexp
localeEvaluates to true if the request locale matches the specified value
local-portEvaluates to true if the local port is the specified value (the local port is the actual port that Resin is using)
methodEvaluates to true if the http method used for the request is the specified value
<not>A subgroup of conditions, none of which may pass
<or>A subgroup of conditions, any of which may pass
query-paramEvaluates to true if a query parameter exists and matches an optional regexp
regexpUsed in conjunction with cookie, header, and query-param
remote-addrEvaluates to true if the remote address of the client matches the specified ip address
remote-userEvaluates to true if the user is authenticated and has the specified name
secureEvaluates to true if the ssl status of the request is equal to the specified value of true or false
server-nameEvaluates to true if the server name used by the client matches the specified value
server-portEvaluates to true if the port used by the client equals the specified value
user-in-roleEvaluates to true if the user is authenticated and in the specified role

Logging and Debugging

Logging for the name com.caucho.server.rewrite at the "finer" level reveals successful matches. At the "finest" level both successful and unsuccessful matches are logged.

Logging example
<logger name="com.caucho.server.rewrite" level="finest"/>
[1998/05/08 02:51:31.000] forward ^/foo: '/baz/test.jsp'  no match
[1998/05/08 02:51:31.000] forward ^/bar: '/baz/test.jsp'  no match
[1998/05/08 02:51:31.000] forward ^/baz: '/baz/test.jsp'  -->  '/hogwarts/test.jsp'

session tags
tags
service tags
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Resin ® is a registered trademark, and Quercustm, Ambertm, and Hessiantm are trademarks of Caucho Technology.