HostSelector
| NAME | host |
| WHAT | The HostSelector component is used to
select appropriate sitemap processing depending on Host header
value.
|
| TYPE | Selector, Sitemap Component |
| BLOCK | Core |
| CLASS | org.apache.cocoon.selection.HostSelector |
| SINCE | Cocoon 2.0 |
| CACHEABLE | not applicable |
Description
The HostSelector tests the Host header field from the
request against the test attribute of the selectors when clause.
Usage
The HostSelector allows to define host specific sitemap
processing. This way Cocoon can do multi-homed sitemap processing.
Sitemap pipeline examples
The snippet below uses a HostSelector named host,
and testing against symbolic host-sites which are configured in the host
selector section.
 | | |
|
<map:select type="host">
<map:when test="uk-site">
....
</map:when>
<map:when test="de-site">
...
</map:when>
...
<map:otherwise>
...
</map:otherwise>
</map:select>
| |
| | |
Sitemap component configuration example
The snippet below declares a HostSelector
defining symbolic host-site names for some host domains.
| | |
|
<map:selectors...
<map:selector name="host"
src="org.apache.cocoon.selection.HostSelector"
logger="sitemap.selector.host"
<host name="uk-site" value="foo.bar.uk"/>
...
<host name="de-site" useragent="foo.bar.de"/>
<host name="us-site" useragent="foo.bar.com"/>
</map:selectors>
...
| |
| | |
Configuration
The configuration section of HostSelector specifies
a mapping from host strings to symbolic host-site names.
Each host element specifies a name attribute holding the symbolic host-site name
used in the test attribute expression. The attribute name contains
a matchable substring of some real host header values.
It is allowed to specify for a host name more than one entry. This way
a symbolic host-site name is matched by different host header substrings.
The snippet belows will yield true for test="central-europe" if
the user-agent header contains foo.bar.cz, foo.bar.at, or
foo.bar.hu.
| | |
|
...
<host name="central-europe" useragent="foo.bar.cz"/>
<host name="central-europe" useragent="foo.bar.at"/>
<host name="central-europe" useragent="foo.bar.uk"/>
...
| |
| | |
Setup
Setting up a HostSelector includes choosing the
<map:when> test expressions, and a
optional <map:otherwise> clause.
The test attribute of the <map:when> clause must match
a host attribute name value. The value of the test attribute in a
<map:when> clause must be declared in a
host name attribute.
Effect on Object Model and Sitemap Parameters
The HostSelector has no side effects on the object model, or
any sitemap parameters.
Bugs/Caveats
The HostSelector adds the response header attribute
Vary having value Host indicating
that the response differ for different user agents. This information
especially meaningfull for an http-proxy server.
History
28-12-02: initial creation
Copyright
Copyright (C) 1999-2002 The Apache Software Foundation. All rights reserved.
See also
A general documentation about selectors is available at
Matchers and Selectors.
For a detailed Host header documentation
see RFC 2068, especially
if Cocoon's run time environment is an http servlet environment.
|
