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Fixes #2069 - Update the PushCacheFilter documentation. (#2070) 

Signed-off-by: Simone Bordet <simone.bordet@gmail.com>
This commit is contained in:
Simone Bordet 2017-12-19 07:03:30 -08:00 committed by Chris Walker
parent b68fbc4cfb
commit 19dbab7971
1 changed files with 40 additions and 11 deletions
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51
jetty-documentation/src/main/asciidoc/administration/http2/configuring-push.adoc
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@ -17,10 +17,14 @@
[[http2-configuring-push]]
=== Configuring HTTP/2 Push
HTTP/2 Push is a mechanism that allows the server to send multiple resources to the client for a single client request.
This will reduce the amount of round-trips necessary to retrieve all the resources that make up a web page and can significantly improve the page load time.
HTTP/2 Push is a mechanism that allows the server to send multiple resources
to the client for a single client request.
This will reduce the amount of round-trips necessary to retrieve all the
resources that make up a web page and can significantly improve the page load time.
HTTP/2 Push can be automated in your application by configuring a link:{JDURL}/org/eclipse/jetty/servlets/PushCacheFilter.html[`PushCacheFilter`] in the `web.xml`, in this way:
HTTP/2 Push can be automated in your application by configuring a
link:{JDURL}/org/eclipse/jetty/servlets/PushCacheFilter.html[`PushCacheFilter`]
in the `web.xml`, in this way:
[source, xml, subs="{sub-order}"]
----
@ -47,13 +51,38 @@ HTTP/2 Push can be automated in your application by configuring a link:{JDURL}/o
</web-app>
----
`PushCacheFilter` analyzes the HTTP requests for resources that arrive to your web application.
Some of these requests contain the HTTP `Referrer` header that points to a resource that has been requested previously.
This allows the `PushCacheFilter` to organize resources in to two categories: _primary_ resources (those referenced by the `Referrer` header) and _secondary_ resources (those that have the `Referer` header).
`PushCacheFilter` analyzes the HTTP requests for resources that arrive to your web
application.
Some of these requests contain the HTTP `Referer` header that points to a resource
that has been requested previously.
`PushCacheFilter` associates secondary resources to primary resources.
Only secondary resources that have been requested within a time window from the request of the primary resource are associated with the primary resource.
This allows the `PushCacheFilter` to organize resources in a tree, for example
a root `index.html` resource having two children resources, `styles.css` and
`application.js`, and `styles.css` having a child resource, `background.png`.
The root resource is called the _primary_ resource, while descendant resources
are called _secondary_ resources.
`PushCacheFilter` can be configured with the following `init-params`::
* `associatePeriod`: the time window, in milliseconds, within which a request for a secondary resource will be associated to a primary resource.
* `maxAssociations`: the max number of secondary resources that may be associated to a primary resource.
The resource tree is built using a time window so that when a root resource is
requested, only subsequent requests that are made within the time window will
be added to the resource tree.
The resource tree can also be limited in size so that the number of secondary
resources associated to a primary resource is limited.
By default, only the resource _path_ (without the _query_ string) is used to
associate secondary resources to the primary resource, but you can configure
`PushCacheFilter` to take the query string into account.
`PushCacheFilter` can be configured with the following `init-params`:
* `associatePeriod`: the time window, in milliseconds, within which a request
for a secondary resource will be associated to a primary resource; defaults to
4000 ms
* `maxAssociations`: the max number of secondary resources that may be
associated to a primary resource; defaults to 16
* `hosts`: a comma separated list of hosts that are allowed in the `Referer`
header; defaults to the host in the `Host` header
* `ports`: a comma separated list of ports that are allowed in the `Referer`
header; defaults to the port in the `Host` header
* `useQueryInKey`: a boolean indicating whether the query string of the
request should be considered when associating secondary resources to
primary resources; defaults to false