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<title>OpenACS WebDAV Support</title>
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<h2>OpenACS WebDAV Support</h2>
<h3>Introduction</h3>
<p>This package implements a WebDAV interface to the OpenACS
Content Repository. In addition to generic access to content
items, there is a service-contract interface so packages can
define custom handlers for WebDAV methods for objects that belong
to that package.
</p>
<h3>Installation</h3> <p>Install through the APM. If you install
file-storage, WebDAV support is installed automatically. In
addtion you should check the tDAV specific configuration
parameters to the AOLserver configuration file. The default parameters work fine, they will create webdav URLs like <i>yoursite/</i>dav/*
<p>
You can visit the /webdav-support/ page to control webdav access on a per-folder basis. Packages that support WebDAV will add folders to this list and an administrator can then activate or deactivate the folders.
</p>
<h3>How
it Works</h3> <p>OpenACS WebDAV Support requires the tDAV
AOLserver module to implement most of the WebDAV protocol. OpenACS
WebDAV Support just provides and interface between tDAV and the
Content Repository
</p>
<p>Each content_type that requires a custom handler much implement
the <code>dav</code> service contract. Each content type should
implement the <code>dav</code> service contract with the implementation name the same as the content_type. This includes operations
for every WebDAV method. Some operations do not make sense for
certian object types. Specifically, content_items, which are
mapped to WebDAV resources, should not perform a MKCOL (make
collection) method. Likewise, a content_folder, or WebDAV
collection, should not allow a PUT method. In addition to the
<code>dav</code> service contract is a helper contract to allow
packages to set the initial content_type for new items created
through WebDAV. Each package should implement the
<code>dav_put_type</code> service contract with the implementation
named the same as the package key.</p>
<p>Each package instance that will allow WebDAV access should
register a package_id and folder_id for the root content_folder
that corresponds with the URI of the package's mount point using <code>oacs_dav::register_folder</code>.</p>
<h3>Dispatching Requests</h3>
<p>A preauth filter is registered for all WebDAV methods. This
calls oacs_dav::authorize which will set oacs_dav::conn user_id to
the OpenACS user_id or 0 is the request is not authenticated. This
filter also calls oacs_dav::setup_conn sets up the basic
information needed to authorize the request. If authorization
fails a 401 HTTP response is returned requesting authentication
information. If authorization is successful the filter returns
filter_ok and the tdav::filter* filter for the method is called.</p>
<p>The tdav::filter* commands setup global information for each
method that is independent of the storage type. After this filter
runs, the request is handled by the registered procedure for
OpenACS oacs_dav::handle_request.</p>
<p>oacs_dav::handle_request determines the package_id that should
handle the URI. This is based on the standard OpenACS site_node
Tcl API. After the package is found, the root folder for that
package is retreived from the dav_package_folder_map table. Using
the folder_id, and the URI of the request, the
<code>content_item__get_id</code> pl/sql(plpgsql) procedure is
called to find the item_id for the request. If no item_id is found
and the requested method is PUT, a new item should be created. If
the method is not PUT, a 404 error should be returned.
</p>
<p>oacs_dav::handle_request will call the service contract
implemenation for the content_type of the item. If the request is a
PUT, first the dav_put_type service contract for the package_key of
the request is called. For file-storage this returns
"file_storage_object" so items created by PUT are created as
file_storage_objects instead of generic content_revisions. </p>
<p>The service contract implementation for each operation must return
the response data in the format required by tDAV. The documentation
for the tdav::respond::* procedures named for each method describe
what is required.</p>