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The File Content Provider

Preface

The File Content Provider (FCP), a Content Provider for the Universal ContentBroker (UCB), provides access to the local file system. It does this by providing file content objects, which represent either a directory or a file in the local file system. The FCP is able to restrict access to the file system to a number of directories shown to the client under configurable aliases.

File Contents

The FCP provides content representing either a Directory or File in the local file system.

A directory contains other directories or files.
A file is a container for document data/content. The FCP is not able to determine the MediaType property of a file content.

Creation Of New File Contents

A content representing directories implements the interface XContentCreator. A file content object supports the command „insert. To create a new directory/file in a directory:

Let the parent directory create a new content by calling its createNewContent method. The content type to use for new folders is application/vnd.sun.staroffice.fsys-folder. To create a new file, use the type string application/vnd.sun.staroffice.fsys-file. As return value you get a new file content object.
Set a title at the new file content object. ( Let the new child execute a setPropertyValues – command, which sets at least the property„Title to a non-empty value ).
Let the new file content object ( not the parent! ) execute the command „insert“. This will create the corresponding physical file or directory. For files, you need to supply the implementation of an XInputStream with the command's parameters, that provides access to the stream data.

URL Schemes for File Contents

The 'file' URL Scheme

Each file content has an identifier corresponding to the following scheme:

file:///<path>

where <path> is a hierarchical path of the form

<name1>/<name>/.../<name>.

The first part of <path> ( <name1> ) need not denote a physically existing directory, but may be re-mapped to such a directory. If this is done, the FCP refuses file access for any URL whose <name1>-part is not an element of a predefined list of alias names.

The 'vnd.sun.star.wfs' URL Scheme

In the Sun ONE Webtop, the server side file system is addressed with vnd.sun.star.wfs URLs (wfs stands for Webtop File System), while the file URL scheme is reserved for a potential client side file system.

In that scenario, a trick is used to completely hide the vnd.sun.star.wfs URL scheme from the FCP (i.e., the server side FCP internally works with file URLs, just like any other FCP): There is a special Remote Access Content Provider (RAP) between the UCB and the FCP. That RAP, among other things, can route requests to another UCP and rewrite URLs "on the fly." This feature is used here, so that the client of the UCB works with vnd.sun.star.wfs URLs and the FCP remains unmodified and works with file URLs, with a RAP in between that maps between those two URL schemes:

Except for the different scheme name, the syntax of the vnd.sun.star.wfs URL scheme is exactly the same as that of the file URL scheme.

Appendix

The following table gives an overview of the different properties of file contents and the supported commands and interfaces.

UCB Type

(returned by XContent::getContentType )

Properties

Commands

Interfaces

File

application/vnd.sun.staroffice.fsys-file

[readonly] ContentType

DateModified

[readonly] IsDocument

[readonly] IsFolder

Size

Title

IsReadOnly

IsVolume

IsRemoveable

IsRemote

IsCompactDisc

IsFloppy

IsHidden

getCommandInfo

getPropertySetInfo

getPropertyValues

setPropertyValues

insert

delete

open

transfer

lang::XServiceInfo

lang::XComponent

ucb::XContent

ucb::XCommandProcessor

beans::XPropertiesChangeNotifier

beans::XPropertyContainer

beans::XPropertySetInfoChangeNotifier

ucb::XCommandInfoChangeNotifier

container::XChild

ucb::XContentCreator

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