Preferences Registry Format
1.0 Specification
Abstract:
Preferences Registry Format (is short: "PRF") is an XML-based simple
configuration file format meant to be used in software that needs a
simple, yet powerful, platform-independent way of storing
configuration data. It is based on the simple name-value principle
commonly used in many software configuration formats.
This format is meant to be generic and multi-purpose, but it is not
designed to be universal. If you need a more complex, or a more
specialised way of storing application configuration data, it is
suggested to refer to a more comprehensive preferences file format
named "CC/PP" which stands for Composite Capabilities/Preference
Profiles [3]. The Preferences Registry Format is a major
simplification of the ideas put into the CC/PP Resource Description
Framework [4] based file format.
This document is a ``request for comments'' (RFC) draft document. It
is a work in progress. Comments about any part of this document are
welcome.
The design solutions, expressed in this document, are not yet intended
for production use.
This document is subject to the copyright notice below.
Permission is granted to copy distribute and/or modify the text of
this document under the terms of the GNU Free Documentation License,
Version 1.2 or any later version published by the Free Software
Foundation; with no Invariant Sections, with no Front-Cover Texts, and
with no Back-Cover Texts.
© 2003, 2004 Andrei Sosnin
It is required for the PRF file to be a well-formed XML file and fully
conform to the following specification. Validation of PRF files can be
performed using the DTD in section 3.2 (non-normative). For
validation it is required that a PRF file contains the following line
before the PRF root element:
<!DOCTYPE prf "/dtd/prf-1.0.dtd">
or, optionally, with a public ID:
<!DOCTYPE prf PUBLIC "-//tomatensaft//DTD prf 1.0 -//EN"
"http://tomato.dyn.ee/dtd/prf-1.0.dtd">
Note that the public ID is optional and may be ommitted. The system ID
is better to point to a real DTD location, so that a validating DOM
library could validate this file.
Also note, that, as defined in the XML 1.0 Recommendation [1],
a common minimal XML parsing directive is required in the beginning of
a PRF file before the document type declaration, e.g.:
<?xml version="1.0"?>
Optionally, there may be a declaration of the encoding, used in the
file, using the encoding attribute. It defaults to ``UTF-8'',
which is a recommended PRF file encoding.
PRF supports multiple configuration profiles, which are delimited by
the profile element. Each profile must have a unique ID,
which is set with the id attribute. A profile may have an
optional name. It is set using the name
attribute. profile elements can only contain
component elements inside.
Applications must use the id attribute to select needed
profile elements. The name attribute is meant for a
descriptive name specification (e.g. storing the user-selected name of
a profile).
The component elements are meant to logically stucturise PRF
files. It is recommended to divide different configuration parts into
different logical ``component'' sections, because it simplifies
configuration file maintenance and software debugging.
Each component must have a unique ID defined with the id
attribute. Please note, that it must be unique even between different
profiles, so it is recommended to give their ID an appropriate value
(e.g. ``HTTPUpload1'', ``HTTPUpload2'' etc.).
A component element can have an optional name attribute that can
describe the nature of the component (e.g. ``FTPUpload'', if it is
connected to FTP-based file uploading). Applications may use this
field to find needed components with needed configuration options. The
name field isn't meant for descriptive name specification, although
the name may be somewhat descriptive.
Options define name-value pairs of an application's configuration
state. Each option element must have a name (NMTOKEN,
alpha-numerical) associated with it. Note that in option
element this field is mandatory. The value of each option is written
inside the option element as PCDATA (parsed character data).
Note that this specification does not define any ``list'' or other
complex data type support. The users of this format may enhance the
format by providing additional option content
specifications. This format's option element is not, though,
limited to contain simple text data and may contain embedded
structured data, such as XML.
The following is an example of a PRF configuration file:
<?xml version="1.0"?>
<!DOCTYPE prf "dtd/prf-1.0.dtd">
<prf>
<profile id="default1" name="default">
<component id="c1" name="Setup">
<option name="ExecDir">/home/tomato/tale2c</option>
<option name="ConfDir">conf</option>
</component>
<component id="c2" name="HTTPUpload">
<option name="ServerHostName">zzx.dyn.ee</option>
<option name="ServerPortNumber">80</option>
<option name="ScriptName">/edit.php</option>
</component>
<component id="c3" name="FTPUpload">
<option name="ServerHostName">album.dyn.ee</option>
<option name="ServerPortNumber">21</option>
<option name="UploadDir">/tale2/albums/</option>
</component>
<component id="c4" name="DocumentSetup">
<option name="DefaultFilename">Untitled.xml</option>
</component>
</profile>
</prf>
Document Type Definition
The following code is a non-normative DTD, useful for Preferences
Registry Format files validation:
<!ELEMENT prf (profile*)>
<!ATTLIST profile
xmlns CDATA #IMPLIED >
<!ELEMENT profile (component*)>
<!ATTLIST profile
id ID #REQUIRED
name CDATA #IMPLIED >
<!ELEMENT component (option*)>
<!ATTLIST component
id ID #REQUIRED
name CDATA #IMPLIED >
<!ELEMENT option (#PCDATA)*>
<!ATTLIST option
name NMTOKEN #REQUIRED >
-
1
Extensible Markup Language 1.0, Second Edition, W3C
Recommendation 2 October 2000, http://www.w3.org/TR/REC-xml
2
PRF 1.0 API, Specification and Implementation Notes
DRAFT, http://zzx.dyn.ee/pub/doc/free/prf1-api/libprf1.pdf
3
CC/PP (Composite Capabilities/Preference Profiles):
Structure and Vocabularies 1.0, W3C Proposed Recommendation 15 October
2003, http://www.w3c.org/TR/2003/PR-CCPP-struct-vocab-20031015/
4
Resource Description Framework (RDF) Model and Syntax
Specification, W3C Recommendation 22 February 1999,
http://www.w3.org/TR/REC-rdf-syntax/
Preferences Registry Format
1.0 Specification
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The translation was initiated by Andrei Sosnin on 2004-05-11
Andrei Sosnin
2004-05-11
