X3D MIME-Type

Current work to gain final MIME-type approval

In 1997 the Internet Engineering Task Force (IETF) approved IETF RFC 2077 for the Model MIME type. This supports VRML and establishes a MIME basis for other 3D model formats. However, the IETF has not yet approved X3D as an official MIME type, primarily due our incomplete prior efforts which did not submit a formal final application. This page is where we are building that formal application for official status of the X3D MIME-Type.

The current round of work started in 2008 with an initial application submission late that year. Review comments were received from IETF MIME-Type task force, reconciled and incorporated back into the application in February 2009. This effort was reported and collected as Registration of media type model/x3d+XXX.

The updated document appears below. All edits need to be done in conformance with the current application standard. When completed, the application needs to be sent to 'ietf-types@iana.org' with the subject line "Registration of media type model/x3d+XXX" included.

References

ISO 19776-1 X3D XML encoding, 4.4.1 File extension and MIME types
ISO 19776-2 ClassicVrml encoding, 4.4.1 File extension and MIME type
ISO 19776-3 Compressed binary encoding, 4.5.2 File extensions and MIME types

Web3D X3D MIME Types and File Extensions

Work list

Ensure that the application is fully complete
- Develop Section 6, Security Considerations
- "Encoding considerations" to update the binary encoding to current state
- Update all X3D specification references to the latest version and description
Perform public review on x3d-public@web3d.org mailing list
Gain approval of X3D Working Group and concurrence of Web3D Board of Directors

Submission steps

Review the IETF MIME Type Submission references
Finalize application details that follow
Submit to IETF and follow up on any resulting actions or approvals

Our goal is make this submission during May 2012.

Registration application for X3D MIME type (draft)

Editors note: XML, ClassicVRML, and Binary responses merged together. In the end, three separate applications will need to be created. See RFC 3023, XML Media Types for requirements specific to XML media types.

1. Media Type Name:

Model

2. Subtype names:

Standards Tree

x3d-vrml
x3d+xml
x3d+fastinfoset

3. Required parameters:

None

4. Optional parameters:

None

5. Encoding considerations:

This application represents the different MIME types used for three different encodings of the X3D ISO standard (see [1]). The standard defines an abstract information structural representation, for which several file formats are available. These formats are currently defined to be:

XML: '8-bit text'
ClassicVRML: '8-bit text'
Compressed Binary: 'binary'

6. Security considerations:

Editors note: This needs to be rewritten to address the questions and statements in RFC 4288, Media Type Specifications and Registration Procedures (Security Requirements).

Specifically we need to address/state response for

Complex media types
Active content
Release of information
Decompression issues
External security considerations

Scripting is defined as being available for the specification. Two languages are defined: Java and ECMAScript. Each scripting language is controlled by its local security model. As the content may run in many different situations, the X3D specification does not impose specific security policies. For example, some standalone applications will want to directly interact with the local file system, network or database, while others that run in a web browser would use the web-browser's security model.

7. Interoperability considerations:

The definition of the file format is maintained by the Web3d Consortium (http://www.web3d.org) and published through the ISO process. Several revisions of the specification have been made and it continues to be made. All revisions use the same MIME type definitions, and are backwards compatible internally and structurally. In addition, each of the file format encodings may be losslessly transformed between each other.

There are no known interoperability issues. There are existing applications that run on PC, Macintosh, and Unix/Linux systems that work with the file format. The Web3D Consortium makes an effort to keep the file format interoperable across all platforms.

8. Published specification:

See RFC 4288, Media Type Specifications and Registration Procedures (Publication Requirements) for detailed instructions. All revisions of the X3D specification can be found here: http://www.web3d.org/realtime-3d/specification/all The most recent specification is available from the ISO website (for a fee) or from Web3D Consortium

9. Applications that use this media type:

The applications that use (or would use) the

model/x3d+xml
model/x3d-vrml
model/x3d+fastinfoset

media type are those that display, create, edit, import, or export 3D model content using the X3D standard. A short list of the applications include:

BS Contact (Bitmanagement)
Instant Reality (Fraunhofer)
X3D-Edit and X3D Validator (Naval Postgraduate School)
Blender
Maya exporter
TBD

10. Additional information:

XML Encoding
- Magic number(s): Use XML's specification
- File extension: '.x3d'
- Macintosh File Type Code(s): TBD
- Object Identifier(s): TBD

ClassicVRML Encoding
- Magic number(s): #X3D
- File extension: '.x3dv'
- Macintosh File Type Code(s): TBD
- Object Identifier(s): TBD

Compressed Binary Encoding
- Magic number(s): TBD
- File extension: '.x3db'
- Macintosh File Type Code(s): TBD
- Object Identifier(s): TBD

11. Intended usage:

COMMON

12. Other Information/GeneralComment:

Editors note: It is not clear what should (or needs) to go in this section. The text below is what was previously here.

The X3D standard is a continuation of the VRML standard that is defined in RFC2077. As part of this work, several large modifications were made to the file format and specification. The basic premise for the specification continues the VRML design rational. The MIME types and file extensions were changed to indicate this modified standard.

Content Sub-types

Each content type may have an additional Content-Encoding to indicate whether the content has been compressed using GZIP in addition to the basic textual encoding. This is also indicated by modifying each file extension with the character "z". For example, the plaintext VRML-encoded file format would use the extension ".x3dv", and if compressed using GZIP uses the extension ".x3dvz"

13. Person to contact for further information:

Name: Leonard Daly (X3D Working Group Co-Chair)
E-mail: <use appropriate alias>
Author / Change controller: The Web3D Consortium