As per Relevance of the word specific, we have this rfc below:
Network Working Group S.
Request for Comments: 2077
Category: Standards Track C.
January 1997
The Model Primary Content Type
Multipurpose Internet Mail
Status of this
This document specifies an Internet standards track protocol for
Internet community, and requests discussion and suggestions
improvements. Please refer to the current edition of the "
Official Protocol Standards" (STD 1) for the standardization
and status of this protocol. Distribution of this memo is unlimited
The purpose of this memo is to propose an update to Internet RFC 2045
to include a new primary content-type to be known as "model".
2045 [1] describes mechanisms for specifying and describing
format of Internet Message Bodies via content-type/subtype pairs.
believe that "model" defines a fundamental type of content
unique presentational, hardware, and processing aspects.
subtypes of this primary type are immediately anticipated but will
covered under separate documents
Table of
1. Overview............................................. 2
2. Definition........................................... 2
3. Consultation Mechanisms.............................. 4
4. Encoding and Transport............................... 5
5. Security Considerations Section...................... 6
6. Authors' Addresses................................... 7
7. Expected subtypes.................................... 7
8. Appendix............................................. 9
9. Acknowledgements..................................... 13
Nelson, et. al. Standards Track [Page 1]
RFC 2077 Model Primary MIME Types January 1997
1.
This document will outline what a model is, show examples of models
and discuss the benefits of grouping models together. This
will not directly deal with the intended subtypes since those will
covered by their separate registrations. Some immediately
subtypes are listed in section 7.
This document is a discussion document for an agreed definition
intended eventually to form a standard accepted extension to
2045. We are also targeting developers of input/output filters
viewer software and hardware, those involved in MIME transport,
decoders
2. Definition of a
A model primary MIME type is an electronically
behavioral or physical representation within a given domain.
subtype in the model structure has unique features, just as does
subtype in the other primary types. The important fact is that
various subtypes can be converted between each other with less
of information then to that of other primary types. This fact
these subtypes together into the model primary type. All of
expected subtypes have several features in common and that are
to this primary type
To loosely summarize: models are multidimensional structures
of one or more objects. If there are multiple objects then
object defines the arrangement/setting/relationship of the others
These objects all have calibrated coordinate systems but
systems need not be in the same units nor need they have the
dimensionality. In detail
1. have 3 or more dimensions which are bases of the system
form an orthogonal system (any orthogonal system is sufficient).
This system is specifically defined in terms of an
set of basis functions [for a subspace of the L^2 function space
over a coordinate system of dimension 3 or more. Note that
does not preclude regular skewed systems, elliptical coordinates
different vector spaces, etc
2. contain a structural relationship between model elements
3. have scaling or calibration factors which are related to
units (force, momentum, time, velocity, acceleration, size, etc.).
Thus, an IGES file will specify a building of non-arbitrary size
computational meshes and VRML models will have real spatial
Nelson, et. al. Standards Track [Page 2]
RFC 2077 Model Primary MIME Types January 1997
temporal units. This allows for differing elements to be
non-arbitrarily
4. Models can be single objects or composed of a collection
objects. These normally independent objects are
in a master/slave scenario so that one object acts as
reference, or primary object, which defines how the
objects interrelate and behave. This allows for the
of mathematical, physical, economic, behavioral, etc.
which typically are composed of different elements. The key
in the description: these types describe how
"behaves"; contrasted to typical data types which
how something "is".
The inclusion of this "collective" system works similar to
Email system's multipart/related type which defines the
of the individual parts. Further specification of the model/*
subtypes utilizing these properties is left to the
authors
With these assumptions
a. the default dimensionality will be spatial and temporal (
any are allowed).
b. it is presumed that models will contain underlying
which may or may not be immediately available to
user. (fluid dynamics vector fields,
propagation, interrelated IGES dimensional specifiers,
materials and operators, etc.)
c. it is assumed that basis set conversion between model
is lossless. The interpretation of the data may change
the specification will not. i.e. convert the model of
U.S.A. Gross Domestic Product into a VRML model and
it to explore the variances and interrelationships. The
has many dimensions but also "passages" and "corridors
linking different parts of it. A similar situation is
for meshes and CAD files. The key is identifying the basis
conversion which makes sense
d. models are grouped to assure LESS loss of information
the model subtypes than to subtypes of other
types. (i.e. converting a chemical model into an image
more lossy than concerting it into a VRML model).
Nelson, et. al. Standards Track [Page 3]
RFC 2077 Model Primary MIME Types January 1997
Items c and d above define the grouping for model similar to the
that "images" and "videos" are grouped together; to assure less
of information. Obviously converting from a GIF image to a
image looses less information than converting from a GIF image to
AU audio file
3. Consultation
Before proposing a subtype for the model/* primary type, it
suggested that the subtype author examine the definition (above)
what a model/* is and the listing (below) of what a model/* is not
Additional consultations with the authors of the existing model/*
subtypes is also suggested
Copies of RFCs are available on
ftp://ftp.isi.edu/in-notes
Copies of Internet-Drafts are available on
ftp://ftp.ietf.org/internet-drafts
Similarly, the VRML discussion list has been archived as
http://vrml.wired.com/arch
and discussions on the comp.mail.mime group may be of interest
Discussion digests for the existing model/* subtypes may
referenced in the respective documents
The mesh community presently has numerous different mesh
as part of different packages. Freely available libraries need to
advertised more than they have been in the past to spur
development of interoperable packages. It is hoped that by
the example of the VRML community and creating a freely
comprehensive library of input/output functions for meshes [11]
this problem will be alleviated for the mesh community. A
available mesh viewer conforming to these standards is available
for various platforms. Consulations with the authors of the
system
http://www-dsed.llnl.gov/documents/tests/mesh.
will be beneficial
The IGES community has a suite of tests and conformance utilities
gauge the conformance to specifications and software authors
encouraged to seek those out from NIST [14].
Nelson, et. al. Standards Track [Page 4]
RFC 2077 Model Primary MIME Types January 1997
4. Encoding and
a. Unrecognized subtypes of model should at a minimum be
as "application/octet-stream". Implementations may
elect to pass subtypes of model that they do not
recognize to a robust general-purpose model
application, if such an application is available
b. Different subtypes of model may be encoded as
representations or as binary data. Unless noted in
subtype registration, subtypes of model should be assumed
contain binary data, implying a content encoding of base64
email and binary transfer for ftp and http
c. The formal syntax for the subtypes of the model primary
should look like this
Media type name:
Media subtype name:
Required parameters:
Optional parameters: dimensionality,
(see below
Encoding considerations: base64 encoding is recommended
transmitting model/* documents
MIME electronic mail
Security considerations: see section 5
Published specification: This document
See Appendix B for references to some
the expected subtypes
Person and email address to contact for further information
Scott D. Nelson
7000 East Ave
Lawrence Livermore National
Livermore, CA 94550
The optional parameters consist of starting conditions and
values used as part of the subtypes. A base set is listed here
illustration purposes only and will be covered in detail as part
the respective subtypes
dimension := string ; a number indicating the number of dimensions
This is used as a "hint" in
applicable viewer programs
Nelson, et. al. Standards Track [Page 5]
RFC 2077 Model Primary MIME Types January 1997
state := string ; "static" or "dynamic". In "static",
observer may move about, thus
translations, rotations, pans, zooms, etc
but the data does not change. In "dynamic",
the data itself is manipulated
skews, elongations, scales, etc. Note
time evolution is still a static
since it is just a translation along one
the principal dimensions while the
of a cube or object deformation are
operations
Note that this optional parameter list does not limit
specified by the various subtypes
d. The specific issues relating to the various subtypes are
as part of the description of those specific subtypes.
following is an example of a typical MIME header used for
transport purposes
To: you@some.
From: nelson18@llnl.
Date: Fri, 30 Aug 96 13:33:19 -0700
Content-Type: model/mesh; dimension="4"; state="static
Content-Transfer-Encoding: base64
MIME-Version: 1.0
Subject: model data
I1ZSTUwgVjEuMCBhc2NpaQojIFRoaXMgZmlsZSB3YXMgIGdlbmVyY...
byBDb21tdW5pY2F0aW9ucwojIGh0dHA6Ly93d3cuY2hhY28uY29tC...
IyB1c2VkIGluIHJvb20gMTkyICh0ZXN0IHJvb20pCiAgIAojIFRvc...
.
.
.
5. Security Considerations
Note that the data files are "read-only" and do not contain
system modifiers or batch/macro commands. The transported data
not self-modifying but may contain interrelationships. The
files may however contain a "default view" which is added by
author at file creation time. This "default view" may
viewer variables, default look angle, lighting,
options, etc. This visualization may also involve the computation
variables or values for display based on the given raw data.
motorized equipment, this may change the position from the hardware'
rest state to the object's starting orientation
Nelson, et. al. Standards Track [Page 6]
RFC 2077 Model Primary MIME Types January 1997
The internal structure of the data files may direct agents to
additional data from the network (i.e. inclusions); the
limits of whom are not pre-supposed. Actions based on
inclusions are left to the security definitions of the inclusions
Further comments about the security considerations for the
will be contained in each subtype's registration
6. Authors'
S. D.
Lawrence Livermore National Laboratory
7000 East Ave., L-153,
Livermore CA 94550, USA
E-Mail: nelson18@llnl.
C.
National Institute of Standards &
Bldg 220, Room B-344
Gaithersburg, MD 20899, USA
E-Mail: parks@eeel.nist.
1056
San Francisco, CA 94114
E-Mail: mitra@earth.path.
7. Expected
Table 1 lists some of the expected model sub-type names. Suggested 3
letter extensions are also provided for DOS compatibility but
need is hopefully diminished by the use of more robust
systems on PC platforms. The "silo" extension is provided
backwards compatibility. Mesh has an extensive list of hints
the present variability is so great. In the future, the need
these hints will diminish since the files are self describing.
document is not registering these subtypes. They will be
under separate documents
Nelson, et. al. Standards Track [Page 7]
RFC 2077 Model Primary MIME Types January 1997
Table 1.
Primary/sub-type Suggested extension(s)
model/iges igs,iges [8]
model/vrml wrl [9]
model/mesh msh, mesh, silo [10]
It is expected that model/mesh will also make use of a number
parameters which will help the end user determine the data
without examine the data. However, note that mesh files are self
describing
regular+static, unstructed+static, unstructured+dynamic
conformal+static, conformal+dynamic, isoparametric+static
isoparametric+
The sub-types listed above are some of the anticipated types that
already in use. Notice that the IGES type is already registered
"application/iges" and that RFC states that a more appropriate
is desired. Note that the author of "application/iges" is one of
authors of this "model" submission and application/iges will be re
registered as model/iges at the appropriate time
The VRML type is gaining wide acceptance and has numerous
development efforts for different platforms. These efforts
fueled by the release of the QvLib library for reading VRML files
without which the VRML effort would be less further along. This
allowed for a consistent data type and has by defacto established
set of standards. Further VRML efforts include interfaces to
kinds of hardware (beyond just visual displays) and it is proposed
those involved in the VRML effort to encompass more of the
senses. Unlike other kinds of "reality modeling" schemes, VRML
not proprietary to any one vendor and should experience
growth as do other open standards
The mesh type is an offshoot of existing computational
efforts and, like VRML, builds on a freely available library set
Also like VRML, there are other proprietary meshing systems but
are converters which will convert from those closed systems to
mesh type. Meshes in general have an association feature so that
connectivity between nodes is maintained. It should be noted
most modern meshes are derived from CAD solids files
Nelson, et. al. Standards Track [Page 8]
RFC 2077 Model Primary MIME Types January 1997
8.
8.1 Appendix A -- extraneous details about expected
VRML Data
The 3D modeling and CAD communities use a number of file formats
represent 3D models, these formats are widely used to
information, and full, or lossy, converters between the formats
both independently and integrated into widely used applications.
VRML format is rapidly becoming a standard for the display of 3
information on the WWW
Mesh Data
For many decades, finite element and finite difference time
codes have generated mesh structures which attempt to use
physical geometry of the structures in connection with
physics packages to generate real world simulations of
including electromagnetic wave propagation, fluid dynamics,
design, etc. The resulting output data is then post processed
examine the results in a variety of forms. This proposed
subtype will include both geometry and scalar/vector/tensor
data. An important point to note is that many modern meshes
generated from solids constructed using CAD packages
Motivation for mesh grew out of discussions with other
about their design requirements. Many CAD or scene descriptions
composed of a small number of complex objects while
meshes are composed of large numbers of simple objects. A 1,000,000
element 3D mesh is small. A 100,000,000 element 3D structured
is large. Each object can also have an arbitrary amount
associated data and the mesh connectivity information is important
optimizing usage of the mesh. Also, the mesh itself is
uninteresting but postprocessing packages may act on the
data or a computational engine may process the data as input
Meshes differ principally from other kinds of scenes in that
are composed of a large number of simple objects which may
arbitrary non-spatial parameters, not all of whom need be visible
and who have an implicit connectivity and neighbor list. This
point is the key feature of a mesh. It should be noted that
meshes are generated from CAD files however. The mesh type
association functions because the underlying physics was used
calculate the interaction (if you crash a car into a telephone pole
you get a crumpled car and a bent pole). Most
computational meshes are 4D with additional multidimensional
components
Nelson, et. al. Standards Track [Page 9]
RFC 2077 Model Primary MIME Types January 1997
IGES CAD Data
(The following text, reproduced for reference purposes only, is
"U.S. Product Data Association and IGES/PDES Organization
Manual," June 1995; by permission.)
IGES, the Initial Graphics Exchange Specification, defines a
data format that allows for the digital exchange of information
computer-aided design (CAD) systems
CAD systems are in use today in increasing numbers for
in all phases of the design, analysis, and manufacture and testing
products. Since the designer may use one supplier's system while
contractor and subcontractor may use other systems, there is a
to be able to exchange data digitally among all CAD systems
The databases of CAD systems from different vendors often
the same CAD constructs differently. A circular arc on one system
be defined by a center point, its starting point and end point,
on another it is defined by its center, its diameter starting
ending angle. IGES enables the exchange of such data by providing,
the public domain, a neutral definition and format for the
of such data
Using IGES, the user can exchange product data models in the form
wireframe, surface, or solid representations as well as
representations. Translators convert a vendor's proprietary
database format into the neutral IGES format and from the IGES
into another vendor's internal database. The translators, called pre
and post-processors, are usually available from vendors as part
their product lines
Applications supported by IGES include traditional
drawings as well as models for analysis and/or various
functions. In addition to the general specification, IGES
includes application protocols in which the standard is
to meet discipline specific requirements
IGES technology assumes that a person is available on the
end to interpret the meaning of the product model data. For instance
a person is needed to determine how many holes are in the
because the hole itself is not defined. It is represented in IGES
its component geometry and therefore, is indistinguishable from
circular edges of a rod
The IGES format has been registered with the Internet
Numbers Authority (IANA) as a Multipurpose Internet Mail
(MIME) type "application/iges". The use of the message type/
Nelson, et. al. Standards Track [Page 10]
RFC 2077 Model Primary MIME Types January 1997
in Internet messages facilitates the uniform recognition of an
file for routing to a viewer or translator
Version 1.0 of the specification was adopted as an American
Standards (ANS Y14.26M-1981) in November of 1981. Versions 3.0
4.0 of the specification have subsequently been approved by ANSI.
current version of IGES 5.2 was approved by ANSI under the
guidelines of the U.S. Product Data Association. Under
guidelines, the IGES/PDES Organization (IPO) became the
standards body for product data exchange standards. This
standard is USPRO/IPO-100-1993.
8.2 Appendix B -- References and
[1] Freed, N., and N. Borenstein, "Multipurpose Internet
Extensions (MIME) Part One: Format of Internet Message Bodies",
2045, Innosoft, First Virtual, November 1996.
[2] Fitzgerald P., "Molecules-R-Us Interface to the Brookhaven
Base", Computational Molecular Biology Section, National
of Health, USA; see http://www.nih.gov/htbin/pdb for further details
Peitsch M.C, Wells T.N.C., Stampf D.R., Sussman S. J., "The Swiss-3
Image Collection And PDP-Browser On The Worldwide Web", Trends
Biochemical Sciences, 1995, 20, 82.
[3] "Proceedings of the First Electronic Computational
Conference", Eds. Bachrach, S. M., Boyd D. B., Gray S. K, Hase W.,
Rzepa H.S, ARInternet: Landover, Nov. 7- Dec. 2, 1994, in press
Bachrach S. M, J. Chem. Inf. Comp. Sci., 1995, in press
[4] Richardson D.C., and Richardson J.S., Protein Science, 1992, 1,
3; D. C. Richardson D. C., and Richardson J.S., Trends in Biochem
Sci.,1994, 19, 135.
[5] Rzepa H. S., Whitaker B. J., and Winter M. J., "
Applications of the World-Wide-Web", J. Chem. Soc., Chem. Commun.,
1994, 1907; Casher O., Chandramohan G., Hargreaves M., Murray-
P., Sayle R., Rzepa H.S., and Whitaker B. J., "Hyperactive
and the World-Wide-Web Information System", J. Chem. Soc.,
Trans 2, 1995, 7; Baggott J., "Biochemistry On The Web", Chemical &
Engineering News, 1995, 73, 36; Schwartz A.T, Bunce D.M,
R.G, Stanitski C.L, Stratton W.J, Zipp A.P, "Chemistry In Context -
Weaving The Web", Journal Of Chemical Education, 1994, 71, 1041.
[6] Rzepa H.S., "WWW94 Chemistry Workshop", Computer Networks
ISDN Systems, 1994, 27, 317 and 328.
Nelson, et. al. Standards Track [Page 11]
RFC 2077 Model Primary MIME Types January 1997
[7] S.D. Nelson, "Email MIME test page", Lawrence Livermore
Laboratory, 1994. See http://www-dsed.llnl.gov/documents/WWWtest.
and http://www-dsed.llnl.gov/documents/tests/email.
[8] C. Parks, "Registration of new Media Type application/iges",
ftp://ftp.isi.edu/in-notes/iana/assignments/media-types
application/iges, 1995.
[9] G. Bell, A. Parisi, M. Pesce, "The Virtual Reality
Language",
http://sdsc.edu/SDSC/Partners/vrml/Archives/vrml10-3.html, 1995.
[10] S.D. Nelson, "Registration of new Media Type model/mesh",
ftp://ftp.isi.edu/in-notes/iana/assignments/media-types/model
mesh, 1997.
[11] "SILO User's Guide", Lawrence Livermore National Laboratory
University of California, UCRL-MA-118751, March 7, 1995,
[12] E. Brugger, "Mesh-TV: a graphical analysis tool",
Livermore National Laboratory, University of California
UCRL-TB-115079-8, http://www.llnl.gov/liv_comp/meshtv/mesh.
[13] S. Brown, "Portable Application Code Toolkit (PACT)",
printed documentation is accessible from the PACT Home
http://www.llnl.gov/def_sci/pact/pact_homepage.
[14] L. Rosenthal, "Initial Graphics Exchange
(IGES) Test Service",
http://speckle.ncsl.nist.gov/~jacki/igests.
8.3 Appendix C --
Numerous kinds of hardware already exist which can process some
the expected model data types and are listed here for
purposes only
stereo glasses, 3D lithography machines, automated
systems, data gloves (with feedback), milling machines
aromascopes, treadmills
Nelson, et. al. Standards Track [Page 12]
RFC 2077 Model Primary MIME Types January 1997
8.4 Appendix D --
This section contains a collection of various pointers to examples
what the model type encompasses
Example mesh model objects can be found on this mesh page
http://www-dsed.llnl.gov/documents/tests/mesh.
Various IGES compliant test objects
http://www.eeel.nist.gov/iges/specfigures/index.
VRML Test Suite
http://www.chaco.com/vrml/test
An image of a model of a shipping cage crashing into the ground
http://www.llnl.gov/liv_comp/meiko/apps/dyna3d/cagefig2.
An image of a 100,000,000 zone mesh
http://www.llnl.gov/liv_comp/meiko/apps/hardin/PMESH.
A video of a seismic wave propagation through a computational mesh
http://www.llnl.gov/liv_comp/meiko/apps/larsen/movie.
9.
Thanks go to Henry Rzepa (h.rzepa@ic.ac.uk), Peter Murray-
(pmr1716@ggr.co.uk), Benjamin
(B.J.Whitaker@chemistry.leeds.ac.uk), Bill Ross (ross@cgl.ucsf.EDU),
and others in the chemical community on which the initial draft
this document is based. That document updated an IETF Internet
in which the initial chemical submission was made,
suggestions received during the subsequent discussion period,
indicated scientific support for and uptake of a higher
document incorporating physical sciences[2-7]. This Model
benefited greatly from the previous groundwork laid, and
continued interest by, those communities
The authors would additionally like to thank Keith
(moore@cs.utk.edu), lilley (lilley@afs.mcc.ac.uk), Wilson
(ross@cgl.ucsf.EDU), hansen (hansen@pegasus.att.com), Alfred
(asg@severn.wash.inmet.com), and Jan Hardenbergh (jch@nell.oki.com
without which this document would not have been possible.
thanks go to Mark Crispin (MRC@CAC.Washington.EDU) for his
on the previous version and Cynthia Clark (cclark@ietf.org)
editing the submitted versions
Nelson, et. al. Standards Track [Page 13]
if you see any problems within the linking, don't worry be happy,
this is version 0.1 of the Relevance System and you gotta expect some crappy subroutines sometimes,
just be content we did not write this in Java, which would have made this "bigger and better" HAHAHHA.
RFC documents can be found at I.E.T.F.
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