Here is the process document which describes how we will build the next-gen specification. Many thanks to the many people who have contributed to this effort. As you will see, a lot more work and some wonderful results lie ahead of us. 1999 will be a busy year! Comments are welcome. Details of the December 17-18 1998 design summit are being placed on the http://www.web3d.org website for member access. Eventually these documents will also be made public on www-vrml. New members are also welcome, especially those interested in ringside seats and direct influence on specification priorities. Happy holidays folks! all the best, Don -- Don Brutzman Naval Postgraduate School, Code UW/Br Root 200 work 831.656.2149 Monterey California 93943-5000 USA fax 831.656.3679 Virtual worlds/underwater robots/Internet http://www.stl.nps.navy.mil/~brutzmanTitle: VRML Next-Generation (VRML-NG) Specification Process
VRML Next-Generation (VRML-NG) Specification Process
Goals, Requirements, Design, Implementation and Standardization
public review draft: 24 December 1998
| Summary . | This document describes the development process being used by the Web3D Consortium & VRML community to define requirements, produce a design, rapidly implement, repeatedly evaluate and rigorously standardize the VRML-NG specification. |
Contents
- Document Status
- VRML-NG Motivation
- VRML-NG Mission Goals
- Phase 0. Process Definition
- Phase 1. Requirements
- Phase 2. Design
- Phase 3. Implementation and Evaluation
- Phase 4. Standardization
- Feedback
Document Status
| 1 SEP 98 | Began process definition (phase 0). Began public discussion of VRML-NG technical requirements. |
| 22 SEP 98 | Fourth draft by VRMLC executive committee |
| 29 OCT 98 | Exec/VRB/Board of Directors review |
| 19 NOV 98 | Consortium member review period complete |
| 19 NOV 98 | VRMLC BoD/VRB reviewed process document and Design Team candidates |
| 1 DEC 98 | Deadline for final comments by BoD, VRB & Design Team |
| 18 DEC 98 | Web3D Summit and technical review by execs, Design Team and several contributors |
| 24 DEC 98 | Process document goes public, review comments are welcome. |
| (goal) 10 JAN 99 | Final comments reviewed and incorporated, Process Definition phase complete. |
VRML-NG Motivation
The VRML-NG process balances many needs, requirements and interests. The best features of open design and working group progress are included. Hundreds of recommendations are being considered while generating VRML-NG requirements. A small design team then integrates & balances requirements to produce a coherent software architecture framework. A group of key contributors provide targeted supporting efforts for the design team. A group of key reviewers will provide additional technical support. Multiple implementations, example applications and conformance test suites will be produced prior to formal standardization. Deliberate open review periods will consider all critical technical and strategic issues.This is a fast-track partnership led by business members who will implement the browsers, supported by the working group technical progress and the benefits of public review from the VRML community. All of the above must fit within a framework of standards-follow success and vendor-driven design.
We will rapidly produce VRML-NG software products and specification. We will follow principles of rapid application development and a spiral design process.
VRML-NG Mission Goals
This work began during VRMLC Summit in Orlando Florida during SIGGRAPH, July 1998. Consortium leadership met with representatives of member companies and organizations. This group reaffirmed the need for VRML-NG, building a list of specification goals and priorities to best meet consortium, community and market needs.VRML-NG is intended to architect a platform that is applicable to a broad range of distributed 3D graphics applications, rather than one focused specifically on immersive worlds. This means that there will need to be an architecture that allows VRML to be a meaningful technology for everything from adding 3D effects in Web pages to applications to immersive worlds. While VRML 97 provides the foundation for such a platform, VRML-NG should not be a monolithic architecture. Instead VRML-NG will provide building blocks that may be used in appropriate configurations to work across a spectrum of applications.
The name of this specification may be changed from VRML-NG if technically appropriate.
A key goal of VRML-NG will be interoperability with technologies beyond VRML 97 that enable Web-based and broadcast applications. The architecture must present a clear model for how technologies may interface with VRML, and also how profiles of VRML can be defined on an application-specific basis. The Web3D Consortium will be the body for establishing consensus on profiles that are appropriate to standardize.
Our goal outcomes include building markets and enabling commercially viable products so that 3D graphics are implemented everywhere.
Phase 0. Process Definition
Objective: produce this process document for VRML-NG requirements, design, implementation and standardization. Also begin public discussions on VRML-NG requirements.Sequence of events:
- Executive committee (exec) identifies VRML-NG mission goals
- Exec drafts a clear, detailed and balanced process document
- Jeff Close & VRB initiate requirements discussions on www-vrml
- Exec/VRB/Bod review process document and discuss selection of design team members
- Review by Web3D Consortium members, while executive committee discusses process with design team candidates
- BoD approves final process document & design team members
VRML-NG will be designed by a small team composed of individuals from the leading vendor companies (and called the "Design Team"). The Design Team will work closely with the VRB and the executive committee throughout all phases of the process. Each phase will begin with a controlled, "closed" period, during which a VRML-NG Key Contributors group will provide supporting work and feedback to the design team. Detailed scrutiny will be initially provided by the Key Reviewers group and consortium officers. After the closed period, review is opened up to consortium membership and the community at large. This approach allows for a rapid, focused debate on key issues while assuring the broadest coverage and inclusion.
Design Team attributes
- small number of people (3-4) to ensure rapid & feasible results
- primarily people who can build VRML-NG browsers
- must compose numerous technical and business/strategic goals
- significant dedicated time for 1-2 years will be needed to fully participate
- can help to include individuals who understand the technical lessons learned during VRML 1.0 through VRML 97 design
- naming an editor is an important initial task
VRML-NG Key Contributors attributes
- provide direct support to design team
- membership requires a substantial amount of work
- individuals provide substantive input and review of draft designs
- work on specific subset tasks in VRML-NG architectural design
- key technology contribution areas include Core Design (Prototypes, API, Event Model, Design Patterns), Web Integration (XML, 2D, External Access), Rendering, Component Architectures, Media Integration, Compression, Collaboration (Multi-user and Distributed Simulation) and Navigation/Input.
VRML-NG Key Reviewers attributes
- provide additional support to design team
- conduct general and specialty reviews of draft designs
- key technology review areas include Content (Authorability, Univeral Media Element Library - UMEL), Process (Web3D, ISO), Database/Enterprise, Human Animation (H-Anim), GeoVrml, Interoperability (MPEG-4, XML, 2D standards, etc.) and Applications.
| The review team organization for the specification (in order, starting at the source):
Design Team, Key Contributors, Key Reviewers, VRML Review Board (VRB) and Consortium Board of Directors (BoD), Web3D Consortium members, and the VRML Community. |
It is noteworthy that VRML-NG design will not be performed using a Request for Proposals (RFP). The Design Team designs VRML-NG, subject to the mission goals, requirements and process documents.
Phase 1. Requirements
Objective: produce a comprehensive VRML-NG requirements document.Initial requirements recommendations on www-vrml list can come from
- Browser vendors and vendor alignment group
- Software tool builders and application developers
- Working groups provide consensus requirements based on results
- Consortium members
- Recommended practices and other results developed by working groups
- Anybody! the voices of the vrml community are always welcome
Triage: requirements ought to be labeled in 1 of 3 categories
- Essential/must have
- Valuable/good to have
- Harmful/bad (or perhaps controversial)
Note that requirements contributions during this stage are open, diverse, and numerous. Some may even be mutually exclusive. The goal is not to solve the final problem, but rather determine all of the many requirements which need to be considered when designing VRML-NG.
Mission goals for VRML-NG need to be clearly articulated to define the primary objectives of VRML Consortium members. Community goals and market needs must also be considered. Mission goals are intended to provide guidance on expected outcomes for VRML-NG. They will also be used to help resolve conflicting technical requirements.
Backwards compatibility with the VRML 97 specification is an important consideration that the final design needs to address in detail.
Profiles are another crucial consideration. Profiles (i.e. approved subsets or versions of VRML-NG) must make sense from the perspective of authors, users & platforms. Profiles are likely to be needed for MPEG-4 streaming or specialized hardware (such as one-way delivery to cable-TV set-top boxes). Reusability of content (both VRML-NG & VRML 97) in multiple playback environments is a major goal.
Requirements generated by working groups will be a major consideration in the design of VRML-NG. WG specifications approved through the existing WG Process are subject to the same backward compatibility requirements as the base VRML97 specification. WG specifications and recommended practices may be submitted as candidates for inclusion in VRML-NG. The design team reserves the right to modify or subset such specifications to ensure design consistency. Because not all working group outputs may be appropriate for VRML-NG, the design team might also reject or request specific modifications to any such submissions.
The initial requirements document will be produced by the Technical Requirements Editor (Jeff Close), with direct feedback from individuals in the Design Team and Key Contributors group. Subsequent edits are performed by the Design Team. All technical suggestions will be considered. Essential, valuable and harmful requirements will all be explicitly listed.
Numerous major design priorities have already been discussed in detail at the December 1999 design summit meeting:
- VRML-NG is a set of interoperating component standards
- Overall structure will be defined by Componentization Specification
- Initial draft specifications for these components must be available in Spring 1999
- Components include:
- Lightweight 3D runtime vehicle
- Backward compatible to pass the "Floops test" in the core
- Transformation specification defines precise compatibility (or similar approach) with VRML 97
- Expectation: 100% VRML 97 compatibility is possible with extra components
- Set of standard XML tags for 3D (e.g. pick up where Chrome left off)
- Enables use of 3D by 2D HTML programmers
- Enable embedding of "intelligent" 3D in XML
- 3D file formats
- Interchange format for authoring/publishing possibly including hierarchical geometry, interpolators etc.
- Design or adopt a complete binary format, including compression, streaming, fast-loading, low decompression overhead, and ability for lossless decompression
- 3D application programming interfaces (APIs)
- Includes media integration, plug-in rendering, streaming, application integration
Review period on completed requirements document: December 1998 - January 1999
- Review by executive committee, design team and key contributors
- Key beachhead applications of greatest value to Web3D Consortium members identified
- Application walkthroughs performed to ensure all key requirements identified
- Comment by Web3D Consortium membership, then public mailing lists
- Changes incorporated and VRB review, simultaneously
- Progress schedule established by Design Team and Executive Committee
- Board of Directors approval
Phase 2. Design
Objective: produce an implementable VRML-NG design.
Mission goals for VRML-NG provide priorities and strategic guidance during the design stage when a variety of technical trade-offs must be considered and weighed. Again, these help to resolve apparently conflicting technical requirements.
Design team meets and produces Design Specification
- produce an implementable solution that best meets requirements
- substantial work by Key Contributors
- browser builders agree they can/will execute the result
- design results are also implementable for software tool builders and work for application developers
- profile rationales and differences must be clearly justified and explained
- explains how mission goals and requirements were resolved
- initially the design document does not have to look like an ISO specification
Details and schedules regarding ISO liason and co-editing will be resolved early in the design process, when the scope of the specification and its associated components have been established.
Review period on completed design document:
- Review by VRML-NG Key Contributors and Key Reviewers
- Review by ISO committee liaisons
- Comment by Web3D Consortium membership, then public mailing lists
- Changes incorporated and VRB review, simultaneously
- Board of Directors approval
Phase 3. Implementation and Evaluation
Objectives: produce multiple VRML-NG implementations, the draft specification, example applications and a conformance suite.
Browser builders:
- build multiple initial VRML-NG browser implementations
- build example implementations for each profile
- design is also shown implementable for software tool developers
- cooperate with working group testing and evaluation of components
- Web3D Consortium encourages development of an open-source sample implementation, eventually maintained by open Web3D working group
Content teams and working groups:
- work in combination with their partner browser builders
- produce compelling example applications
- showcase VRML-NG capabilities and improvements
- demonstrate examples for each profile
Conformance and interoperability working group:
- develops open conformance test suite
- certifies appropriate backwards compatibility with VRML 97
- publicly reports browser interoperability and conformance
- collaborates with and provides inputs to specification committee
- note test applicability for each profile
Specification committee:
- formed during Implementation phase to draft VRML-NG specification
- named by executive committee and Board of Directors
- 1-2 year personal commitment
- VRML-NG specification draft produced from design document, in parallel with browser-builder efforts and conformance suite
- expedited Web3D-ISO cooperative effort similar to VRML 97
- perform appropriate reviews and administrative tasks pertaining to ISO requirements
- coordinate profile definitions with other emerging specifications, as appropriate
The Design Team will support in-depth collaboration & cooperation among these multiple interests, including incorporating feedback from implementors to ensure that the Design Specification is consistent with practice in implementations; working with the Conformance and Interoperability working group to develop appropriate tests; working with the Specification Committee to ensure consistency between the Design Specification and any standards documents.
We anticipate that working group contributions will continue to be a major source of innovation and progress throughout the VRML-NG process. Working groups are expected to have a major role in evaluating the design and implementation of requirement solutions.
Note that browsers, specification, content and conformance results are all needed prior to standardization. This is a significant difference from the VRML 97 process. We expect to spiral several times through the design, implementation and evaluation issues of VRML-NG before being robust & mature enough to consider readiness for standardization. The specification review committee will supervise the review and repetition schedules.
Review period on readiness to proceed with standardization phase:
- Review by VRML-NG Key Contributors and Key Reviewers
- Review by Specification Committee and ISO committee liaisons
- Comment by Web3D Consortium membership, then public mailing lists
- Changes incorporated and VRB review, simultaneously
- Board of Directors approval
Phase 4. Standardization
Objective: Review and approval of the VRML-NG Specification, first by VRML/Web3D Consortium and then by ISO.Specification committee:
- works with Design Team to resolve differences between Design Specification and Standards Specification, either by clarifying language or modifying design, keeping design modifications to a minimum
- May begin work fairly early during the Design and Implementation Phase
- updates and maintains the VRML-NG specification
- accounts for specification changes and accompanying rationales
- attends ISO meetings as appropriate
- All Web3D liaisons with ISO are via SC 24
- Web3D/SC 24 coordinates with ISO SC 29 liaisons for MPEG-4
- Web3D coordinates with other standards organizations as appropriate
Two working implementations are expected to fully demonstrate VRML-NG specification functionality prior to standardization. Furthermore, an open-source sample implementation is expected to be an important contribution to VRML-NG specification review, in order to demonstrate unambiguous compliance and justify tradeoff decisions made during the design and implementation phases. Open source is also expected to provide direct value to consortium members, but the basis and maintenance of such a source tree remains unresolved.
This standardization process closely matches the approach used to produce the VRML 97 International Standard (IS).
Public specification review attributes:
- formally review document produced by specification committee, and review again following each ISO specification milestone (listed below). Consortium & community comments are integrated into a formal consortium review document, submitted during each round of ISO ballots.
- considered, deliberate, in-depth analysis and testing by VRML community, candidate customers and Web3D members
- validation of results against mission goals and requirements
Milestones:
- VRB reviews spec and (when satisfied) recommends approval
- Board of Directors reviews and (when satisfied) endorses
- Web3D membership vote: approved as a Web3D specification
- Declare VRML-NG specification functionality freeze, then proceed with the following ISO ratification process steps
- Register as ISO Committee Draft (CD) and circulate for comment
- Register as ISO Final Committee Draft (FCD) and circulate for comment
- Register as ISO Draft International Standard (FDIS) and ballot for approval
- Balloted and approved result is the new ISO International Standard (IS)
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