Ian & Stuart's Australian Mac: Not for Sale/Another.not.for.sale (Australia).iso/fade into you/being there/Issues & Ideas/VMRL/Concepts/pesce-www

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                                  CYBERSPACE


Mark D. Pesce, Peter Kennard and Anthony S. Parisi
Labyrinth Group
45 Henry Street #2
San Francisco, CA 94114
[e-mail] [e-mail] [e-mail]



Abstract



   This work describes a visualization tool for WWW, "Labyrinth", which
   uses WWW and a newly defined protocol, Cyberspace Protocol (CP) to
   visualize and maintain a uniform definition of objects, scene
   arragement, and spatio-location which is consistent across all of
   Internet. Several technologies have been invented to handle the
   scaling problems associated with widely-shared spaces, including a
   distributed server methodology for resolving spatial requests. A new
   languague, Virtual Reality Markup Language (VRML) is introduced as a
   beginning proposal for WWW visualization.

Introduction



   The emergence, in 1991, of the World Wide Web, added a new dimension
   of accessibility and functionality to Internet. For the first time,
   both users and programmers of Internet could access all of the various
   types of Internet services (FTP, Gopher, Telnet, etc.) through a
   consistent and abstract mechanism. In addition, WWW added two new
   services, HTTP, the Hypertext Transfer Protocol, which provides a
   rapid file-transfer mechanism; and the Uniform Resource Locator, or
   URL, which defines a universal locator mechanism for a data set
   resident anywhere within Internet'ís domain.

   The first major consequence of the presence of WWW on Internet has
   manifested itself in an explosion in the usability of data sets within
   it. This is directly correlatable to the navigability of these data
   sets: in other words, Internet is useful (and will be used) to the
   degree it is capable of conforming to requests made of it. WWW has
   made Internet navigable, where it was not before, except in the most
   occult and hermetic manner. Furthermore, it added a universal
   organization to the data within it; through WWW, all four million
   Internet hosts can be treated as a single, unified data source, and
   all of the data can be treated as a single, albeit complexly
   structured, document.

   It would appear that WWW, as a phenomenon, has induced two other
   processes to begin. The first is an upswing in the amount of traffic
   on Internet (1993 WWW traffic was 3000x greater than in 1992!); the
   second is a process of organization: the data available on Internet is
   being restructured, tailored to fit within WWW. (This is a clear
   example of ìthe medium is the messageî, as the presence of a new
   medium, WWW, forces a reconfiguration of all pre- existing media into
   it.) This organization is occurring at right angles to the previous
   form of organization; that is to say that, previously, Internet
   appeared as a linear source, a unidimensional stream, while now, an
   arbitrary linkage of documents, in at least two dimensions (generally
   defined as ìpagesî), is possible. As fitting the organization skills
   most common in Western Civilization, this structure is often
   hierarchical, with occasional exceptions. (Most rare are
   anti-hierarchical documents which are not intrinsically confusing.)

   Navigability in a purely symbolic domain has limits. The amount of
   ìdepthî present in a subject before it exceeds human capacity for
   comprehension (and hence, navigation) is finite and relatively
   limited. Humans, however, are superb visualizers, holding within their
   craniums the most powerful visualization tool known. Human beings
   navigate in three dimensions; we are born to it, and, except in the
   case of severe organic damage, have a comprehensive ability to
   spatio-locate and spatio-organize.

   It seems reasonable to propose that WWW should be extended, bringing
   its conceptual model from two dimensions, out, at a right angle, into
   three. To do this, two things are required; extensions to HTML to
   describe both geometry and space; and a unified representation of
   ìspaceî across Internet. This work proposes solutions to both of these
   issues, and describes a WWW client built upon them, called
   ìLabyrinthî, which visualizes WWW as a space.

Visualization and VRML



   As of this writing, HTML is capable of expressing both textual and
   pictorial data, and can provide some limited formatting features for
   each of them; beyond this it provides a linkage mechanism to express
   the connection between data sets. HTMLís roots are in text; its
   parent, SGML, specifies a format for printed media, a expression which
   is intrinsically two-dimensional. For this reason, we have stepped
   ìoutsideî of HTML in our language specifications for geometry and
   place, defining a simple, easily parsed scripting language for the
   generation of objects and spaces.

   The basic functionality for any three-dimensional language interface
   to WWW can be broken into three parts; object definitions, which
   include the definitions of the geometric representations for these
   objects; scene definitions, which define ìplacementî of these objects
   inside of a larger context; and a mechanism which ìbindsî a URL to an
   object within a scene. The current revision of Labyrinth's Virtual
   Reality Markup Language (VRML), while unsophisticated, does fulfill
   all of these requirements, and therefore provides all of the basic
   functionality required in a fully visualized WWW client.

   As currently defined, Labyrinth's VRMLdî files are a unique data type,
   like MPEG or AIFF, and must be integrated with MIME in order to launch
   a companion ìviewerî. This is not an optimal solution; rather, it
   should be possible to extend HTML to encapsulate ìspatialî data types;
   these, then, could be visualized or ignored given the capabilities of
   the WWW client. The OpenGL, OpenInventor, or HOOPS specifications
   could form a basis, insofar as object definitions are concerned, for
   HTML extensions, and should be examined as a possible (and
   well-supported) solution to this issue. Our scripting language should
   serve as a starting example, rather than a proposal for an all-
   inclusive solution.

   Any conceptualization of space contains within it, implicitly, the
   quality of number; i.e., ìhow muchî or ìhow farî is contained within
   the simple expression of existence. Space, in its electronic
   representation, is numbered, and, if it is to be shared by billions of
   simultaneous participants, it must be consistent, unique, and very
   large/ dense. Despite this, it is rarely necessary for a WWW client to
   deal with the totality of space; operations occur local to the
   position of the WWW viewer, and this local description of space is
   nearly always a great deal more constrained than the entire spatial
   representation.

   It is necessary for VRML to define a numbering system for
   visualization which conforms to the three principles outlined above.
   Another section of this work describes such a system.

Cyberspace



   For the purposes of continuity in navigation, it is necessary to
   create a unified conceptualization of space spanning the entire
   Internet, a spatial equivalent of WWW. This has been called
   ìCyberspaceî, in the sense that it has at least three dimensions,
   but exists only as a ìconsensual hallucinationî on the part of the
   hosts and users which participate within it. There is only one
   cyberspace, just as there is only one WWW; to imply multiplicity is to
   defeat the objective of unity.

   At its fundamental level, cyberspace is a map that is maintained
   between a regular spatial topology and an irregular network topology.
   The continuity of cyberspace implies nothing about the internetwork
   upon which it exists. Cyberspace is complete abstraction, divorced at
   every point from concrete representation.

   All of the examples used in the following explanation of the
   algorithmic nature of cyberspace are derived from our implementation
   of a system that conforms to this basic principle, a system developed
   for TCP/IP and Internet.

Metrics in Cyberspace



   Internet defines an address ìspaceî for its hosts, specifying these
   addresses as 32-bit numbers, expressed in dotted octet notation, where
   the general form is {s.t.u.v}. Into this unidimensional address space,
   cyberspace places a map of N dimensions (N = 3 in the canonical,
   ìGibsonianî cyberspace under discussion here), so that any ìplaceî can
   be uniquely identified by the tuple {x.y.z}.

   In order to ensure sufficient volume and density within cyberspace, it
   is necessary to use a numbering system which has a truly vast dynamic
   range. We have developed a system of ìaddress elementsî where each
   element contains a specific portion of the entire expressible dynamic
   range in the form:

   {p.x.y.z}

   where p is the place value, and x, y, and z are the metrics for each
   dimension. The address element is currently implemented as a 32-bit
   construct, so the range of p is ±127, and x, y, and z, are unsigned
   octets. Address elements may be concatenated to any level of
   resolution desired; as most operations in cyberspace occur within a
   constrained context, 32, or at most, 64 bits is sufficient to express
   the vast majority of interactions. This gives the numbering system the
   twin benefits of wide dynamic range and compactness; compactness is an
   essential quality in a networked environment.

   This is only one possible numbering scheme; others may be developed
   which conform to the principles as given, perhaps more effectively.

   Cyberspace has now been given a universal, unique, dense numbering
   system; it is now possible to quantify it. The first quantification is
   that of existence (metrics); the second quantification is that of
   content. Content is not provided by cyberspace itself, but rather by
   the participants within it. The only service cyberspace needs to
   provide is a binding between a spatial descriptor and a host address.
   This can be described by the function:



f(s) => a

   where s is a spatial identifier, and a is an internetwork address.

   This is the essential mathematical construction of cyberspace.

Implementation of Cyberspace Protocol



   If cyberspace is reducible to a simple function, it can be expressed
   through a transaction-based protocol, where every request yields a
   reply, even if that reply is Δ. In the implementation under
   examination, cyberspace protocol (CP) is implemented through a
   straightforward client-server mechanism, in which there are very few
   basic operations; registration, investigation, and deletion.

   In the registration process, a cyberspace client announces to a server
   that it has populated a volume of space; in this sense, cyberspace
   does not exist until it is populated: this is a corollary to
   Benedikt'ís Principle of Indifference, which states: ìabsence from
   cyberspace will have a cost.î

   The investigation process will be discussed in detail later in this
   work. The basic transaction is simple: given a circumscribed volume of
   space, return a set of all hosts which contribute to it. The reply to
   such a transaction could be NULL or practically infinite (consider the
   case where the request specifies a volume which describes the entirety
   of cyberspace); this implies that level-of-detail must be implemented
   within the transaction (and hence, within registration), in order to
   optimize the process of investigation. Often, it is enough to know
   cyberspace is populated, nothing more, and many other times, it is
   enough to know only the gross features of the landscape, not the
   particularities of it. In this sense, level of detail is a quality
   intrinsic to cyberspace.

   Registration contains within it the investigation process; before a
   volume can be registered successfully, ìpermissionî must be received
   from cyberspace itself, and this must include an active collaboration
   and authentication process with whatever other hosts help to define
   the volume. This is an enforcement of the rule which forbids
   interpenetration of objects within the physical world; it need not be
   enforced, but unless it is observed in most situations, cyberspace
   will tend toward being intrinsically disorienting.

   Finally, the deletion process is the logical inverse of the
   registration process, where a volume defined by a client is removed
   from cyberspace. These three basic transactions form the core of
   cyberspace protocol, as implemented between the client and the server.


Cyberspace Servers



   Cyberspace is a unified whole; therefore, from a transaction-oriented
   point of view, every server must behave exactly like any other server
   (specifically with respect to investigation requests). The same
   requests should evoke the same responses. This would appear to imply
   that every server must comprehend the ìtotalityî of cyberspace, a
   requirement which is functionally beyond any computer yet conceived
   of, or it places a severe restriction on the total content of
   cyberspace. Both of these constraints are unacceptable, and a
   methodology to surmount these constraints must be incorporated into
   the cyberspace server implementation.

   The cyberspace server is implemented as a three-dimensional database
   with at least three implemented operations; insertion, deletion, and
   search. These correspond to the registration, deletion, and
   investigation transactions. Each element within the database is
   composed of at least three items of data; the volumetric identifier of
   the space; the IP address of the host which ìmanifestsî within that
   space; and the IP address of the cyberspace server through which it is
   registered.

   The investigation transaction is the core of the server
   implementation. Cyberspace servers use a repeated, refined query
   mechanism, which iteratively narrows the possible range of servers
   which are capable of affirmatively answering an investigation request
   until the set exactly conforms to the volumetric parameters of the
   request. This set of servers contains the entire possible list of
   hosts which collaborate in creating some volume of cyberspace, and
   will return a non-null reply to an investigation request for a given
   volume of space. The complete details of the investigation algorythm
   are beyond the scope of the current work and will be explained in
   greater detail in a subsequent publication.

   An assumption implicit in the investigation algorithm is that
   investigative searches have ìdepthî, that investigation is not
   performed to its exhaustive limit, but to some limit determined by
   both client and server, based upon the ìimportanceî of the request.
   Registrations, on the other hand, must be performed exhaustively, but
   can (and should) occur asynchronously.

   The primary side-effect of this methodology is that cyberspace is not
   instantaneous, but is bounded by bandwidth, processor capacity, and
   level of detail, in the form:

   [IMAGE]

   where c is a constant, the ìspeed limitî of cyberspace (as c is the
   speed of light in physical space), l is the level of detail, b is
   bandwidth of the internetwork, p is processor capacity, D is the
   number of dimensions of the cyberspace, and r is the position within
   the space. The function rho defines the "density" of a volume of
   cyberspace under examination.

   This expression is intended to describe the primary relationships
   between the elements which create cyberspace, and is not
   mathematically rigorous, but can be deduced from Benedikt'ís Law.

   Finally, because cyberspace servers do not attempt to contain the
   entirety of cyberspace, but rather, search through it, based upon
   client transaction requests, it can be seen that the content of a
   cyberspace server is entirely determined by the requests made to it
   by its clients.

   One way to visualize the operation of cyberspace servers is with the
   metaphor of Indra'ís Net, from Vedanta Hinduism; finely woven of
   glittering jewels, each jewel reflecting every other.

Cyberspace and the World Wide Web



   Having defined, specified, and implemented an architecture which
   provides a binding between spatio-location and data set location, this
   architecture needs to be integrated with the existing WWW libraries so
   that their functionality can be similarly extended. As ìlocationî is
   being augmented by the addition of CP to WWW, it is the Universal
   Resource Locator which must be extended to incorporate these new
   capabilities.

   The URL, in its present definition, has three parts: an access
   identifier (type of service), a host name (specified either as an IP
   address or DNS-resolvable name), and a ìfilenameî, which is really
   more of a message passed along to the host at the point of service.
   Cyberspace Protocol fits well into this model, with two exceptions;
   multiple hosts which collaborate on a space, and the identification of
   a ìfilenameî associated with a registered volume of space.

   We propose a new URL of the following form:

cs://{pa.x.y.z}{pb.x.y.z}.../filename



   where {pn...} is a set of CP address elements.

   Resolution of this URL into a data set is a two-stage process: first
   the client CP mechanism must be used to translate the given
   spatio-location into a host address, then the request must be sent to
   the host address. Two issues arise here; multiple host addresses, as
   mentioned previously, and a default access mechanism for CP. If a set
   of host addresses are returned by CP, a request must be sent to each
   specified host; otherwise, the description of the space will be
   incomplete. Ideally, all visualized WWW clients will implement a
   threaded execution mechanism (with re-entrant WWW libraries) so that
   these requests can occur simultaneously and asynchronously.

   A default access mechanism for CP within WWW must be selected. The
   authors have chosen HTTP, for two reasons; it is efficient, and it is
   available at all WWW servers. Nonetheless, this is not a closed issue;
   it may make sense to allow for some variety of access mechanisms, or
   perhaps a fallback mechanism; if one service is not present at a host,
   another attempt, on another service, could be made.

Labyrinth



   It is now possible, from the previous discussion, to describe the
   architecture and operation of a fully visualized WWW client. It is
   composed of several pieces; WWW libraries with an integrated CP client
   interface; an interpreter for an VRML-derived language which describes
   object geometry, placement, and linkage; and a user interface which
   presents a navigable ìwindow on the webî.

   The operation of the client is very straightforward, as is the case of
   the other WWW clients. After launching, the client queries the ìspaceî
   at ìhomeî, and loads the world as the axis mundi of the client's view
   of the web. As a user moves through cyberspace, the client makes
   requests, through CP, to determine the content of all spaces passed
   through or looked upon. A great deal of design effort needs to be put
   into the development of look-ahead caching algorithms for cyberspace
   viewers; without them, the user will experience a discontinuous,
   ìjerkyî trip through cyberspace. The optimal design of these
   algorithms will be the subject of a subsequent work.

   At this time, visualized objects in WWW have only two possible
   behaviors; no behavior at all, or linkage, through an attached URL, to
   another data set. This linkage could be to another ìworldî (actually
   another place in cyberspace), which is called a ìportalî, or it could
   link to another data type, in which case the client must launch the
   appropriate viewer. Labyrinth is designed to augment the functionality
   of existing WWW viewers, such as NCSA Mosaic, rather than to supplant
   them, and therefore does not need a well-integrated facility for
   viewing other types of HTML documents.

Data Abstraction Protocols



   Cyberspace Protocol is a specific implementation of a general theory,
   which has implications well beyond WWW. CP is the solution, in three
   dimensions, of an N-dimensional practice for data set location
   abstraction. Data abstraction places a referent between the ìnameî of
   a data set locator and the physical location, allowing physical data
   set location to become mutable.

   If an implementation were to be developed for the case where N = 1, it
   would be an effective replacement Internet'ís Domain Name Service
   (DNS), which maintains a static mapping of ìnamesî to IP addresses.
   Any network which used a dynamic abstraction mechanism could mirror or
   reassign hosts on a continuous basis (assuming that all write-through
   mirroring could be maintained by the hosts themselves), so that the
   selection of a host for a transaction could be made based upon
   criteria that would tend to optimize the performance of the network
   from the perspective of the transaction. It would also be easy to
   create a data set which could ìfollowî its user(s), adjusting its
   location dynamically in response to changes in the physical location
   or connectivity of the user. In an age of wireless, worldwide
   networking, this could be a very powerful methodology.

Conclusions



   This work attempts to outline the requirements for architectures which
   can fully visualize WWW, and proposes solutions to the issues raised
   by these requirements. While much further study needs to be done, this
   work is meant to serve as a starting point for an understanding of the
   subtleties of wide-area, distributed, visualized data sets.

   Labyrinth and Cyberspace Protocol are logical extensions to the World
   Wide Web and Internet. Indeed, without the existence of WWW, neither
   would be very useful immediately; they would operate, but lack
   content, and individuals would hardly be compelled either to use them
   or adapt their existing data sets to realize their new potentials.
   Used together, they work to make both WWW and Internet inherently more
   navigable, because they help to make Internet more human-centered,
   adapting data sets to human capabilities rather than vice versa. This,
   thus far, is the single largest contribution that ìvirtual realityî
   research has offered to the field of computing; a human-centered
   design approach that lowers or erases the barriers to usage by
   creating user-interface paradigms which serve humans to the full of
   their potential.

   Finally, network visualization marks the end of the ìfirst ageî of
   networking, where protocols, services, and infrastructure dominated
   the discourse within the field. In the ìsecond ageî of networking,
   questions like data architecture and the inherent navigability of a
   well- designed data set become infinitely more important than ìfirst
   ageî questions; where ìhow do I find what Iím looking for?î becomes
   more relevant than ìwhere did it come from?î

Acknowledgments



   The authors would like to thank the following individuals, who
   contributed their own thoughts to the formation and development of the
   ideas expressed in this work: Michael J. Donahue, Owen Rowley, Dr.
   Stuart D. Brorson, Clayton Graham, Christopher Morin, Neil Redding,
   James Curnow, Marina Berlin, Casey Caston and the Fugawi tribe.