Subject: Re: Hyper-G als... - Diskussionsbeitrag R.Calliau
From: [email-masked]
To: [email-masked]

>From luegger  Wed Aug  3 10:21:06 1994
>From: luegger (Joachim Luegger)

Robert (Cailliau), you wrote:

>1) (strong) you should not judge the Web only by how Mosaic presents it.
>There are many browsers (including Midas for X) that have other features,
>built into the Web, but not available through Mosaic.  I believe that in
>any further discussion, Mosaic features will be actually unimportant.

This is an important remark - I fully agree with you. Is there any written
reference to or overview of alternative browsers? Where to get the sources?

Furthermore, at present we are developing a conceptual schema for the
evaluation of information systems built on top of the WorldWideWeb.
The lesson learned from you is that within this context we clearly have
to discriminate between the different combinations of implementations
and browsers/viewers, namely:

	WWW with	Hyper-G with	Hyper-G with	WWW with
	Mosaic		Mosaic		Harmony		e.g. Midas

Within the evaluation, however, we have to refer to Mosaic too, because
most of the existing hypertexts are built having Mosaic in mind (most of
the implementers wrongly ask themselves "looks it good under Mosaic?").
And, we intend to "measure" against real implementations of information
webs in order to discriminate the implementation specific details from the
general system characteristics of the used hypertext system.

>2) there are a number of features of the Web that are accessible but were
>perhaps not given the right emphasis: it is possible to use existing data
>bases, and there are already now caching features, searching and indexing
>etc.

I agree with you. The Web, however, is well known and Hyper-G is not
known so far. In reasoning "pro Hyper-G" we did not intend to argue
against the Web. WWW is a very fundamental structure for global
information exchange. To give account for all its advantages and
potential simply would have blown up our "short" argumentation.

Within the planned evaluation however there will be the duty and the
opportunity to elaborate on all the (main) pro's and con's.

>We will hopefully start a fruitful collaboration with the Hyper-G people
>soon.  The arrival of the Grif WWW Browser/Editor will also give an impetus
>to the authoring of distributed documents.

In order to demonstrate -- from our point of view -- the importance of
the WWW project at CERN for the scientific community (in particular for
the mathematicians) and the need for a concentration of related European
activities an excerpt of my recent mail to you is appended.

>Hyper-G has better local technology, the Web scales better.  I am quite
>certain that we can fuse these properties as time goes on, and so your
>choice is a good one.

I ask you to explain the "scaling" argument a little bit (which is an
important feature of the web). Probably at presnt this is not
understood very well within the mathematical community (where
hypertexts are quite new).

Thank you very much for your serious comments.

Joachim Luegger
---------------------------------------------------------
Konrad-Zuse-Zentrum fuer Informationstechnik Berlin (ZIB)
Director of Department: Software-Information
Heilbronner Str. 10
10711 Berlin (Wilmersdorf)
Germany

E-mail: [email-masked] (Internet)
Phone.: +49 30 / 89604-173
Fax.:   +49 30 / 89604-125
---------------------------------------------------------

Appendix - EXCERPT ONLY
--------------------------------------------------------------------------

>From luegger Wed Jul 20 12:01:11 1994
To: [email-masked]
Subject: Your talk in Halle -- and possible joint WWW activities
Cc: [email-masked], groetschel, sperber, dalitz

Robert,
....
But, first of all, let me express my gratitude for the serious talk you
gave in Halle. This was a very open-minded and honest discussion which
-- not only to my view -- demonstrated a thorough and profound way of
thinking about the things to come around with electronic publishing via
global hypertexts.

My institute is willing to support the efforts of your group at CERN at
least from an ideal point of view. Furthermore we are interrested in
taking an active part in the forthcoming development of the WWW project
and in cooperating in the development of related international standards.

Being aware now of the possible danger for the WWW project at CERN
this statement certainly should have some conclusions to be explained
below. Let me elaborate on some specific points:

1. We are willing to give momentum to the WWW project not only on the
   German but also on an European level. The Konrad-Zuse-Zentrum will
   publish the project plans on a "Distributed Information System for
   Mathematics" in one of the next newsletters of the European
   Mathematical Society. This is a first attempt to involve the
   Mathematical Community in Europe in the realization of related
   activities. ......      We should possibly think about common
   steps and projects in that direction.
....
2. We are also interested in sharing any global activity regarding the
   further development of the Web. One of your slides showed the formation
   of a forthcoming cooperative between CERN and MIT with a box (not
   occupied by some name) designed for the care for user-related 
   interests. If there is still room for us the Konrad-Zuse-Zentrum is
   willing to represent the interests of mathematicians. In particular
   we are interested to participate in any HTML-standardization activities
   ....
....
3. Combining the WWW with an SGML editor (GRIF) is another fundamental
   step in the development of the Web. This will very probably adapt
   the Web according to the special needs of mathematicians and
   sciences applying mathematics, thus giving hope for the appearance
   of a new (still embryonic) paradigm of programming: the document-
   oriented desktop processing ......   Within
   this context we would also very much like to see (and to support)
   the cooperation of any such activities in Europe focussing their
   forces in order to survive in the global competition.

   In particalur, do you see a realistic chance to also cooperate with 
   the Hyper-G people in Graz? We have seen that they are engaged on
   the grounds of some fundamental thoughts very similar to yours.

4. The Hyper-G people have implemented some very fundamental concepts
   which -- to our view -- are essential for the building of an integral
   distributed Hypertext of a specialized community (such as the 
   mathematicians).
   ....
....
We also will engage ourselves within the Internet society and the
European scientific network groups (RARE) with the intent to represent
the users' perspectives. There -- in Prague -- also some very
fundamental things happened: It was the first joint meeting of the
Internet society with the European academic network societies (RARE and
EARN - the former one was OSI oriented up to now, which was
counterproductive for the academic community in some way). 
....
With the best wishes for you and your important activity.
Joachim

From [email-masked] Mon Aug  8 13:19:53 1994
Date: Mon, 8 Aug 94 13:19:34 +0200
From: [email-masked]
To: [email-masked]
Subject: message to [email-masked]
Status: RO

>From: [email-masked] (Robert Cailliau)
Subject: Re: Hyper-G als... - Diskussionsbeitrag R.Calliau

Joachim,

>This is an important remark - I fully agree with you. Is there any written
>reference to or overview of alternative browsers? Where to get the sources?
A list of available software is kept on a page referred to from
http://info.cern.ch/

>The lesson learned from you is that within this context we clearly have
>to discriminate between the different combinations of implementations
>and browsers/viewers, namely:
>
>        WWW with        Hyper-G with    Hyper-G with    WWW with
>        Mosaic          Mosaic          Harmony         e.g. Midas
Hmm... Maybe I did not pass the message entirely correctly then.  In
principle, it would matter only little whether you used Midas or Mosaic or
Viola.  You might have a prettier view of the path you have taken in one
than in the other.
But there are other tools we need than just browsers:  viewers of subwebs,
tools for making global changes to links over an entire set of documents
(here undoubtedly hyper-G is better positioned!) and so on.  For an editor,
I find fast multi-windowing an absolute must, and especially xMosaic is not
good at that because it uses X.  Etc.

>Within the evaluation, however, we have to refer to Mosaic too, because
>most of the existing hypertexts are built having Mosaic in mind (most of
>the implementers wrongly ask themselves "looks it good under Mosaic?").
Obviously you must always include Mosaic.

>And, we intend to "measure" against real implementations of information
>webs in order to discriminate the implementation specific details from the
>general system characteristics of the used hypertext system.
Yes.  Therefore also the need for clarifying the underlying assumptions and
limitations of the models.

>I agree with you. The Web, however, is well known and Hyper-G is not
>known so far. In reasoning "pro Hyper-G" we did not intend to argue
>against the Web.
I think I have understood that, and I also believe that Hyper-G has a lot
to give us.  perhaps we should make a special EU-funded project for merging
the technologies.

>I ask you to explain the "scaling" argument a little bit (which is an
>important feature of the web). Probably at presnt this is not
>understood very well within the mathematical community (where
>hypertexts are quite new).

The performance of a networked system which is global should not depend on
the number of users, the number of documents and the usage made.
If you have a central system or one in which some part of the essential
function is done in a central fashion, the system will have dificulty
growing.  For example, the very attractive property that links are kept
outside the documents so that they can be operated upon by a data base is
something that does not scale.

The Internet naming scheme scales, because the names are structured simply,
and the routing computers keep partial tables.  As the Internet grows,
there is a slight increase in traffic among the routing machines and some
increase in the number of routers.  Had there been a single name
dictionary, with unstructured names, we would not have the Internet now.
The Apple LocalTalk network which has entirely dynamic assignment of
identities as computers connect and disconnect from the network, does not
scale, because each computer needs an identification agreement from all
other computers onthe net.  It is perfect for the small enterprise (less
than 256 computers) that wants to operate without any network management
and just plug the portable in when the boss comes to the office again.

The Internet does not have that problem, but it cannot assign identities
dynamically, so it scales well, but you cannot move your computer around:
there are "zones" and when you change zones you must acquire a new
identity, which has to be done manually by an administrator. (I am not of
course taking into account "dynamic" IP numbers from dial-up machines where
entire blocks get allocated beforehand to a single machine which then rents
them out temporarily,  that does not help anyway).  Thus, as long as I stay
put, the Internet is fabulous in its scaling capacities.

The Web is built on top of this routing scheme, and therefore scales
equally well.  But do not move the documents around from one site to
another!  This is the well-known reason why we have URLs and not URNs.
URNs do not work:  they are a name for a document, like the ISBN number of
a book.  The idea is fine, but ISBN numbers must be looked up in one single
gigantic data base; the idea does not scale.

For similar reasons it is difficult to implement automatic mirroring and
global caching etc.  You want to address a document by one single unique
identifier ("the proof of Fermat's last theorem by A. Wiles").  You do not
really care where it sits or whether there is a copy close to you.  But we
cannot do that automatically without sending a lot of messages to different
machines on the net.

Now, in practice, libraries do not just move around, and you are willing to
personally find out whether there is a copy of the journal you want in the
local library etc.  So there is some hope for a compromise:  if it is
locally there, you get it fast, if not, you will have to pay and wait.  Or
else you will have to know beforehand where to go.  The latter is what I
think will really happen: you will use a hierarchy of encyclopedias
(collections of URLs) the top one of which you have locally on your disk.
You will already know (by education) that to ask it about Fermat's last
theorem you will have to look under mathematics.  There you will find
references to several collections of documents on the Web, one probably
kept by the DMV.  The DMV will have further catalogs physically located in
Germany about its works and also pointers to collections elsewhere.
Interrogating those you will finally find the pointer to a list of works on
the theorem, which is kept in one place somewhere by a specialist.

So, both Hyper-G and WWW have aspects that do not scale.  But they are not
the same ones.

Robert.