Hypertext:Are we still not there yet?

a hypertext “unkeynote”

Prof. dr. Paul De BraEindhoven University of Technology

Hypertext, are we still not there yet?

• At HT’98 we asked “Are we here yet?”• What was the answer, and why?

• if “yes” then stop HT else continue HT

• What was the answer really (each year), and why?• if “yes”

then start making hypertext ubiquitous else continue to further develop hypertext

• In fact we kept saying “No” until HT’2006• Once we said “Yes” HT started doing well (again)

Let’s step back into history…

• Vannevar Bush inventor of hypertext?“As We May Think” (Atlantic Monthly, 1945):But what did he really suggest:• The human mind … operates by association.

With one item in its grasp, it snaps instantly to the next that is suggested by the association of thoughts, in accordance with some intricate web of trails carried by the cells of the brain. It has other characteristics, of course; trails that are not frequently followed are prone to fade, items are not fully permanent, memory is transitory.

• Selection by association, rather than indexing, may yet be mechanized…. it should be possible to beat the mind decisively in regard to the permanence and clarity of the items resurrected from storage.

www.theatlantic.com/magazine/archive/1969/12/as-we-may-think/3881/

Let’s step back into history…

• What did Bush really suggest (cont.):• If affords an immediate step, however, to associative indexing, the

basic idea of which is a provision whereby any item may be caused at will to select immediately and automatically another. This is the essential feature of the memex. The process of tying two items together is the important thing.

• …he runs through an encyclopedia, finds an interesting but sketchy article, leaves it projected. Next, in a history, he finds another pertinent item, and ties the two together. Thus he goes, building a trail of many items. Occasionally, he inserts a comment of his own, either linking it into the main trail or joining it by a side trail to a particular item…

• There is a new profession of trail blazers, those who find delight in the task of establishing useful trails through the enormous mass of the common record.

If Bush did not invent “hypertext”, who did?

• clue 1: who wrote

If Bush did not invent “hypertext”, who did?

• clue 2: who wrote

What is “hypertext” according to Ted Nelson?

Some Basic Hypertext Ideas

• Hypertext connects all texts• Xanadu = magic place of literary memory

• Copying (even quoting) is evil: why quote when you can show the original in-line?• cross-reference links are a referral to information

elsewhere; (following the link takes you elsewhere)• transclusions look like quotes but the original source is

shown in-line; it’s not a copy(note: transclusion requires fine-grained addressing)

• (to avoid broken links) you can never really delete anything; you can only create new versions

Quick look at hypertext between 1960 and 1990

• Working hypertext:• Hypertext Editing System (1967), FRESS (1968)• NLS, the oN-Line System (1968), successor of the

Augment project to augment the human mind• ZOG, first hypertext system with “real” application (1972

- 1982), used on the USS Carl Vinson• Performance through simplicity:

• KMS let you navigate quickly (hoping to reduce disorientation)

• Cards:• Nodes became “cards” in NoteCards (over 50 types),

later also in HyperCard (with programmed behavior)

Quick look at hypertext between 1960 and 1990

• More and more functionality: Intermedia• linking protocol to integrate different applications (for

different media); this is like “mash-ups”• bidirectional links• links not hardwired to nodes, users can create their own

web of links• Complete programmability: HyperCard

• link is just the “goto” statement of a programming language; link anchors are independent of content

• Link databases: Hyperties• database of anchor-destination pairs• open hypermedia takes this idea further

Some illustrations:

• Intermedia web view• Intermedia create link

(and other options)• HyperCard stacks

So hypertext systems became sophisticated!

• All functionality of all systems represented in a model: the Dexter Model (NIST Workshop, 1990)

Essential Dexter elements/properties

• Components: atom, link, composite component• atom is an atomic fragment• composite:

− a page is a composite element (consists of atoms)− an abstract composite component consists of other

(smaller) components, either abstract or atoms(a composite with atoms is a “page”)

• link: sequence of two or more endpoints (unidirectional, bidirectional or even undirected)

• Page selector: when a link destination is abstract (composite) a page must be selected to be displayed

• Page constructor: after a page is selected the presentation must be constructed from the atoms

And then…

The (early) Web

• Tim Berners Lee (1989/1990): the Web as an aid for physicists for sharing documents

• Marc Andreessen (1992): the Mosaic browser made the Web read-only

• Key properties/limitations in the basic Web:• uni-directional links between single nodes• links are not objects (have no properties of their own)• links are hardwired to their source anchor• only pre-authored link destinations are possible• monolithic browser• static content, limited dynamic content through CGI• links can break• no transclusion of text, only of images

So why was this primitive Web successful?

1. Simplicity• Especially publishing was very simple (HTML)

2. Availability• “Everyone” could get it and use it (and it was free)

3. Timeliness• The Web became available when Unix and X-Windows

became popular, and when Internet became available4. (Pure) Client-Server Architecture

• This was fitting for the typical computing infrastructure with powerful file servers and less powerful workstations

Are we there yet? Take two

• 1990 (start of the Web) threw us back to pre-1960• Two approaches to recover:

• “This is bad, let’s build a better alternative.”• “This is bad, let’s make it better.”

• Since 1990 we are working on the second approach:“If you can’t beat them, join them.”

• “Are we there yet?” = “Have we integrated everything from 1960-1990 into the Web yet?”

• but also: “Are we using everything from 1960-1990 on the Web yet?”

So how do we get “there”?

• Take the Web browser and server for granted!Build extensions into this architecture• browser plugins• browser applets

• proxy services

• server side scripts• servlets

• database back-end

• extend user interface,• browser offers network int.

• change content “on the fly”

• select or compute content

• better storage

Example: GRAPPLE / GALE

• Overall GRAPPLE Infrastructure:

GRAPPLE Adaptive Learning Environment

Things that make GALE into “real” hypertext

• Domain Model (DM) with concepts and relations• for each concept there may be several resources• concepts and resources identified by URI

• User Model (UM) with for each concept certain attributes (values)

• Links always refer to concepts:• page selection: concept access involves (recursive)

resource selection• page construction: page may contain

− conditionally included fragments− conditionally included objects (object transclusion)

Things that make GALE able to get “there”

• Spring configuration lets you change most things:• Processing is done by a pipeline of processors

(LayoutProc., Loadproc., XMLProcessor, …)• XML adaptation is done by modules (one per tag)

− <if> for conditional fragments− <object> for transclusion of objects (concepts)− <a> for adaptive links− <for> for generating a list of elements− <variable> for selecting DM or UM info− <view> for arbitrary generated views over DM− <test> for multiple choice tests (specific for e-learning)

Example application: Milkyway

Are we there yet?

• Yes (for the most part) we are there. So…• Time to look into hypertext applications more closely• Careful not to confuse “hypertext” with “web

application”• Time to look for new hypertext concepts that go beyond

the state of the art from 1990.Visionaries have already done so:− Semantic Web (web of data, leading to web of things)− Multi-dimensional structures/browsing: ZigZag− Mobile applications, combining on-line location-

aware communication and information sources− … what *you* will come up with!

See you all…

• at HT2011!