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Structur<strong>in</strong>g and classification of documents <strong>in</strong> standard first generation Web servers has to be hand-coded us<strong>in</strong>g HTML<br />

documents. For this reason poor structure and no document classification is provided on most servers because it is too<br />

much work. This makes navigation rather difficult [see Andrews 95], because after a hav<strong>in</strong>g followed a few hyperl<strong>in</strong>ks<br />

the readers no longer know where they are (the ``lost <strong>in</strong> hyperspace'' syndrome). Once a reader has found an <strong>in</strong>terest<strong>in</strong>g<br />

paper it is absolutely necessary to immediately store a bookmark. If the way to the paper was longer than e.g. 3<br />

mouseclicks it is nearly impossible to remember the way the next time it is needed.<br />

One of the really severe problems of electronic publish<strong>in</strong>g today is the lack of account<strong>in</strong>g and bill<strong>in</strong>g mechanisms as<br />

well as user access rights [see Maurer 94]. For this reason electronic publications on the Web are mostly free of charge<br />

which is not <strong>in</strong> the sense of publish<strong>in</strong>g companies.<br />

Very often it would be <strong>in</strong>terest<strong>in</strong>g for server operators to have statistical <strong>in</strong><strong>format</strong>ion on a user session basis to be able to<br />

follow users on their way through a server and optimize their offer. As an example one could f<strong>in</strong>d out that 60% of the<br />

readers from overseas are leav<strong>in</strong>g the server after hav<strong>in</strong>g followed 4 hyperl<strong>in</strong>ks. Hav<strong>in</strong>g a closer look it could come out<br />

that the document after the 4th hyperl<strong>in</strong>k conta<strong>in</strong>s a huge <strong>in</strong>l<strong>in</strong>e image that is <strong>in</strong>acceptable for an overseas data<br />

transmission and that this document has to be changed.<br />

2 Hyper-G as a Basis for Electronic Publish<strong>in</strong>g<br />

All the problems and difficulties mentioned above have lead to the development of a Web server with a completely new<br />

underly<strong>in</strong>g concept compared to first generation Web systems: Hyper-G [Maurer 96]. Hyper-G now allows it to really<br />

do professional electronic publish<strong>in</strong>g on the Web and to enter a new era of electronic publications <strong>in</strong> terms of usability<br />

and content.<br />

Up to now electronic publish<strong>in</strong>g was either done on the Web or on CD-ROM basis. Us<strong>in</strong>g Hyper-G one can do hybrid<br />

Web and CD-ROM publication without additional effort as has been successfully proven over the last two years with<br />

J.UCS, the Journal of Universal Computer Science by Spr<strong>in</strong>ger Pub. Co. [see Maurer 94]. The only th<strong>in</strong>g publishers<br />

have to do to produce a CD-ROM is to prepare the data on a Hyper-G server and then export the whole collection tree or<br />

parts of it.<br />

The kernel of the Hyper-G server is an object-oriented distributed network database with a separate l<strong>in</strong>k database.<br />

In<strong>format</strong>ion structure as well as document meta <strong>in</strong><strong>format</strong>ion are a basic part of the concept [see Kappe 91]. This makes it<br />

possible to present the user a seamless world-wide structured <strong>in</strong><strong>format</strong>ion space across server boundaries.<br />

Document meta <strong>in</strong><strong>format</strong>ion such as author, title, keywords, creation date, modification date as well as expiry date and<br />

many more support the Web surfer <strong>in</strong> gett<strong>in</strong>g as much <strong>in</strong><strong>format</strong>ion as possible. Naturally document meta <strong>in</strong><strong>format</strong>ion is<br />

searchable as well as fulltext search can be performed. The scope of searches is user def<strong>in</strong>able and can be one small part<br />

of one server or even the whole content of all servers worldwide <strong>in</strong> one s<strong>in</strong>gle operation. Even when do<strong>in</strong>g searches on<br />

multiple servers it is not necessary to know about the server addresses.<br />

More than that: meta <strong>in</strong><strong>format</strong>ion cannot only be applied to documents but also to hyperl<strong>in</strong>ks! This means that l<strong>in</strong>ks can<br />

have types, such as annotation l<strong>in</strong>ks, <strong>in</strong>l<strong>in</strong>e l<strong>in</strong>ks, also version l<strong>in</strong>ks for documents where multiple versions exist and<br />

many more.<br />

Hyper-G servers do not only provide read access but also write access is possible. Read and write access to documents<br />

are controlled on a user and group access right basis and bill<strong>in</strong>g is <strong>in</strong>tegrated <strong>in</strong> the server.<br />

This concept opens completely new perspectives of electronic publish<strong>in</strong>g: hav<strong>in</strong>g the hyperl<strong>in</strong>ks <strong>in</strong> a separate l<strong>in</strong>k<br />

database makes every document hyperl<strong>in</strong>kable even when the document <strong>format</strong> does not allow l<strong>in</strong>ks [see Maurer 96].<br />

All l<strong>in</strong>ks <strong>in</strong> Hyper-G are bidirectional, mak<strong>in</strong>g it possible to not only follow the l<strong>in</strong>ks po<strong>in</strong>t<strong>in</strong>g from one document to<br />

another but also to see l<strong>in</strong>ks referenc<strong>in</strong>g a document and follow them <strong>in</strong> reverse direction. Be<strong>in</strong>g able to exam<strong>in</strong>e the<br />

neighbourhood of a paper makes it possible to f<strong>in</strong>d other <strong>in</strong>terest<strong>in</strong>g papers on the same topic that very likely are<br />

difficult if not impossible to locate if only unidirectional l<strong>in</strong>ks were possible as is the case with first generation Web<br />

servers.<br />

Hyperl<strong>in</strong>ks <strong>in</strong> arbitrary document types such as PostScript, images, movies, 3D scenes and even sound make navigation<br />

<strong>in</strong> hyperspace easy and a structured hierarchical view of the database with location feedback helps overcom<strong>in</strong>g the ``lost<br />

<strong>in</strong> hyperspace'' syndrom.

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